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1. IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare

Author: Kouch, Pouya M., Liodakis, Ioannis, Fenu, Francesco, Zhang, Haocheng, Boula, Stella, Middei, Riccardo, Di Gesu, Laura, Paraschos, Georgios F., Agudo, Iván, Jorstad, Svetlana G., Lindfors, Elina, Marscher, Alan P., Krawczynski, Henric, Negro, Michela, Hu, Kun, Kim, Dawoon E., Cavazzuti, Elisabetta, Errando, Manel, Blinov, Dmitry, Gourni, Anastasia, Kiehlmann, Sebastian, Kourtidis, Angelos, Mandarakas, Nikos, Triantafyllou, Nikolaos, Vervelaki, Anna, Borman, George A., Kopatskaya, Evgenia N., Larionova, Elena G., Morozova, Daria A., Savchenko, Sergey S., Vasilyev, Andrey A., Troitskiy, Ivan S., Grishina, Tatiana S., Zhovtan, Alexey V., Aceituno, Francisco José, Bonnoli, Giacomo, Casanova, Víctor, Escudero, Juan, Agís-González, Beatriz, Husillos, César, Otero-Santos, Jorge, Piirola, Vilppu, Sota, Alfredo, Myserlis, Ioannis, Gurwell, Mark, Keating, Garrett K., Rao, Ramprasad, Angelakis, Emmanouil, Kraus, Alexander, Antonelli, Lucio Angelo, Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Lalla, Niccolò, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Romani, Roger W., Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here we report on the first X-ray polarization observation of the blazar S4 0954+65 in a high optical and X-ray state. During our multi-wavelength campaign on the source, we detected an optical flare whose peak coincided with the peak of an X-ray flare. This optical-X-ray flare most likely took place in a feature moving along the parsec-scale jet, imaged at 43 GHz by the Very Long Baseline Array. The 43 GHz polarization angle of the moving component underwent a rotation near the time of the flare. In the optical band, prior to the IXPE observation, we measured the polarization angle to be aligned with the jet axis. In contrast, during the optical flare the optical polarization angle was perpendicular to the jet axis; after the flare, it reverted to being parallel to the jet axis. Due to the smooth behavior of the optical polarization angle during the flare, we favor shocks as the main acceleration mechanism. We also infer that the ambient magnetic field lines in the jet were parallel to the jet position angle. The average degree of optical polarization during the IXPE observation was (14.3$\pm$4.1)%. Despite the flare, we only detected an upper limit of 14% (at 3$\sigma$ level) on the X-ray polarization degree; although a reasonable assumption on the X-ray polarization angle results in an upper limit of 8.8% ($3\sigma$). We model the spectral energy distribution (SED) and spectral polarization distribution (SPD) of S4 0954+65 with leptonic (synchrotron self-Compton) and hadronic (proton and pair synchrotron) models. The constraints we obtain with our combined multi-wavelength polarization observations and SED modeling tentatively disfavor hadronic models for the X-ray emission in S4 0954+65., Comment: Submitted to A&A, 16 pages, 5 figures, and 7 tables
Published: 2024

2. Data-Driven Gradient Optimization for Field Emission Management in a Superconducting Radio-Frequency Linac

Author: Goldenberg, Steven, Ahammed, Kawser, Carpenter, Adam, Li, Jiang, Suleiman, Riad, and Tennant, Chris
Subjects: Physics - Accelerator Physics, Computer Science - Machine Learning
Abstract: Field emission can cause significant problems in superconducting radio-frequency linear accelerators (linacs). When cavity gradients are pushed higher, radiation levels within the linacs may rise exponentially, causing degradation of many nearby systems. This research aims to utilize machine learning with uncertainty quantification to predict radiation levels at multiple locations throughout the linacs and ultimately optimize cavity gradients to reduce field emission induced radiation while maintaining the total linac energy gain necessary for the experimental physics program. The optimized solutions show over 40% reductions for both neutron and gamma radiation from the standard operational settings., Comment: 14 pages, 6 figures, 10 tables
Published: 2024

3. Observation of Critical Scaling in Spin Glasses below Tc using the Thermoremanent Magnetization

Author: Kenning, G. G., Brandt, M., Brake, R., Hepler, M., and Tennant, D.
Subjects: Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Statistical Mechanics
Abstract: Time-dependent Thermoremanent Magnetization (TRM) studies have been instrumental in probing energy dynamics within the spin glass phase. In this paper, we will review the evolution of the TRM experiment over the last half century and discuss some aspects related to how it has been employed in the understanding of spin glasses. We will also report on recent experiments using high resolution DC SQUID magnetometry to probe the TRM at temperatures less than but near to the transition temperature Tc. These experiments have been performed as a function of waiting time, temperature, and five different magnetic fields. We find that as the transition temperature is approached from below, the characteristic time scale of the TRM is suppressed up to several orders of magnitude in time. In the highest temperature region, we find that the waiting time effect goes away, and a waiting time independent crossover line is reached. We also find that increasing the magnetic field, further suppresses the crossover line. Using a first principles energy argument across the crossover line, we derive an equation that is an excellent fit to the crossover lines for all magnetic fields probed. The data show strong evidence for an H = 0 Oe phase transition.
Published: 2024

4. Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry

Author: Prokhorov, Dmitry A., Yang, Yi-Jung, Ferrazzoli, Riccardo, Vink, Jacco, Slane, Patrick, Costa, Enrico, Silvestri, Stefano, Zhou, Ping, Bucciantini, Niccolò, Di Marco, Alessandro, Weisskopf, Martin C., Baldini, Luca, Doroshenko, Victor, Ehlert, Steven R., Heyl, Jeremy, Kaaret, Philip, Kim, Dawoon E., Marin, Frédéric, Mizuno, Tsunefumi, Ng, Chi-Yung, Pesce-Rollins, Melissa, Sgrò, Carmelo, Soffitta, Paolo, Swartz, Douglas A., Tamagawa, Toru, Xie, Fei, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Donnarumma, Immacolata, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, García, Javier A., Gunji, Shuichi, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Negro, Michela, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Spandre, Gloria, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Wu, Kinwah, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray emission from four such SNRs has already been reported on the basis of observations with the Imaging X-ray Polarimetry Explorer (IXPE). The magnetic-field structure as derived from IXPE observations is radial for Cassiopeia A, Tycho's SNR, and SN 1006, and tangential for RX J1713.7-3946. The latter together with the recent detection of a tangential magnetic field in SNR 1E 0102.2-7219 by the Australia Telescope Compact Array in the radio band shows that tangential magnetic fields can also be present in young SNRs. Thus, the dichotomy in polarization between young and middle-aged SNRs (radial magnetic fields in young SNRs, but tangential magnetic fields in middle-aged SNRs), previously noticed in the radio band, deserves additional attention. The present analysis of IXPE observations determines, for the first time, a magnetic-field structure in the northwestern rim of Vela Jr, also known as RX J0852.0-4622, and provides a new example of a young SNR with a tangential magnetic field., Comment: Accepted for publication in Astronomy and Astrophysics
Published: 2024

5. A Two-Week $IXPE$ Monitoring Campaign on Mrk 421

Author: Maksym, W. Peter, Liodakis, Ioannis, Saade, M. Lynne, Kim, Dawoon E., Middei, Riccardo, Di Gesu, Laura, Kiehlmann, Sebastian, Matzeu, Gabriele, Agudo, Iván, Marscher, Alan P., Ehlert, Steven R., Jorstad, Svetlana G., Kaaret, Philip, Marshall, Herman L., Pacciani, Luigi, Perri, Matteo, Puccetti, Simonetta, Kouch, Pouya M., Lindfors, Elina, Aceituno, Francisco José, Bonnoli, Giacomo, Casanova, Víctor, Escudero, Juan, Agís-González, Beatriz, Husillos, César, Morcuende, Daniel, Otero-Santos, Jorge, Sota, Alfredo, Piirola, Vilppu, Imazawa, Ryo, Sasada, Mahito, Fukazawa, Yasushi, Kawabata, Koji S., Uemura, Makoto, Mizuno, Tsunefumi, Nakaoka, Tatsuya, Akitaya, Hiroshi, McCall, Callum, Jermak, Helen E., Steele, Iain A., Borman, George A., Grishina, Tatiana S., Hagen-Thorn, Vladimir A., Kopatskaya, Evgenia N., Larionova, Elena G., Morozova, Daria A., Savchenko, Sergey S., Shishkina, Ekaterina V., Troitskiy, Ivan S., Troitskaya, Yulia V., Vasilyev, Andrey A., Zhovtan, Alexey V., Myserlis, Ioannis, Gurwell, Mark, Keating, Garrett, Rao, Ramprasad, Pauley, Colt, Angelakis, Emmanouil, Kraus, Alexander, Berdyugin, Andrei V., Kagitani, Masato, Kravtsov, Vadim, Poutanen, Juri, Sakanoi, Takeshi, Kang, Sincheol, Lee, Sang-Sung, Kim, Sang-Hyun, Cheong, Whee Yeon, Jeong, Hyeon-Woo, Song, Chanwoo, Blinov, Dmitry, Shablovinskaya, Elena, Antonelli, Lucio Angelo, Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccoló, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Lalla, Niccoló, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Negro, Michela, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel Lawrence, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgró, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blazar Mrk 421. Our observations were accompanied by an even denser radio and optical polarization campaign. We find significant short-timescale variability in both X-ray polarization degree and angle, including a $\sim90^\circ$ angle rotation about the jet axis. We attribute this to random variations of the magnetic field, consistent with the presence of turbulence but also unlikely to be explained by turbulence alone. At the same time, the degree of lower-energy polarization is significantly lower and shows no more than mild variability. Our campaign provides further evidence for a scenario in which energy-stratified shock-acceleration of relativistic electrons, combined with a turbulent magnetic field, is responsible for optical to X-ray synchrotron emission in blazar jets., Comment: 23 pages, including 8 pages of appendices. 12 figures, 3 tables. Submitted to ApJ
Published: 2024

6. Simulating Neutron Scattering on an Analog Quantum Processor

Author: Bauer, Nora, Ale, Victor, Laurell, Pontus, Huang, Serena, Watabe, Seth, Tennant, David Alan, and Siopsis, George
Subjects: Quantum Physics
Abstract: Neutron scattering characterization of materials allows for the study of entanglement and microscopic structure, but is inefficient to simulate classically for comparison to theoretical models and predictions. However, quantum processors, notably analog quantum simulators, have the potential to offer an unprecedented, efficient method of Hamiltonian simulation by evolving a state in real time to compute phase transitions, dynamical properties, and entanglement witnesses. Here, we present a method for simulating neutron scattering on QuEra's Aquila processor by measuring the dynamic structure factor (DSF) for the prototypical example of the critical transverse field Ising chain, and propose a method for error mitigation. We provide numerical simulations and experimental results for the performance of the procedure on the hardware, up to a chain of length $L=25$. Additionally, the DSF result is used to compute the quantum Fisher information (QFI) density, where we confirm bipartite entanglement in the system experimentally., Comment: 13 pages, 10 figures
Published: 2024

7. Moral Alignment for LLM Agents

Author: Tennant, Elizaveta, Hailes, Stephen, and Musolesi, Mirco
Subjects: Computer Science - Machine Learning, Computer Science - Artificial Intelligence, Computer Science - Computers and Society
Abstract: Decision-making agents based on pre-trained Large Language Models (LLMs) are increasingly being deployed across various domains of human activity. While their applications are currently rather specialized, several research efforts are under way to develop more generalist agents. As LLM-based systems become more agentic, their influence on human activity will grow and the transparency of this will decrease. Consequently, developing effective methods for aligning them to human values is vital. The prevailing practice in alignment often relies on human preference data (e.g., in RLHF or DPO), in which values are implicit and are essentially deduced from relative preferences over different model outputs. In this work, instead of relying on human feedback, we introduce the design of reward functions that explicitly encode core human values for Reinforcement Learning-based fine-tuning of foundation agent models. Specifically, we use intrinsic rewards for the moral alignment of LLM agents. We evaluate our approach using the traditional philosophical frameworks of Deontological Ethics and Utilitarianism, quantifying moral rewards for agents in terms of actions and consequences on the Iterated Prisoner's Dilemma (IPD) environment. We also show how moral fine-tuning can be deployed to enable an agent to unlearn a previously developed selfish strategy. Finally, we find that certain moral strategies learned on the IPD game generalize to several other matrix game environments. In summary, we demonstrate that fine-tuning with intrinsic rewards is a promising general solution for aligning LLM agents to human values, and it might represent a more transparent and cost-effective alternative to currently predominant alignment techniques.
Published: 2024

8. Tutorial: Extracting entanglement signatures from neutron spectroscopy

Author: Scheie, Allen, Laurell, Pontus, Simeth, Wolfgang, Dagotto, Elbio, and Tennant, D. Alan
Subjects: Condensed Matter - Strongly Correlated Electrons, Quantum Physics
Abstract: This tutorial is a pedagogical introduction to recent methods of computing quantum spin entanglement witnesses from spectroscopy, with a special focus on neutron scattering on quantum spin systems. We offer a brief introduction to the concepts and equations, define a data analysis protocol, and discuss the interpretation of three entanglement witnesses: one-tangle, two-tangle, and Quantum Fisher Information. We also discuss practical experimental considerations, and give three examples of extracting entanglement witnesses from experimental data: Copper Nitrate, KCuF3, and NiPS3., Comment: 11 pages, 5 figures
Published: 2024

9. The Continuous Electron Beam Accelerator Facility at 12 GeV

Author: Adderley, P. A., Ahmed, S., Allison, T., Bachimanchi, R., Baggett, K., BastaniNejad, M., Bevins, B., Bevins, M., Bickley, M., Bodenstein, R. M., Bogacz, S. A., Bruker, M., Burrill, A., Cardman, L., Creel, J., Chao, Y. -C., Cheng, G., Ciovati, G., Chattopadhyay, S., Clark, J., Clemens, W. A., Croke, G., Daly, E., Davis, G. K., Delayen, J., De Silva, S. U., Dickson, R., Diaz, M., Drury, M., Doolittle, L., Douglas, D., Feldl, E., Fischer, J., Freyberger, A., Ganni, V., Geng, R. L., Ginsburg, C., Gomez, J., Grames, J., Gubeli, J., Guo, J., Hannon, F., Hansknecht, J., Harwood, L., Henry, J., Hernandez-Garcia, C., Higgins, S., Higinbotham, D., Hofler, A. S., Hiatt, T., Hogan, J., Hovater, C., Hutton, A., Jones, C., Jordan, K., Joyce, M., Kazimi, R., Keesee, M., Kelley, M. J., Keppel, C., Kimber, A., King, L., Kjeldsen, P., Kneisel, P., Koval, J., Krafft, G. A., Lahti, G., Larrieu, T., Lauze, R., Leemann, C., Legg, R., Li, R., Lin, F., Machie, D., Mammosser, J., Macha, K., Mahoney, K., Marhauser, F., Mastracci, B., Matalevich, J., McCarter, J., McCaughan, M., Merminga, L., Michaud, R., Morozov, V., Mounts, C., Musson, J., Nelson, R., Oren, W., Overton, R. B., Palacios-Serrano, G., Park, H. -K., Phillips, L., Philip, S., Pilat, F., Plawski, T., Poelker, M., Powers, P., Powers, T., Preble, J., Reilly, T., Rimmer, R., Reece, C., Robertson, H., Roblin, Y., Rode, C., Satogata, T., Seidman, D. J., Seryi, A., Shabalina, A., Shin, I., Slominski, R., Slominski, C., Spata, M., Spell, D., Spradlin, J., Stirbet, M., Stutzman, M. L., Suhring, S., Surles-Law, K., Suleiman, R., Tennant, C., Tian, H., Turner, D., Tiefenback, M., Trofimova, O., Valente, A. -M., Wang, H., Wang, Y., White, K., Whitlatch, C., Whitlatch, T., Wiseman, M., Wissman, M. J., Wu, G., Yang, S., Yunn, B., Zhang, S., and Zhang, Y.
Subjects: Physics - Accelerator Physics, Nuclear Experiment
Abstract: This review paper describes the energy-upgraded CEBAF accelerator. This superconducting linac has achieved 12 GeV beam energy by adding 11 new high-performance cryomodules containing eighty-eight superconducting cavities that have operated CW at an average accelerating gradient of 20 MV/m. After reviewing the attributes and performance of the previous 6 GeV CEBAF accelerator, we discuss the upgraded CEBAF accelerator system in detail with particular attention paid to the new beam acceleration systems. In addition to doubling the acceleration in each linac, the upgrade included improving the beam recirculation magnets, adding more helium cooling capacity to allow the newly installed modules to run cold, adding a new experimental hall, and improving numerous other accelerator components. We review several of the techniques deployed to operate and analyze the accelerator performance, and document system operating experience and performance. In the final portion of the document, we present much of the current planning regarding projects to improve accelerator performance and enhance operating margins, and our plans for ensuring CEBAF operates reliably into the future. For the benefit of potential users of CEBAF, the performance and quality measures for beam delivered to each of the experimental halls is summarized in the appendix., Comment: 66 pages, 73 figures, 21 tables
Published: 2024
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10. Measurement of inclusive jet cross section and substructure in $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV

Author: PHENIX Collaboration, Abdulameer, N. J., Acharya, U., Aidala, C., Ajitanand, N. N., Akiba, Y., Akimoto, R., Alexander, J., Alfred, M., Andrieux, V., Antsupov, S., Aoki, K., Apadula, N., Asano, H., Atomssa, E. T., Awes, T. C., Azmoun, B., Babintsev, V., Bai, M., Bai, X., Bandara, N. S., Bannier, B., Bannikov, E., Barish, K. N., Bathe, S., Baublis, V., Baumann, C., Baumgart, S., Bazilevsky, A., Beaumier, M., Belmont, R., Berdnikov, A., Berdnikov, Y., Bichon, L., Black, D., Blankenship, B., Blau, D. S., Bok, J. S., Borisov, V., Boyle, K., Brooks, M. L., Bryslawskyj, J., Buesching, H., Bumazhnov, V., Butsyk, S., Campbell, S., Cervantes, R., Chen, C. -H., Chen, D., Chiu, M., Chi, C. Y., Choi, I. J., Choi, J. B., Choi, S., Christiansen, P., Chujo, T., Cianciolo, V., Citron, Z., Cole, B. A., Connors, M., Corliss, R., Cronin, N., Crossette, N., Csanád, M., Csörgő, T., D'Orazio, L., Danley, T. W., Datta, A., Daugherity, M. S., David, G., DeBlasio, K., Dehmelt, K., Denisov, A., Deshpande, A., Desmond, E. J., Ding, L., Dion, A., Dixit, D., Doomra, V., Do, J. H., Drapier, O., Drees, A., Drees, K. A., Durham, J. M., Durum, A., En'yo, H., Engelmore, T., Enokizono, A., Esha, R., Eyser, K. O., Fadem, B., Fan, W., Feege, N., Fields, D. E., Finger, Jr., M., Finger, M., Firak, D., Fitzgerald, D., Fleuret, F., Fokin, S. L., Frantz, J. E., Franz, A., Frawley, A. D., Fukao, Y., Fukuda, Y., Fusayasu, T., Gainey, K., Gallus, P., Gal, C., Garg, P., Garishvili, A., Garishvili, I., Ge, H., Giordano, F., Glenn, A., Gong, X., Gonin, M., Goto, Y., de Cassagnac, R. Granier, Grau, N., Greene, S. V., Perdekamp, M. Grosse, Gunji, T., Guo, T., Guragain, H., Gu, Y., Hachiya, T., Haggerty, J. S., Hahn, K. I., Hamagaki, H., Hamilton, H. F., Hanks, J., Han, S. Y., Hasegawa, S., Haseler, T. O. S., Hashimoto, K., Hayano, R., Hemmick, T. K., Hester, T., He, X., Hill, J. C., Hill, K., Hodges, A., Hollis, R. S., Homma, K., Hong, B., Hoshino, T., Hotvedt, N., Huang, J., Ichihara, T., Ikeda, Y., Imai, K., Imazu, Y., Inaba, M., Iordanova, A., Isenhower, D., Isinhue, A., Ivanishchev, D., Jeon, S. J., Jezghani, M., Jiang, X., Ji, Z., Johnson, B. M., Joo, K. S., Jouan, D., Jumper, D. S., Kamin, J., Kanda, S., Kang, B. H., Kang, J. H., Kang, J. S., Kapukchyan, D., Kapustinsky, J., Karthas, S., Kawall, D., Kazantsev, A. V., Key, J. A., Khachatryan, V., Khandai, P. K., Khanzadeev, A., Kijima, K. M., Kim, C., Kim, D. J., Kim, E. -J., Kim, M., Kim, Y. -J., Kim, Y. K., Kincses, D., Kistenev, E., Klatsky, J., Kleinjan, D., Kline, P., Koblesky, T., Kofarago, M., Komkov, B., Koster, J., Kotchetkov, D., Kotov, D., Kovacs, L., Krizek, F., Kudo, S., Kurita, K., Kurosawa, M., Kwon, Y., Lai, Y. S., Lajoie, J. G., Lebedev, A., Lee, D. M., Lee, G. H., Lee, J., Lee, K. B., Lee, K. S., Lee, S., Lee, S. H., Leitch, M. J., Leitgab, M., Leung, Y. H., Lewis, B., Lim, S. H., Liu, M. X., Li, X., Loggins, V. -R., Lokos, S., Loomis, D. A., Lovasz, K., Lynch, D., Maguire, C. F., Majoros, T., Makdisi, Y. I., Makek, M., Manion, A., Manko, V. I., Mannel, E., McCumber, M., McGaughey, P. L., McGlinchey, D., McKinney, C., Meles, A., Mendoza, M., Meredith, B., Miake, Y., Mibe, T., Mignerey, A. C., Milov, A., Mishra, D. K., Mitchell, J. T., Mitrankova, M., Mitrankov, Iu., Mitsuka, G., Miyasaka, S., Mizuno, S., Mohanty, A. K., Mohapatra, S., Montuenga, P., Moon, T., Morrison, D. P., Moskowitz, M., Moukhanova, T. V., Mulilo, B., Murakami, T., Murata, J., Mwai, A., Nagae, T., Nagai, K., Nagamiya, S., Nagashima, K., Nagashima, T., Nagle, J. L., Nagy, M. I., Nakagawa, I., Nakamiya, Y., Nakamura, K. R., Nakamura, T., Nakano, K., Nattrass, C., Netrakanti, P. K., Nihashi, M., Niida, T., Nouicer, R., Novitzky, N., Novák, T., Nukazuka, G., Nyanin, A. S., O'Brien, E., Ogilvie, C. A., Oide, H., Okada, K., Koop, J. D. Orjuela, Orosz, M., Osborn, J. D., Oskarsson, A., Ottino, G. J., Ozawa, K., Pak, R., Pantuev, V., Papavassiliou, V., Park, I. H., Park, J. S., Park, S., Park, S. K., Patel, L., Patel, M., Pate, S. F., Peng, J. -C., Perepelitsa, D. V., Perera, G. D. N., Peressounko, D. Yu., PerezLara, C. E., Perry, J., Petti, R., Phipps, M., Pinkenburg, C., Pisani, R. P., Potekhin, M., Purschke, M. L., Qu, H., Rak, J., Ravinovich, I., Read, K. F., Reynolds, D., Riabov, V., Riabov, Y., Richardson, E., Richford, D., Rinn, T., Riveli, N., Roach, D., Rolnick, S. D., Rosati, M., Rowan, Z., Ryu, M. S., Safonov, A. S., Sahlmueller, B., Saito, N., Sakaguchi, T., Sako, H., Samsonov, V., Sarsour, M., Sato, S., Sawada, S., Schaefer, B., Schmoll, B. K., Sedgwick, K., Seele, J., Seidl, R., Sekiguchi, Y., Seleznev, A., Sen, A., Seto, R., Sett, P., Sexton, A., Sharma, D., Shaver, A., Shein, I., Shibata, T. -A., Shigaki, K., Shimomura, M., Shioya, T., Shoji, K., Shukla, P., Sickles, A., Silva, C. L., Silvermyr, D., Singh, B. K., Singh, C. P., Singh, V., Skolnik, M., Slunečka, M., Smith, K. L., Snowball, M., Solano, S., Soltz, R. A., Sondheim, W. E., Sorensen, S. P., Sourikova, I. V., Stankus, P. W., Steinberg, P., Stenlund, E., Stepanov, M., Ster, A., Stoll, S. P., Stone, M. R., Sugitate, T., Sukhanov, A., Sumita, T., Sun, J., Sun, Z., Sziklai, J., Takahara, A., Taketani, A., Tanaka, Y., Tanida, K., Tannenbaum, M. J., Tarafdar, S., Taranenko, A., Tarnai, G., Tennant, E., Tieulent, R., Timilsina, A., Todoroki, T., Tomášek, M., Torii, H., Towell, C. L., Towell, R. S., Tserruya, I., Ueda, Y., Ujvari, B., van Hecke, H. W., Vargyas, M., Vazquez-Zambrano, E., Veicht, A., Velkovska, J., Virius, M., Vrba, V., Vukman, N., Vznuzdaev, E., Vértesi, R., Wang, X. R., Watanabe, D., Watanabe, K., Watanabe, Y., Watanabe, Y. S., Wei, F., Whitaker, S., Wolin, S., Woody, C. L., Wysocki, M., Xia, B., Xue, L., Xu, C., Xu, Q., Yalcin, S., Yamaguchi, Y. L., Yamamoto, H., Yanovich, A., Yokkaichi, S., Yoon, I., Yoo, J. H., Younus, I., You, Z., Yushmanov, I. E., Yu, H., Zajc, W. A., Zelenski, A., Zhou, S., and Zou, L.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: The jet cross-section and jet-substructure observables in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-$k_{t}$ algorithm with a jet radius $R=0.3$ for jets with transverse momentum within $8.0
Published: 2024

11. Direct Observation and Analysis of Low-Energy Magnons with Raman Spectroscopy in Atomically Thin NiPS3

Author: Na, Woongki, Park, Pyeongjae, Oh, Siwon, Kim, Junghyun, Scheie, Allen, Tennant, David Alan, Lee, Hyun Cheol, Park, Je-Geun, and Cheong, Hyeonsik
Subjects: Condensed Matter - Mesoscale and Nanoscale Physics
Abstract: Van der Waals (vdW) magnets have rapidly emerged as a fertile playground for novel fundamental physics and exciting applications. Despite the impressive developments over the past few years, technical limitations pose a severe challenge to many other potential breakthroughs. High on the list is the lack of suitable experimental tools for studying spin dynamics on atomically thin samples. Here, Raman scattering techniques are employed to observe directly the low-lying magnon (~1 meV) even in bilayer NiPS3. The unique advantage is that it offers excellent energy resolutions far better on low-energy sides than most inelastic neutron spectrometers can offer. More importantly, with appropriate theoretical analysis, the polarization dependence of the Raman scattering by those low-lying magnons also provides otherwise hidden information on the dominant spin-exchange scattering paths for different magnons. By comparing with high-resolution inelastic neutron scattering data, these low-energy Raman modes are confirmed to be indeed of magnon origin. Because of the different scattering mechanisms involved in inelastic neutron and Raman scattering, this new information is fundamental in pinning down the final spin Hamiltonian. This work demonstrates the capability of Raman spectroscopy to probe the genuine two-dimensional spin dynamics in atomically-thin vdW magnets, which can provide novel insights that are obscured in bulk spin dynamics., Comment: 37 pages, 5 figures, supplementary information 11 pages
Published: 2024
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12. Analysis of Crab X-ray Polarization using Deeper IXPE Observations

Author: Wong, Josephine, Mizuno, Tsunefumi, Bucciantini, Niccoló, Romani, Roger W., Yang, Yi-Jung, Liu, Kuan, Deng, Wei, Goya, Kazuho, Xie, Fei, Pilia, Maura, Kaaret, Philip, Weisskopf, Martin C., Silvestri, Stefano, Ng, C. -Y., Chen, Chien-Ting, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccoló, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Negro, Michela, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Sgró, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey, Turolla, Roberto, Vink, Jacco, Wu, Kinwah, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present Crab X-ray polarization measurements using IXPE data with a total exposure of 300ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped $+40^\circ$ polarization angle sweep in the main pulse and ${>}1\sigma$ departures from the OPTIMA optical polarization in both pulses, suggesting different radiation mechanisms or sites for the polarized emission at the two wavebands. Our polarization map of the inner nebula reveals a toroidal magnetic field, as seen in prior IXPE analyses. Along the southern jet, the magnetic field orientation relative to the jet axis changes from perpendicular to parallel and the polarization degree decreases by ${\sim}6\%$. These observations may be explained by kink instabilities along the jet or a collision with a dense, jet-deflecting medium at the tip. Using spectropolarimetric analysis, we find asymmetric polarization in the four quadrants of the inner nebula, as expected for a toroidal field geometry, and a spatial correlation between polarization degree and photon index., Comment: 14 pages, 7 figures, 3 tables. Accepted by The Astrophysical Journal
Published: 2024

13. X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023

Author: Chen, Chien-Ting J., Liodakis, Ioannis, Middei, Riccardo, Kim, Dawoon E., Di Gesu, Laura, Di Marco, Alessandro, Ehlert, Steven R., Errando, Manel, Negro, Michela, Jorstad, Svetlana G., Marscher, Alan P., Wu, Kinwah, Agudo, Iván, Poutanen, Juri, Mizuno, Tsunefumi, Kouch, Pouya M., Lindfors, Elina, Borman, George A., Grishina, Tatiana S., Kopatskaya, Evgenia N., Larionova, Elena G., Morozova, Daria A., Savchenko, Sergey S., Troitsky, Ivan S., Troitskaya, Yulia V., Vasilyev, Andrey A., Zhovtan, Alexey V., Aceituno, Francisco José, Bonnoli, Giacomo, Casanova, Víctor, Escudero, Juan, Agís-González, Beatriz, Husillos, César, Santos, Jorge Otero, Sota, Alfredo, Piirola, Vilppu, Myserlis, Ioannis, Angelakis, Emmanouil, Kraus, Alexander, Gurwell, Mark, Keating, Garrett, Rao, Ramprasad, Kang, Sincheol, Lee, Sang-Sung, Kim, Sang-Hyun, Cheong, Whee Yeon, Jeong, Hyeon-Woo, Song, Chanwoo, Berdyugin, Andrei V., Kagitani, Masato, Kravtsov, Vadim, Nitindala, Anagha P., Sakanoi, Takeshi, Imazawa, Ryo, Sasada, Mahito, Fukazawa, Yasushi, Kawabata, Koji S., Uemura, Makoto, Nakaoka, Tatsuya, Akitaya, Hiroshi, Casadio, Carolina, Sievers, Albrecht, Antonelli, Lucio Angelo, Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccoló, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Lalla, Niccoló, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgró, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical-infrared polarization measurements were also available in the B, V, R, I, and J bands, as were radio polarization measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at $>3\sigma$ above the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE observations, the X-ray polarization degree remained higher than, or similar to, the R-band optical polarization degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission arises from different regions., Comment: Accepted for publication in ApJ
Published: 2024

14. Centrality dependence of L\'evy-stable two-pion Bose-Einstein correlations in $\sqrt{s_{_{NN}}}=200$ GeV Au$+$Au collisions

Author: PHENIX Collaboration, Abdulameer, N. J., Acharya, U., Adare, A., Aidala, C., Ajitanand, N. N., Akiba, Y., Akimoto, R., Al-Ta'ani, H., Alexander, J., Angerami, A., Aoki, K., Apadula, N., Aramaki, Y., Asano, H., Aschenauer, E. C., Atomssa, E. T., Awes, T. C., Azmoun, B., Babintsev, V., Bai, M., Bannier, B., Barish, K. N., Bassalleck, B., Bathe, S., Baublis, V., Baumgart, S., Bazilevsky, A., Belmont, R., Berdnikov, A., Berdnikov, Y., Bichon, L., Blankenship, B., Blau, D. S., Bok, J. S., Borisov, V., Boyle, K., Brooks, M. L., Buesching, H., Bumazhnov, V., Butsyk, S., Campbell, S., Castera, P., Chen, C. -H., Chen, D., Chiu, M., Chi, C. Y., Choi, I. J., Choi, J. B., Choi, S., Choudhury, R. K., Christiansen, P., Chujo, T., Chvala, O., Cianciolo, V., Citron, Z., Cole, B. A., Connors, M., Corliss, R., Csanád, M., Csörgő, T., D'Orazio, L., Dairaku, S., Datta, A., Daugherity, M. S., David, G., Denisov, A., Deshpande, A., Desmond, E. J., Dharmawardane, K. V., Dietzsch, O., Ding, L., Dion, A., Donadelli, M., Doomra, V., Drapier, O., Drees, A., Drees, K. A., Durham, J. M., Durum, A., Edwards, S., Efremenko, Y. V., Engelmore, T., Enokizono, A., Esha, R., Eyser, K. O., Fadem, B., Fields, D. E., Finger, Jr., M., Finger, M., Firak, D., Fitzgerald, D., Fleuret, F., Fokin, S. L., Frantz, J. E., Franz, A., Frawley, A. D., Fukao, Y., Fusayasu, T., Gainey, K., Gal, C., Garishvili, A., Garishvili, I., Glenn, A., Gong, X., Gonin, M., Goto, Y., de Cassagnac, R. Granier, Grau, N., Greene, S. V., Perdekamp, M. Grosse, Gunji, T., Guo, L., Guo, T., Gustafsson, H. -Å., Hachiya, T., Haggerty, J. S., Hahn, K. I., Hamagaki, H., Hanks, J., Hashimoto, K., Haslum, E., Hayano, R., Hemmick, T. K., Hester, T., He, X., Hill, J. C., Hodges, A., Hollis, R. S., Homma, K., Hong, B., Horaguchi, T., Hori, Y., Ichihara, T., Iinuma, H., Ikeda, Y., Imrek, J., Inaba, M., Iordanova, A., Isenhower, D., Issah, M., Ivanishchev, D., Jacak, B. V., Javani, M., Jiang, X., Ji, Z., Johnson, B. M., Joo, K. S., Jouan, D., Jumper, D. S., Kamin, J., Kaneti, S., Kang, B. H., Kang, J. H., Kang, J. S., Kapustinsky, J., Karatsu, K., Kasai, M., Kasza, G., Kawall, D., Kazantsev, A. V., Kempel, T., Khanzadeev, A., Kijima, K. M., Kim, B. I., Kim, C., Kim, D. J., Kim, E. -J., Kim, H. J., Kim, K. -B., Kim, Y. -J., Kim, Y. K., Kinney, E., Kiss, Á., Kistenev, E., Klatsky, J., Kleinjan, D., Kline, P., Komatsu, Y., Komkov, B., Koster, J., Kotchetkov, D., Kotov, D., Kovacs, L., Krizek, F., Král, A., Kunde, G. J., Kurgyis, B., Kurita, K., Kurosawa, M., Kwon, Y., Kyle, G. S., Lai, Y. S., Lajoie, J. G., Lebedev, A., Lee, B., Lee, D. M., Lee, J., Lee, K. B., Lee, K. S., Lee, S. H., Lee, S. R., Leitch, M. J., Leite, M. A. L., Leitgab, M., Lewis, B., Lim, S. H., Levy, L. A. Linden, Liu, M. X., Lökös, S., Loomis, D. A., Love, B., Maguire, C. F., Makdisi, Y. I., Makek, M., Manion, A., Manko, V. I., Mannel, E., Masumoto, S., McCumber, M., McGaughey, P. L., McGlinchey, D., McKinney, C., Mendoza, M., Meredith, B., Miake, Y., Mibe, T., Mignerey, A. C., Milov, A., Mishra, D. K., Mitchell, J. T., Mitrankova, M., Mitrankov, Iu., Miyachi, Y., Miyasaka, S., Mohanty, A. K., Mohapatra, S., Moon, H. J., Morrison, D. P., Motschwiller, S., Moukhanova, T. V., Mulilo, B., Murakami, T., Murata, J., Mwai, A., Nagae, T., Nagamiya, S., Nagle, J. L., Nagy, M. I., Nakagawa, I., Nakamiya, Y., Nakamura, K. R., Nakamura, T., Nakano, K., Nattrass, C., Nederlof, A., Nihashi, M., Nouicer, R., Novák, T., Novitzky, N., Nukazuka, G., Nyanin, A. S., O'Brien, E., Ogilvie, C. A., Okada, K., Orosz, M., Oskarsson, A., Ouchida, M., Ozawa, K., Pak, R., Pantuev, V., Papavassiliou, V., Park, B. H., Park, I. H., Park, J. S., Park, S., Park, S. K., Patel, L., Pate, S. F., Pei, H., Peng, J. -C., Pereira, H., Peressounko, D. Yu., Petti, R., Pinkenburg, C., Pisani, R. P., Potekhin, M., Proissl, M., Purschke, M. L., Qu, H., Rak, J., Ravinovich, I., Read, K. F., Reynolds, D., Riabov, V., Riabov, Y., Richardson, E., Richford, D., Roach, D., Roche, G., Rolnick, S. D., Rosati, M., Sahlmueller, B., Saito, N., Sakaguchi, T., Samsonov, V., Sano, M., Sarsour, M., Sawada, S., Sedgwick, K., Seidl, R., Sen, A., Seto, R., Sharma, D., Shein, I., Shibata, T. -A., Shigaki, K., Shimomura, M., Shoji, K., Shukla, P., Sickles, A., Silva, C. L., Silvermyr, D., Sim, K. S., Singh, B. K., Singh, C. P., Singh, V., Slunečka, M., Smith, K. L., Soltz, R. A., Sondheim, W. E., Sorensen, S. P., Sourikova, I. V., Stankus, P. W., Stenlund, E., Stepanov, M., Ster, A., Stoll, S. P., Sugitate, T., Sukhanov, A., Sun, J., Sun, Z., Sziklai, J., Takagui, E. M., Takahara, A., Taketani, A., Tanaka, Y., Taneja, S., Tanida, K., Tannenbaum, M. J., Tarafdar, S., Taranenko, A., Tennant, E., Themann, H., Todoroki, T., Tomášek, L., Tomášek, M., Torii, H., Towell, R. S., Tserruya, I., Tsuchimoto, Y., Tsuji, T., Ujvari, B., Vale, C., van Hecke, H. W., Vargyas, M., Vazquez-Zambrano, E., Veicht, A., Velkovska, J., Virius, M., Vossen, A., Vrba, V., Vznuzdaev, E., Vértesi, R., Wang, X. R., Watanabe, D., Watanabe, K., Watanabe, Y., Watanabe, Y. S., Wei, F., Wei, R., White, S. N., Winter, D., Wolin, S., Woody, C. L., Wysocki, M., Xia, B., Yamaguchi, Y. L., Yang, R., Yanovich, A., Ying, J., Yokkaichi, S., Younus, I., You, Z., Yushmanov, I. E., Zajc, W. A., and Zelenski, A.
Subjects: Nuclear Experiment
Abstract: The PHENIX experiment measured the centrality dependence of two-pion Bose-Einstein correlation functions in $\sqrt{s_{_{NN}}}=200$~GeV Au$+$Au collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The data are well represented by L\'evy-stable source distributions. The extracted source parameters are the correlation-strength parameter $\lambda$, the L\'evy index of stability $\alpha$, and the L\'evy-scale parameter $R$ as a function of transverse mass $m_T$ and centrality. The $\lambda(m_T)$ parameter is constant at larger values of $m_T$, but decreases as $m_T$ decreases. The L\'evy scale parameter $R(m_T)$ decreases with $m_T$ and exhibits proportionality to the length scale of the nuclear overlap region. The L\'evy exponent $\alpha(m_T)$ is independent of $m_T$ within uncertainties in each investigated centrality bin, but shows a clear centrality dependence. At all centralities, the L\'evy exponent $\alpha$ is significantly different from that of Gaussian ($\alpha=2$) or Cauchy ($\alpha=1$) source distributions. Comparisons to the predictions of Monte-Carlo simulations of resonance-decay chains show that in all but the most peripheral centrality class (50%-60%), the obtained results are inconsistent with the measurements, unless a significant reduction of the in-medium mass of the $\eta'$ meson is included. In each centrality class, the best value of the in-medium $\eta'$ mass is compared to the mass of the $\eta$ meson, as well as to several theoretical predictions that consider restoration of $U_A(1)$ symmetry in hot hadronic matter., Comment: 401 authors from 75 institutions, 20 pages, 15 figures, 2 tables. v1 is version submitted to Physical Review C. HEPdata tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html
Published: 2024

15. Spectrum and low-energy gap in triangular quantum spin liquid NaYbSe$_2$

Author: Scheie, A. O., Lee, Minseong, Wang, Kevin, Laurell, P., Choi, E. S., Pajerowski, D., Zhang, Qingming, Ma, Jie, Zhou, H. D., Lee, Sangyun, Thomas, S. M., Ajeesh, M. O., Rosa, P. F. S., Chen, Ao, Zapf, Vivien S., Heyl, M., Batista, C. D., Dagotto, E., Moore, J. E., and Tennant, D. Alan
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: We report neutron scattering, pressure-dependent AC calorimetry, and AC magnetic susceptibility measurements of triangular lattice NaYbSe$_2$. We observe a continuum of scattering, which is reproduced by matrix product simulations, and no phase transition is detected in any bulk measurements. Comparison to heat capacity simulations suggest the material is within the Heisenberg spin liquid phase. AC Susceptibility shows a significant 23~mK downturn, indicating a gap in the magnetic spectrum. The combination of a gap with no detectable magnetic order, comparison to theoretical models, and comparison to other $A$YbSe$_2$ compounds all strongly indicate NaYbSe$_2$ is within the quantum spin liquid phase. The gap also allows us to rule out a gapless Dirac spin liquid, with a gapped $\mathbb{Z}_2$ liquid the most natural explanation., Comment: 5 pages, 4 figures; 7 pages and 13 figures supplemental materials
Published: 2024

16. An IXPE-Led X-ray Spectro-Polarimetric Campaign on the Soft State of Cygnus X-1: X-ray Polarimetric Evidence for Strong Gravitational Lensing

Author: Steiner, James F., Nathan, Edward, Hu, Kun, Krawczynski, Henric, Dovciak, Michal, Veledina, Alexandra, Muleri, Fabio, Svoboda, Jiri, Alabarta, Kevin, Parra, Maxime, Bhargava, Yash, Matt, Giorgio, Poutanen, Juri, Petrucci, Pierre-Olivier, Tennant, Allyn F., Baglio, M. Cristina, Baldini, Luca, Barnier, Samuel, Bhattacharyya, Sudip, Bianchi, Stefano, Brigitte, Maimouna, Cabezas, Mauricio, Cangemi, Floriane, Capitanio, Fiamma, Casey, Jacob, Cavero, Nicole Rodriguez, Castellano, Simone, Cavazzuti, Elisabetta, Chun, Sohee, Churazov, Eugene, Costa, Enrico, Di Lalla, Niccolo, Di Marco, Alessandro, Egron, Elise, Ewing, Melissa, Fabiani, Sergio, Garcia, Javier A., Green, David A., Grinberg, Victoria, Hadrava, Petr, Ingram, Adam, Kaaret, Philip, Kislat, Fabian, Kitaguchi, Takao, Kravtsov, Vadim, Kubatova, Brankica, La Monaca, Fabio, Latronico, Luca, Loktev, Vladislav, Malacaria, Christian, Marin, Frederic, Marinucci, Andrea, Maryeva, Olga, Mastroserio, Guglielmo, Mizuno, Tsunefumi, Negro, Michela, Omodei, Nicola, Podgorny, Jakub, Rankin, John, Ratheesh, Ajay, Rhodes, Lauren, Russell, David M., Slechta, Miroslav, Soffitta, Paolo, Spooner, Sean, Suleimanov, Valery, Tombesi, Francesco, Trushkin, Sergei A., Weisskopf, Martin C., Zane, Silvia, Zdziarski, Andrzej A., Zhang, Sixuan, Zhang, Wenda, Zhou, Menglei, Agudo, Ivan, Antonelli, Lucio A., Bachetti, Matteo, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolo, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Donnarumma, Immacolata, Doroshenko, Victor, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Ferrazzoli, Riccardo, Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kolodziejczak, Jeffery J., Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Mitsuishi, Ikuyuki, Ng, Chi-Yung, O'Dell, Stephen L., Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Roberts, Oliver J., Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Thomas, Nicholas E., Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Wu, Kinwah, and Xie, Fei
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwavelength data during the campaign are likewise shown. The 2-8 keV X-rays exhibit a net polarization degree PD=1.99%+/-0.13% (68% confidence). The polarization signal is found to increase with energy across IXPE's 2-8 keV bandpass. The polarized X-rays exhibit an energy-independent polarization angle of PA=-25.7+/-1.8 deg. East of North (68% confidence). This is consistent with being aligned to Cyg X-1's AU-scale compact radio jet and its pc-scale radio lobes. In comparison to earlier hard-state observations, the soft state exhibits a factor of 2 lower polarization degree, but a similar trend with energy and a similar (also energy-independent) position angle. When scaling by the natural unit of the disk temperature, we find the appearance of a consistent trendline in the polarization degree between soft and hard states. Our favored polarimetric model indicates Cyg X-1's spin is likely high (a* above ~0.96). The substantial X-ray polarization in Cyg X-1's soft state is most readily explained as resulting from a large portion of X-rays emitted from the disk returning and reflecting off the disk surface, generating a high polarization degree and a polarization direction parallel to the black hole spin axis and radio jet. In IXPE's bandpass, the polarization signal is dominated by the returning reflection emission. This constitutes polarimetric evidence for strong gravitational lensing of X-rays close to the black hole., Comment: 20 pages, accepted for publication in ApJL
Published: 2024

17. Probing the polarized emission from SMC X-1: the brightest X-ray pulsar observed by IXPE

Author: Forsblom, Sofia V., Tsygankov, Sergey S., Poutanen, Juri, Doroshenko, Victor, Mushtukov, Alexander A., Ng, Mason, Ravi, Swati, Marshall, Herman L., Di Marco, Alessandro, La Monaca, Fabio, Malacaria, Christian, Mastroserio, Guglielmo, Loktev, Vladislav, Possenti, Andrea, Suleimanov, Valery F., Taverna, Roberto, Agudo, Ivan, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolo, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolo, Donnarumma, Immacolata, Dovciak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frederic, Marinucci, Andrea, Marscher, Alan P., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Negro, Michela, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Recent observations of X-ray pulsars (XRPs) performed by the Imaging X-ray Polarimetry Explorer (IXPE) have made it possible to investigate the intricate details of these objects in a new way, thanks to the added value of X-ray polarimetry. Here we present the results of the IXPE observations of SMC X-1, a member of the small group of XRPs displaying super-orbital variability. SMC X-1 was observed by IXPE three separate times during the high state of its super-orbital period. The observed luminosity in the 2-8 keV energy band of $L=2\times10^{38}$ erg/s makes SMC X-1 the brightest XRP ever observed by IXPE. We detect significant polarization in all three observations, with values of the phase-averaged polarization degree (PD) and polarization angle (PA) of $3.2\pm0.8$% and $97\deg\pm8\deg$ for Observation 1, $3.0\pm0.9$% and $90\deg\pm8\deg$ for Observation 2, and $5.5\pm1.1$% and $80\deg\pm6\deg$ for Observation 3, for the spectro-polarimetric analysis. The observed PD shows an increase over time with decreasing luminosity, while the PA decreases in decrements of 10\deg. The phase-resolved spectro-polarimetric analysis reveals significant detection of polarization in three out of seven phase bins, with the PD ranging between 2% and 10%, and a corresponding range in the PA from $\sim$70\deg\ to $\sim$100\deg. The pulse-phase resolved PD displays an apparent anti-correlation with the flux. Using the rotating vector model, we obtain constraints on the pulsar's geometrical properties for the individual observations. The position angle of the pulsar displays an evolution over time supporting the idea that we observe changes related to different super-orbital phases. Scattering in the wind of the precessing accretion disk may be responsible for the behavior of the polarimetric properties observed during the high-state of SMC X-1's super-orbital period., Comment: 11 pages, 11 figures, submitted to A&A
Published: 2024
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18. IXPE observation of PKS 2155-304 reveals the most highly polarized blazar

Author: Kouch, Pouya M., Liodakis, Ioannis, Middei, Riccardo, Kim, Dawoon E., Tavecchio, Fabrizio, Marscher, Alan P., Marshall, Herman L., Ehlert, Steven R., Di Gesu, Laura, Jorstad, Svetlana G., Agudo, Iván, Madejski, Grzegorz M., Romani, Roger W., Errando, Manel, Lindfors, Elina, Nilsson, Kari, Toppari, Ella, Potter, Stephen B., Imazawa, Ryo, Sasada, Mahito, Fukazawa, Yasushi, Kawabata, Koji S., Uemura, Makoto, Mizuno, Tsunefumi, Nakaoka, Tatsuya, Akitaya, Hiroshi, McCall, Callum, Jermak, Helen E., Steele, Iain A., Myserlis, Ioannis, Gurwell, Mark, Keating, Garrett K., Rao, Ramprasad, Kang, Sincheol, Lee, Sang-Sung, Kim, Sang-Hyun, Cheong, Whee Yeon, Jeong, Hyeon-Woo, Angelakis, Emmanouil, Kraus, Alexander, Aceituno, Francisco José, Bonnoli, Giacomo, Casanova, Víctor, Escudero, Juan, Agís-González, Beatriz, Husillos, César, Morcuende, Daniel, Otero-Santos, Jorge, Sota, Alfredo, Bachev, Rumen, Antonelli, Lucio Angelo, Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Lalla, Niccolò, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Negro, Michela, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half ($T_1$) of the IXPE pointing, the source exhibited the highest X-ray polarization degree detected for an HSP blazar thus far, (30.7$\pm$2.0)%, which dropped to (15.3$\pm$2.1)% during the second half ($T_2$). The X-ray polarization angle remained stable during the IXPE pointing at 129.4$^\circ$$\pm$1.8$^\circ$ and 125.4$^\circ$$\pm$3.9$^\circ$ during $T_1$ and $T_2$, respectively. Meanwhile, the optical polarization degree remained stable during the IXPE pointing, with average host-galaxy-corrected values of (4.3$\pm$0.7)% and (3.8$\pm$0.9)% during the $T_1$ and $T_2$, respectively. During the IXPE pointing, the optical polarization angle changed achromatically from $\sim$140$^\circ$ to $\sim$90$^\circ$ and back to $\sim$130$^\circ$. Despite several attempts, we only detected (99.7% conf.) the radio polarization once (during $T_2$, at 225.5 GHz): with degree (1.7$\pm$0.4)% and angle 112.5$^\circ$$\pm$5.5$^\circ$. The direction of the broad pc-scale jet is rather ambiguous and has been found to point to the east and south at different epochs; however, on larger scales (> 1.5 pc) the jet points toward the southeast ($\sim$135$^\circ$), similar to all of the MW polarization angles. Moreover, the X-ray to optical polarization degree ratios of $\sim$7 and $\sim$4 during $T_1$ and $T_2$, respectively, are similar to previous IXPE results for several HSP blazars. These findings, combined with the lack of correlation of temporal variability between the MW polarization properties, agree with an energy-stratified shock-acceleration scenario in HSP blazars., Comment: 17 pages, 10 figures, 4 tables, Accepted for publication in A&A
Published: 2024
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19. Witnessing Entanglement and Quantum Correlations in Condensed Matter: A Review

Author: Laurell, Pontus, Scheie, Allen, Dagotto, Elbio, and Tennant, D. Alan
Subjects: Quantum Physics, Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract: The detection and certification of entanglement and quantum correlations in materials is of fundamental and far-reaching importance, and has seen significant recent progress. It impacts both our understanding of the basic science of quantum many-body phenomena as well as the identification of systems suitable for novel technologies. Frameworks suitable to condensed matter that connect measurements to entanglement and coherence have been developed in the context of quantum information theory. These take the form of entanglement witnesses and quantum correlation measures. The underlying theory of these quantities, their relation to condensed matter experimental techniques, and their application to real materials are comprehensively reviewed. In addition, their usage in e.g. protocols, the relative advantages and disadvantages of witnesses and measures, and future prospects in, e.g., correlated electrons, entanglement dynamics, and entangled spectroscopic probes, are presented. Consideration is given to the interdisciplinary nature of this emerging research and substantial ongoing progress by providing an accessible and practical treatment from fundamentals to application. Particular emphasis is placed on quantities accessible to collective measurements, including by susceptibility and spectroscopic techniques. This includes the magnetic susceptibility witness, one-tangle, concurrence and two-tangle, two-site quantum discord, and quantum coherence measures such as the quantum Fisher information., Comment: 41 pages, 13 figures, 2 tables
Published: 2024

20. Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry

Author: Poutanen, Juri, Tsygankov, Sergey S., Doroshenko, Victor, Forsblom, Sofia V., Jenke, Peter, Kaaret, Philip, Berdyugin, Andrei V., Blinov, Dmitry, Kravtsov, Vadim, Liodakis, Ioannis, Tzouvanou, Anastasia, Di Marco, Alessandro, Heyl, Jeremy, La Monaca, Fabio, Mushtukov, Alexander A., Pavlov, George G., Salganik, Alexander, Veledina, Alexandra, Weisskopf, Martin C., Zane, Silvia, Loktev, Vladislav, Suleimanov, Valery F., Wilson-Hodge, Colleen, Berdyugina, Svetlana V., Kagitani, Masato, Piirola, Vilppu, Sakanoi, Takeshi, Agudo, Ivan, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolo, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolo, Donnarumma, Immacolata, Dovciak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frederic, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Negro, Michela, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Turolla, Roberto, Vink, Jacco, Wu, Kinwah, and Xie, Fei
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract: Discovery of pulsations from a number of ULXs proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve such high luminosities as well as the exact geometry of the accretion flow in the neutron star vicinity are, however, a matter of debate. The pulse phase-resolved polarization measurements that became possible with the launch of the Imaging X-ray Polarimetry Explorer (IXPE) can be used to determine the pulsar geometry and its orientation relative to the orbital plane. They provide an avenue to test different theoretical models of ULX pulsars. In this paper we present the results of three IXPE observations of the first Galactic ULX pulsar Swift J0243.6+6124 during its 2023 outburst. We find strong variations in the polarization characteristics with the pulsar phase. The average polarization degree increases from about 5% to 15% as the flux dropped by a factor of three in the course of the outburst. The polarization angle (PA) as a function of the pulsar phase shows two peaks in the first two observations, but changes to a characteristic sawtooth pattern in the remaining data set. This is not consistent with a simple rotating vector model. Assuming the existence of an additional constant polarized component, we were able to fit the three observations with a common rotating vector model and obtain constraints on the pulsar geometry. In particular, we find the pulsar angular momentum inclination with respect to the line of sight of 15-40 deg, the magnetic obliquity of 60-80 deg, and the pulsar spin position angle of -50 deg, which significantly differs from the constant component PA of about 10 deg. Combining these X-ray measurements with the optical PA, we find evidence for at least a 30 deg misalignment between the pulsar angular momentum and the binary orbital axis., Comment: 13 pages, 10 figures, version published in A&A
Published: 2024
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21. Discovery of a shock-compressed magnetic field in the north-western rim of the young supernova remnant RX J1713.7-3946 with X-ray polarimetry

Author: Ferrazzoli, Riccardo, Prokhorov, Dmitry, Bucciantini, Niccolò, Slane, Patrick, Vink, Jacco, Cardillo, Martina, Yang, Yi-Jung, Silvestri, Stefano, Zhou, Ping, Costa, Enrico, Omodei, Nicola, Ng, C. -Y., Soffitta, Paolo, Weisskopf, Martin C., Baldini, Luca, Di Marco, Alessandro, Doroshenko, Victor, Heyl, Jeremy, Kaaret, Philip, Kim, Dawoon E., Marin, Frédéric, Mizuno, Tsunefumi, Pesce-Rollins, Melissa, Sgrò, Carmelo, Swartz, Douglas A., Tamagawa, Toru, Xie, Fei, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Donnarumma, Immacolata, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Negro, Michela, O'Dell, Stephen L., Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Spandre, Gloria, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Wu, Kinwah, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: Supernova remnants (SNRs) provide insights into cosmic-ray acceleration and magnetic field dynamics at shock fronts. Recent X-ray polarimetric measurements by the Imaging X-ray Polarimetry Explorer (IXPE) have revealed radial magnetic fields near particle acceleration sites in young SNRs, including Cassiopeia A, Tycho, and SN 1006. We present here the spatially-resolved IXPE X-ray polarimetric observation of the northwestern rim of SNR RX J1713.7-3946. For the first time, our analysis shows that the magnetic field in particle acceleration sites of this SNR is oriented tangentially with respect to the shock front. Because of the lack of precise Faraday-rotation measurements in the radio band, this was not possible before. The average measured polarization degree (PD) of the synchtrotron emission is 12.5 {\pm} 3.3%, lower than the one measured by IXPE in SN 1006, comparable to the Tycho one, but notably higher than the one in Cassiopeia A. On sub-parsec scales, localized patches within RX J1713.7-3946 display PD up to 41.5 {\pm} 9.5%. These results are compatible with a shock-compressed magnetic field. However, in order to explain the observed PD, either the presence of a radial net magnetic field upstream of the shock, or partial reisotropization of the turbulence downstream by radial magneto-hydrodynamical instabilities, can be invoked. From comparison of PD and magnetic field distribution with {\gamma}-rays and 12 CO data, our results provide new inputs in favor of a leptonic origin of the {\gamma}-ray emission., Comment: 18 pages, 6 figures, 2 tables, published in ApJ Letters
Published: 2024
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22. P53 Orchestrates Cancer Metabolism: Unveiling Strategies to Reverse the Warburg Effect

Author: Abukwaik, Roba, Vera-Siguenza, Elias, Tennant, Daniel, and Spill, Fabian
Subjects: Quantitative Biology - Molecular Networks, Mathematics - Dynamical Systems
Abstract: Cancer cells exhibit significant alterations in their metabolism, characterised by a reduction in oxidative phosphorylation (OXPHOS) and an increased reliance on glycolysis, even in the presence of oxygen. This metabolic shift, known as the Warburg effect, is pivotal in fuelling cancer's uncontrolled growth, invasion, and therapeutic resistance. While dysregulation of many genes contributes to this metabolic shift, the tumour suppressor gene p53 emerges as a master player. Yet, the molecular mechanisms remain elusive. This study introduces a comprehensive mathematical model, integrating essential p53 targets, offering insights into how p53 orchestrates its targets to redirect cancer metabolism towards an OXPHOS-dominant state. Simulation outcomes align closely with experimental data comparing glucose metabolism in colon cancer cells with wild-type and mutated p53. Additionally, our findings reveal the dynamic capability of elevated p53 activation to fully reverse the Warburg effect, highlighting the significance of its activity levels not just in triggering apoptosis (programmed cell death) post-chemotherapy but also in modifying the metabolic pathways implicated in treatment resistance. In scenarios of p53 mutations, our analysis suggests targeting glycolysis-instigating signalling pathways as an alternative strategy, whereas targeting solely synthesis of cytochrome c oxidase 2 (SCO2) does support mitochondrial respiration but may not effectively suppress the glycolysis pathway, potentially boosting the energy production and cancer cell viability.
Published: 2024

23. Accelerating Cavity Fault Prediction Using Deep Learning at Jefferson Laboratory

Author: Rahman, Monibor, Carpenter, Adam, Iftekharuddin, Khan, and Tennant, Chris
Subjects: Physics - Accelerator Physics, Computer Science - Machine Learning
Abstract: Accelerating cavities are an integral part of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory. When any of the over 400 cavities in CEBAF experiences a fault, it disrupts beam delivery to experimental user halls. In this study, we propose the use of a deep learning model to predict slowly developing cavity faults. By utilizing pre-fault signals, we train a LSTM-CNN binary classifier to distinguish between radio-frequency (RF) signals during normal operation and RF signals indicative of impending faults. We optimize the model by adjusting the fault confidence threshold and implementing a multiple consecutive window criterion to identify fault events, ensuring a low false positive rate. Results obtained from analysis of a real dataset collected from the accelerating cavities simulating a deployed scenario demonstrate the model's ability to identify normal signals with 99.99% accuracy and correctly predict 80% of slowly developing faults. Notably, these achievements were achieved in the context of a highly imbalanced dataset, and fault predictions were made several hundred milliseconds before the onset of the fault. Anticipating faults enables preemptive measures to improve operational efficiency by preventing or mitigating their occurrence., Comment: 18 pages, 9 figures
Published: 2024

24. Learning Experience Design and Unpacking Sociocultural, Technological, and Pedagogical Design Considerations of Spherical Video-Based Virtual Reality Systems for Autistic Learners: A Systematic Literature Review

Author: Glaser, Noah, Thull, Charles, Schmidt, Matthew, Tennant, Alice, Moon, Jewoong, and Ousley, Cannon
Published: 2024
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25. Dynamics of Moral Behavior in Heterogeneous Populations of Learning Agents

Author: Tennant, Elizaveta, Hailes, Stephen, and Musolesi, Mirco
Subjects: Computer Science - Multiagent Systems, Computer Science - Artificial Intelligence, Computer Science - Computers and Society, Computer Science - Machine Learning
Abstract: Growing concerns about safety and alignment of AI systems highlight the importance of embedding moral capabilities in artificial agents: a promising solution is the use of learning from experience, i.e., Reinforcement Learning. In multi-agent (social) environments, complex population-level phenomena may emerge from interactions between individual learning agents. Many of the existing studies rely on simulated social dilemma environments to study the interactions of independent learning agents; however, they tend to ignore the moral heterogeneity that is likely to be present in societies of agents in practice. For example, at different points in time a single learning agent may face opponents who are consequentialist (i.e., focused on maximizing outcomes over time), norm-based (i.e., conforming to specific norms), or virtue-based (i.e., considering a combination of different virtues). The extent to which agents' co-development may be impacted by such moral heterogeneity in populations is not well understood. In this paper, we present a study of the learning dynamics of morally heterogeneous populations interacting in a social dilemma setting. Using an Iterated Prisoner's Dilemma environment with a partner selection mechanism, we investigate the extent to which the prevalence of diverse moral agents in populations affects individual agents' learning behaviors and emergent population-level outcomes. We observe several types of non-trivial interactions between pro-social and anti-social agents, and find that certain types of moral agents are able to steer selfish agents towards more cooperative behavior., Comment: Presented at AIES 2024 (7th AAAI/ACM Conference on AI, Ethics, and Society - San Jose, CA, USA) https://ojs.aaai.org/index.php/AIES/article/view/31736
Published: 2024

26. X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei : NGC 1068

Author: Marin, F., Marinucci, A., Laurenti, M., Kim, D. E., Barnouin, T., Di Marco, A., Ursini, F., Bianchi, S., Ravi, S., Marshall, H. L., Matt, G., Chen, C. -T., Gianolli, V. E., Ingram, A., Maksym, W. P., Panagiotou, C., Podgorny, J., Puccetti, S., Ratheesh, A., Tombesi, F., Agudo, I., Antonelli, L. A., Bachetti, M., Baldini, L., Baumgartner, W., Bellazzini, R., Bongiorno, S., Bonino, R., Brez, A., Bucciantini, N., Capitanio, F., Castellano, S., Cavazzuti, E., Ciprini, S., Costa, E., De Rosa, A., Del Monte, E., Di Gesu, L., Di Lalla, N., Donnarumma, I., Doroshenko, V., Dovciak, M., Ehlert, S., Enoto, T., Evangelista, Y., Fabiani, S., Ferrazzoli, R., Garcia, J., Gunji, S., Heyl, J., Iwakiri, W., Jorstad, S., Kaaret, P., Karas, V., Kislat, F., Kitaguchi, T., Kolodziejczak, J., Krawczynski, H., La Monaca, F., Latronico, L., Liodakis, I., Madejski, G., Maldera, S., Manfreda, A., Marscher, A., Massaro, F., Mitsuishi, I., Mizuno, T., Muleri, F., Negro, M., Ng, S., O'Dell, S., Omodei, N., Oppedisano, C., Papitto, A., Pavlov, G., Perri, M., Pesce-Rollins, M., Petrucci, P. -O., Pilia, M., Possenti, A., Poutanen, J., Ramsey, B., Rankin, J., Roberts, O., Romani, R., Sgro, C., Slane, P., Soffitta, P., Spandre, G., Swartz, D., Tamagawa, T., Tavecchio, F., Taverna, R., Tawara, Y., Tennant, A., Thomas, N., Trois, A., Tsygankov, S., Turolla, R., Vink, J., Weisskopf, M., Wu, K., Xie, F., and Zane, S.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, J.2.3, J.2.9
Abstract: We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2-8 keV polarization of NGC 1068. We pointed IXPE for a net exposure time of 1.15 Ms on the target, in addition to two ~ 10 ks each Chandra snapshots in order to account for the potential impact of several ultraluminous X-ray source (ULXs) within IXPE's field-of-view. We measured a 2 - 8 keV polarization degree of 12.4% +/- 3.6% and an electric vector polarization angle of 101{\deg} +/- 8{\deg} at 68% confidence level. If we exclude the spectral region containing the bright Fe K lines and other soft X-ray lines where depolarization occurs, the polarization fraction rises up to 21.3% +/- 6.7% in the 3.5 - 6.0 keV band, with a similar polarization angle. The observed polarization angle is found to be perpendicular to the parsec scale radio jet. Using a combined Chandra and IXPE analysis plus multi-wavelength constraints, we estimated that the circumnuclear "torus" may sustain a half-opening angle of 50{\deg} - 55{\deg} (from the vertical axis of the system). Thanks to IXPE, we have measured the X-ray polarization of NGC 1068 and found comparable results, both in terms of polarization angle orientation with respect to the radio-jet and torus half-opening angle, to the X-ray polarimetric measurement achieved for the other archetypal Compton-thick AGN : the Circinus galaxy. Probing the geometric arrangement of parsec-scale matter in extragalactic object is now feasible thanks to X-ray polarimetry., Comment: 9 pages, 5 figures, 2 tables, submited to A&A
Published: 2024
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27. Magnetic field-temperature phase diagram of spin-1/2 triangular lattice antiferromagnet KYbSe$_2$

Author: Lee, Sangyun, Woods, Andrew J., Lee, Minseong, Zhang, Shengzhi, Choi, Eun Sang, Scheie, A. O., Tennant, D. A., Xing, J., Sefat, A. S., and Movshovich, R.
Subjects: Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Abstract: A quantum spin liquid (QSL) is a state of matter characterized by fractionalized quasiparticle excitations, quantum entanglement, and a lack of long-range magnetic order. However, QSLs have evaded definitive experimental observation. Several Yb$^{3+}$-based triangular lattice antiferromagnets with effective $S$ = $\frac{1}{2}$ have been suggested to stabilize the QSL state as the ground state. Here, we build a comprehensive magnetic temperature phase diagram of a high-quality single crystalline KYbSe$_2$ via heat capacity and magnetocaloric effect down to 30 mK with magnetic field applied along the $a$-axis. At zero magnetic field, we observe the magnetic long-range order at $T_N$ = 0.29 K entering 120 degrees ordered state in heat capacity, consistent with neutron scattering studies. Analysis of the low-temperature ($T$) specific heat ($C$) at zero magnetic field indicates linear $T$-dependence of $C/T$ and a broad hump of $C/T$ in the proximate QSL region above $T_N$. By applying magnetic field, we observe the up-up-down phase with 1/3 magnetization plateau and oblique phases, in addition to two new phases. These observations strongly indicate that while KYbSe$_2$ closely exhibits characteristics resembling an ideal triangular lattice, deviations may exist, such as the effect of the next-nearest-neighbor exchange interaction, calling for careful consideration for spin Hamiltonian modeling. Further investigations into tuning parameters, such as chemical pressure, could potentially induce an intriguing QSL phase in the material.
Published: 2024

28. First detection of polarization in X-rays for PSR B0540-69 and its nebula

Author: Xie, Fei, Wong, Josephine, La Monaca, Fabio, Romani, Roger W., Heyl, Jeremy, Kaaret, Philip, Di Marco, Alessandro, Bucciantini, Niccolò, Liu, Kuan, Ng, Chi-Yung, Di Lalla, Niccolò, Weisskopf, Martin C., Costa, Enrico, Soffitta, Paolo, Muleri, Fabio, Bachetti, Matteo, Pilia, Maura, Rankin, John, Fabiani, Sergio, Agudo, Iván, Antonelli, Lucio A., Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Negro, Michela, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Ratheesh, Ajay, Roberts, Oliver J., Sgrò, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Wu, Kinwah, Zane, Silvia, Wadiasingh, Zorawar, Ho, Wynn C. G., Harding, Alice K., Gendreau, Keith C., and Arzoumanian, Zaven
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on X-ray polarization measurements of the extra-galactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud (LMC), using a ~850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is unresolved by IXPE. No statistically significant polarization is detected for the image-averaged data, giving a 99% confidence polarization upper limit (MDP99) of 5.3% in 2-8 keV energy range. However, a phase-resolved analysis detects polarization for both the nebula and pulsar in the 4-6 keV energy range. For the PWN defined as the off-pulse phases, the polarization degree (PD) of (24.5 ${\pm}$ 5.3)% and polarization angle (PA) of (78.1 ${\pm}$ 6.2){\deg} is detected at 4.6${\sigma}$ significance level, consistent with the PA observed in the optical band. In a single on-pulse window, a hint of polarization is measured at 3.8${\sigma}$ with polarization degree of (50.0 ${\pm}$ 13.1)% and polarization angle of (6.2 ${\pm}$ 7.4){\deg}. A 'simultaneous' PSR/PWN analysis finds two bins at the edges of the pulse exceeding 3${\sigma}$ PD significance, with PD of (68 ${\pm}$ 20)% and (62 ${\pm}$ 20)%; intervening bins at 2-3${\sigma}$ significance have lower PD, hinting at additional polarization structure., Comment: 10 pages, 7 figures, 4 tables, author's version of the paper accepted for publication in ApJ
Published: 2024

29. Red shift of the superconductivity cavity resonance in Josephson junction qubits as a direct signature of TLS population inversion

Author: Burin, Alexander L., Schechter, Moshe, Tennant, Daniel, Ray, Keith G., and Rosen, Yaniv J.
Subjects: Condensed Matter - Disordered Systems and Neural Networks
Abstract: Quantum two-level systems (TLSs) limit the performance of superconducting qubits and superconducting and optomechanical resonators breaking down the coherence and absorbing the energy of oscillations. TLS absorption can be suppressed or even switched to the gain regime by inverting TLS populations. Here we theoretically explore the regime where the full inversion of TLS populations is attained at energies below a pump field quantization energy by simultaneously applying the pump field and the time varying bias. This regime is attained changing the bias sufficiently slowly to fully invert TLS populations when their energies cross resonance with the pump field and sufficiently fast to avoid TLS relaxation between two resonance crossing events. This population inversion is accompanied by a significant red shift of cavity resonance due to quantum level repulsion. The red-shift in frequency serves as a signature of the population inversion, as its re-entrant behavior as function of bias sweep rate and of the magnitude of the pump field allows the determination of the TLSs dipole moment and relaxation time. The predicted behavior is qualitatively consistent with the recent experimental observations in Al superconducting resonators., Comment: 9 pages, 6 figures, to be submitted, comments are welcome!
Published: 2024

30. Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1

Author: Bobrikova, Anna, Forsblom, Sofia V., Di Marco, Alessandro, La Monaca, Fabio, Poutanen, Juri, Ng, Mason, Ravi, Swati, Loktev, Vladislav, Kajava, Jari J. E., Ursini, Francesco, Veledina, Alexandra, Rogantini, Daniele, Salmi, Tuomo, Bianchi, Stefano, Capitanio, Fiamma, Done, Chris, Fabiani, Sergio, Gnarini, Andrea, Heyl, Jeremy, Kaaret, Philip, Matt, Giorgio, Muleri, Fabio, Nitindala, Anagha P., Rankin, John, Weisskopf, Martin C., Agudo, Ivan, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolo, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolo, Donnarumma, Immacolata, Doroshenko, Victor, Dovciak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frederic, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Negro, Michela, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Ratheesh, Ajay J., Roberts, Oliver, Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Weakly magnetized neutron stars in X-ray binaries show complex phenomenology with several spectral components that can be associated with the accretion disk, boundary and/or spreading layer, a corona, and a wind. Spectroscopic information alone is, however, not enough to disentangle these components. Additional information about the nature of the spectral components and in particular the geometry of the emission region can be provided by X-ray polarimetry. One of the objects of the class, a bright, persistent, and rather peculiar galactic Type I X-ray burster was observed with the Imaging X-ray Polarimetry Explorer (IXPE) and the X-ray Multi-Mirror Mission Newton (XMM-Newton). Using the XMM-Newton data we estimated the current state of the source as well as detected strong absorption lines associated with the accretion disk wind. IXPE data showed the source to be significantly polarized in the 2-8 keV energy band with the overall polarization degree (PD) of 1.4% at a polarization angle (PA) of -2 degrees (errors at 68% confidence level). During the two-day long observation, we detected rotation of the PA by about 70 degrees with the corresponding changes in the PD from 2% to non-detectable and then up to 5%. These variations in polarization properties are not accompanied by visible changes in spectroscopic characteristics. The energy-resolved polarimetric analysis showed a significant change in polarization, from being strongly dependent on energy at the beginning of the observation to being almost constant with energy in the later parts of the observation. As a possible interpretation, we suggest the presence of a constant component of polarization, strong wind scattering, or different polarization of the two main spectral components with individually peculiar behavior. The rotation of the PA suggests a 30-degree misalignment of the neutron star spin from the orbital axis., Comment: 12 pages, 12 figures
Published: 2024
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31. Detection of X-ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-ray Polarimetry Explorer

Author: Errando, Manel, Liodakis, Ioannis, Marscher, Alan P., Marshall, Herman L., Middei, Riccardo, Negro, Michela, Peirson, Abel Lawrence, Perri, Matteo, Puccetti, Simonetta, Rabinowitz, Pazit L., Agudo, Iván, Jorstad, Svetlana G., Savchenko, Sergey S., Blinov, Dmitry, Bourbah, Ioakeim G., Kiehlmann, Sebastian, Kontopodis, Evangelos, Mandarakas, Nikos, Romanopoulos, Stylianos, Skalidis, Raphael, Vervelaki, Anna, Aceituno, Francisco José, Bernardos, Maria I., Bonnoli, Giacomo, Casanova, Víctor, Agís-González, Beatriz, Husillos, César, Marchini, Alessandro, Sota, Alfredo, Kouch, Pouya M., Lindfors, Elina, Casadio, Carolina, Escudero, Juan, Myserlis, Ioannis, Imazawa, Ryo, Sasada, Mahito, Fukazawa, Yasushi, Kawabata, Koji S., Uemura, Makoto, Mizuno, Tsunefumi, Nakaoka, Tatsuya, Akitaya, Hiroshi, Gurwell, Mark, Keating, Garrett K., Rao, Ramprasad, Ingram, Adam, Massaro, Francesco, Antonelli, Lucio Angelo, Bonino, Raffaella, Cavazzuti, Elisabetta, Chen, Chien-Ting, Cibrario, Nicolò, Ciprini, Stefano, De Rosa, Alessandra, Di Gesu, Laura, Di Pierro, Federico, Donnarumma, Immacolata, Ehlert, Steven R., Fenu, Francesco, Gau, Ephraim, Karas, Vladimir, Kim, Dawoon E., Krawczynski, Henric, Laurenti, Marco, Lisalda, Lindsey, López-Coto, Rubén, Madejski, Grzegorz, Marin, Frédéric, Marinucci, Andrea, Mitsuishi, Ikuyuki, Muleri, Fabio, Pacciani, Luigi, Paggi, Alessandro, Petrucci, Pierre-Olivier, Cavero, Nicole Rodriguez, Romani, Roger W., Tavecchio, Fabrizio, Tugliani, Stefano, Wu, Kinwah, Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Costa, Enrico, Del Monte, Ettore, Di Lalla, Niccolò, Di Marco, Alessandro, Doroshenko, Victor, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Kaaret, Philip, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Matt, Giorgio, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Pesce-Rollins, Melissa, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy particles within the jet. IXPE observations of the X-ray selected BL Lac-type blazar 1ES 1959+650 in 2022 May 3-4 showed a significant linear polarization degree of $\Pi_\mathrm{x} = 8.0\% \pm 2.3\%$ at an electric-vector position angle $\psi_\mathrm{x} = 123^\circ \pm 8^\circ$. However, in 2022 June 9-12, only an upper limit of $\Pi_\mathrm{x} \leq 5.1\%$ could be derived (at the 99% confidence level). The degree of optical polarization at that time $\Pi_\mathrm{O} \sim 5\%$ is comparable to the X-ray measurement. We investigate possible scenarios for these findings, including temporal and geometrical depolarization effects. Unlike some other X-ray selected BL Lac objects, there is no significant chromatic dependence of the measured polarization in 1ES 1959+650, and its low X-ray polarization may be attributed to turbulence in the jet flow with dynamical timescales shorter than 1 day., Comment: 16 pages, 4 figures, accepted for publication in The Astrophysical Journal
Published: 2024
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32. Complex rotational dynamics of the neutron star in Hercules X-1 revealed by X-ray polarization

Author: Heyl, Jeremy, Doroshenko, Victor, González-Caniulef, Denis, Caiazzo, Ilaria, Poutanen, Juri, Mushtukov, Alexander, Tsygankov, Sergey S., Kirmizibayrak, Demet, Bachetti, Matteo, Pavlov, George G., Forsblom, Sofia V., Malacaria, Christian, Suleimanov, Valery F., Agudo, Iván, Antonelli, Lucio Angelo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Di Marco, Alessandro, Donnarumma, Immacolata, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Negro, Michela, Ng, C.-Y., O’Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Published: 2024
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33. Cygnus X-3 revealed as a Galactic ultraluminous X-ray source by IXPE

Author: Veledina, Alexandra, Muleri, Fabio, Poutanen, Juri, Podgorný, Jakub, Dovčiak, Michal, Capitanio, Fiamma, Churazov, Eugene, De Rosa, Alessandra, Di Marco, Alessandro, Forsblom, Sofia V., Kaaret, Philip, Krawczynski, Henric, La Monaca, Fabio, Loktev, Vladislav, Lutovinov, Alexander A., Molkov, Sergey V., Mushtukov, Alexander A., Ratheesh, Ajay, Rodriguez Cavero, Nicole, Steiner, James F., Sunyaev, Rashid A., Tsygankov, Sergey S., Weisskopf, Martin C., Zdziarski, Andrzej A., Bianchi, Stefano, Bright, Joe S., Bursov, Nikolaj, Costa, Enrico, Egron, Elise, Garcia, Javier A., Green, David A., Gurwell, Mark, Ingram, Adam, Kajava, Jari J. E., Kale, Ruta, Kraus, Alex, Malyshev, Denys, Marin, Frédéric, Matt, Giorgio, McCollough, Michael, Mereminskiy, Ilya A., Nizhelsky, Nikolaj, Piano, Giovanni, Pilia, Maura, Pittori, Carlotta, Rao, Ramprasad, Righini, Simona, Soffitta, Paolo, Shevchenko, Anton, Svoboda, Jiri, Tombesi, Francesco, Trushkin, Sergei A., Tsybulev, Peter, Ursini, Francesco, Wu, Kinwah, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Donnarumma, Immacolata, Doroshenko, Victor, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Negro, Michela, Ng, Chi-Yung, O’Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Roberts, Oliver, Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Doug, Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Trois, Alessio, Turolla, Roberto, Vink, Jacco, Xie, Fei, and Zane, Silvia
Published: 2024
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34. Identified charged-hadron production in $p$$+$Al, $^3$He$+$Au, and Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV and in U$+$U collisions at $\sqrt{s_{_{NN}}}=193$ GeV

Author: PHENIX Collaboration, Abdulameer, N. J., Acharya, U., Adare, A., Aidala, C., Ajitanand, N. N., Akiba, Y., Akimoto, R., Alexander, J., Alfred, M., Andrieux, V., Aoki, K., Apadula, N., Asano, H., Atomssa, E. T., Awes, T. C., Azmoun, B., Babintsev, V., Bai, M., Bai, X., Bandara, N. S., Bannier, B., Barish, K. N., Bathe, S., Baublis, V., Baumann, C., Baumgart, S., Bazilevsky, A., Beaumier, M., Beckman, S., Belmont, R., Berdnikov, A., Berdnikov, Y., Bichon, L., Black, D., Blankenship, B., Blau, D. S., Bok, J. S., Borisov, V., Boyle, K., Brooks, M. L., Bryslawskyj, J., Buesching, H., Bumazhnov, V., Butsyk, S., Campbell, S., Roman, V. Canoa, Cervantes, R., Chen, C. -H., Chiu, M., Chi, C. Y., Choi, I. J., Choi, J. B., Choi, S., Christiansen, P., Chujo, T., Cianciolo, V., Citron, Z., Cole, B. A., Connors, M., Corliss, R., Morales, Y. Corrales, Cronin, N., Crossette, N., Csanád, M., Csörgő, T., D'Orazio, L., Danley, T. W., Datta, A., Daugherity, M. S., David, G., Dean, C. T., DeBlasio, K., Dehmelt, K., Denisov, A., Deshpande, A., Desmond, E. J., Ding, L., Dion, A., Diss, P. B., Dixit, D., Doomra, V., Do, J. H., Drapier, O., Drees, A., Drees, K. A., Durham, J. M., Durum, A., En'yo, H., Engelmore, T., Enokizono, A., Esha, R., Eyser, K. O., Fadem, B., Fan, W., Feege, N., Fields, D. E., Finger, Jr., M., Finger, M., Firak, D., Fitzgerald, D., Fleuret, F., Fokin, S. L., Frantz, J. E., Franz, A., Frawley, A. D., Fukao, Y., Fukuda, Y., Fusayasu, T., Gainey, K., Gallus, P., Gal, C., Garg, P., Garishvili, A., Garishvili, I., Ge, H., Giles, M., Giordano, F., Glenn, A., Gong, X., Gonin, M., Goto, Y., de Cassagnac, R. Granier, Grau, N., Greene, S. V., Perdekamp, M. Grosse, Gu, Y., Gunji, T., Guo, T., Guragain, H., Hachiya, T., Haggerty, J. S., Hahn, K. I., Hamagaki, H., Hamilton, H. F., Hanks, J., Han, S. Y., Harvey, M., Hasegawa, S., Haseler, T. O. S., Hashimoto, K., Hayano, R., Hemmick, T. K., Hester, T., He, X., Hill, J. C., Hill, K., Hodges, A., Hollis, R. S., Homma, K., Hong, B., Hoshino, T., Hotvedt, N., Huang, J., Ichihara, T., Ikeda, Y., Imai, K., Imazu, Y., Inaba, M., Iordanova, A., Isenhower, D., Isinhue, A., Ivanishchev, D., Jacak, B. V., Jeon, S. J., Jezghani, M., Jiang, X., Ji, Z., Johnson, B. M., Joo, K. S., Jouan, D., Jumper, D. S., Kamin, J., Kanda, S., Kang, B. H., Kang, J. H., Kang, J. S., Kapukchyan, D., Kapustinsky, J., Karthas, S., Kawall, D., Kazantsev, A. V., Key, J. A., Khachatryan, V., Khandai, P. K., Khanzadeev, A., Khatiwada, A., Kijima, K. M., Kimelman, B., Kim, C., Kim, D. J., Kim, E. -J., Kim, G. W., Kim, M., Kim, T., Kim, Y. -J., Kim, Y. K., Kincses, D., Kingan, A., Kistenev, E., Kitamura, R., Klatsky, J., Kleinjan, D., Kline, P., Koblesky, T., Kofarago, M., Komkov, B., Koster, J., Kotchetkov, D., Kotov, D., Kovacs, L., Krizek, F., Kudo, S., Kurgyis, B., Kurita, K., Kurosawa, M., Kwon, Y., Lai, Y. S., Lajoie, J. G., Larionova, D., Lebedev, A., Lee, D. M., Lee, G. H., Lee, J., Lee, K. B., Lee, K. S., Lee, S., Lee, S. H., Leitch, M. J., Leitgab, M., Leung, Y. H., Lewis, B., Lewis, N. A., Lim, S. H., Liu, M. X., Li, X., Loggins, V. -R., Loomis, D. A., Lovasz, K., Lynch, D., Lökös, S., Maguire, C. F., Majoros, T., Makdisi, Y. I., Makek, M., Manion, A., Manko, V. I., Mannel, E., McCumber, M., McGaughey, P. L., McGlinchey, D., McKinney, C., Meles, A., Mendoza, M., Meredith, B., Miake, Y., Mibe, T., Mignerey, A. C., Milov, A., Mishra, D. K., Mitchell, J. T., Mitrankova, M., Mitrankov, Iu., Mitsuka, G., Miyasaka, S., Mizuno, S., Mohanty, A. K., Mohapatra, S., Mondal, M. M., Montuenga, P., Moon, T., Morrison, D. P., Moskowitz, M., Moukhanova, T. V., Muhammad, A., Mulilo, B., Murakami, T., Murata, J., Mwai, A., Nagae, T., Nagai, K., Nagamiya, S., Nagashima, K., Nagashima, T., Nagle, J. L., Nagy, M. I., Nakagawa, I., Nakagomi, H., Nakamiya, Y., Nakamura, K. R., Nakamura, T., Nakano, K., Nattrass, C., Nelson, S., Netrakanti, P. K., Nihashi, M., Niida, T., Nishimura, S., Nouicer, R., Novitzky, N., Novák, T., Nukazuka, G., Nyanin, A. S., O'Brien, E., Ogilvie, C. A., Oh, J., Oide, H., Okada, K., Koop, J. D. Orjuela, Orosz, M., Osborn, J. D., Oskarsson, A., Ottino, G. J., Ozawa, K., Pak, R., Pantuev, V., Papavassiliou, V., Park, I. H., Park, J. S., Park, S., Park, S. K., Patel, L., Patel, M., Pate, S. F., Peng, J. -C., Peng, W., Perepelitsa, D. V., Perera, G. D. N., Peressounko, D. Yu., PerezLara, C. E., Perry, J., Petti, R., Phipps, M., Pinkenburg, C., Pinson, R., Pisani, R. P., Potekhin, M., Pun, A., Purschke, M. L., Qu, H., Radzevich, P. V., Rak, J., Ramasubramanian, N., Ramson, B. J., Ravinovich, I., Read, K. F., Reynolds, D., Riabov, V., Riabov, Y., Richardson, E., Richford, D., Rinn, T., Riveli, N., Roach, D., Rolnick, S. D., Rosati, M., Rowan, Z., Rubin, J. G., Runchey, J., Ryu, M. S., Safonov, A. S., Sahlmueller, B., Saito, N., Sakaguchi, T., Sako, H., Samsonov, V., Sarsour, M., Sato, S., Sawada, S., Schaefer, B., Schmoll, B. K., Sedgwick, K., Seele, J., Seidl, R., Sekiguchi, Y., Sen, A., Seto, R., Sett, P., Sexton, A., Sharma, D., Shaver, A., Shein, I., Shibata, M., Shibata, T. -A., Shigaki, K., Shimomura, M., Shioya, T., Shi, Z., Shoji, K., Shukla, P., Sickles, A., Silva, C. L., Silvermyr, D., Singh, B. K., Singh, V., Skolnik, M., Slunečka, M., Smith, K. L., Snowball, M., Solano, S., Soltz, R. A., Sondheim, W. E., Sorensen, S. P., Sourikova, I. V., Stankus, P. W., Steinberg, P., Stenlund, E., Stepanov, M., Ster, A., Stoll, S. P., Stone, M. R., Sugitate, T., Sukhanov, A., Sumita, T., Sun, J., Sun, Z., Sziklai, J., Takahama, R., Takahara, A., Taketani, A., Tanaka, Y., Tanida, K., Tannenbaum, M. J., Tarafdar, S., Taranenko, A., Tarnai, G., Tennant, E., Tieulent, R., Timilsina, A., Todoroki, T., Tomášek, M., Torii, H., Towell, C. L., Towell, R., Towell, R. S., Tserruya, I., Ueda, Y., Ujvari, B., van Hecke, H. W., Vargyas, M., Vazquez-Zambrano, E., Veicht, A., Velkovska, J., Virius, M., Vrba, V., Vukman, N., Vznuzdaev, E., Vértesi, R., Wang, X. R., Wang, Z., Watanabe, D., Watanabe, K., Watanabe, Y., Watanabe, Y. S., Wei, F., Whitaker, S., White, A. S., Wolin, S., Wong, C. P., Woody, C. L., Wysocki, M., Xia, B., Xue, L., Xu, C., Xu, Q., Yalcin, S., Yamaguchi, Y. L., Yamamoto, H., Yanovich, A., Yokkaichi, S., Yoon, I., Yoo, J. H., Younus, I., You, Z., Yushmanov, I. E., Yu, H., Zajc, W. A., Zelenski, A., Zhou, S., and Zou, L.
Subjects: Nuclear Experiment
Abstract: The PHENIX experiment has performed a systematic study of identified charged-hadron ($\pi^\pm$, $K^\pm$, $p$, $\bar{p}$) production at midrapidity in $p$$+$Al, $^3$He$+$Au, Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV and U$+$U collisions at $\sqrt{s_{_{NN}}}=193$ GeV. Identified charged-hadron invariant transverse-momentum ($p_T$) and transverse-mass ($m_T$) spectra are presented and interpreted in terms of radially expanding thermalized systems. The particle ratios of $K/\pi$ and $p/\pi$ have been measured in different centrality ranges of large (Cu$+$Au, U$+$U) and small ($p$$+$Al, $^3$He$+$Au) collision systems. The values of $K/\pi$ ratios measured in all considered collision systems were found to be consistent with those measured in $p$$+$$p$ collisions. However the values of $p/\pi$ ratios measured in large collision systems reach the values of $\approx0.6$, which is $\approx2$ times larger than in $p$$+$$p$ collisions. These results can be qualitatively understood in terms of the baryon enhancement expected from hadronization by recombination. Identified charged-hadron nuclear-modification factors ($R_{AB}$) are also presented. Enhancement of proton $R_{AB}$ values over meson $R_{AB}$ values was observed in central $^3$He$+$Au, Cu$+$Au, and U$+$U collisions. The proton $R_{AB}$ values measured in $p$$+$Al collision system were found to be consistent with $R_{AB}$ values of $\phi$, $\pi^\pm$, $K^\pm$, and $\pi^0$ mesons, which may indicate that the size of the system produced in $p$$+$Al collisions is too small for recombination to cause a noticeable increase in proton production., Comment: 480 authors from 78 institutions, 18 pages, 6 tables, 16 figures. v2 is version accepted for publication in Physical Review C. HEPdata tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html
Published: 2023
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35. Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13-0.11: Proof of the synchrotron nature by IXPE

Author: Churazov, Eugene, Khabibullin, Ildar, Barnouin, Thibault, Bucciantini, Niccolò, Costa, Enrico, Di Gesu, Laura, Di Marco, Alessandro, Ferrazzoli, Riccardo, Forman, William, Kaaret, Philip, Kim, Dawoon E., Kolodziejczak, Jeffery J., Kraft, Ralph, Marin, Frédéric, Matt, Giorgio, Negro, Michela, Romani, Roger W., Silvestri, Stefano, Soffitta, Paolo, Sunyaev, Rashid, Svoboda, Jiri, Vikhlinin, Alexey, Weisskopf, Martin C., Xie, Fei, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Lalla, Niccolò, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, García, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Sgrò, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Wu, Kinwah, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the discovery of X-ray polarization from the X-ray-bright filament. G0.13-0.11 in the Galactic center (GC) region. This filament features a bright, hard X-ray source that is most plausibly a pulsar wind nebula (PWN) and an extended and structured diffuse component. Combining the polarization signal from IXPE with the imaging/spectroscopic data from Chandra, we find that X-ray emission of G0.13-0.11 is highly polarized PD=$57(\pm18)$% in the 3-6 keV band, while the polarization angle is PA=$21^\circ(\pm9^\circ)$. This high degree of polarization proves the synchrotron origin of the X-ray emission from G0.13-0.11. In turn, the measured polarization angle implies that the X-ray emission is polarized approximately perpendicular to a sequence of nonthermal radio filaments that may be part of the GC Radio Arc. The magnetic field on the order of $100\,{\rm\mu G}$ appears to be preferentially ordered along the filaments. The above field strength is the fiducial value that makes our model self-consistent, while the other conclusions are largely model independent., Comment: Accepted for publication in A&A
Published: 2023
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36. Learning Machine Morality through Experience and Interaction

Author: Tennant, Elizaveta, Hailes, Stephen, and Musolesi, Mirco
Subjects: Computer Science - Artificial Intelligence, Computer Science - Computers and Society, Computer Science - Machine Learning, Computer Science - Multiagent Systems
Abstract: Increasing interest in ensuring safety of next-generation Artificial Intelligence (AI) systems calls for novel approaches to embedding morality into autonomous agents. Traditionally, this has been done by imposing explicit top-down rules or hard constraints on systems, for example by filtering system outputs through pre-defined ethical rules. Recently, instead, entirely bottom-up methods for learning implicit preferences from human behavior have become increasingly popular, such as those for training and fine-tuning Large Language Models. In this paper, we provide a systematization of existing approaches to the problem of introducing morality in machines - modeled as a continuum, and argue that the majority of popular techniques lie at the extremes - either being fully hard-coded, or entirely learned, where no explicit statement of any moral principle is required. Given the relative strengths and weaknesses of each type of methodology, we argue that more hybrid solutions are needed to create adaptable and robust, yet more controllable and interpretable agents. In particular, we present three case studies of recent works which use learning from experience (i.e., Reinforcement Learning) to explicitly provide moral principles to learning agents - either as intrinsic rewards, moral logical constraints or textual principles for language models. For example, using intrinsic rewards in Social Dilemma games, we demonstrate how it is possible to represent classical moral frameworks for agents. We also present an overview of the existing work in this area in order to provide empirical evidence for the potential of this hybrid approach. We then discuss strategies for evaluating the effectiveness of moral learning agents. Finally, we present open research questions and implications for the future of AI safety and ethics which are emerging from this framework.
Published: 2023

37. Highly Significant Detection of X-Ray Polarization from the Brightest Accreting Neutron Star Sco X-1

Author: La Monaca, Fabio, Di Marco, Alessandro, Poutanen, Juri, Bachetti, Matteo, Motta, Sara E., Papitto, Alessandro, Pilia, Maura, Xie, Fei, Bianchi, Stefano, Bobrikova, Anna, Costa, Enrico, Deng, Wei, Ge, Mingyu, Illiano, Giulia, Jia, Shu-Mei, Krawczynski, Henric, Lai, Eleonora V., Liu, Kuan, Mastroserio, Guglielmo, Muleri, Fabio, Rankin, John, Soffitta, Paolo, Veledina, Alexandra, Ambrosino, Filippo, Del Santo, Melania, Chen, Wei, Garcia, Javier A., Kaaret, Philip, Russell, Thomas D., Wei, Wen-Hao, Zhang, Shuang-Nan, Zuo, Chao, Arzoumanian, Zaven, Cocchi, Massimo, Gnarini, Andrea, Farinelli, Ruben, Gendreau, Keith C., Ursini, Francesco, Weisskopf, Martin C., Zane, Silvia, Agudo, Ivan, Antonelli, Lucio Angelo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting J., Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Donnarumma, Immacolata, Doroshenko, Victor, Dovciak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Gunji, Shuichi, Hayashidadag, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Fre'de'ric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Negro, Michela, Ng, Stephen Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Pavlov, George, Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas, Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, and Wu, Kinwah
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Imaging X-ray Polarimetry Explorer (IXPE) measured with high significance the X-ray polarization of the brightest Z-source Scorpius X-1, resulting in the nominal 2-8 keV energy band in a polarization degree of 1.0(0.2)% and a polarization angle of 8(6){\deg} at 90% of confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which allowed for a precise characterization of its broad-band spectrum from soft to hard X-rays. The source has been observed mainly in its soft state, with short periods of flaring. We also observed low-frequency quasi-periodic oscillations. From a spectro-polarimetric analysis, we associate a polarization to the accretion disk at <3.2% at 90% of confidence level, compatible with expectations for an electron-scattering dominated optically thick atmosphere at the Sco X-1 inclination of 44{\deg}; for the higher-energy Comptonized component, we obtain a polarization of 1.3(0.4)%, in agreement with expectations for a slab of Thomson optical depth of ~7 and an electron temperature of ~3 keV. A polarization rotation with respect to previous observations by OSO-8 and PolarLight, and also with respect to the radio-jet position angle, is observed. This result may indicate a variation of the polarization with the source state that can be related to relativistic precession or to a change in the corona geometry with the accretion flow.
Published: 2023
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38. Tracking the X-ray Polarization of the Black Hole Transient Swift J1727.8-1613 during a State Transition

Author: Ingram, Adam, Bollemeijer, Niek, Veledina, Alexandra, Dovciak, Michal, Poutanen, Juri, Egron, Elise, Russell, Thomas D., Trushkin, Sergei A., Negro, Michela, Ratheesh, Ajay, Capitanio, Fiamma, Connors, Riley, Neilsen, Joseph, Kraus, Alexander, Iacolina, Maria Noemi, Pellizzoni, Alberto, Pilia, Maura, Carotenuto, Francesco, Matt, Giorgio, Mastroserio, Guglielmo, Kaaret, Philip, Bianchi, Stefano, Garcia, Javier A., Bachetti, Matteo, Wu, Kinwah, Costa, Enrico, Ewing, Melissa, Kravtsov, Vadim, Krawczynski, Henric, Loktev, Vladislav, Marinucci, Andrea, Marra, Lorenzo, Mikusincova, Romana, Nathan, Edward, Parra, Maxime, Petrucci, Pierre-Olivier, Righini, Simona, Soffitta, Paolo, Steiner, James F., Svoboda, Jiri, Tombesi, Francesco, Tugliani, Stefano, Ursini, Francesco, Yang, Yi-Jung, Zane, Silvia, Zhang, Wenda, Agudo, Ivan, Antonelli, Lucio A., Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolo, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolo, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frederic, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Roberts, Oliver J., Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., and Xie, Fei
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on an observational campaign on the bright black hole X-ray binary Swift J1727.8$-$1613 centered around five observations by the Imaging X-ray Polarimetry Explorer (IXPE). These observations track for the first time the evolution of the X-ray polarization of a black hole X-ray binary across a hard to soft state transition. The 2--8 keV polarization degree decreased from $\sim$4\% to $\sim$3\% across the five observations, but the polarization angle remained oriented in the North-South direction throughout. Based on observations with the Australia Telescope Compact Array (ATCA), we find that the intrinsic 7.25 GHz radio polarization aligns with the X-ray polarization. Assuming the radio polarization aligns with the jet direction (which can be tested in the future with higher spatial resolution images of the jet), our results imply that the X-ray corona is extended in the disk plane, rather than along the jet axis, for the entire hard intermediate state. This in turn implies that the long ($\gtrsim$10 ms) soft lags that we measure with the Neutron star Interior Composition ExploreR (NICER) are dominated by processes other than pure light-crossing delays. Moreover, we find that the evolution of the soft lag amplitude with spectral state does not follow the trend seen for other sources, implying that Swift J1727.8$-$1613 is a member of a hitherto under-sampled sub-population., Comment: Accepted for publication in ApJ. 21 pages, 8 figures
Published: 2023

39. X-Ray Polarized View on the Accretion Geometry in the X-Ray Binary Circinus X-1

Author: Rankin, John, La Monaca, Fabio, Di Marco, Alessandro, Poutanen, Juri, Bobrikova, Anna, Kravtsov, Vadim, Muleri, Fabio, Pilia, Maura, Veledina, Alexandra, Fender, Rob, Kaaret, Philip, Kim, Dawoon E., Marinucci, Andrea, Marshall, Herman L., Papitto, Alessandro, Tennant, Allyn F., Tsygankov, Sergey S., Weisskopf, Martin C., Wu, Kinwah, Zane, Silvia, Ambrosino, Filippo, Farinelli, Ruben, Gnarini, Andrea, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, di Lalla, Niccolò, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marscher, Alan P., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Negro, Michela, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Turolla, Roberto, Vink, Jacco, and Xie, Fei
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric $\sim$16.6 days orbit. There are also strong variations in the spectral state, and historically it has shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263~ks. We find an X-ray polarization degree in these segments of $1.6\%\pm0.3\%$ and $1.4\%\pm0.3\%$ at polarization angles of $37^\circ\pm5^\circ$ and $-12^\circ\pm7^\circ$, respectively. Thus we observed a rotation of the polarization angle by $49^\circ\pm8^\circ$ along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio, and found the polarization angle differing by $67^\circ\pm11^\circ$ between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star's angular momentum with respect to the orbital one., Comment: 15 pages, 6 figures, Accepted for publication in ApJL
Published: 2023
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40. X-ray Polarization Reveals the Precessions of the Neutron Star in Hercules X-1

Author: Heyl, Jeremy, Doroshenko, Victor, González-Caniulef, Denis, Caiazzo, Ilaria, Poutanen, Juri, Mushtukov, Alexander, Tsygankov, Sergey S., Kirmizibayrak, Demet, Bachetti, Matteo, Pavlov, George G., Forsblom, Sofia V., Malacaria, Christian, Suleimanov, Valery F., Agudo, Iván, Antonelli, Lucio Angelo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Di Marco, Alessandro, Donnarumma, Immacolata, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Negro, Michela, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: In an accreting X-ray pulsar, a neutron star accretes matter from a stellar companion through an accretion disk. The high magnetic field of the rotating neutron star disrupts the inner edge of the disc, funneling the gas to flow onto the magnetic poles on its surface. Hercules X-1 is in many ways the prototypical X-ray pulsar; it shows persistent X-ray emission and it resides with its companion HZ Her, a two-solar-mass star, at about 7~kpc from Earth. Its emission varies on three distinct timescales: the neutron star rotates every 1.2~seconds, it is eclipsed by its companion each 1.7~days, and the system exhibits a superorbital period of 35~days which has remained remarkably stable since its discovery. Several lines of evidence point to the source of this variation as the precession of the accretion disc, the precession of the neutron star or both. Despite the many hints over the past fifty years, the precession of the neutron star itself has yet not been confirmed or refuted. We here present X-ray polarization measurements with the Imaging X-ray Polarimetry Explorer (IXPE) which probe the spin geometry of the neutron star. These observations provide direct evidence that the 35-day-period is set by the free precession of the neutron star crust, which has the important implication that its crust is somewhat asymmetric fractionally by a few parts per ten million. Furthermore, we find indications that the basic spin geometry of the neutron star is altered by torques on timescale of a few hundred days., Comment: 37 pages
Published: 2023

41. The detection of polarized x-ray emission from the magnetar 1E 2259+586

Author: Heyl, Jeremy, Taverna, Roberto, Turolla, Roberto, Israel, Gian Luca, Ng, Mason, Kirmizibayrak, Demet, González-Caniulef, Denis, Caiazzo, Ilaria, Zane, Silvia, Ehlert, Steven R., Negro, Michela, Agudo, Iván, Antonelli, Lucio Angelo, Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Iwakiri, Wataru, Jorstad, Svetlana G., Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel Lawrence, Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, and Xie, Fei
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on IXPE, NICER and XMM-Newton observations of the magnetar 1E 2259+586. We find that the source is significantly polarized at about or above 20% for all phases except for the secondary peak where it is more weakly polarized. The polarization degree is strongest during the primary minimum which is also the phase where an absorption feature has been identified previously (Pizzocaro et al. 2019). The polarization angle of the photons are consistent with a rotating vector model with a mode switch between the primary minimum and the rest of the rotation of the neutron star. We propose a scenario in which the emission at the source is weakly polarized (as in a condensed surface) and, as the radiation passes through a plasma arch, resonant cyclotron scattering off of protons produces the observed polarized radiation. This confirms the magnetar nature of the source with a surface field greater than about 1015 G, Comment: 13 pages, 13 figures, 5 tables
Published: 2023

42. Experimental Evidence for Non-spherical Magnetic Form Factor in Ru$^{3+}$

Author: Sarkis, Colin L., Villanova, John W., Eichstaedt, Casey, Eguiluz, Adolfo G., Fernandez-Baca, Jaime A., Matsuda, Masaaki, Yan, Jiaqiang, Balz, Christian, Banerjee, Arnab, Tennant, D. Alan, Berlijn, Tom, and Nagler, Stephen E.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: The Mott insulator $\alpha$-RuCl$_3$ has generated great interest in the community due to its possible field-induced Kitaev quantum spin liquid state. Despite enormous effort spent trying to obtain the form of the low energy Hamiltonian, there is currently no agreed upon set of parameters which is able to explain all of the data. A key piece of missing information lies in the determination of the magnetic form factor of Ru$^{3+}$, particularly for a true quantitative treatment of inelastic neutron scattering data. Here we present the experimentally derived magnetic form factor of Ru$^{3+}$ in the low spin 4$d^5$ state using polarized neutron diffraction within the paramagnetic regime on high quality single crystals of $\alpha$-RuCl$_3$. We observe strong evidence of an anisotropic form factor, expected of the spin-orbit coupled $j_{\textrm{eff}} = \frac{1}{2}$ ground state. We model the static magnetization density in increasing complexity from simple isotropic cases, to a multipolar expansion, and finally \emph{ab initio} calculations of the generalized $j_{\textrm{eff}} = \frac{1}{2}$ ground state. Comparison of both single ion models and inclusion of Cl$^-$ anions support the presence of hybridization of Ru$^{3+}$ with the surrounding Cl$^{-}$ ligands.
Published: 2023

43. Dynamics of nonequilibrium magnons in gapped Heisenberg antiferromagnets

Author: Hua, Chengyun, Lindsay, Lucas, Shinohara, Yuya, and Tennant, David Alan
Subjects: Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Quantum Gases
Abstract: Nonequilibrium dynamics in spin systems is a topic currently under intense investigation as it provides fundamental insights into thermalization, universality, and exotic transport phenomena. While most of the studies have been focused on ideal closed quantum many-body systems such as ultracold atomic quantum gases and one-dimensional spin chains, driven-dissipative Bose gases in steady states away from equilibrium in classical systems also lead to intriguing nonequilibrium physics. In this work, we theoretically investigate out-of-equilibrium dynamics of magnons in a gapped Heisenberg quantum antiferromagnet based on Boltzmann transport theory. We show that, by treating scattering terms beyond the relaxation time approximation in the Boltzmann transport equation, energy and particle number conservation mandate that nonequilibrium magnons cannot relax to equilibrium, but decay to other nonequilibrium stationary states, partially containing information about the initial states. The only decay channel for these stationary states back to equilibrium is through the non-conserving interactions such as boundary or magnon-phonon scattering. At low temperatures, these non-conserving interactions are much slower processes than intrinsic magnon-magnon interaction in a gapped spin system. Using magnon-phonon interaction as a quintessential type of non-conserving interaction, we then propose that nonequilibrium steady states of magnons can be maintained and tailored using periodic driving at frequencies faster than relaxation due to phonon interactions. These findings reveal a class of classical material systems that are suitable platforms to study nonequilibrium statistical physics and macroscopic phenomena such as classical Bose-Einstein condensation of quasiparticles and magnon supercurrents that are relevant for spintronic applications.
Published: 2023

44. Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-ray Polarimetry Explorer

Author: Marshall, Herman L., Liodakis, Ioannis, Marscher, Alan P., Di Lalla, Niccolo, Jorstad, Svetlana G., Kim, Dawoon E., Middei, Riccardo, Negro, Michela, Omodei, Nicola, Peirson, Abel L., Perri, Matteo, Puccetti, Simonetta, Agudo, Ivan, Bonnoli, Giacomo, Berdyugin, Andrei V., Cavazzuti, Elisabetta, Cavero, Nicole Rodriguez, Donnarumma, Immacolata, Di Gesu, Laura, Jormanainen, Jenni, Krawczynski, Henric, Lindfors, Elina, Marin, Frederic, Massaro, Francesco, Pacciani, Luigi, Poutanen, Juri, Tavecchio, Fabrizio, Kouch, Pouya M., Aceituno, Francisco Jose, Bernardos, Maria I., Casanova, Victor, Garcia-Comas, Maya, Agis-Gonzalez, Beatriz, Husillos, Cesar, Marchini, Alessandro, Sota, Alfredo, Blinov, Dmitry, Bourbah, Ioakeim G., Kielhmann, Sebastian, Kontopodis, Evangelos, Mandarakas, Nikos, Romanopoulos, Stylianos, Skalidis, Raphael, Vervelaki, Anna, Borman, George A., Kopatskaya, Evgenia N., Larionova, Elena G., Morozova, Daria A., Savchenko, Sergey S., Vasilyev, Andrey A., Zhovtan, Alexey V., Casadio, Carolina, Escudero, Juan, Kramer, Joana, Myserlis, Ioannis, Trainou, Efthalia, Imazawa, Ryo, Sasada, Mahito, Fukazawa, Yasushi, Kawabata, Koji S., Uemura, Makoto, Mizuno, Tsunefumi, Nakaoka, Tatsuya, Akitaya, Hiroshi, Masiero, Joseph R., Mawet, Dimitri, Millar-Blanchaer, Maxwell A., Panopoulou, Georgia V., Tinyanont, Samaporn, Kagitani, Masato, Kravtsov, Vadim, Sakanoi, Takeshi, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolo, Capitanio, Fiamma, Castellano, Simone, Chen, Chen-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Marco, Alessandro, Doroshenko, Victor, Dovvciak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marinucci, Andrea, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Ng, C. -Y., ODell, Stephen L., Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$\sigma$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polarizations favor models where the X-ray band is dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our contemporaneous multiwavelength polarization campaigns., Comment: 19 pages, 10 figures, 6 tables; submitted to the Astrophysical Journal
Published: 2023

45. IXPE observation confirms a high spin in the accreting black hole 4U 1957+115

Author: Marra, L., Brigitte, M., Cavero, N. Rodriguez, Chun, S., Steiner, J. F., Dovčiak, M., Nowak, M., Bianchi, S., Capitanio, F., Ingram, A., Matt, G., Muleri, F., Podgorný, J., Poutanen, J., Svoboda, J., Taverna, R., Ursini, F., Veledina, A., De Rosa, A., Garcia, J. A., Lutovinov, A. A., Mereminskiy, I. A., Farinelli, R., Gunji, S., Kaaret, P., Kallman, T., Krawczynski, H., Kan, Y., Hu, K., Marinucci, A., Mastroserio, G., Mikušincová, R., Parra, M., Petrucci, P. O., Ratheesh, A., Soffitta, P., Tombesi, F., Zane, S., Agudo, I., Antonelli, L. A., Bachetti, M., Baldini, L., Baumgartner, W. H., Bellazzini, R., Bongiorno, S. D., Bonino, R., Brez, A., Bucciantini, N., Castellano, S., Cavazzuti, E., Chen, C., Ciprini, S., Costa, E., Del Monte, E., Di Gesu, L., Di Lalla, N., Di Marco, A., Donnarumma, I., Doroshenko, V., Ehlert, S. R., Enoto, T., Evangelista, Y., Fabiani, S., Ferrazzoli, R., Hayashida, K., Heyl, J., Iwakiri, W., Jorstad, S. G., Karas, V., Kislat, F., Kitaguchi, T., Kolodziejczak, J. J., La Monaca, F., Latronico, L., Liodakis, I., Maldera, S., Manfreda, A., Marin, F., Marscher, A. P., Marshall, H. L., Massaro, F., Mitsuishi, I., Mizuno, T., Negro, M., Ng, C. Y., O'Dell, S. L., Omodei, N., Oppedisano, C., Papitto, A., Pavlov, G. G., Peirson, A. L., Perri, M., Pesce-Rollins, M., Pilia, M., Possenti, A., Puccetti, S., Ramsey, B. D., Rankin, J., Roberts, O. J., Romani, R. W., Sgro, C., Slane, P., Spandre, G., Swartz, D. A., Tamagawa, T., Tavecchio, F., Tawara, Y., Tennant, A. F., Thomas, N. E., Trois, A., Tsygankov, S. S., Turolla, R., Vink, J., Weisskopf, M. C., Wu, K., and Xie, F.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the results of the first X-ray polarimetric observation of the low-mass X-ray binary 4U 1957+115, performed with the Imaging X-ray Polarimetry Explorer in May 2023. The binary system has been in a high-soft spectral state since its discovery and is thought to host a black hole. The $\sim$571 ks observation reveals a linear polarisation degree of $1.9\% \pm 0.6\%$ and a polarisation angle of $-41^\circ.8 \pm 7^\circ.9$ in the 2-8 keV energy range. Spectral modelling is consistent with the dominant contribution coming from the standard accretion disc, while polarimetric data suggest a significant role of returning radiation: photons that are bent by strong gravity effects and forced to return to the disc surface, where they can be reflected before eventually reaching the observer. In this setting, we find that models with a black hole spin lower than 0.96 and an inclination lower than $50^\circ$ are disfavoured., Comment: 12 pages, 10 figures, 2 tables, accepted for publication in A&A
Published: 2023

46. Implementation of a laser-neutron pump-probe capability at HYSPEC

Author: Hua, Chengyun, Tennant, David A., Savici, Andrei, Sedov, Vladislav, Sala, Gabriele, and Winn, Barry
Subjects: Condensed Matter - Materials Science, Physics - Instrumentation and Detectors
Abstract: Exciting new fundamental scientific questions are currently being raised regarding nonequilibrium dynamics in spin systems, as this directly relates to low power and low loss energy transport for spintronics. Inelastic neutron scattering (INS) is an indispensable tool to study spin excitations in complex magnetic materials. However, conventional INS spectrometers currently only perform steady-state measurements and probe averaged properties over many collision events between spin excitations in thermodynamic equilibrium, while the exact picture of re-equilibration of these excitations remains unknown. In this work, we designed and implemented a time-resolved laser-neutron pump-probe capability at HYSPEC (Hybrid Spectrometer, beamline 14-B) at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. This capability allows us to excite out-of-equilibrium magnons with a nanosecond pulsed laser source and probe the resulting dynamics using INS. Here, we discussed technical aspects to implement such a capability in a neutron beamline, including choices of suitable neutron instrumentation and material systems, laser excitation scheme, experimental configurations, and relevant firmware and software development to allow for time-synchronized pump-probe measurements. We demonstrated that the laser-induced nonequilibrium structural factor is able to be resolved by INS in a quantum magnet. The method developed in this work will provide SNS with advanced capabilities for performing out-of-equilibrium measurements, opening up an entirely new research direction to study out-of-equilibrium phenomena using neutrons.
Published: 2023

47. Discovery of a variable energy-dependent X-ray polarization in the accreting neutron star GX 5-1

Author: Fabiani, Sergio, Capitanio, Fiamma, Iaria, Rosario, Poutanen, Juri, Gnarini, Andrea, Ursini, Francesco, Farinelli, Ruben, Bobrikova, Anna, Steiner, James F., Svoboda, Jiri, Anitra, Alessio, Baglio, Maria C., Carotenuto, Francesco, Del Santo, Melania, Ferrigno, Carlo, Lewis, Fraser, Russell, David M., Russell, Thomas D., Eijnden, Jakob van den, Cocchi, Massimo, Di Marco, Alessandro, La Monaca, Fabio, Liu, Kuan, Rankin, John, Weisskopf, Martin C., Xie, Fei, Bianchi, Stefano, Burderi, Luciano, Di Salvo, Tiziana, Egron, Elise, Illiano, Giulia, Kaaret, Philip, Matt, Giorgio, Mikušincová, Romana, Muleri, Fabio, Papitto, Alessandro, Agudo, Iván, Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, Latronico, Luca, Liodakis, Ioannis, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marscher, Alan P., Marshall, Herman L., Massaro, Francesco, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Negro, Michela, Ng, Chi-Yung, O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Puccetti, Simonetta, Ramsey, Brian D., Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Tavecchio, Fabrizio, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Wu, Kinwah, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the coordinated observations of the neutron star low-mass X-ray binary (NS-LMXB) \gx in X-rays (IXPE, NICER, Nustar and INTEGRAL), optical (REM and LCO), near-infrared (REM), mid-infrared (VLT VISIR), and radio (ATCA). This Z-source was observed by \IXPE twice in March-April 2023 (Obs. 1 and 2). In the radio band, the source was detected, but only upper-limits to the linear polarization were obtained at a $3\sigma$ level of $6.1\%$ at 5.5 GHz and $5.9\%$ at 9 GHz in Obs.~1 and $12.5\%$ at 5.5~GHz and $20\%$ at 9~GHz in Obs.~2. The mid-IR, near-IR and optical observations suggest the presence of a compact jet which peaks in the mid- or far-IR. The X-ray polarization degree was found to be $3.7\% \pm 0.4 \%$ (at $90\%$ confidence level) during Obs.~1 when the source was in the horizontal branch of the Z-track and $1.8\% \pm 0.4 \%$ during Obs.~2 when the source was in the normal-flaring branch. These results confirm the variation of polarization degree as a function of the position of the source in the color-color diagram as for previously observed Z-track sources (Cyg~X-2 and XTE~1701$-$462). Evidence for a variation of the polarization angle $\sim 20^\circ$ with energy is found in both observations, likely related to the different, non-orthogonal polarization angles of the disk and Comptonization components which peak at different energies., Comment: Submitted to Astronomy and Astrophysics on 06 July 2023. Accepted on 21 November 2023
Published: 2023

48. Cup Stacking in Graphs

Author: Fay, Paul, Hurlbert, Glenn, and Tennant, Maya
Subjects: Mathematics - Combinatorics, 05C99 (Primary) 05C85, 05C70 (Secondary)
Abstract: Here we introduce a new game on graphs, called cup stacking, following a line of what can be considered as $0$-, $1$-, or $2$-person games such as chip firing, percolation, graph burning, zero forcing, cops and robbers, graph pebbling, and graph pegging, among others. It can be more general, but the most basic scenario begins with a single cup on each vertex of a graph. (This simplification coincides with an earlier game devised by Gordon Hamilton.) For a vertex with $k$ cups on it we can move all its cups to a vertex at distance $k$ from it, provided the second vertex already has at least one cup on it. The object is to stack all cups onto some pre-described target vertex. We say that a graph is stackable if this can be accomplished for all possible target vertices. In this paper we study cup stacking on many families of graphs, developing a characterization of stackability in graphs and using it to prove the stackability of complete graphs, paths, cycles, grids, the Petersen graph, many Kneser graphs, some trees, cubes of dimension up to 20, "somewhat balanced" complete $t$-partite graphs, and Hamiltonian diameter two graphs. Additionally we use the Gallai-Edmonds Structure Theorem, the Edmonds Blossom Algorithm, and the Hungarian algorithm to devise a polynomial algorithm to decide if a diameter two graph is stackable. Our proof that cubes up to dimension 20 are stackable uses Kleitman's Symmetric Chain Decomposition and the new result of Merino, M\"utze, and Namrata that all generalized Johnson graphs (excluding the Petersen graph) are Hamiltonian. We conjecture that all cubes and higher-dimensional grids are stackable, and leave the reader with several open problems, questions, and generalizations., Comment: Revision including original sources
Published: 2023

49. Magnetic Field Properties inside the Jet of Mrk 421: Multiwavelength Polarimetry Including the Imaging X-ray Polarimetry Explorer

Author: Kim, Dawoon E., Di Gesu, Laura, Liodakis, Ioannis, Marscher, Alan P., Jorstad, Svetlana G., Midde, Riccardo, Marshall, Herman L., Pacciani, Luigi, Agudo, Iván, Tavecchio, Fabrizio, Cibrario, Nicolò, Tugliani, Stefano, Bonino, Raffaella, Negro, Michela, Puccetti, Simonetta, Tombesi, Francesco, Costa, Enrico, Donnarumma, Immacolata, Soffitta, Paolo, Mizuno, Tsunefumi, Fukazawa, Yasushi, Kawabata, Koji S., Nakaoka, Tatsuya, Uemura, Makoto, Imazawa, Ryo, Sasada, Mahito, Akitaya, Hiroshi, Aceituno, Francisco Josè, Bonnoli, Giacomo, Casanova, Vìctor, Myserlis, Ioannis, Sievers, Albrecht, Angelakis, Emmanouil, Kraus, Alexander, Cheong, Whee Yeon, Jeong, Hyeon-Woo, Kang, Sincheol, Kim, Sang-Hyun, Lee, Sang-Sung, Agìs-Gonzàlez, Beatriz, Sota, Alfredo, Escudero, Juan, Gurwell, Mark, Keating, Garrett K., Rao, Ramprasad, Kouch, Pouya M., Lindfors, Elina, Bourbah, Ioakeim G., Kiehlmann, Sebastian, Kontopodis, Evangelos, Mandarakas, Nikos, Romanopoulos, Stylianos, Skalidis, Raphael, Vervelaki, Anna, Savchenko, Sergey S., Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, De Rosa, Alessandra, Del Monte, Ettore, Di Lalla, Niccolò, Di Marco, Alessandro, Doroshenko, Victor, Dovčiak, Michal, Ehlert, Steven R., Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Muleri, Fabio, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver, Romani, Roger W., Sgrò, Carmelo, Slane, Patrick, Spandre, Gloria, Swartz, Doug, Tamagawa, Toru, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measurements on 2022 December 6-8. We detected X-ray polarization of Mrk 421 with a degree of $\Pi_{\rm X}$=14$\pm$1$\%$ and an electric-vector position angle $\psi_{\rm X}$=107$\pm$3$^{\circ}$ in the 2-8 keV band. From the time variability analysis, we find a significant episodic variation in $\psi_{\rm X}$. During 7 months from the first IXPE pointing of Mrk 421 in 2022 May, $\psi_{\rm X}$ varied across the range of 0$^{\circ}$ to 180$^{\circ}$, while $\Pi_{\rm X}$ maintained similar values within $\sim$10-15$\%$. Furthermore, a swing in $\psi_{\rm X}$ in 2022 June was accompanied by simultaneous spectral variations. The results of the multiwavelength polarimetry show that the X-ray polarization degree was generally $\sim$2-3 times greater than that at longer wavelengths, while the polarization angle fluctuated. Additionally, based on radio, infrared, and optical polarimetry, we find that rotation of $\psi$ occurred in the opposite direction with respect to the rotation of $\psi_{\rm X}$ over longer timescales at similar epochs. The polarization behavior observed across multiple wavelengths is consistent with previous IXPE findings for HSP blazars. This result favors the energy-stratified shock model developed to explain variable emission in relativistic jets. The accompanying spectral variation during the $\psi_{\rm X}$ rotation can be explained by a fluctuation in the physical conditions, e.g., in the energy distribution of relativistic electrons. The opposite rotation direction of $\psi$ between the X-ray and longer-wavelength polarization accentuates the conclusion that the X-ray emitting region is spatially separated from that at longer wavelengths., Comment: 17 pages, 13 figures, 4 tables; Accepted for publication in A&A
Published: 2023
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50. X-ray Polarization of the BL Lac Type Blazar 1ES 0229+200

Author: Ehlert, Steven R., Liodakis, Ioannis, Middei, Riccardo, Marscher, Alan P., Tavecchio, Fabrizio, Agudo, Iván, Kouch, Pouya M., Lindfors, Elina, Nilsson, Kari, Myserlis, Ioannis, Gurwell, Mark, Rao, Ramprasad, Aceituno, Francisco Jose, Bonnoli, Giacomo, Casanova, Victor, Agiz-Gonzalez, Beatriz, Escudero, Juan, Santos, Jorge Otero, Sota, Alfredo, Angelakis, Emmanouil, Kraus, Alexander, Keating, Garrett K., Antonelli, Lucio A., Bachetti, Matteo, Baldini, Luca, Baumgartner, Wayne H., Bellazzini, Ronaldo, Bianchi, Stefano, Bongiorno, Stephen D., Bonino, Raffaella, Brez, Alessandro, Bucciantini, Niccolò, Capitanio, Fiamma, Castellano, Simone, Cavazzuti, Elisabetta, Chen, Chien-Ting, Ciprini, Stefano, Costa, Enrico, De Rosa, Alessandra, Del Monte, Ettore, Di Gesu, Laura, Di Lalla, Niccolò, Di Marco, Alessandro, Donnarumma, Immacolata, Doroshenko, Victor, Dovčiak, Michal, Enoto, Teruaki, Evangelista, Yuri, Fabiani, Sergio, Ferrazzoli, Riccardo, Garcia, Javier A., Gunji, Shuichi, Hayashida, Kiyoshi, Heyl, Jeremy, Iwakiri, Wataru, Jorstad, Svetlana G., Kaaret, Philip, Karas, Vladimir, Kislat, Fabian, Kitaguchi, Takao, Kolodziejczak, Jeffery J., Krawczynski, Henric, La Monaca, Fabio, Latronico, Luca, Maldera, Simone, Manfreda, Alberto, Marin, Frédéric, Marinucci, Andrea, Marshall, Herman L., Massaro, Francesco, Matt, Giorgio, Mitsuishi, Ikuyuki, Mizuno, Tsunefumi, Muleri, Fabio, Negro, Michela, Ng, C. -Y., O'Dell, Stephen L., Omodei, Nicola, Oppedisano, Chiara, Papitto, Alessandro, Pavlov, George G., Peirson, Abel L., Perri, Matteo, Pesce-Rollins, Melissa, Petrucci, Pierre-Olivier, Pilia, Maura, Possenti, Andrea, Poutanen, Juri, Puccetti, Simonetta, Ramsey, Brian D., Rankin, John, Ratheesh, Ajay, Roberts, Oliver J., Romani, Roger W., Sgro, Carmelo, Slane, Patrick, Soffitta, Paolo, Spandre, Gloria, Swartz, Douglas A., Tamagawa, Toru, Taverna, Roberto, Tawara, Yuzuru, Tennant, Allyn F., Thomas, Nicholas E., Tombesi, Francesco, Trois, Alessio, Tsygankov, Sergey S., Turolla, Roberto, Vink, Jacco, Weisskopf, Martin C., Wu, Kinwah, Xie, Fei, and Zane, Silvia
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present polarization measurements in the $2-8 \thinspace \mathrm{keV}$ band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be $\Pi_{X} = 17.9 \pm 2.8 \%$ at an electric-vector position angle $\psi_X = 25.0 \pm 4.6^{\circ}$ using a spectropolarimetric fit from joint IXPE and XMM-Newton observations. There is no evidence for the polarization degree or angle varying significantly with energy or time on both short time scales (hours) or longer time scales (days). The contemporaneous polarization degree at optical wavelengths was $>$7$\times$ lower, making 1ES 0229+200 the most strongly chromatic blazar yet observed. This high X-ray polarization compared to the optical provides further support that X-ray emission in high-peaked blazars originates in shock-accelerated, energy-stratified electron populations, but is in tension with many recent modeling efforts attempting to reproduce the spectral energy distribution of 1ES 0229+200 which attribute the extremely high energy synchrotron and Compton peaks to Fermi acceleration in the vicinity of strongly turbulent magnetic fields., Comment: 17 Pages, 6 Figures, Resubmitted to ApJ after addressing referee comments
Published: 2023

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