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8 results on '"R. Hložek"'

1. Results of the Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC)

Author

R. Hložek, A. I. Malz, K. A. Ponder, M. Dai, G. Narayan, E. E. O. Ishida, T. Allam Jr, A. Bahmanyar, X. Bi, R. Biswas, K. Boone, S. Chen, N. Du, A. Erdem, L. Galbany, A. Garreta, S. W. Jha, D. O. Jones, R. Kessler, M. Lin, J. Liu, M. Lochner, A. A. Mahabal, K. S. Mandel, P. Margolis, J. R. Martínez-Galarza, J. D. McEwen, D. Muthukrishna, Y. Nakatsuka, T. Noumi, T. Oya, H. V. Peiris, C. M. Peters, J. F. Puget, C. N. Setzer, Siddhartha, S. Stefanov, T. Xie, L. Yan, K.-H. Yeh, and W. Zuo

Subjects
Astrostatistics, Observational cosmology, Transient detection, Astronomy software, Astrophysics, QB460-466
Abstract

Next-generation surveys like the Legacy Survey of Space and Time (LSST) on the Vera C. Rubin Observatory (Rubin) will generate orders of magnitude more discoveries of transients and variable stars than previous surveys. To prepare for this data deluge, we developed the Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC), a competition that aimed to catalyze the development of robust classifiers under LSST-like conditions of a nonrepresentative training set for a large photometric test set of imbalanced classes. Over 1000 teams participated in PLAsTiCC, which was hosted in the Kaggle data science competition platform between 2018 September 28 and 2018 December 17, ultimately identifying three winners in 2019 February. Participants produced classifiers employing a diverse set of machine-learning techniques including hybrid combinations and ensemble averages of a range of approaches, among them boosted decision trees, neural networks, and multilayer perceptrons. The strong performance of the top three classifiers on Type Ia supernovae and kilonovae represent a major improvement over the current state of the art within astronomy. This paper summarizes the most promising methods and evaluates their results in detail, highlighting future directions both for classifier development and simulation needs for a next-generation PLAsTiCC data set.

Published
2023
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2. Superclustering with the Atacama Cosmology Telescope and Dark Energy Survey. I. Evidence for Thermal Energy Anisotropy Using Oriented Stacking

Author

M. Lokken, R. Hložek, A. van Engelen, M. Madhavacheril, E. Baxter, J. DeRose, C. Doux, S. Pandey, E. S. Rykoff, G. Stein, C. To, T. M. C. Abbott, S. Adhikari, M. Aguena, S. Allam, F. Andrade-Oliveira, J. Annis, N. Battaglia, G. M. Bernstein, E. Bertin, J. R. Bond, D. Brooks, E. Calabrese, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, R. Cawthon, A. Choi, M. Costanzi, M. Crocce, L. N. da Costa, M. E. da Silva Pereira, J. De Vicente, S. Desai, J. P. Dietrich, J. Dunkley, S. Ferraro, P. A. Gallardo, and E. J. Wollack

Subjects
Astrophysics
Abstract

The cosmic web contains filamentary structure on a wide range of scales. On the largest scales, superclustering aligns multiple galaxy clusters along intercluster bridges, visible through their thermal Sunyaev–Zel'dovich signal in the cosmic microwave background. We demonstrate a new, flexible method to analyze the hot gas signal from multiscale extended structures. We use a Compton y-map from the Atacama Cosmology Telescope (ACT) stacked on redMaPPer cluster positions from the optical Dark Energy Survey (DES). Cutout images from the y-map are oriented with large-scale structure information from DES galaxy data such that the superclustering signal is aligned before being overlaid. We find evidence of an extended quadrupole moment of the stacked y signal at the 3.5σ level, demonstrating that the large-scale thermal energy surrounding galaxy clusters is anisotropically distributed. We compare our ACT × DES results with the Buzzard simulations, finding broad agreement. Using simulations, we highlight the promise of this novel technique for constraining the evolution of anisotropic, non-Gaussian structure using future combinations of microwave and optical surveys.

Published
2022
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4. The Atacama Cosmology Telescope: Probing the baryon content of SDSS DR15 galaxies with the thermal and kinematic Sunyaev-Zel’dovich effects

Author

Nick Battaglia, J. P. Hughes, K. Moodley, Erminia Calabrese, Leila R. Vale, David N. Spergel, Michael D. Niemack, Nicholas F. Cothard, R. Hložek, Victoria Calafut, Eve M. Vavagiakis, Lyman A. Page, Rachel Bean, B. Partridge, Shannon M. Duff, S. Ferraro, M. Hilton, J. A. Beall, Gene C. Hilton, Kevin M. Huffenberger, Simone Aiola, Y. Guan, J. R. Bond, Jason E. Austermann, Sigurd Naess, C. Sifon, A. van Engelen, A. Kosowsky, E. Schaan, M. Lokken, J. C. Hill, L. B. Newburgh, S. T. Staggs, Cody J. Duell, Yaqiong Li, J. Van Lanen, Zachary B. Huber, Joel N. Ullom, Alessandro Schillaci, S. Amodeo, Edward J. Wollack, F. Nati, Johannes Hubmayr, Mark J. Devlin, Patricio A. Gallardo, A. J. Duivenvoorden, R. Dunner, Jo Dunkley, Elia S. Battistelli, Steve K. Choi, M. Madhavacheril, Zhilei Xu, Brian J. Koopman, Jeff McMahon, Vavagiakis, E, Gallardo, P, Calafut, V, Amodeo, S, Aiola, S, Austermann, J, Battaglia, N, Battistelli, E, Beall, J, Bean, R, Bond, J, Calabrese, E, Choi, S, Cothard, N, Devlin, M, Duell, C, Duff, S, Duivenvoorden, A, Dunkley, J, Dunner, R, Ferraro, S, Guan, Y, Hill, J, Hilton, G, Hilton, M, Hlozek, R, Huber, Z, Hubmayr, J, Huffenberger, K, Hughes, J, Koopman, B, Kosowsky, A, Li, Y, Lokken, M, Madhavacheril, M, Mcmahon, J, Moodley, K, Naess, S, Nati, F, Newburgh, L, Niemack, M, Page, L, Partridge, B, Schaan, E, Schillaci, A, Sifon, C, Spergel, D, Staggs, S, Ullom, J, Vale, L, Van Engelen, A, Van Lanen, J, Wollack, E, and Xu, Z

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Cosmic microwave background, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Atomic, 01 natural sciences, Luminosity, Particle and Plasma Physics, Galaxy groups and clusters, 0103 physical sciences, Optical depth (astrophysics), CMB, Cosmology, SZ Effect, Nuclear, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Quantum Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Molecular, Nuclear & Particles Physics, Galaxy, Baryon, 13. Climate action, Atacama Cosmology Telescope, Content (measure theory), astro-ph.CO, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present high signal-to-noise measurements (up to 12$\sigma$) of the average thermal Sunyaev Zel'dovich (tSZ) effect from optically selected galaxy groups and clusters and estimate their baryon content within a 2.1$^\prime$ radius aperture. Sources from the Sloan Digital Sky Survey (SDSS) Baryon Oscillation Spectroscopic Survey (BOSS) DR15 catalog overlap with 3,700 sq. deg. of sky observed by the Atacama Cosmology Telescope (ACT) from 2008 to 2018 at 150 and 98 GHz (ACT DR5), and 2,089 sq. deg. of internal linear combination component-separated maps combining ACT and $\it{Planck}$ data (ACT DR4). The corresponding optical depths, $\bar{\tau}$, which depend on the baryon content of the halos, are estimated using results from cosmological hydrodynamic simulations assuming an AGN feedback radiative cooling model. We estimate the mean mass of the halos in multiple luminosity bins, and compare the tSZ-based $\bar{\tau}$ estimates to theoretical predictions of the baryon content for a Navarro-Frenk-White profile. We do the same for $\bar{\tau}$ estimates extracted from fits to pairwise baryon momentum measurements of the kinematic Sunyaev-Zel'dovich effect (kSZ) for the same data set obtained in a companion paper. We find that the $\bar{\tau}$ estimates from the tSZ measurements in this work and the kSZ measurements in the companion paper agree within $1\sigma$ for two out of the three disjoint luminosity bins studied, while they differ by 2-3$\sigma$ in the highest luminosity bin. The optical depth estimates account for one third to all of the theoretically predicted baryon content in the halos across luminosity bins. Potential systematic uncertainties are discussed. The tSZ and kSZ measurements provide a step towards empirical Compton-$\bar{y}$-$\bar{\tau}$ relationships to provide new tests of cluster formation and evolution models., Comment: 19 pages, 9 figures

Published
2021

5. The Atacama Cosmology Telescope: Detection of the pairwise kinematic Sunyaev-Zel’dovich effect with SDSS DR15 galaxies

Author

C. Sifon, S. T. Staggs, E. Schaan, Brian J. Koopman, Edward J. Wollack, M. Lokken, Jeff McMahon, Michael D. Niemack, Johannes Hubmayr, A. van Engelen, Mark J. Devlin, Patricio A. Gallardo, A. Kosowsky, Nicholas F. Cothard, Victoria Calafut, Elia S. Battistelli, Yaqiong Li, Nick Battaglia, J. Van Lanen, Joel N. Ullom, M. Hilton, Kevin M. Huffenberger, David N. Spergel, F. Nati, Zhilei Xu, Gene C. Hilton, Y. Guan, Alessandro Schillaci, Erminia Calabrese, Jason E. Austermann, Jo Dunkley, Zachary B. Huber, A. J. Duivenvoorden, S. Amodeo, K. Moodley, Leila R. Vale, R. Hložek, Eve M. Vavagiakis, R. Dunner, M. Madhavacheril, Steve K. Choi, Sigurd Naess, J. P. Hughes, J. C. Hill, J. R. Bond, Shannon M. Duff, S. Ferraro, Cody J. Duell, Rachel Bean, B. Partridge, J. A. Beall, L. B. Newburgh, Lyman A. Page, Simone Aiola, Calafut, V, Gallardo, P, Vavagiakis, E, Amodeo, S, Aiola, S, Austermann, J, Battaglia, N, Battistelli, E, Beall, J, Bean, R, Bond, J, Calabrese, E, Choi, S, Cothard, N, Devlin, M, Duell, C, Duff, S, Duivenvoorden, A, Dunkley, J, Dunner, R, Ferraro, S, Guan, Y, Hill, J, Hilton, G, Hilton, M, Hlozek, R, Huber, Z, Hubmayr, J, Huffenberger, K, Hughes, J, Koopman, B, Kosowsky, A, Li, Y, Lokken, M, Madhavacheril, M, Mcmahon, J, Moodley, K, Naess, S, Nati, F, Newburgh, L, Niemack, M, Page, L, Partridge, B, Schaan, E, Schillaci, A, Sifon, C, Spergel, D, Staggs, S, Ullom, J, Vale, L, Van Engelen, A, Van Lanen, J, Wollack, E, and Xu, Z

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), media_common.quotation_subject, Cosmic microwave background, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Sunyaev–Zel'dovich effect, 01 natural sciences, Atomic, Cosmology, Photometry (optics), Galaxy groups and clusters, Particle and Plasma Physics, CMB, Cosmology, SZ Effect, 0103 physical sciences, Nuclear, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Physics, Quantum Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Molecular, Nuclear & Particles Physics, Galaxy, 13. Climate action, Sky, Atacama Cosmology Telescope, astro-ph.CO, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a 5.4$\sigma$ detection of the pairwise kinematic Sunyaev-Zel'dovich (kSZ) effect using Atacama Cosmology Telescope (ACT) and $\it{Planck}$ CMB observations in combination with Luminous Red Galaxy samples from the Sloan Digital Sky Survey (SDSS) DR15 catalog. Results are obtained using three ACT CMB maps: co-added 150 GHz and 98 GHz maps, combining observations from 2008-2018 (ACT DR5), which overlap with SDSS DR15 over 3,700 sq. deg., and a component-separated map using night-time only observations from 2014-2015 (ACT DR4), overlapping with SDSS DR15 over 2,089 sq. deg. Comparisons of the results from these three maps provide consistency checks in relation to potential frequency-dependent foreground contamination. A total of 343,647 galaxies are used as tracers to identify and locate galaxy groups and clusters from which the kSZ signal is extracted using aperture photometry. We consider the impact of various aperture photometry assumptions and covariance estimation methods on the signal extraction. Theoretical predictions of the pairwise velocities are used to obtain best-fit, mass-averaged, optical depth estimates for each of five luminosity-selected tracer samples. A comparison of the kSZ-derived optical depth measurements obtained here to those derived from the thermal SZ effect for the same sample is presented in a companion paper., Comment: 17 pages, 10 figures. Updated to match published version in PRD

Published
2021

7. The Photometric LSST Astronomical Time-series Classification Challenge PLAsTiCC: Selection of a Performance Metric for Classification Probabilities Balancing Diverse Science Goals.

Author

A. I. Malz, R. Hložek, T. Allam Jr, A. Bahmanyar, R. Biswas, M. Dai, L. Galbany, E. E. O. Ishida, S. W. Jha, D. O. Jones, R. Kessler, M. Lochner, A. A. Mahabal, K. S. Mandel, J. R. Martínez-Galarza, J. D. McEwen, D. Muthukrishna, G. Narayan, H. Peiris, and C. M. Peters

Published
2019
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8. Models and Simulations for the Photometric LSST Astronomical Time Series Classification Challenge (PLAsTiCC).

Author

R. Kessler, G. Narayan, A. Avelino, E. Bachelet, R. Biswas, P. J. Brown, D. F. Chernoff, A. J. Connolly, M. Dai, S. Daniel, R. Di Stefano, M. R. Drout, L. Galbany, S. González-Gaitán, M. L. Graham, R. Hložek, E. E. O. Ishida, J. Guillochon, S. W. Jha, and D. O. Jones

Subjects
LARGE Synoptic Survey Telescope, TIME series analysis, SIMULATION methods & models
Abstract

We describe the simulated data sample for the Photometric Large Synoptic Survey Telescope (LSST) Astronomical Time Series Classification Challenge (PLAsTiCC), a publicly available challenge to classify transient and variable events that will be observed by the LSST, a new facility expected to start in the early 2020s. The challenge was hosted by Kaggle, ran from 2018 September 28 to December 17, and included 1094 teams competing for prizes. Here we provide details of the 18 transient and variable source models, which were not revealed until after the challenge, and release the model libraries at https://doi.org/10.5281/zenodo.2612896. We describe the LSST Operations Simulator used to predict realistic observing conditions, and we describe the publicly available SNANA simulation code used to transform the models into observed fluxes and uncertainties in the LSST passbands (ugrizy). Although PLAsTiCC has finished, the publicly available models and simulation tools are being used within the astronomy community to further improve classification, and to study contamination in photometrically identified samples of SN Ia used to measure properties of dark energy. Our simulation framework will continue serving as a platform to improve the PLAsTiCC models, and to develop new models. [ABSTRACT FROM AUTHOR]

Published
2019
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