10 results on '"S. Colafrancesco"'
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2. The role of dark matter annihilation in the radio emission of the galaxy cluster A520
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Nthabiseng Khanye, Paolo Marchegiani, and S. Colafrancesco
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Dark matter ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Galaxy ,Radio spectrum ,Gravitational lens ,Radio halo ,Space and Planetary Science ,0103 physical sciences ,Neutralino ,Cluster (physics) ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Galaxy cluster - Abstract
A520 is a hot and luminous galaxy cluster, where gravitational lensing and X-ray measures reveal a different spatial distribution of baryonic and Dark Matter. This cluster hosts a radio halo, whose map shows a separation between the North-East and the South-West part of the cluster, similarly to what is observed in gravitational lensing maps. In this paper we study the possibility that the diffuse radio emission in this cluster is produced by Dark Matter annihilation. We find that in the whole cluster the radio emission should be dominated by baryonic phenomena; if a contribution from Dark Matter is present, it should be searched in a region in the NE part of the cluster, where a peak of the radio emission is located close to a Dark Matter sub-halo, in a region where the X-ray emission is not very strong. By estimating the radio spectrum integrated in this region using data from publicly available surveys, we find that this spectrum can be reproduced by a Dark Matter model for a neutralino with mass 43 GeV and annihilation final state $b \bar b$ for a magnetic field of 5 $\mu$G., Comment: 6 pages, 5 figures; accepted for publication in MNRAS
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- 2018
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3. The correlation between radio power and Mach number for radio relics in galaxy clusters
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S. Colafrancesco, Paolo Marchegiani, and C. M. Paulo
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,education.field_of_study ,Spectral index ,Shock (fluid dynamics) ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Population ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Electron ,Astrophysics ,01 natural sciences ,symbols.namesake ,Radio relics ,Mach number ,Space and Planetary Science ,0103 physical sciences ,symbols ,Astrophysics - High Energy Astrophysical Phenomena ,Adiabatic process ,education ,010303 astronomy & astrophysics ,Galaxy cluster - Abstract
We discuss a new technique to constrain models for the origin of radio relics in galaxy clusters using the correlation between the shock Mach number and the radio power of relics. This analysis is carried out using a sample of relics with information on both the Mach numbers derived from X-ray observation, $\mathcal{M}_X$, and using spectral information from radio observations of the peak and the average values of the spectral index along the relic, $\mathcal{M}_R$. We find that there is a lack of correlation between $\mathcal{M}_X$ and $\mathcal{M}_R$; this result is an indication that the spectral index of the relic is likely not due to the acceleration of particles operated by the shock but it is related to the properties of a fossil electrons population. We also find that the available data on the correlation between the radio power $P_{1.4}$ and Mach numbers ($\mathcal{M}_R$ and $\mathcal{M}_X$) in relics indicate that neither the DSA nor the adiabatic compression can simply reproduce the observed $P_{1.4}-\mathcal{M}$ correlations. Furthermore, we find that the radio power is not correlated with $\mathcal{M}_X$, whereas it is not possible to exclude a correlation with $\mathcal{M}_R$. This also indicates that the relic power is mainly determined by the properties of a fossil electron population rather than by the properties of the shock. Our results require either to consider models of shock (re)acceleration that go beyond the proposed scenarios of DSA and adiabatic compression at shocks, or to reconsider the origin of radio relics in terms of other physical scenarios., 14 pages, 8 figures. MNRAS, in press
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- 2017
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4. Effect of the non-thermal Sunyaev–Zel'dovich effect on the temperature determination of galaxy clusters
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P. Marchegiani and S. Colafrancesco
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Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,galaxies: clusters: intracluster medium ,Cosmic background radiation ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Electron ,Astrophysics ,Sunyaev–Zel'dovich effect ,01 natural sciences ,Momentum ,symbols.namesake ,0103 physical sciences ,Cluster (physics) ,Planck ,010303 astronomy & astrophysics ,Galaxy cluster ,Physics ,galaxies: clusters: general ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Plasma ,Space and Planetary Science ,symbols ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
A recent stacking analysis of Planck HFI data of galaxy clusters (Hurier 2016) allowed to derive the cluster temperatures by using the relativistic corrections to the Sunyaev-Zel'dovich effect (SZE). However, the temperatures of high-temperature clusters, as derived from this analysis, resulted to be basically higher than the temperatures derived from X-ray measurements, at a moderate statistical significance of $1.5\sigma$. This discrepancy has been attributed by Hurier (2016) to calibration issues. In this paper we discuss an alternative explanation for this discrepancy in terms of a non-thermal SZE astrophysical component. We find that this explanation can work if non-thermal electrons in galaxy clusters have a low value of their minimum momentum ($p_1\sim0.5-1$), and if their pressure is of the order of $20-30\%$ of the thermal gas pressure. Both these conditions are hard to obtain if the non-thermal electrons are mixed with the hot gas in the intra cluster medium, but can be possibly obtained if the non-thermal electrons are mainly confined in bubbles with high content of non-thermal plasma and low content of thermal plasma, or in giant radio lobes/relics located in the outskirts of clusters. In order to derive more precise results on the properties of non-thermal electrons in clusters, and in view of more solid detections of a discrepancy between X-rays and SZE derived clusters temperatures that cannot be explained in other ways, it would be necessary to reproduce the full analysis done by Hurier (2016) by adding systematically the non-thermal component of the SZE., Comment: MNRAS, in press; 5 pages, 1 figure
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- 2017
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5. OUP accepted manuscript
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N. Shafi, S. A. Thwala, Federica Govoni, Matteo Murgia, and S. Colafrancesco
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Physics ,Space and Planetary Science ,Sky ,Radio galaxy ,media_common.quotation_subject ,Astronomy ,Metre ,Astronomy and Astrophysics ,LOFAR ,media_common - Published
- 2019
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6. VHE γ-ray discovery and multi-wavelength study of the blazar 1ES 2322-409
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M. Zacharias, Marek Jamrozy, Jim Hinton, A. Schulz, R. Tuffs, R. Simoni, Dmitry Khangulyan, D. A. Sanchez, Helene Sol, H. Ndiyavala, S. Bernhard, J. Devin, M. Böttcher, F. Ait Benkhali, S. Eschbach, C. Stegmann, Nu. Komin, M. Holler, B. van Soelen, Gerd Puehlhofer, F. Jankowsky, J. Veh, D. J. van der Walt, M. Fuessling, M. Lemoine-Goumard, M.A. Kastendieck, S. Bonnefoy, Axel Donath, A. W. Chen, I. Shilon, T. Tavernier, G. Emery, Matteo Cerruti, Michael Punch, M. Spir-Jacob, Manami Sasaki, S. Schwemmer, Andrea Santangelo, J. Lau, B. Peyaud, E. Leser, G. Hermann, Regis Terrier, Carlo Romoli, F. Gaté, R. Rauth, Fabian Schüssler, A. Jacholkowska, M. de Naurois, A. Woernlein, P. Bordas, D. A. Prokhorov, R. Marx, Werner Hofmann, Felix Spanier, Catherine Boisson, Stefan Funk, R. Zanin, R. C. G. Chaves, E. O. Angüner, D. Tiziani, I. Lypova, Stefan Wagner, Yasunobu Uchiyama, Christo Venter, D. Berge, D. Huber, D. Gottschall, P. T. O'Brien, Ullrich Schwanke, C. Perennes, Ruizhi Yang, S. Gabici, C. van Rensburg, J.F. Glicenstein, A. Marcowith, C. Hoischen, Wlodek Kluzniak, S. Saito, G. Fontaine, A. Zech, G. Maurin, K. Kosack, Jacek Niemiec, M. Lorentz, J. Becker Tjus, P.-O. Petrucci, L. Mohrmann, R. Steenkamp, A. Djannati-Ataï, S. Nakashima, Robert Wagner, J. Lefaucheur, A. Wierzcholska, Atreyee Sinha, C. van Eldik, C. Mariaud, A.M. Taylor, Aion Viana, S. Klepser, Olaf Reimer, R. J. White, G. Martí-Devesa, J.-P. Lenain, N. Shafi, Pierre Brun, T. Takahashi, Michael Backes, Gianluca Giavitto, T. Garrigoux, R. Blackwell, J. Hahn, N. Zywucka, Dieter Horns, I.D. Davids, S. Raab, Thomas Murach, E. Ruiz-Velasco, K. Egberts, Tim Holch, Reinhard Schlickeiser, M. Tsirou, G. Henri, A. M. W. Mitche, M. Mohamed, G. Vasileiadis, M. Ostrowski, H. Odaka, S. Chandra, P.J. Meintjes, S. Fegan, Marco Padovani, T. Lohse, A. Reimer, J. Bregeon, M. Renaud, H. Iwasaki, A. Carosi, R. R. Kruger, A. Lemière, H. Abdalla, B. Khélifi, Denys Malyshev, Nachiketa Chakraborty, K. Bernloehr, Stefan Ohm, S. Caroff, S. Pita, E. Moulin, Tomasz Bulik, D. Glawion, M. Panter, T. Bylund, Mohanraj Senniappan, A. Fiasson, L. Dirson, V. Poireau, L. Oakes, I. Sushch, A.A. Zdziarski, I. Jung-Richardt, Yvonne Becherini, D. Kerszberg, Masanori Arakawa, I. Oya, G. Heinzelmann, Felix Aharonian, L. Tibaldo, Zorawar Wadiasingh, B. Condon, Monica Barnard, F. Zefi, M. Buechele, M. Capasso, S. Krakau, V. Sahakian, D. Jankowsky, Q. Piel, J. Zorn, U. Katz, A.S. Seyffert, J.-P. Tavernet, P. Vincent, G. Lamanna, T. Vuillaume, P. deWilt, M. Seglar-Arroyo, J. King, B. Rudak, A. Priyana Noel, A. Dmytriiev, R. Moderski, V. Marandon, K. Katarzyński, L. Rinchiuso, L. Jouvin, M. Katsuragawa, C. Arcaro, M. Kraus, A. Specovius, Francois Brun, M. Tluczykont, Celine Armand, C. Steppa, M. Arrieta, Heike Prokoph, M. Haupt, Lukasz Stawarz, J. Dyks, K. Shiningayamwe, Andreas Quirrenbach, N. Tsuji, C. Trichard, J.-P. Ernenwein, R. D. Parsons, A. Ziegler, L. O. 'C. Drury, Ruben Lopez-Coto, M.-H. Grondin, P. Wagner, C. Dei, Y.A. Gallant, Gavin Rowell, M. Bryan, D. Zaborov, F. Niederwanger, Jacco Vink, Sabrina Casanova, H. J. Voelk, Frank M. Rieger, F. Voisin, J. Bolmont, S. Colafrancesco, Centre de Physique des Particules de Marseille (CPPM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Collège de France (CdF), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique (ex SAP) (DAP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Electronique et des Technologies de l'Information (CEA-LETI), Université Grenoble Alpes (UGA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), H.E.S.S., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 31125417 - Chandra, Sunil, 26909995 - Garrigoux, Tania, 11749903 - Krüger, Petrus Paulus, 26403366 - Ndiyavala, Hambeleleni, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 24922986 - Sushch, Iurii, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Collège de France (CdF (institution)), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Faculty of Science, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
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gamma-rays: galaxies ,principal component analysis ,Energy flux ,Astrophysics ,01 natural sciences ,pixel ,HESS ,ultraviolet ,optical ,energy: flux ,HESS - Abteilung Hofmann ,photon: flux ,010303 astronomy & astrophysics ,model: leptonic ,Physics ,radio wave ,density ,active, [Galaxies] ,Gamma ray ,galaxies [Gamma-rays] ,individual: 1ES 2322-409 [BL Lacertae objects] ,active [galaxies] ,infrared ,Spectral energy distribution ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics::High Energy Astrophysical Phenomena ,galaxies: active ,Astrophysics::Cosmology and Extragalactic Astrophysics ,gamma ray: energy spectrum ,GLAST ,blazar ,X-ray ,0103 physical sciences ,Blazar ,Astroparticle physics ,non-thermal [Radiation mechanisms] ,synchrotron radiation ,background ,010308 nuclear & particles physics ,Institut für Physik und Astronomie ,Astronomy and Astrophysics ,radiation mechanisms: non-thermal ,redshift ,proton synchrotron ,MAGIC ,Redshift ,Crab Nebula ,gamma ray: VHE ,Space and Planetary Science ,spectral ,ddc:520 ,High Energy Physics::Experiment ,BL Lacertae objects: individual: 1ES 2322−409 ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Fermi Gamma-ray Space Telescope - Abstract
著者人数: H.E.S.S. Collaboration 233名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 桂川, 美穂; 中島, 真也; 小高, 裕和; 高橋, 忠幸), Number of authors: H.E.S.S. Collaboration 233 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Katsuragawa, Miho; Nakashima, Shinya; Odaka, Hirokazu; Takahashi, Tadayuki), Accepted: 2018-09-29, 資料番号: SA1180422000
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- 2018
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7. Local Group dSph radio survey with ATCA – I: observations and background sources
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W. J. G. de Blok, Marco Regis, Laura Richter, Stefano Profumo, Nicola Orford, S. Colafrancesco, Marcella Massardi, and Astronomy
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Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Stellar population ,Astrophysics::High Energy Astrophysical Phenomena ,Population ,Dark matter ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Cosmology ,law.invention ,Telescope ,law ,Galaxy formation and evolution ,education ,catalogues ,Astrophysics::Galaxy Astrophysics ,radio continuum: galaxies ,Physics ,education.field_of_study ,Catalogues ,Galaxies: dwarf ,Radio continuum: galaxies ,Space and Planetary Science ,Astronomy and Astrophysics ,Local Group ,Astronomy ,galaxies: dwarf ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Dwarf spheroidal (dSph) galaxies are key objects in near-field cosmology, especially in connection to the study of galaxy formation and evolution at small scales. In addition, dSphs are optimal targets to investigate the nature of dark matter. However, while we begin to have deep optical photometric observations of the stellar population in these objects, little is known so far about their diffuse emission at any observing frequency, and hence on thermal and non-thermal plasma possibly residing within dSphs. In this paper, we present deep radio observations of six local dSphs performed with the Australia Telescope Compact Array at 16 cm wavelength. We mosaiced a region of radius of about one degree around three "classical" dSphs, Carina, Fornax, and Sculptor, and of about half of degree around three "ultra-faint" dSphs, BootesII, Segue2, and Hercules. The rms noise level is below 0.05 mJy for all the maps. The restoring beams FWHM ranged from 4.2 x 2.5 arcseconds to 30.0 x 2.1 arcseconds in the most elongated case. A catalogue including the 1392 sources detected in the six dSph fields is reported. The main properties of the background sources are discussed, with positions and fluxes of brightest objects compared with the FIRST, NVSS, and SUMSS observations of the same fields. The observed population of radio emitters in these fields is dominated by synchrotron sources. We compute the associated source number counts at 2 GHz down to fluxes of 0.25 mJy, which prove to be in agreement with AGN count models., Comment: 18 pages, 9 figure panels. Companion papers: arXiv:1407.5482 and arXiv:1407.4948. v3: minor revision, matches version accepted in MNRAS
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- 2015
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8. A high-resolution study of the X-ray emission and Sunyaev-Zel'dovich effect in the Bullet cluster (1E 0657−56)
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Michael Zemcov, Takuya Akahori, Anthony Moraghan, Shigehiro Nagataki, Dmitry Prokhorov, Kohji Yoshikawa, Evan T. Million, Eiichi Egami, T. D. Rawle, and S. Colafrancesco
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Astroparticle physics ,Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Plasma ,Astrophysics ,Sunyaev–Zel'dovich effect ,Galaxy ,Spectral line ,Space and Planetary Science ,Thermal ,Cluster (physics) ,Galaxy cluster - Abstract
High-resolution imaging of the Sunyaev–Zel'dovich (SZ) effect opens new possibilities for testing the presence of various high-energy particle populations in clusters of galaxies. A detailed X-ray analysis of the ‘Bullet cluster’ (1E 0657−56) with Chandra has revealed the presence of additional X-ray spectral components beyond a simple, single-temperature plasma in its X-ray spectra. X-ray methods alone are insufficient to elucidate the origins of these spectral components. We show that the morphology and magnitude of the SZ effect at high frequencies are critically dependent upon the mechanism by which the additional X-ray spectra are created. We examine the differences between the predicted SZ effect emission maps at 600 GHz assuming the X-ray spectra are composed of thermal gas with a steep power-law index component and also thermal gas with a significant contribution of strongly heated gas. A two-temperature model with a hot (kT ≃ 30–40 keV) second component is the most consistent with existing SZ data at high frequencies. However, significant morphological differences remain. High-angular-resolution SZ intensity maps at high frequencies in combination with deep X-ray data provide a new window into understanding particle energization processes in the hottest, massive merging galaxy clusters.
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- 2012
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9. SZ effect from radio-galaxy lobes: astrophysical and cosmological relevance
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S. Colafrancesco
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Physics ,Radio galaxy ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Extrapolation ,FOS: Physical sciences ,Astronomy and Astrophysics ,Context (language use) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Electron ,Space and Planetary Science ,Astrophysics::Galaxy Astrophysics ,Microwave - Abstract
We derive the SZ effect arising in radio-galaxy lobes that are filled with high-energy, non-thermal electrons. We provide here quantitative estimates for SZ effect expected from the radio galaxy lobes by normalizing it to the Inverse-Compton light, observed in the X-ray band, as produced by the extrapolation to low energies of the radio emitting electron spectrum in these radio lobes. We compute the spectral and spatial characteristics of the SZ effect associated to the radio lobes of two distant radio galaxies (3C294 and 3C432) recently observed by Chandra, and we further discuss its detectability with the next generation microwave and sub-mm experiments with arcsec and $\sim \mu$K sensitivity. We finally highlight the potential use of the SZE from radio-galaxy lobes in the astrophysical and cosmological context., Comment: 8 pages, 5 figures, MNRAS in press
- Published
- 2008
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10. Observations of a nearby filament of galaxy clusters with the Sardinia Radio Telescope
- Author
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F. de Gasperin, Rosita Paladino, Matteo Murgia, Claudio Gheller, Tracy E. Clarke, Gianni Bernardi, Emanuela Orrú, Sergio Poppi, Gabriele Giovannini, V. Vacca, Luigina Feretti, G. B. Taylor, Melanie Johnston-Hollitt, L. Gregorini, Federica Govoni, Franco Vazza, Chiara Ferrari, M. Brienza, Fabio Gastaldello, H. Junklewitz, Marisa Girardi, Alexis Finoguenov, Raimondo Concu, Richard A. Perley, Ettore Carretti, G. Valente, Torsten A. Enßlin, Walter Boschin, Andrea Melis, P. Parma, F. Loi, S. Colafrancesco, Department of Physics, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Vacca, V, Murgia, M, Govoni, F, Loi, F, Vazza, F, Finoguenov, A, Carretti, E, Feretti, L, Giovannini, G, Concu, R, Melis, A, Gheller, C, Paladino, R, Poppi, S, Valente, G, Bernardi, G, Boschin, W, Brienza, M, Clarke, T E, Colafrancesco, S, Enßlin, T A, Ferrari, C, de Gasperin, F, Gastaldello, F, Girardi, M, Gregorini, L, Johnston-Hollitt, M, Junklewitz, H, Orrù, E, Parma, P, Perley, R, Taylor, G B, DIP. DI ASTRONOMIA, DIP. DI DISCIPLINE GIURIDICHE DELL'ECONOMIA E DELL'AZIENDA, DIPARTIMENTO DI FISICA E ASTRONOMIA 'AUGUSTO RIGHI', Facolta' di SCIENZE MATEMATICHE FISICHE e NATURALI, Da definire, AREA MIN. 02 - Scienze fisiche, Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and De gasperin, F
- Subjects
Radio galaxy ,magnetic field ,magnetic fields ,01 natural sciences ,VLA SKY SURVEY ,010303 astronomy & astrophysics ,acceleration of particle ,SCALE ,media_common ,acceleration of particles ,Physics ,BARYONS ,galaxies: clusters: intracluster medium ,cosmology: observations, large-scale structure of Universe ,clusters: intracluster medium [galaxies] ,LOW-FREQUENCY ,large-scale structure of Universe ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,media_common.quotation_subject ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,observations, large-scale structure of Universe [cosmology] ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Low frequency ,MAGNETIC-FIELDS ,COSMIC FILAMENTS ,Radio telescope ,0103 physical sciences ,Galaxy cluster ,Astrophysics::Galaxy Astrophysics ,NRAO VLA Sky Survey ,SPECTRUM ,010308 nuclear & particles physics ,Astronomy ,Astronomy and Astrophysics ,115 Astronomy, Space science ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,EVOLUTION ,acceleration of particles, magnetic fields, galaxies: clusters: intracluster medium, cosmology: observations, large-scale structure of Universe ,Radio halo ,Space and Planetary Science ,Sky ,Astrophysics of Galaxies (astro-ph.GA) ,cosmology: observations ,galaxies: clusters medium ,ABELL ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,EMISSION - Abstract
We report the detection of diffuse radio emission which might be connected to a large-scale filament of the cosmic web covering a 8deg x 8deg area in the sky, likely associated with a z~0.1 over-density traced by nine massive galaxy clusters. In this work, we present radio observations of this region taken with the Sardinia Radio Telescope. Two of the clusters in the field host a powerful radio halo sustained by violent ongoing mergers and provide direct proof of intra-cluster magnetic fields. In order to investigate the presence of large-scale diffuse radio synchrotron emission in and beyond the galaxy clusters in this complex system, we combined the data taken at 1.4 GHz obtained with the Sardinia Radio Telescope with higher resolution data taken with the NRAO VLA Sky Survey. We found 28 candidate new sources with a size larger and X-ray emission fainter than known diffuse large-scale synchrotron cluster sources for a given radio power. This new population is potentially the tip of the iceberg of a class of diffuse large-scale synchrotron sources associated with the filaments of the cosmic web. In addition, we found in the field a candidate new giant radio galaxy., 35 pages, 30 figures, MNRAS Accepted, A high-resolution version of the paper can be found at the link http://erg.oa-cagliari.inaf.it/preprints/paper_filament.pdf
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