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Title: Chandra Observations of the Spectacular A3411–12 Merger Event

Abstract

We present deep Chandra observations of A3411–12, a remarkable merging cluster that hosts the most compelling evidence for electron reacceleration at cluster shocks to date. Using the $${Y}_{{\rm{X}}}\mbox{--}M$$ scaling relation, we find r 500 ~ 1.3 Mpc, $${M}_{500}=(7.1\pm 0.7)\times {10}^{14}\ {M}_{\odot }$$, $${kT}=6.5\pm 0.1\,\mathrm{keV}$$, and a gas mass of $${M}_{{\rm{g}},500}=(9.7\pm 0.1)\times {10}^{13}{M}_{\odot }$$. The gas mass fraction within r 500 is $${f}_{{\rm{g}}}=0.14\pm 0.01$$. We compute the shock strength using density jumps to conclude that the Mach number of the merging subcluster is small ($$M\leqslant {1.15}_{-0.09}^{+0.14}$$). Here, we also present density, temperature, pseudo-pressure, and pseudo-entropy maps. Based on the pseudo-entropy map, we conclude that the cluster is undergoing a mild merger, consistent with the small Mach number. On the other hand, radio relics extend over Mpc scale in the A3411–12 system, which strongly suggests that a population of energetic electrons already existed over extended regions of the cluster.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [6]; ORCiD logo [7];  [8];  [9]; ORCiD logo [10]; ORCiD logo [9];  [9]; ORCiD logo [9];  [11];  [12]; ORCiD logo [13]; ORCiD logo [14]; ORCiD logo [15]; ORCiD logo [15]
  1. Clay Center Observatory, Brookline, MA (United States); Harvard & Smithsonian, Cambridge, MA (United States)
  2. Leiden University (The Netherlands)
  3. Univ. of California, Davis, CA (United States)
  4. UNIST, Ulsan (Korea)
  5. National Centre for Radio Astrophysics—Tata Institute of Fundamental Research, Pune (India)
  6. Univ. of Notre Dame, IN (United States); Joint Institute for Nuclear Astrophysics, Lansing, MI (United States)
  7. California Institute of Technology (CalTech), Pasadena, CA (United States); Space Telescope Science Institute, Baltimore, MD (United States)
  8. Yonsei University, Seoul (Korea); Univ. of California, Davis, CA (United States)
  9. Harvard & Smithsonian, Cambridge, MA (United States)
  10. Leiden University (The Netherlands); Lancaster University (United Kingdom)
  11. Johns Hopkins Univ., Baltimore, MD (United States)
  12. Univ. of Hamburg (Germany)
  13. Pusan National Univ., Busan (Korea)
  14. Universidade Federal de Goiás (Brazil)
  15. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1647147
Report Number(s):
LLNL-JRNL-813509
Journal ID: ISSN 1538-4357; 1021549
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 887; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxy clusters: general; cosmology: large-structure formation

Citation Formats

Andrade-Santos, Felipe, van Weeren, Reinout J., Di Gennaro, Gabriella, Wittman, David, Ryu, Dongsu, Lal, Dharam Vir, Placco, Vinicius M., Fogarty, Kevin, Jee, M. James, Stroe, Andra, Sobral, David, Forman, William R., Jones, Christine, Kraft, Ralph P., Murray, Stephen S., Brüggen, Marcus, Kang, Hyesung, Santucci, Rafael, Golovich, Nathan, and Dawson, William. Chandra Observations of the Spectacular A3411–12 Merger Event. United States: N. p., 2019. Web. https://doi.org/10.3847/1538-4357/ab4ce5.
Andrade-Santos, Felipe, van Weeren, Reinout J., Di Gennaro, Gabriella, Wittman, David, Ryu, Dongsu, Lal, Dharam Vir, Placco, Vinicius M., Fogarty, Kevin, Jee, M. James, Stroe, Andra, Sobral, David, Forman, William R., Jones, Christine, Kraft, Ralph P., Murray, Stephen S., Brüggen, Marcus, Kang, Hyesung, Santucci, Rafael, Golovich, Nathan, & Dawson, William. Chandra Observations of the Spectacular A3411–12 Merger Event. United States. https://doi.org/10.3847/1538-4357/ab4ce5
Andrade-Santos, Felipe, van Weeren, Reinout J., Di Gennaro, Gabriella, Wittman, David, Ryu, Dongsu, Lal, Dharam Vir, Placco, Vinicius M., Fogarty, Kevin, Jee, M. James, Stroe, Andra, Sobral, David, Forman, William R., Jones, Christine, Kraft, Ralph P., Murray, Stephen S., Brüggen, Marcus, Kang, Hyesung, Santucci, Rafael, Golovich, Nathan, and Dawson, William. Fri . "Chandra Observations of the Spectacular A3411–12 Merger Event". United States. https://doi.org/10.3847/1538-4357/ab4ce5. https://www.osti.gov/servlets/purl/1647147.
@article{osti_1647147,
title = {Chandra Observations of the Spectacular A3411–12 Merger Event},
author = {Andrade-Santos, Felipe and van Weeren, Reinout J. and Di Gennaro, Gabriella and Wittman, David and Ryu, Dongsu and Lal, Dharam Vir and Placco, Vinicius M. and Fogarty, Kevin and Jee, M. James and Stroe, Andra and Sobral, David and Forman, William R. and Jones, Christine and Kraft, Ralph P. and Murray, Stephen S. and Brüggen, Marcus and Kang, Hyesung and Santucci, Rafael and Golovich, Nathan and Dawson, William},
abstractNote = {We present deep Chandra observations of A3411–12, a remarkable merging cluster that hosts the most compelling evidence for electron reacceleration at cluster shocks to date. Using the ${Y}_{{\rm{X}}}\mbox{--}M$ scaling relation, we find r 500 ~ 1.3 Mpc, ${M}_{500}=(7.1\pm 0.7)\times {10}^{14}\ {M}_{\odot }$, ${kT}=6.5\pm 0.1\,\mathrm{keV}$, and a gas mass of ${M}_{{\rm{g}},500}=(9.7\pm 0.1)\times {10}^{13}{M}_{\odot }$. The gas mass fraction within r 500 is ${f}_{{\rm{g}}}=0.14\pm 0.01$. We compute the shock strength using density jumps to conclude that the Mach number of the merging subcluster is small ($M\leqslant {1.15}_{-0.09}^{+0.14}$). Here, we also present density, temperature, pseudo-pressure, and pseudo-entropy maps. Based on the pseudo-entropy map, we conclude that the cluster is undergoing a mild merger, consistent with the small Mach number. On the other hand, radio relics extend over Mpc scale in the A3411–12 system, which strongly suggests that a population of energetic electrons already existed over extended regions of the cluster.},
doi = {10.3847/1538-4357/ab4ce5},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 887,
place = {United States},
year = {2019},
month = {12}
}

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