Chandra Observations of the Spectacular A3411–12 Merger Event

Journal Article · Fri Dec 06 00:00:00 EST 2019 · The Astrophysical Journal (Online)

DOI:https://doi.org/10.3847/1538-4357/ab4ce5· OSTI ID:1647147

Andrade-Santos, Felipe  ^[1]; van Weeren, Reinout J.  ^[2]; Di Gennaro, Gabriella  ^[2]; Wittman, David  ^[3]; Ryu, Dongsu  ^[4]; Lal, Dharam Vir  ^[5]; Placco, Vinicius M.  ^[6]; Fogarty, Kevin  ^[7]; Jee, M. James ^[8]; Stroe, Andra ^[9]; Sobral, David  ^[10]; Forman, William R.  ^[9]; Jones, Christine ^[9]; Kraft, Ralph P.  ^[9]; Murray, Stephen S. ^[11]; Brüggen, Marcus ^[12]; Kang, Hyesung  ^[13]; Santucci, Rafael  ^[14]; Golovich, Nathan  ^[15]; Dawson, William  ^[15]

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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)

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.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1647147
• Report Number(s): LLNL-JRNL-813509; 1021549; TRN: US2202984
• Journal Information: The Astrophysical Journal (Online), Vol. 887, Issue 1; ISSN 1538-4357
• Publisher: Institute of Physics (IOP)
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
galaxy clusters: general
cosmology: large-structure formation