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Published December 10, 2019 | Published + Accepted Version
Journal Article Open

Chandra Observations of the Spectacular A3411–12 Merger Event


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_X−M scaling relation, we find r₅₀₀ ~ 1.3 Mpc, M₅₀₀ = (7.1±0.7)×10¹⁴ M_⊙, kT = 6.5±0.1 keV, and a gas mass of M_g,₅₀₀ = (9.7±0.1)×10¹³ M_⊙. The gas mass fraction within r₅₀₀ is f_g = 0.14±0.01. We compute the shock strength using density jumps to conclude that the Mach number of the merging subcluster is small (M⩽1.15+^(0.14)_(−0.09)). 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.

Additional Information

© 2019 The American Astronomical Society. Received 2019 May 31; revised 2019 October 8; accepted 2019 October 9; published 2019 December 6. We thank Joseph DePasquale for creating the spectacular image displayed in Figure 1. F.A.-S. acknowledges support from Chandra grant G05-16133X. R.J.vW. acknowledges support from the VIDI research programme with project number 639.042.729, which is financed by the Netherlands Organisation for Scientific Research (NWO). G.D.G. acknowledges support from the ERC Advanced Investigator programme NewClusters 321271. W.R.F., and C.J. are supported by the Smithsonian Institution. C.J. acknowledges support from Chandra grant G016619003. M.J.J. acknowledges support for the current research from the National Research Foundation of Korea under the programs 2017R1A2B2004644 and 2017R1A4A1015178. D.R. and H.K. acknowledge support for the current research from the National Research Foundation of Korea under the programs 2016R1A5A1013277 and 2017R1A2A1A05071429. V.M.P. acknowledges partial support for this work from grant PHY 1430152; Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE), awarded by the US National Science Foundation (NSF). A.S. acknowledges support from the Clay Fellowship. Part of this was work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Attached Files

Accepted Version - 1910.07405.pdf

Published - Andrade-Santos_2019_ApJ_887_31.pdf


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August 19, 2023
August 19, 2023