TY - JOUR

T1 - Chandra Observations of the Spectacular A3411-12 Merger Event

AU - Andrade-Santos, Felipe

AU - Weeren, Reinout J. van

AU - Gennaro, Gabriella Di

AU - Wittman, David

AU - Ryu, Dongsu

AU - Lal, Dharam Vir

AU - Placco, Vinicius M.

AU - Fogarty, Kevin

AU - Jee, M. James

AU - Stroe, Andra

AU - Sobral, David

AU - Forman, William R.

AU - Jones, Christine

AU - Kraft, Ralph P.

AU - Murray, Stephen S.

AU - Brüggen, Marcus

AU - Kang, Hyesung

AU - Santucci, Rafael

AU - Golovich, Nathan

AU - Dawson, William

N1 - This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: https://doi.org/10.3847/1538-4357/ab4ce5

PY - 2019/12/6

Y1 - 2019/12/6

N2 - We present deep Chandra observations of A3411-12, a remarkable merging cluster that hosts the most compelling evidence for electron re-acceleration at cluster shocks to date. Using the $Y_X-M$ scaling relation, we find $r_{500} \sim 1.3$ Mpc, $M_{500} = (7.1 \pm 0.7) \times 10^{14} \ M_{\rm{\odot}}$, $kT=6.5\pm 0.1$ 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 ($M \leq 1.15_{-0.09}^{+0.14}$). We also present pseudo-density, projected 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.

AB - We present deep Chandra observations of A3411-12, a remarkable merging cluster that hosts the most compelling evidence for electron re-acceleration at cluster shocks to date. Using the $Y_X-M$ scaling relation, we find $r_{500} \sim 1.3$ Mpc, $M_{500} = (7.1 \pm 0.7) \times 10^{14} \ M_{\rm{\odot}}$, $kT=6.5\pm 0.1$ 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 ($M \leq 1.15_{-0.09}^{+0.14}$). We also present pseudo-density, projected 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.

KW - astro-ph.HE

KW - astro-ph.GA

U2 - 10.3847/1538-4357/ab4ce5

DO - 10.3847/1538-4357/ab4ce5

M3 - Journal article

VL - 887

JO - The Astrophysical Journal

JF - The Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 31

ER -