2018ApJ...868...45W


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.15CEST07:46:22

2018ApJ...868...45W - Astrophys. J., 868, 45-45 (2018/November-3)

A deep X-ray look at Abell 2142-viscosity constraints from Kelvin-Helmholtz eddies, a displaced cool peak that makes a warm core, and a possible plasma depletion layer.

WANG Q.H.S. and MARKEVITCH M.

Abstract (from CDS):

We analyzed 200 ks of Chandra ACIS observations of the merging galaxy cluster A2142 to examine its prominent cold fronts in detail. We find that the southern cold front exhibits well-developed Kelvin-Helmholtz (KH) eddies seen in the sky plane. Comparing their wavelength and amplitude with those in hydrodynamic simulations of cold fronts in viscous gas, and estimating the gas tangential velocity from centripetal acceleration, we constrain the effective viscosity to be at most 1/5 of Spitzer isotropic viscosity, but consistent with full Braginskii anisotropic viscosity for magnetized plasma. While the northwestern front does not show obvious eddies, its shape and the structure of its brightness profile suggest KH eddies seen in projection. The southern cold front continues in a spiral to the center of the cluster, ending with another cold front only 12 kpc from the gas density peak. The cool peak itself is displaced ∼30 kpc from the brightest cluster galaxy (BCG) (the biggest such offset among centrally peaked clusters), while the X-ray emission on a larger scale is still centered on the BCG, indicating that the BCG is at the center of the gravitational potential and the cool gas is sloshing in it. The specific entropy index of the gas in the peak (K ≃ 49 keV cm2) makes A2142 a rare "warm core"; apparently the large displacement of the cool peak by sloshing is the reason. Finally, we find a subtle narrow, straight channel with a 10% drop in X-ray brightness, aligned with the southern cold front-possibly a plasma depletion layer in projection.

Abstract Copyright: © 2018. The American Astronomical Society. All rights reserved.

Journal keyword(s): galaxies: clusters: individual: A2142 - galaxies: clusters: intracluster medium - X-rays: galaxies: clusters

Simbad objects: 14

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Number of rows : 14

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2004 1
2 NGC 1404 GiP 03 38 51.917 -35 35 39.81 11.53 10.69 10.00 9.03   ~ 679 1
3 ACO 496 ClG 04 33 30.3838 -13 14 21.584           ~ 664 2
4 ACO 520 ClG 04 54 19.0 +02 56 49           ~ 390 0
5 ClG 0657-56 ClG 06 58 29.6 -55 56 39           ~ 830 1
6 ACO 644 ClG 08 17 24.5 -07 30 46           ~ 207 0
7 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 6010 0
8 ACO 1991 ClG 14 54 30.2 +18 37 51           ~ 314 1
9 ACO 2029 ClG 15 10 58.7 +05 45 42           ~ 876 0
10 ACO 2142 ClG 15 58 20.00 +27 14 00.3           ~ 688 0
11 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3156 1
12 ClG J1720+2638 ClG 17 20 09.6 +26 37 35           ~ 211 0
13 ZwCl 1742+3306 ClG 17 44 16.2753 +32 59 55.115           ~ 64 0
14 ACO 3667 ClG 20 12 33.68 -56 50 26.3           ~ 573 1

    Equat.    Gal    SGal    Ecl

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2021.04.15-07:46:22

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