2014A&A...566A..42C


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.10CEST02:51:25

2014A&A...566A..42C - Astronomy and Astrophysics, volume 566A, 42-42 (2014/6-1)

Multifrequency constraints on the nonthermal pressure in galaxy clusters.

COLAFRANCESCO S., EMRITTE M.S., MHLAHLO N. and MARCHEGIANI P.

Abstract (from CDS):

The origin of radio halos in galaxy clusters is still unknown and is the subject of a vibrant debate from both observational and theoretical points of view. In particular, the amount and the nature of nonthermal plasma and of the magnetic field energy density in clusters hosting radio halos is still unclear. The aim of this paper is to derive an estimate of the pressure ratio X=Pnon–th/Pth between the nonthermal and thermal plasma in radio halo clusters that have combined radio, X-ray and Sunyaev-Zel'dovich (SZ) effect observations. From the simultaneous P1.4-LX and P1,4-YSZ correlations for a sample of clusters observed with Planck, we derive a correlation between YSZ and LX that we use to derive a value for X. This is possible since the Compton parameter YSZ is proportional to the total plasma pressure in the cluster, which we characterize as the sum of the thermal and nonthermal pressure, while the X-ray luminosity LX is proportional only to the thermal pressure of the intracluster plasma. Our results indicate that the average (best-fit) value of the pressure ratio in a self-similar cluster formation model is X=0.55±0.05 in the case of an isothermal β-model with β=2/3 and a core radius rc=0.3. R500, holding on average for the cluster sample. We also show that the theoretical prediction for the YSZ-LX correlation in this model has a slope that is steeper than the best-fit value for the available data. The agreement with the data can be recovered if the pressure ratio X decreases with increasing X-ray luminosity as LX–0.96. We conclude that the available data on radio halo clusters indicate a substantial amount of nonthermal pressure in cluster atmospheres whose value must decrease with increasing X-ray luminosity or increasing cluster mass (temperature). This is in agreement with the idea that nonthermal pressure is related to nonthermal sources of cosmic rays that live in cluster cores and inject nonthermal plasma in the cluster atmospheres, which is subsequently diluted by the intracluster medium acquired during cluster collapse, and has relevant impact for further studies of high-energy phenomena in galaxy clusters.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: general - cosmic background radiation - galaxies: clusters: intracluster medium - cosmology: theory

Simbad objects: 24

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Number of rows : 24

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 ACO 2744 ClG 00 14 20.03 -30 23 17.8           ~ 571 0
2 ACO 209 ClG 01 31 57.5 -13 34 35           ~ 250 0
3 ACO 401 ClG 02 58 56.9 +13 34 56           ~ 519 0
4 ACO 520 ClG 04 54 19.0 +02 56 49           ~ 381 0
5 ClG 0657-56 ClG 06 58 29.6 -55 56 39           ~ 799 1
6 B3 0714+378 Rad 07 17 36.50 +37 45 23.0           ~ 169 2
7 ClG J0717+3745 ClG 07 17 36.50 +37 45 23.0           ~ 357 0
8 ACO 665 ClG 08 30 45.2 +65 52 55           ~ 402 0
9 ACO 697 ClG 08 42 57.6 +36 21 45           ~ 214 0
10 ACO 754 ClG 09 08 50.1 -09 38 12           ~ 631 1
11 ACO 773 ClG 09 17 51.3 +51 43 20           ~ 261 0
12 ACO 781 ClG 09 20 25.4 +30 30 07           ~ 129 0
13 ACO 1300 ClG 11 32 00.7 -19 53 34           ~ 132 0
14 ACO 1656 ClG 12 59 48.7 +27 58 50           ~ 4208 2
15 ACO 1689 ClG 13 11 29.5 -01 20 28           ~ 1021 0
16 ACO 1914 ClG 14 26 01.3 +37 49 36           ~ 273 0
17 ACO 1995 ClG 14 52 55.0 +58 02 59           ~ 118 0
18 ACO 2034 ClG 15 10 10.80 +33 30 21.6           ~ 176 1
19 ACO 2163 ClG 16 15 34.1 -06 07 26           ~ 519 0
20 ACO 2218 ClG 16 35 54.0 +66 13 00           ~ 780 1
21 ACO 2219 ClG 16 40 22.1 +46 42 20           ~ 317 0
22 ACO 2256 ClG 17 03 43.5 +78 43 03           ~ 830 1
23 ACO 2255 ClG 17 12 50.04 +64 03 10.6           ~ 502 0
24 RXC J2003.5-2323 ClG 20 03 32.3 -23 23 30           ~ 53 0

    Equat.    Gal    SGal    Ecl

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2020.07.10-02:51:25

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