2000MNRAS.315..689L


C.D.S. - SIMBAD4 rel 1.7 - 2020.05.25CEST01:10:32

2000MNRAS.315..689L - Mon. Not. R. Astron. Soc., 315, 689-702 (2000/July-2)

The entropy and energy of intergalactic gas in galaxy clusters.

LLOYD-DAVIES E.J., PONMAN T.J. and CANNON D.B.

Abstract (from CDS):

Studies of the X-ray surface brightness profiles of clusters, coupled with theoretical considerations, suggest that the breaking of self-similarity in the hot gas results from an `entropy floor', established by some heating process, which affects the structure of the intracluster gas strongly in lower-mass systems. By fitting analytical models for the radial variation in gas density and temperature to X-ray spectral images from the ROSAT PSPC and ASCA GIS, we have derived gas entropy profiles for 20 galaxy clusters and groups. We show that, when these profiles are scaled such that they should lie on top of one another in the case of self-similarity, the lowest-mass systems have higher-scaled entropy profiles than more massive systems. This appears to be due to a baseline entropy of {formmu1} depending on the extent to which shocks have been suppressed in low-mass systems. The extra entropy may be present in all systems, but is detectable only in poor clusters, where it is significant compared with the entropy generated by gravitational collapse. This excess entropy appears to be distributed uniformly with radius outside the central cooling regions.

We determine the energy associated with this entropy floor, by studying the net reduction in binding energy of the gas in low-mass systems, and find that it corresponds to a pre-heating temperature of ∼0.3keV. Since the relationship between entropy and energy injection depends upon gas density, we are able to combine the excesses of 70-140keV.cm2 and 0.3keV to derive the typical electron density of the gas into which the energy was injected. The resulting value of {formmu2} implies that the heating must have happened prior to cluster collapse but after a redshift z∼7-10. The energy requirement is well matched to the energy from supernova explosions responsible for the metals which now pollute the intracluster gas.


Abstract Copyright: Blackwell Science Ltd

Journal keyword(s): galaxies: clusters: general - intergalactic medium - X-rays: general

Status at CDS:  

Simbad objects: 22

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Number of rows : 22

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 NAME NGC 383 Group GrG 01 07 27.7 +32 23 59   11.1 14.1     ~ 76 0
2 NGC 507 BiC 01 23 39.950 +33 15 22.22   13.0       ~ 391 3
3 ZwCl 0120+3300 ClG 01 23 41.0 +33 15 40           ~ 71 0
4 ACO 262 ClG 01 52 50.4 +36 08 46           ~ 649 1
5 2MAXI J0254+416 ClG 02 54 32.2 +41 35 10           ~ 296 1
6 ACO 400 ClG 02 57 37.4 +06 00 45           ~ 382 3
7 ACO 478 ClG 04 13 20.7 +10 28 35           ~ 464 0
8 ACO 496 ClG 04 33 30.3838 -13 14 21.584           ~ 656 2
9 ACO 665 ClG 08 30 45.2 +65 52 55           ~ 399 0
10 ACO 780 ClG 09 18 30 -12 15.7           ~ 425 0
11 NAME Hydra I Cluster ClG 10 36 36.0 -27 31 04           ~ 771 1
12 HCG 62 CGG 12 53 05.6 -09 12 21           ~ 290 0
13 ACO 1689 ClG 13 11 29.5 -01 20 28           ~ 1016 0
14 NAME NGC 5044 Group GrG 13 14 22.7 -16 32 04           ~ 169 0
15 ACO 1795 ClG 13 49 00.5 +26 35 07           ~ 1148 0
16 HCG 68 CGG 13 53 40.9 +40 19 07     12.4     ~ 107 0
17 NAME NGC 5920 Group ClG 15 21 50.7 +07 42 18     15.13     ~ 284 0
18 ACO 2163 ClG 16 15 34.1 -06 07 26           ~ 517 0
19 ACO 2199 ClG 16 28 37.0 +39 31 28           ~ 1096 1
20 ACO 2218 ClG 16 35 54.0 +66 13 00           ~ 777 1
21 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3903 0
22 HCG 97 CGG 23 47 24.0 -02 19 08           ~ 92 0

    Equat.    Gal    SGal    Ecl

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2020.05.25-01:10:32

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