2007A&A...461..397P


Query : 2007A&A...461..397P

2007A&A...461..397P - Astronomy and Astrophysics, volume 461, 397-410 (2007/1-2)

RASS-SDSS galaxy cluster survey. V. The X-ray-underluminous Abell clusters.

POPESSO P., BIVIANO A., BOEHRINGER H. and ROMANIELLO M.

Abstract (from CDS):

In this paper we consider a large sample of optically selected clusters, in order to elucidate the physical reasons for the existence of X-ray underluminous clusters. For this purpose we analyzed the correlations of the X-ray and optical properties of a sample of 137 spectroscopically confirmed Abell clusters in the SDSS database. We searched for the X-ray counterpart of each cluster in the ROSAT All Sky Survey. We find that 40% of our clusters have a marginal X-ray detection or remain undetected in X-rays. These clusters appear too X-ray faint on average for their mass as determined by velocity dispersion; i.e. they do not follow the scaling relation between X-ray luminosity and virial mass traced by the other clusters. On the other hand, they do follow the general scaling relation between optical luminosity and virial mass. We refer to these clusters as the X-ray-underluminous Abell clusters (AXU clusters, for short) and designate as ``normal'' the X-ray detected Abell systems. We separately examined the distributions and properties of the galaxy populations of the normal and the AXU clusters. The AXU clusters are characterized by leptokurtic (more centrally concentrated than a Gaussian) velocity distribution of their member galaxies in the outskirts (1.5<r/r200≤3.5), as expected for the systems in accretion. In addition, the AXU clusters have a higher fraction of blue galaxies in the external region and show a marginally significant paucity of galaxies at the center. Our results seem to support the interpretation that the AXU clusters are systems in formation undergoing a phase of mass accretion. Their low X-ray luminosity should be due to the still accreting intracluster gas or to an ongoing merging process.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: general

VizieR on-line data: <Available at CDS (J/A+A/461/397): tablea1.dat>

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 35

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Number of rows : 35
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 ACO 116 ClG 00 55 55.95 +00 39 40.4           ~ 40 0
2 ACO 117 ClG 00 56 20.03 -10 00 02.1           ~ 66 0
3 ACO 129 ClG 01 01 00 -09 57.9           ~ 11 0
4 ACO 130 ClG 01 01 33 -00 08.9           ~ 11 0
5 ACO 152 ClG 01 10 13.25 +14 00 25.2           ~ 37 0
6 ACO 168 ClG 01 15 09.8 +00 14 51           ~ 345 2
7 ACO 175 ClG 01 19 37.7 +14 53 35           ~ 38 0
8 ACO 190 ClG 01 23 41 -09 51.4           ~ 16 0
9 ACO 208 ClG 01 31 35.08 +00 32 14.4           ~ 37 0
10 ACO 243 ClG 01 42 28 -10 13.9           ~ 16 0
11 ACO 315 ClG 02 10 03.000 -00 59 52.00           ~ 11 0
12 ACO 351 ClG 02 25 21 -08 43.5           ~ 12 0
13 ACO 412 ClG 03 06 17.200 -00 08 34.60           ~ 18 0
14 ACO 441 ClG 03 30 33 -06 57.8           ~ 6 0
15 ACO 607 ClG 07 57 24.72 +39 21 06.7           ~ 18 0
16 ACO 620 ClG 08 05 43.2 +45 40 58           ~ 19 0
17 ACO 628 ClG 08 10 09.68 +35 15 18.3           ~ 38 0
18 ACO 626 ClG 08 10 39 +49 12.1           ~ 10 0
19 ACO 631 ClG 08 11 04.3 +35 59 08           ~ 13 0
20 ACO 646 ClG 08 22 10.0 +47 05 58           ~ 96 1
21 ACO 660 ClG 08 25 20 +36 50.2           ~ 8 0
22 ACO 655 ClG 08 25 30.3 +47 07 48           ~ 95 0
23 ACO 667 ClG 08 28 05.8 +44 46 00           ~ 31 0
24 ACO 685 ClG 08 37 36 +44 14.5           ~ 10 0
25 ACO 682 ClG 08 37 57 +51 50.5           ~ 8 0
26 ACO 714 ClG 08 54 44.68 +41 54 55.4           ~ 13 0
27 ACO 716 ClG 08 55 58 +48 27.5           ~ 10 0
28 ACO 733 ClG 09 01 19 +55 37.2           ~ 26 0
29 ACO 729 ClG 09 01 23.50 +58 16 01.5           ~ 12 0
30 ACO 736 ClG 09 03 02.2 +52 13 32           ~ 16 0
31 ACO 847 ClG 09 40 24.5 +02 28 39           ~ 11 0
32 ACO 861 ClG 09 43 33 +00 03.2           ~ 6 0
33 ACO 860 ClG 09 43 35 +02 06.2           ~ 8 0
34 ACO 856 ClG 09 45 24 +56 33.2           ~ 11 0
35 ACO 866 ClG 09 47 57 +58 08.1           ~ 8 0

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2022.08.18-03:02:38

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