1999ApJ...517...70R


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.19CEST13:41:47

1999ApJ...517...70R - Astrophys. J., 517, 70-77 (1999/May-3)

Constraining q0 with cluster gas mass fractions: a feasibility study.

RINES K., FORMAN W., PEN U., JONES C. and BURG R.

Abstract (from CDS):

As the largest gravitationally bound objects in the universe, clusters of galaxies may contain a fair sample of the baryonic mass fraction of the universe. Since the gas mass fraction from the hot intracluster medium is believed to be constant in time, the value of the cosmological deceleration parameter q0 can be determined, in principle, by comparing the calculated gas mass fraction in nearby and distant clusters. To test the potential of this method, we compare the gas fractions derived for a sample of luminous (LX>1045 ergs.s–1) nearby clusters with those calculated for eight luminous distant (0.3<z<0.6) clusters using ASCA and ROSAT observations. For consistency, we evaluate the gas mass fraction at a fixed physical radius of 1 h–150 Mpc (assuming q0=0.0). We find a best-fit value of q0=0.07 with -0.47<q0<0.67 at 95% confidence. This analysis includes both measurement errors and an intrinsic 25% scatter in the gas fractions due to the effects of cooling flows and mergers. We also determine the gas fraction using the method of Evrard, Metzler, and Navarro to find the total mass within r500, the radius where the mean overdensity of matter is 500 times the critical density. In simulations, this method reduces the scatter in the determination of gravitational mass without biasing the mean. We find that it also reduces the scatter in actual observations for nearby clusters but not as much as simulations suggest. Using this method, the best-fit value is q0=0.04 with -0.50<q0<0.64. The excellent agreement between these two methods suggests that this may be a useful technique for determining q0. The constraints on q0 should improve as more distant clusters are studied and precise temperature profiles are measured to large radii.

Abstract Copyright:

Journal keyword(s): Cosmology: Observations - Galaxies: Clusters: General - Galaxies: Intergalactic Medium - X-Rays: Galaxies

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 - 2021
#notes
1 ACO 2744 ClG 00 14 20.03 -30 23 17.8           ~ 596 0
2 ClG 0016+16 ClG 00 18 33.3 +16 26 36           ~ 477 0
3 ACO 85 ClG 00 41 37.8 -09 20 33           ~ 809 0
4 ACO 401 ClG 02 58 56.9 +13 34 56           ~ 525 0
5 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2004 1
6 ACO 478 ClG 04 13 20.7 +10 28 35           ~ 476 0
7 ACO 3266 ClG 04 31 11.9 -61 24 23           ~ 376 0
8 ClG 0451-03 ClG 04 54 10.9 -03 01 07     20.0     ~ 333 0
9 ACO 644 ClG 08 17 24.5 -07 30 46           ~ 207 0
10 ACO 754 ClG 09 08 50.1 -09 38 12           ~ 638 1
11 ACO 851 ClG 09 42 56.6 +46 59 22           ~ 310 0
12 ACO 959 ClG 10 17 35.0 +59 33 28           ~ 63 0
13 ZwCl 1021+0426 ClG 10 23 39.0 +04 11 14   15.6       ~ 260 0
14 ACO 1576 ClG 12 36 59.5 +63 11 18           ~ 89 0
15 ACO 1650 ClG 12 58 36.76 -01 43 34.2           ~ 278 0
16 ACO 1758 ClG 13 32 32.1 +50 30 37           ~ 216 2
17 ACO 1795 ClG 13 49 00.5 +26 35 07           ~ 1181 0
18 ZwCl 1358+6245 ClG 13 59 54.3 +62 30 36     18.5     ~ 350 0
19 ACO 2029 ClG 15 10 58.7 +05 45 42           ~ 876 0
20 ACO 2065 ClG 15 22 42.6 +27 43 21           ~ 348 0
21 ACO 2256 ClG 17 03 43.5 +78 43 03           ~ 841 1
22 ACO 2319 ClG 19 20 45.3 +43 57 43           ~ 423 1
23 ACO 3667 ClG 20 12 33.68 -56 50 26.3           ~ 574 1
24 ClG 2137-2353 ClG 21 40 12.8 -23 39 27     18.5     ~ 353 0

    Equat.    Gal    SGal    Ecl

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