J/A+A/361/429 Baryon content of groups and clusters (Roussel+, 2000)
The baryon content of groups and clusters of galaxies
Roussel H., Sadat R., Blanchard A.
<Astron. Astrophys. 361, 429 (2000)>
=2000A&A...361..429R 2000A&A...361..429R
ADC_Keywords: Clusters, galaxy ; X-ray sources
Keywords: cosmology: observations - galaxies: clusters: general -
X-rays: general
Abstract:
We have analyzed the properties of a sample of 33 groups and clusters
of galaxies for which both optical and X-ray data were available in
the literature. This sample was built to examine the baryon content
and to check for trends over a decade in temperature down to 1keV. We
examine the relative contribution of galaxies and ICM to baryons in
clusters through the gas-to-stellar mass ratio (Mgas/M*). We find
that the typical stellar contribution to the baryonic mass is between
5 and 20%, at the virial radius. The ratio (Mgas/M*) is found to
be roughly independent of temperature. Therefore, we do not confirm
the trend of increasing gas-to-stellar mass ratio with increasing
temperature as previously claimed.
Description:
Tables 1 and 2 summarize the data taken from the literature (except
for A665, whose X-ray parameters were derived by us) used for our
study.
Tables 3 and 5 present some dynamical quantities for each cluster or
group, in the frame of two different normalizations of the scaling law
used to compute the virial radius (EMN : Evrard, Metzler & Navarro,
1996ApJ...469..494E 1996ApJ...469..494E ; BN : Bryan & Norman , 1998ApJ...495...80B 1998ApJ...495...80B)
Tables 4 and 6 contain average quantities, as a function of
temperature category (groups, cool clusters and hot clusters) and at
three different density contrasts, again with either EMN or BN
normalization. Results emphasize differences arising from the use of
two mass estimators, SLM (for scaling law model) and IHE (for
isothermal hydrostatic equilibrium).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 100 35 X-ray data. Parameters refer to Eq. 8 and 9 of
the paper.
table2.dat 80 33 Optical data. The first part corresponds to the
galaxy spatial distribution and the second part
to the luminosity function (Eq. 5).
table3.dat 51 33 Dynamical quantities for the whole sample, at the
limiting radius r200 and with the r500-TX
normalization of EMN (the redshift is taken into
account in this relationship).
table4.dat 75 12 Average dynamical quantities for the objects with
the most reliable data (details on those that
have been discarded can be found in the
paragraph ``notes on individual clusters''),
using the EMN normalization and at various
limiting radii.
table5.dat 51 33 Same as Table 3, but with the r200-TX
normalization of BN
table6.dat 75 12 Same as Table 4, but using the BN normalization.
refs.dat 52 44 References
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Name(s) of cluster (abbreviated)
11- 17 F7.5 --- z ? Redshift
20- 24 F5.2 keV TX ? Intracluster gas temperature
27- 30 F4.2 keV E_TX ? Upper error on TX (1)
33- 36 F4.2 keV e_TX ? Lower error on TX (1)
39- 43 A5 --- r_TX Reference code for TX (2)
46- 49 F4.2 Mpc RXlim ? Limiting radius of X-ray emission (3)
52- 56 F5.3 --- beta Slope of gas profile (4)
59- 63 F5.3 Mpc rcX Core radius (4)
66- 70 F5.2 10-3cm-3 ne0 Central electron density (4)
73- 83 A11 --- r_beta Reference codes for gas profile (2)
86-100 A15 --- Names Other name or complete name for RXJ
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Note (1): When only E_TX is given, the error bar is symmetric.
Temperature error bars of clusters are computed from different
reliable references (taking into account or not a cooling flow) as the
maximum of two estimates : the dispersion among the measures and the
quadratic mean of the quoted uncertainties (this procedure produces a
large uncertainty when there exists a possibility for a strong
temperature gradient). They are given at a 90% confidence level,
multiplying when necessary 1σ errors by 1.64 (the errors of
Fornax and RX J1340.6 given by I96 and PA94, which confidence levels
are not stated, are assumed to be 1σ).
Note (2): Codes are explicited in refs.dat file.
Note (3): When no limiting radius is given, we assumed
RXlim(Mpc)=TX/3(keV),
a relationship calibrated on other clusters.
Note (4): Fornax and HCG 62 have got a two-component gas density profile,
parameters of the second entry corresponding to the core.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Name of cluster (abbreviated)
10- 12 A3 --- TOP [(1-4)] Type of optical profile (1)
15- 21 F7.2 --- sigma0 Normalization of optical profile (2)
24- 30 F7.5 Mpc rc Scale radius (3)
33- 37 F5.3 --- epsilon ? Slope (4)
40- 45 F6.2 --- MBlim ? Limiting blue magnitude of observations
48- 58 A11 --- r_sigma0 References for optical profile (5)
62- 67 F6.2 --- MB* ? Charac. B magnitude of luminosity function
70- 73 F4.2 --- alpha ? Slope of luminosity function
76- 80 A5 --- r_TOP Reference code for luminosity function (5)
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Note (1): the types are designated by:
(1) : King form (Eq. 2 of the paper)
(2) : de Vaucouleurs form (Eq. 3)
(3) : integrated luminosity profile (Eq. 7)
(4) : de Vaucouleurs projected luminosity density profile (cf Eq. 3)
Note (2): normalizations are defined, depending on TOP value:
for TOP = (1) or (2) : sigma0 (unit : number of galaxies Mpc-2)
for TOP = (3) : L0 (unit : 1011LBsun)
for TOP = (4) : sigmaL0_ (unit : 1011LB(sun)/Mpc2)
Note (3): for TOP = (2) or (4), corresponds to the parameter rV (Eq. 3)
Note (4): for TOP = (2) or (4), corresponds to the parameter gamma (Eq. 3)
Note (5): Codes are explicited in refs.dat file.
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Byte-by-byte Description of file: table3.dat table5.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Name of cluster (abbreviated)
10- 13 F4.2 Mpc r200 Virial radius
16- 21 F6.2 10+13solMass Mtot Total gravitating mass at r200 (1)
24- 28 F5.2 10+13solMass Mgas Gas mass at r200 (1)
31- 34 F4.2 10+13solMass M* Stellar mass at r200 (1)
37- 40 F4.1 % fb Baryon fraction at r200
43- 45 I3 solMass/solLum M/LB Mass to blue luminosity ratio at r200 (1)
48- 51 F4.2 --- MIHE/MSLM Comparison of the two estimators
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Note (1): The scalings with the Hubble constant are :
M_tot and M_* ∝ h-1, Mgas ∝ h-5/2 and
L ∝ h-2.
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Byte-by-byte Description of file: table4.dat table6.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Class Category according to TX (1)
16- 21 A6 --- rdelta Limit in density contrast (2)
24- 27 F4.1 % fgas(SLM) Gas fraction (SLM estimator)
30- 33 F4.1 % fb(SLM) Baryon fraction
36- 39 F4.1 --- Mgas/M*(SLM) Gas to stellar mass ratio
42- 46 F5.1 --- Mtot/M*(SLM) Total to stellar mass ratio
49- 51 I3 solMass/solLum M/LB(SLM) Mass to blue luminosity ratio
54- 57 F4.1 % fgas(IHE) Gas fraction (IHE estimator)
60- 63 F4.1 % fb(IHE) Baryon fraction
66- 70 F5.1 --- Mtot/M*(IHE) Total to stellar mass ratio
73- 75 I3 solMass/solLum M/LB(IHE) Mass to blue luminosity ratio
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Note (1): Groups are defined by TX<2keV and hot clusters by TX>5keV.
Note (2): Dynamical quantities are given at the virial radius
r200 (from SLM) but also at two other ones : r500, the radius
within which EMN claim that the hydrostatic equilibrium is universally
reached ; r2000 which we preferred to use because this represents
the maximal extent of X-ray observations that is valid for the whole
sample, including groups.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Code Reference code
9- 27 A19 --- Bibcode Bibcode
29- 52 A24 --- Aut Author's name
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Acknowledgements: Helene ROUSSEL
(End) Patricia Bauer [CDS] 05-Oct-2000