J/ApJ/805/3 Profiles of clusters of galaxies from Chandra (Elkholy+, 2015)
Are the effects of structure formation seen in the central metallicity of
galaxy clusters?
Elkholy T.Y., Bautz M.W., Canizares C.R.
<Astrophys. J., 805, 3 (2015)>
=2015ApJ...805....3E 2015ApJ...805....3E
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Redshifts ; Abundances
Keywords: galaxies: clusters: general; galaxies: clusters: intracluster medium;
X-rays: galaxies: clusters
Abstract:
A sample of 46 nearby clusters observed with Chandra is analyzed to
produce radial density, temperature, entropy, and metallicity
profiles, as well as other morphological measurements. The entropy
profiles are computed to larger radii than in previous Chandra cluster
sample analyses. We find that the iron mass fraction measured in the
inner 0.15R500 shows a larger dispersion across the sample of
low-mass clusters than it does for the sample of high-mass clusters.
We interpret this finding as the result of the mixing of more halos in
large clusters than in small clusters, leading to an averaging of the
metallicity in the large clusters, and thus less dispersion of
metallicity. This interpretation lends support to the idea that the
low-entropy, metal-rich gas of merging halos reaches the clusters'
centers, which explains observations of core-collapse supernova
product metallicity peaks, and which is seen in hydrodynamical
simulations. The gas in these merging halos would have to reach
cluster centers without mixing in the outer regions. On the other
hand, the metallicity dispersion does not change with mass in the
outer regions of the clusters, suggesting that most of the outer
metals originate from a source with a more uniform metallicity level,
such as during pre-enrichment. We also measure a correlation between
the metal content in low-mass clusters and the morphological
disturbance of their intracluster medium, as measured by centroid
shift. This suggests an alternative interpretation, whereby
transitional metallicity boosts in the center of low-mass clusters
account for the larger dispersion of their metallicities.
Description:
Our sample consists of bright clusters --present in both the HIFLUGCS
(Reiprich+, 2002ApJ...567..716R 2002ApJ...567..716R) and ACCEPT (Cavagnolo+ 2009,
J/ApJS/182/12) samples-- that were observed with Chandra's ACIS
instrument out to at least 0.2R500, where R500 is the radius
enclosing an average density that is 500 times the critical density of
the universe at the redshift of the observed cluster.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 264 46 Chandra observations
table6.dat 82 46 Cluster masses and scales
table7.dat 65 46 Best-fit parameters of the electron density
radial profiles
table8.dat 84 46 Best-fit parameters of the temperature
radial profiles
table9.dat 52 46 Morphological parameters and entropy near the center
table10.dat 54 46 Global metallicity measures
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/A+A/575/A30 : HIFLUGCS XMM/Chandra cross-calibration (Schellenberger+, 2015)
J/ApJ/774/23 : Chandra observations of SPT-SZ clusters (McDonald+, 2013)
J/ApJS/199/23 : IR and UV star formation in ACCEPT BCGs (Hoffer+, 2012)
J/ApJS/182/12 : ICM entropy profiles (ACCEPT) (Cavagnolo+, 2009)
J/ApJS/174/117 : Properties and metal abundances of clusters (Maughan+, 2008)
ftp://space.mit.edu/pub/tamer/ebc2015/ : This article available data
http://astro.uni-bonn.de/~reiprich/act/gcs/ : T.H. Reiprich HIFLUGCS home page
http://www.pa.msu.edu/astro/MC2/accept : Archive of Chandra Cluster
Entropy Profile Tables
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ID Cluster identifier
16- 26 A11 --- Label Label used to denote cluster
28- 29 I2 h RAh Cluster Hour of Right Ascension (J2000)
31- 32 I2 min RAm Cluster Minute of Right Ascension (J2000)
34- 39 F6.3 s RAs Cluster Second of Right Ascension (J2000)
41 A1 --- DE- Sign of the Cluster Declination (J2000)
42- 43 I2 deg DEd Cluster Degree of Declination (J2000)
45- 46 I2 arcmin DEm Cluster Arcminute of Declination (J2000)
48- 52 F5.2 arcsec DEs Cluster Arcsecond of Declination (J2000)
54- 59 F6.4 --- z [0.02/0.3] Cluster redshift
61-260 A200 --- ObsID Chandra ObsID(s) used in this work (1)
262-264 I3 ks Texp [8/437] Total exposure time for spectral analysis
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Note (1): ObsIDs in parantheses were used in imaging analysis, and
excluded from spectral analysis.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ID Cluster identifier
16- 20 F5.2 keV kT [2.1/23.4] X-ray temperature measured
between 0.15 and 1*R500
22- 25 F4.2 keV E_kT [0.01/2] Upper uncertainty in kx
27- 30 F4.2 keV e_kT [0.01/1] Lower uncertainty in kT
32- 36 F5.3 Mpc R500 [0.6/2.2] Radius enclosing 500 times
critical density (2)
38- 42 F5.3 Mpc E_R500 [0.004/0.07] Upper uncertainty in R500
44- 48 F5.3 Mpc e_R500 [0.002/0.10] Lower uncertainty in R500
50- 55 F6.3 10+14Msun M500 [0.9/35.1] Total gravitational mass within R500
57- 60 F4.2 10+14Msun E_M500 [0.03/4] Upper uncertainty in M500
62- 65 F4.2 10+14Msun e_M500 [0.03/6] Lower uncertainty in M500
67- 72 F6.3 10+13Msun Mgas [0.7/43.2] Gass mass within R500
74- 77 F4.2 10+13Msun E_Mgas [0.03/2] Upper uncertainty in Mgas
79- 82 F4.2 10+13Msun e_Mgas [0.02/4] Lower uncertainty in Mgas
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Note (2): Of the Universe at the redshift of the observed cluster.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ID Cluster identifier
16- 24 F9.7 cm-3 n0 ? Density profile normalization n0 (3)
26- 33 F8.6 --- alpha [0/5]? Best-fit α parameter (3)
35- 40 F6.4 --- beta [0.01/5]? Best-fit β parameter (3)
42- 50 F9.6 Mpc rc [0.001/27.3]? Best-fit rc parameter (3)
52- 58 F7.5 Mpc rs [0.01/2.2]? Best-fit rs parameter (3)
60- 65 F6.4 --- eps [0.4/5]? Best-fit ε parameter (3)
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Note (3): The ne(r) model is shown in Equation 1 (section 2.3.1):
(ne(r)/n0)2 = (r/rc)-α / [ (1+(r/rc)2)3β-α/2
(1+(r/rs)3)ε/3 ]
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ID Cluster identifier
16- 24 F9.6 Mpc rt [0.002/19.5]? Best-fit rt parameter (4)
26- 34 F9.6 --- a [-1.6/0.72]? Best-fit α parameter (4)
36- 43 F8.5 --- b [-0.53/7.9]? Best-fit b parameter (4)
45- 52 F8.5 --- c [-1.8/12]? Best-fit c parameter (4)
54- 60 F7.4 --- acool [-1.9/13]? Best-fit αcool parameter (4)
62- 69 F8.6 Mpc rcool [0.004/0.52]? Best-fit rcool parameter (4)
71- 77 F7.4 keV Tmin [0.3/19.3]? Best-fit Tmin parameter (4)
79- 84 F6.3 keV T0 [1.9/83.5]? Best-fit T0 parameter (4)
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Note (4): The kT(r) model is shown in Equation 5 (section 2.3.2):
T(r)/T0 = [(r/r1)-α/(1+(r/r1)b)c/b]
[(x+Tmin/T0) / (x+1)], where
x = (r/rcool)αcool
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ID Cluster identifier
16- 20 F5.2 --- cSB [1.8/29.3] Surface brightness concentration
22- 26 F5.3 --- e_cSB [0.01/0.27] Uncertainty in cSB
28- 32 F5.1 keV.cm2 S40 [40.5/550] Entropy at 40 kpc radius
34- 38 F5.2 keV.cm2 E_S40 [0.2/69] Upper uncertainty in S40
40- 44 F5.2 keV.cm2 e_S40 [0.3/65] Lower uncertainty in S40
46- 51 F6.3 --- [0.5/19] Median centroid shift (5)
52 A1 --- f_ [d] Incomplete coverage (5)
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Note (5): the median centroid shift is the size of of the scatter of the
X-ray centroid measured within various apertures around the X-ray peak
within 0.3R500, expressed in 10-3R500.
d = A measurement in the observations where the FOV does not fully cover
the region r<0.3*R500, and thus are excluded from analysis
involving , but are shown here.
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ID Cluster identifier
16- 20 F5.3 --- Zmid [0.1/0.5] Gas-mass-weighted metallicity (6)
22- 27 F6.4 --- E_Zmid [0.009/0.1] Upper uncertainty in Zmid
29- 34 F6.4 --- e_Zmid [0.009/0.1] Lower uncertainty in Zmid
36- 40 F5.3 --- Zin [0.2/0.6] Bulk core cluster metallicity (7)
42- 47 F6.4 --- E_Zin [0.005/0.09] Upper uncertainty in Zin
49- 54 F6.4 --- e_Zin [0.005/0.08] Lower uncertainty in Zin
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Note (6): In the region 0.15<r<0.3R500. See section 2.3.3 and equation 6.
Note (7): In the region r<0.15R500. See section 2.3.3 and equation 8.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Sep-2015