J/MNRAS/474/1065 SPT-selected galaxy clusters X-ray analysis (Sanders+, 2018)
Hydrostatic Chandra X-ray analysis of SPT-selected galaxy clusters.
I. Evolution of profiles and core properties.
Sanders J.S., Fabian A.C., Russell H.R., Walker S.A.
<Mon. Not. R. Astron. Soc., 474, 1065-1098 (2018)>
=2018MNRAS.474.1065S 2018MNRAS.474.1065S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources
Keywords: galaxies: clusters: intracluster medium - X-rays: galaxies: clusters
Abstract:
We analyse Chandra X-ray Observatory observations of a set of galaxy
clusters selected by the South Pole Telescope using a new publicly
available forward-modelling projection code, MBPROJ2, assuming
hydrostatic equilibrium. By fitting a power law plus constant entropy
model we find no evidence for a central entropy floor in the lowest
entropy systems. A model of the underlying central entropy
distribution shows a narrow peak close to zero entropy which accounts
for 60 per cent of the systems, and a second broader peak around
130keV.cm2. We look for evolution over the 0.2-1.2 redshift range
of the sample in density, pressure, entropy and cooling time at
0.015R500 and at 10kpc radius. By modelling the evolution of the
central quantities with a simple model, we find no evidence for a
non-zero slope with redshift. In addition, a non-parametric sliding
median shows no significant change. The fraction of cool-core clusters
with central cooling times below 2Gyr is consistent above and below
z=0.6 (∼30-40 per cent). Both by comparing the median thermodynamic
profiles, centrally biased towards cool cores, in two redshift bins,
and by modelling the evolution of the unbiased average profile as a
function of redshift, we find no significant evolution beyond
self-similar scaling in any of our examined quantities. Our average
modelled radial density, entropy and cooling-time profiles appear as
power laws with breaks around 0.2R500. The dispersion in these
quantities rises inwards of this radius to around 0.4dex, although
some of this scatter can be fitted by a bimodal model.
Description:
Our sample of systems (listed in table A1) includes the sample of SPT
clusters of Bleem et al. (2015ApJS..216...27B 2015ApJS..216...27B, Cat. J/ApJS/216/27)
marked as having X-ray data, excluding SPT-CLJ0037-5047 which has low
signal to noise. We also include two further systems in that paper
which also have X-ray data and were examined in McDonald et al.
(2013ApJ...774...23M 2013ApJ...774...23M, Cat. J/ApJ/774/23, hereafter MD13),
SPT-CLJ0236-4938 and SPT-CLJ0310-4647. We do not include
SPT-CLJ0446-5849 which has low signal to noise. We also exclude
SPT-CLJ0330-5228 and SPT-CLJ0551-5709 which are contaminated (McDonald
et al., 2014ApJ...794...67M 2014ApJ...794...67M). As MD13 describes, their sample consists
of strongly detected clusters by SPT, with SPT detection significances
between 5.7 and 43. The mass range of M500 is between 2x1014 and
2x1015M☉, while the redshift range is between 0.3 and 1.2. At
the median redshift, the sample should be around 50 per cent complete
at M500=4x1014, increasing to 100 per cent at 6x1014M☉. We
make use of any new public observations from the Chandra archive,
where possible.
The surface-brightness profiles in multiple X-ray bands were fitted
using a new hydrostatic modelling code, MBPROJ2, to obtain dark-matter
and thermodynamic profiles.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 59 83 Positions of the clusters
tablea1.dat 129 83 Sample of objects analysed here
tablea3.dat 61 83 Goodness of fits.
tablec1.dat 314 17604 *Table detailing individual profiles
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Note on tablec1.dat: The profiles for each cluster are repeated for each model
(BIN-NFW, BIN-GNFW, BIN-NONHYDRO, INT-NFW, MBETA-NFW and KPLAW-NFW).
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See also:
J/ApJS/216/27 : Galaxy clusters discovered in the SPT-SZ survey (Bleem+, 2015)
Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- SPT SPT identifier (SPT-CLJHHMM+DDMM)
18- 25 F8.4 deg RAdeg Peak right ascension (J2000) (1)
27- 34 F8.4 deg DEdeg Peak declination (J2000) (1)
36- 43 F8.4 deg RAadeg Annulus right ascension (J2000) (2)
45- 52 F8.4 deg DEadeg Annulus declination (J2000) (2)
54- 55 I2 arcsec Offset Offset between peak and annulus in arcsec
57- 59 I3 kpc Offsetk Offset between peak and annulus in kpc
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Note (1): J2000 coordinates of the peak in degrees used as the cluster centres
for our analysis.
Note (2): Our positions of the centroid using a 250-500kpc annulus.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Index [1/83] Cluster index
4- 19 A16 --- SPT SPT identifier (SPT-CLJHHMM+DDMM)
21- 41 A21 --- Name Main identifier (if any)
43- 47 F5.3 --- z Redshift from Bleem et al.
(2015, Cat. J/ApJS/216/27)
49- 51 F3.1 10+20cm-2 NH Galactic equivalent hydrogen column density
53- 55 F3.1 arcmin rmax ?=- Maximum radius examined
57- 58 I2 % Rebin Percentage uncertainty on the emissivities
in each bin after binning
60- 64 F5.1 ks TExp Total-cleaned exposure
66- 70 F5.1 ct Counts Background-subtracted counts within the
maximum radius
72- 76 F5.1 ct CountsBkg Background counts within the maximum radius
78-129 A52 --- ObsIDs List of Chandra observation identifiers
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- SPT SPT identifier (SPT-CLJHHMM+DDMM)
18- 22 F5.1 --- BIN-NFW Difference in fit statistic BIN-NFW (1)
24- 28 F5.1 --- BIN-GNFW Difference in fit statistic BIN-GNFW (1)
30- 34 F5.1 --- BIN-NONHYDRO Difference in fit statistic BIN-NONHYDRO (1)
36- 40 F5.1 --- INT-NFW Difference in fit statistic INT-NFW (1)
42- 47 F6.1 --- MBETA-NFW Difference in fit statistic MBETA-NFW (1)
49- 54 F6.1 --- KPLAW-NFW Difference in fit statistic KPLAW-NFW (1)
56- 61 F6.1 --- GRAD-NFW Difference in fit statistic GRAD-NFW (1)
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Note (1): Values show the difference in fit statistic from that expected on
average for the model divided by the expected standard deviation.
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- SPT SPT identifier (SPT-CLJHHMM+DDMM)
19- 30 A12 --- Model Model
32- 37 F6.1 kpc rin Inner radius of the annulus on the sky
39- 44 F6.1 kpc rout Outer radius of the annulus on the sky
46- 54 E9.4 keV kT Temperature
56- 64 E9.4 keV E_kT Median 84.1 percentile of kT
66- 74 E9.4 keV e_kT Median 15.9 percentile of kT
76- 84 E9.4 cm-3 ne Electron density
86- 94 E9.4 cm-3 E_ne Median 84.1 percentile of ne
96-104 E9.4 cm-3 e_ne Median 15.9 percentile of ne
106-114 E9.4 keV.cm+2 Ke Electron entropy
116-124 E9.4 keV.cm+2 E_Ke Median 84.1 percentile of Ke
126-134 E9.4 keV.cm+2 e_Ke Median 15.9 percentile of Ke
136-144 E9.4 keV/cm3 Pe Electron pressure
146-154 E9.4 keV/cm3 E_Pe Median 84.1 percentile of Pe
156-164 E9.4 keV/cm3 e_Pe Median 15.9 percentile ofPe
166-174 E9.4 g/cm2 g ?=0 Graviational acceleration (1)
176-184 E9.4 g/cm2 E_g ?=0 Median 84.1 percentile of g (1)
186-194 E9.4 g/cm2 e_g ?=0 Median 15.9 percentile of g (1)
196-204 E9.4 yr tcool Mean radiative cooling time
206-214 E9.4 yr E_tcool Median 84.1 percentile of tcool
216-224 E9.4 yr e_tcool Median 15.9 percentile of tcool
226-234 E9.4 Msun/yr dM/dt Mass deposition rate
236-244 E9.4 Msun/yr E_dM/dt Median 84.1 percentile of dM/dt
246-254 E9.4 Msun/yr e_dM/dt Median 15.9 percentile of dM/dt
256-264 E9.4 Msun Mtot ?=0 Cumulative-total mass
266-274 E9.4 Msun E_Mtot ?=0 Median 84.1 percentile of Mtot (1)
276-284 E9.4 Msun e_Mtot ?=0 Median 15.9 percentile of Mtot (1)
286-294 E9.4 Msun Mgas ?=0 Cumulative-gas mass (1)
296-304 E9.4 Msun E_Mgas ?=0 Median 84.1 percentile of Mgas (1)
306-314 E9.4 Msun e_Mgas ?=0 Median 15.9 percentile of Mgas (1)
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Note (1): not valid for BIN-NONHYDRO.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Jan-2021