J/A+A/585/A130 X-ray halo of 33 clusters of galaxies images (Hofmann+, 2016)
Thermodynamic perturbations in the X-ray halo of 33 clusters of galaxies
observed with Chandra ACIS.
Hofmann F., Sanders J.S., Nandra K., Clerc N., Gaspari M.
<Astron. Astrophys. 585, A130 (2016)>
=2016A&A...585A.130H 2016A&A...585A.130H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources
Keywords: galaxies: clusters - X-rays: galaxies: clusters - turbulence
Abstract:
In high-resolution X-ray observations of the hot plasma in clusters of
galaxies significant structures caused by AGN feedback, mergers, and
turbulence can be detected. Many clusters have been observed by
Chandra in great depth and at high resolution. Using archival data
taken with the Chandra ACIS instrument the aim was to study
thermodynamic perturbations of the X-ray emitting plasma and to apply
this to better understand the thermodynamic and dynamic state of the
intra cluster medium (ICM). We analyzed deep observations for a sample
of 33 clusters with more than 100ks of Chandra exposure each at
distances between redshift 0.025 and 0.45. The combined exposure of
the sample is 8Ms. Fitting emission models to different regions of
the extended X-ray emission we searched for perturbations in density,
temperature, pressure, and entropy of the hot plasma. For individual
clusters we mapped the thermodynamic properties of the ICM and
measured their spread in circular concentric annuli. Comparing the
spread of different gas quantities to high-resolution 3D hydrodynamic
simulations, we constrain the average Mach number regime of the sample
to Mach1D ∼0.16±0.07. In addition we found a tight correlation
between metallicity, temperature and redshift with an average
metallicity of Z∼0.3±0.1 Z(solar). This study provides detailed
perturbation measurements for a large sample of clusters which can be
used to study turbulence and make predictions for future X-ray
observatories like eROSITA, Astro-H, and Athena.
Description:
For a sample of 33 clusters of galaxies all available Chandra X-ray
observations were merged and thermodynamic 2D maps of the ICM were
calculated. Based on these maps deviations from spherical symmetry
were calculated for each thermodynamic property. The
pixlist<cluster><S/N>.fits files list the properties of each pixel
in the 2D maps for each cluster with a fixed signal-to- noise ratio
(S/N) in each 2D spatial bin. The int5.fits files contain
the spread measurements of temperature, density, pressure, and entropy
in five concentric circular annuli.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 165 33 Sample properties and fits files informations
images/* . 33 Individual fits images
tables/* . 66 Individual fits tables
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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- 18 A18 --- Name Cluster name (1)
20- 28 A9 --- cluster Abbreviate name of cluster,
used for the fits file names
30- 34 F5.3 10+22cm-2 nH Hydrogen column density
36- 39 F4.1 keV <Tmap> Mean map temperature
41- 45 F5.3 keV e_<Tmap> rms uncertainty on <Tmap>
47- 50 F4.2 Mpc rFOV Maximum radius (from X-ray peak) covered
in our analysis
52- 55 F4.2 Mpc r500 Overdensity radius (2)
57- 60 F4.2 Mpc e_r500 rms uncertainty on r500 (2)
62- 65 F4.1 10+14Msun M500 Oversensity mass (2)
67- 69 F3.1 10+14Msun e_M500 rms uncertainty on M500 (2)
71- 75 F5.3 --- rFOV/r500 Radius ratio
78- 86 F9.5 deg RAdeg Right ascension of image center (J2000)
87- 95 F9.5 deg DEdeg Declination of image center (J2000)
97-118 A22 --- Image Name of the fits image in subdirectory
images
120-139 A20 --- Int5 Name of the fits file (asymmetry measured
in 5 annuli) in subdirectory tables (3)
141-165 A25 --- Pixlist Name of the fits file (pixel by pixel
thermodynamic map) in subdirectory
tables (4)
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Note (1): Most commonly used cluster name and abbreviated catalogue names of
clusters, sorted on descending mass (M500).
Note (2): Overdensity radii r500 and M500 were calculated using the
mass-temperature scaling relation from Vikhlinin et al. (2009ApJ...692.1033V 2009ApJ...692.1033V)
for an estimate on the r500 fraction covered in each object. We used <Tmap>
as input for the scaling relation and estimated errors assuming a 0.5keV
systematic uncertainty (see scatter in Fig. 4).
Note (3): Content of clusterint5.fits files (asymmetry measured in 5 annuli)
------------------------------------------------------------------------------
Row Units Label Explanations
------------------------------------------------------------------------------
1 kpc rr average radius of annulus (1)
2 keV T average temperature
3 keV Te T uncertainty
4 --- Z average metallicity (2)
5 --- Ze Z uncertainty
6 --- dP frac. spread in pressure (3)
7 --- dP_eu dP positive uncertainty
8 --- dP_el dP negative uncertainty
9 --- dS frac. spread in entropy (3)
10 --- dS_eu dS positive uncertainty
11 --- dS_el dS negative uncertainty
12 --- dn frac. spread in density (3)
13 --- dn_eu dn positive uncertainty
14 --- dn_el dn negative uncertainty
15 --- dT frac. spread in temperature (3)
16 --- dT_eu dP positive uncertainty
17 --- dT_el dP negative uncertainty
----------------------------------------------------------------------------
Note (1): all asymmetry measurements were taken in circular concentric annuli
around the cluster center. confidence ranges are on the 1 sigma level.
Note (2): metallicity is given as a fraction of solar metallicity.
Note (3): fractional intrinsic spread measurements of properties.
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Note (4): Content of pixlistclusterint_NN.fits files
(pixel by pixel thermodynamic map)
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Row Units Label Explanations
------------------------------------------------------------------------------
1 pixel x x pixel coordinate (1)
2 pixel y y pixel coordinate (1)
3 --- binnum Bin number (2)
4 --- cts Counts in observation
5 --- bgcts Counts in background observation
6 cm2s*cts*photon-1 exp Effective exposure (3)
7 keV T Temperature (4)
8 keV Tup T upper limit (4)
9 keV Tlo T lower limit (4)
10 Sun Z Solar metallicity fraction (4)
11 Sun Zup Z upper limit (4)
12 Sun Zlo Z lower limit (4)
13 cm-5 norm Normalization of spectrum (4)
14 cm-5 normup Norm upper limit (4)
15 cm-5 normlo Norm lower limit (4)
16 --- redshift Fixed redshift of the cluster
17 1022cm-2^ NH Foreground column density
18 pixel cen_dist Distance from cluster center
19 rad cen_angl Angle measured from dir. west
20 arcsec rad_arcsec Distance from cluster center
21 kpc rad_kpc Distance from cluster center
22 keV*cm-5/2*arcsec-1 P Pseudo pressure
23 keV*cm5/3*arcsec2/3 S Pseudo entropy
24 cm-5/2*arcsec-1 n Pseudo density
25 keV*cm-5/2*arcsec-1 P_err Symmetric P uncertainty
26 keV*cm5/3*arcsec2/3 S_err Symmetric S uncertainty
27 cm-5/2*arcsec-1 n_err Symmetric n uncertainty
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Note (1): pixelsize∼1arcsecond
Note (2): Number of the spatial bin the pixel belongs to. Pixels with the same
bin number have the same spectral values. Only their coordinates differ.
Note (3): effective exposure of the observation in Chandra default units of
exposure (cm2s*count/photon).
Note that background observation exposure will differ.
Note (4): values obtained from fitting an absorbed XSPEC apec model for
collisionally ionized plasma to the spectrum extracted in one spatial bin.
All confidence ranges are on the 1 sigma level.
Note (5): properties calculated from spectral fits.
See publication for details.
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Acknowledgements:
Florian Hofmann, fhofmann(at)mpe.mpg.de
(End) Florian Hofmann [MPE,Germany], Patricia Vannier [CDS] 30-Oct-2015