J/A+A/637/A58 Chemical evolution of galaxy clusters (Liu+, 2020)
The chemical evolution of galaxy clusters:
Dissecting the iron mass budget of the intracluster medium.
Liu A., Tozzi P., Ettori S., De Grandi S., Gastaldello F., Rosati P.,
Norman C.
<Astron. Astrophys., 637, A58 (2020)>
=2020A&A...637A..58L 2020A&A...637A..58L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Redshifts
Keywords: galaxies: clusters: general -
galaxies: clusters: intracluster medium - X-rays: galaxies: clusters
Abstract:
We study the chemical evolution of galaxy clusters by measuring the
iron mass in the ICM after dissecting the abundance profiles into
different components.
We used Chandra archival observations of 186 morphologically regular
clusters in the redshift range of [0.04, 1.07]. For each cluster, we
computed the azimuthally averaged iron abundance and gas density
profiles. In particular, our aim is to identify a central peak in the
iron distribution, which is associated with the central galaxy, and an
approximately constant plateau reaching the largest observed radii,
which is possibly associated with early enrichment that occurred
before or shortly after achieving virialization within the cluster. We
were able to firmly identify two components in the iron distribution
in a significant fraction of the sample simply by relying on the fit
of the iron abundance profile. From the abundance and ICM density
profiles, we computed the iron mass included in the iron peak and iron
plateau, and the gas mass-weighted iron abundance of the ICM out to an
extraction radius of 0.4r500 and to r500 by extending the
abundance profile as a constant.
We find that the iron plateau shows no evolution with redshift. On the
other hand, we find a marginal (<2σ c.l.) decrease with
redshift in the iron mass included in the iron peak rescaled by the
gas mass. We measure that the fraction of iron peak mass is typically
a few percent (∼1%) of the total iron mass within r500. Therefore,
since the total iron mass budget is dominated by the plateau, we find
consistently that the global gas mass-weighted iron abundance does not
evolve significantly across our sample. We were also able to reproduce
past claims of evolution in the global iron abundance, which turn out
to be due to the use of cluster samples with different selection
methods combined with the use of emission-weighted, instead of gas
mass-weighted, abundance values. Finally, while the intrinsic scatter
in the iron plateau mass is consistent with zero, the iron peak mass
exhibits a large scatter, in line with the fact that the peak is
produced after the virialization of the halo and depends on the
formation history of the hosting cool core and the strength of the
associated feedback processes.
We conclude that only a spatially resolved approach can resolve the
issue of iron abundance evolution in the ICM, reconciling the
contradictory results obtained in the last ten years. Evolutionary
effects below z∼1 are marginally measurable with present-day data,
while at z>1 the constraints are severely limited by poor knowledge of
the high-z cluster population. The path towards a full and
comprehensive chemical history of the ICM requires the application of
high angular resolution X-ray bolometers and a dramatic increase in
the number of faint, extended X-ray sources.
Description:
The amount of mass in iron was measured in a sample of galaxy clusters
observed with Chandra. We select 186 morphologically regular clusters
in the redshift range of [0.04, 1.07] from deep and medium-deep
Chandra archival observations as of February 2019.
The global properties of the clusters, including the X-ray redshift,
the global temperature, the value of r500 and M500, where derived. The
X-ray redshift is measured by fitting the spectrum of the global
emission within the radius maximizing the signal to noise ratio in the
0.5-7keV band image. Among the 186 clusters in the sample, 184 have
optical spectroscopic redshifts published in the literature.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 109 186 Global properties we measured for the 186 clusters
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Name
19- 26 F8.4 deg RAdeg Right ascension (J2000) of cluster emission
28- 35 F8.4 deg DEdeg Declination (J2000) of cluster emission
37- 41 F5.3 --- zX X-ray redshift of the cluster
43- 47 F5.3 --- e_zX rms uncertainty on X-ray redshift
49- 53 F5.2 keV kT Temperature of the cluster measured
within (0.1-0.4)r500
55- 58 F4.2 keV e_kT rms uncertainty on temperature
60- 64 F5.2 10+14Msun M500 Mass within r500
66- 69 F4.2 10+14Msun e_M500 rms uncertainty on mass within r500
71- 74 F4.2 10+14Msun Mgas Gaz mass within r500
76- 79 F4.2 10+14Msun e_Mgas rms uncertainty on gaz mass within r500
81- 84 F4.2 [Sun] Zew Emission-weighted iron abundance
within 0.4r500
86- 89 F4.2 [Sun] e_Zew rms uncertainty on emission-weighted iron
abundance within 0.4r500
91- 94 F4.2 [Sun] Zmw1 Gas mass-weighted iron abundance
within 0.4r500
96- 99 F4.2 [Sun] e_Zmw1 rms uncertainty on gas mass-weighted iron
abundance within 0.4r500
101-104 F4.2 [Sun] Zmw2 Gas mass-weighted iron abundance
within r500
106-109 F4.2 [Sun] e_Zmw2 rms uncertainty on gas mass-weighted iron
abundance within r500
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 28-Jul-2020