J/A+A/607/A56 Distant clusters of galaxies in the 2XMM/SDSS (Rabitz+, 2017)
Distant clusters of galaxies in the 2XMM/SDSS footprint: follow-up observations
with the LBT.
Rabitz A., Lamer G., Schwope A., Takey A.
<Astron. Astrophys. 607, A56 (2017)>
=2017A&A...607A..56R 2017A&A...607A..56R (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Photometry, SDSS
Keywords: galaxies: clusters: general -
galaxies: clusters: intracluster medium - X-rays: galaxies: clusters -
cosmology: observations
Abstract:
Galaxy clusters at high redshift are important to test cosmological
models and models for the growth of structure. They are difficult to
find in wide-angle optical surveys, however, leaving dedicated
follow-up of X-ray selected candidates as one promising identification
route.
We aim to increase the number of galaxy clusters beyond the
SDSS-limit, z∼0.75.
We compiled a list of extended X-ray sources from the 2XMMp catalogue
within the footprint of the Sloan Digital Sky Survey. Fields without
optical counterpart were selected for further investigation. Deep
optical imaging and follow-up spectroscopy were obtained with the
Large Binocular Telescope, Arizona (LBT), of those candidates not
known to the literature. From initially 19 candidates, selected by
visually screening X-ray images of 478 XMM-Newton observations and the
corresponding SDSS images, 6 clusters were found in the literature.
Imaging data through r,z filters were obtained for the remaining
candidates, and 7 were chosen for multi-object (MOS) spectroscopy.
Spectroscopic redshifts, optical magnitudes, and X-ray parameters
(flux, temperature, and luminosity) are presented for the clusters
with spectroscopic redshifts. The distant clusters studied here
constitute one additional redshift bin for studies of the L-T
relation, which does not seem to evolve from high to low redshifts.
The selection method of distant galaxy clusters presented here was
highly successful. It is based solely on archival optical (SDSS) and
X-ray (XMM-Newton) data. Out of 19 selected candidates, 6 of the 7
candidates selected for spectroscopic follow-up were verified as
distant clusters, a further candidate is most likely a group of
galaxies at z∼1.21. Out of the remaining 12 candidates, 6 were known
previously as galaxy clusters, one object is a likely X-ray emission
from an AGN radio jet, and for 5 we see no clear evidence for them to
be high-redshift galaxy clusters.
Description:
Positions and redshifts of the fields with spectroscopic follow-up
with the LBT. The astrometry is based on the SDSS. We give redshifts
based on LBT/MODS observations. Optical magnitudes were measured using
SExtractor's ISO-mag on LBT/LBC imaging in the SLOAN-r and SLOAN-z
filters. The errors for the magnitudes are given in extra columns, the
redshift is printed out to the last two significant digits (except for
stars). A flag indicates the affiliation and/or the astronomical
classification of the object.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 65 193 Photometric and spectroscopic properties of
sources with LBT follow-up
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See also:
J/MNRAS/366/171 : Red AGN in XMM/SDSS fields (Georgakakis+, 2006)
J/ApJS/183/17 : The SDSS DR5/XMM-Newton quasar survey (Young+, 2009)
J/MNRAS/457/110 : Northern XMM-XXL field AGN catalog (Menzel+, 2016)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right Ascension (J2000.0)
4- 5 I2 min RAm Right Ascension (J2000.0)
7- 8 I2 s RAs Right Ascension (J2000.0)
10 A1 --- DE- Declination sign (J2000.0)
11- 12 I2 deg DEd Declination (J2000.0)
14- 15 I2 arcmin DEm Declination (J2000.0)
17- 18 I2 arcsec DEs Declination (J2000.0)
20- 27 F8.6 --- z Redshift
29- 33 F5.1 arcsec Dist Distance to the X-ray center
35- 41 F7.4 mag rmag SLOAN r ISO magnitude
43- 48 F6.4 mag e_rmag Error in the r-SLOAN ISO magnitude
50- 56 F7.4 mag zmag SLOAN z ISO magnitude
58- 63 F6.4 mag e_zmag Error in the z-SLOAN ISO magnitude
65 I1 --- Flag [0/5]? Object type (1)
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Note (1): Object type as follows:
0 = star
1 = bcg
2 = cluster member
3 = group member
4 = galaxy
5 = quasar
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Acknowledgements:
Andreas Rabitz, arabitz(at)aip.de, Leibniz-Institut fur Astrophysik Potsdam
(End) Andreas Rabitz [Potsdam], Patricia Vannier [CDS] 25-Jul-2017