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Published April 2015 | Published + Submitted
Journal Article Open

Ultra-deep catalog of X-ray groups in the Extended Chandra Deep Field South

Abstract

Aims. We present the detection, identification and calibration of extended sources in the deepest X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S). Methods. Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search for extended X-ray emission down to an unprecedented flux of 2 × 10^(-16) ergs s^(-1) cm^(-2). By using simulations and comparing them with the Chandra and XMM data, we show that it is feasible to probe extended sources of this flux level, which is 10 000 times fainter than the first X-ray group catalogs of the ROSAT all sky survey. Extensive spectroscopic surveys at the VLT and Magellan have been completed, providing spectroscopic identification of galaxy groups to high redshifts. Furthermore, available HST imaging enables a weak-lensing calibration of the group masses. Results. We present the search for the extended emission on spatial scales of 32′′ in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the statistical properties of ECDF-S, such as log  N − log  S and X-ray luminosity function are broadly consistent with LCDM, with the exception that dn/dz/dΩ test reveals that a redshift range of 0.2 < z < 0.5 in ECDF-S is sparsely populated. The lack of nearby structure, however, makes studies of high-redshift groups particularly easier both in X-rays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weak-lensing analysis to show that the detected low-luminosity systems are indeed low-mass systems. We verify the applicability of the scaling relations between the X-ray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDF-S by means of stacked weak lensing and clustering analysis, constraining any possible departures to be within 30% in mass. Conclusions. Ultra-deep X-ray surveys uniquely probe the low-mass galaxy groups across a broad range of redshifts. These groups constitute the most common environment for galaxy evolution. Together with the exquisite data set available in the best studied part of the Universe, the ECDF-S group catalog presented here has an exceptional legacy value.

Additional Information

© 2015 ESO. Article published by EDP Sciences. Received 14 November 2013; Accepted 31 January 2015; Published online 17 April 2015. This work has been partially supported through a SAO grant SP1-12006B to UMBC. W.N.B. thanks Chandra grant SP1-12007A and NASA ADP grant NNX10AC99G. A.F. and V.A. wish to acknowledge Finnish Academy award, decision 266918. M.T. acknowledges support by KAKENHI No. 23740144. P.R. acknowledges a grant from the Greek General Secretariat of Research and Technology in the framework of the programme Support of Postdoctoral Researchers. A.C. and C.H. acknowledge support from the European Research Council under the EC FP7 grant number 240185. J.S.M. acknowledges partial support from Chandra grant SP1-12006A. C.S. acknowledges support by DLR grants 50QR1103 and 50QR0803. Y.Q.X. acknowledges support of the Thousand Young Talents program (KJ2030220004), the 973 Program (2015CB857004), the USTC startup funding (ZC9850290195), the National Natural Science Foundation of China (NSFC-11473026, 11421303), and the Strategic Priority Research Program "The Emergence of Cosmological Structures" of the Chinese Academy of Sciences (XDB09000000). F.E.B. acknowledges support from Basal-CATA PFB-06/2007, CONICYT-Chile (FONDECYT 1141218, ALMA-CONICYT 31100004, Gemini-CONICYT 32120003, "EMBIGGEN" Anillo ACT1101), and Project IC120009 "Millennium Institute of Astrophysics (MAS)" of Iniciativa Científica Milenio del Ministerio de Economía, Fomento y Turismo.

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August 22, 2023
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October 23, 2023