分类： 天文学 >> 天文学 提交时间： 2023-02-19
Johan Comparat
Wentao Luo
Andrea Merloni
Surhud More
Mara Salvato
Mirko Krumpe
Takamitsu Miyaji
William Brandt
Antonis Georgakakis
Masayuki Akiyama
Johannes Buchner
Tom Dwelly
Toshihiro Kawaguchi
Teng Liu
Tohru Nagao
Kirpal Nandra
John Silverman
Yoshiki Toba
Scott F. Anderson
Juna Kollmeier
摘要： Which galaxies in the general population turn into active galactic nuclei
(AGN) is a keystone of galaxy formation and evolution. Thanks to SRG/eROSITA's
contiguous 140 square degrees pilot survey field, we constructed a large,
complete, and unbiased soft X-ray flux-limited AGN sample at low redshift
$0.05
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Teng Liu
Andrea Merloni
Johan Comparat
Kirpal Nandra
Jeremy S. Sanders
Georg Lamer
Johannes Buchner
Tom Dwelly
Michael Freyberg
Adam Malyali
Antonis Georgakakis
Mara Salvato
Hermann Brunner
Marcella Brusa
Matthias Klein
Vittorio Ghirardini
Nicolas Clerc
Florian Pacaud
Esra Bulbul
Ang Liu
摘要： The eROSITA X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) satellite has started to detect new X-ray sources over the full sky at an unprecedented rate. Understanding the performance and selection function of the source detection is important for the subsequent scientific analysis of the eROSITA catalogs. Through simulations, we test and optimize the eROSITA source detection procedures, and we characterize the detected catalog quantitatively. Taking the eROSITA Final Equatorial-Depth Survey (eFEDS) as an example, we ran extensive photon-event simulations based on our best knowledge of the instrument characteristics, the background spectrum, and the population of astronomical X-ray sources. We introduce a method of analyzing source detection completeness, purity, and efficiency based on the origin of each photon. According to the source detection efficiency measured in the simulation, we chose a two-pronged strategy to build eROSITA X-ray catalogs, creating a main catalog using only the most sensitive band (0.2-2.3 keV) and an independent hard-band-selected catalog using multiband detection in a range up to 5 keV. Because our mock data are highly representative of the real eFEDS data, we used the mock catalogs to measure the completeness and purity of the eFEDS catalogs as a function of multiple parameters, such as detection likelihood, flux, and luminosity. These measurements provide a basis for choosing the eFEDS catalog selection thresholds. The mock catalogs (available with this paper) can be used to construct the selection function of active galactic nuclei and galaxy clusters. A direct comparison of the output and input mock catalogs also gives rise to a correction curve that converts the raw point-source flux distribution into the intrinsic number counts distribution.
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