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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Junyao Li
John D. Silverman
Andrea Merloni
Mara Salvato
Johannes Buchner
Andy Goulding
Teng Liu
Riccardo Arcodia
Johan Comparat
Xuheng Ding
Kohei Ichikawa
Masatoshi Imanishi
Toshihiro Kawaguchi
Lalitwadee Kawinwanichakij
Yoshiki Toba
摘要： We investigate the physical properties, such as star-forming activity, disk
vs. bulge nature, galaxy size, and obscuration of 3796 X-ray selected AGNs at
$0.2
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
Julien Wolf
Kirpal Nandra
Mara Salvato
Johannes Buchner
Masafusa Onoue
Teng Liu
Riccardo Arcodia
Andrea Merloni
Stefano Ciroi
Francesco Di Mille
Vadim Burwitz
Marcella Brusa
Rikako Ishimoto
Nobunari Kashikawa
Yoshiki Matsuoka
Tanya Urrutia
Sophia Waddell
摘要： This study aims at identifying luminous quasars at $z>5.7$ among X-ray-selected sources in the eROSITA Final Equatorial-Depth Survey (eFEDS) in order to place a lower limit on black hole accretion well into the epoch of re-ionisation. We confirm the low significance detection with eROSITA of a previously known, optically faint $z=6.56$ quasar from the Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs) survey. We obtained a pointed follow-up observation of the source with the Chandra X-ray telescope in order to confirm the eROSITA detection. Using new near-infrared spectroscopy, we derived the physical properties of the super-massive black hole. Finally, we used this detection to infer a lower limit on the black hole accretion density rate at $z>6$. The Chandra observation confirms the eFEDS source as the most distant blind X-ray detection to date. The derived X-ray luminosity is high with respect to the rest-frame optical emission of the quasar. With a narrow MgII line, low derived black hole mass, and high Eddington ratio, as well as its steep photon index, the source shows properties that are similar to local narrow-line Seyfert 1 galaxies, which are thought to be powered by young super-massive black holes. In combination with a previous high-redshift quasar detection in the field, we show that quasars with $L_{2-10 \, \mathrm{keV}} >10^{45} \, \mathrm{erg \, s^{-1}}$ dominate accretion onto super-massive black holes at $z\sim 6$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Kohei Ichikawa
Takuji Yamashita
Andrea Merloni
Junyao Li
Teng Liu
Mara Salvato
Masayuki Akiyama
Riccardo Arcodia
Tom Dwelly
Xiaoyang Chen
Masatoshi Imanishi
Kohei Inayoshi
Toshihiro Kawaguchi
Taiki Kawamuro
Mitsuru Kokubo
Yoshiki Matsuoka
Tohru Nagao
Malte Schramm
Hyewon Suh
Masayuki Tanaka
摘要： We construct the eROSITA X-ray catalog of radio galaxies discovered by the
WERGS survey that is made by the cross-matching of the wide-area Subaru/HSC
optical survey and VLA/FIRST 1.4 GHz radio survey. We find 393 eROSITA detected
radio galaxies in the 0.5--2 keV band in the eFEDS field covering 140~deg$^2$.
Thanks to the wide and medium depth eFEDS X-ray survey, the sample contains the
rare and most X-ray luminous radio galaxies above the knee of the X-ray
luminosity function, spanning 4422$. Those obscured
and radio AGN reside in $0.4
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