The First Distant X-ray Quasars ($$\boldsymbol{z\sim 4}$$) among the Sources Discovered by the eROSITA Telescope of the SRG Orbital Observatory during a Deep Lockman Hole Survey

Хорунжев, Г. А.; Meshcheryakov, A. V.; Burenin, R.; Lyapin, A. R.; Медведев, П. С.; Sazonov, S.; Еселевич, Максим; Sunyaev, R.; Gilfanov, M.

doi:10.1134/s1063773720030032

Cited by 12 publications

(3 citation statements)

References 24 publications

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“…Particularly interesting is the quasar CFHQS J142952+544717 at z = 6.2 (corresponding to the age of the Universe of 900 million years), which has been detected in X-rays for the first time by eROSITA and proved to have the highest X-ray luminosity (∼ 3 × 10 46 erg/s, or ∼ 10 13 bolometric luminosities of the Sun) among quasars at z > 6 (Medvedev et al 2020(Medvedev et al , 2021. During the CalPV phase and in the course of scanning the entire sky, SRG/eROSITA has discovered a number of extremely luminous quasars at redshift z > 5 and a noticeable number at z > 4 (Khorunzhev et al 2020;Dodin et al 2020;Bikmaev et al 2020;Wolf et al 2021). In Fig.…”

Section: X-ray Maps Obtained During the First All-sky Survey And The ...mentioning

confidence: 99%

The SRG X-ray orbital observatory, its telescopes and first scientific results

Sunyaev,

Arefiev,

Babyshkin

et al. 2021

Preprint

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The Orbital Observatory Spektr-RG (SRG), equipped with the grazing-incidence X-ray telescopes Mikhail Pavlinsky ART-XC and eROSITA, was launched by Roscosmos to the Lagrange L2 point of the Sun-Earth system on Jule 13, 2019. The launch was carried out from the Baikonur cosmodrome by a Proton-M rocket with a DM-03 upper stage. The German telescope eROSITA was installed on SRG under an agreement between Roskosmos and the DLR German Aerospace Agency. In December 2019, the Observatory started to perform its main scientific task: scanning the celestial sphere in order to obtain maps of the entire sky in X-rays in several energy ranges (from 0.3 to 8 keV, eROSITA, and from 4 to 30 keV, ART-XC). By mid-December 2020, the second 6-month full-sky scan had been completed. Over a period of 4 years, it is planned to obtain 8 independent maps of the entire sky in each of the energy ranges. The sum of these maps will provide high sensitivity and reveal more than three million quasars and over one hundred thousand massive galaxy clusters and galaxy groups. The availability of 8 sky maps will enable monitoring of long-term variability (every six months) of a huge number of extragalactic and Galactic X-ray sources, including hundreds of thousands of stars with active coronae. In addition, the rotation of the satellite around the axis directed toward the Sun with a period of 4 hours makes it possible to track faster variability of bright X-ray sources during one day every half a year. The chosen strategy of scanning the sky leads to the formation of deep survey zones near both ecliptic poles. The paper presents sky maps obtained by the telescopes aboard SRG during the first scan of the entire sky and a number of results of deep observations performed during the flight to the L2 point in the frame of the Performance Verification program, demonstrating the capabilities of the Observatory in imaging, spectroscopy and timing of X-ray sources. It is planned that in December 2023 the Observatory will switch, for at least two years, to observations of the most interesting sources in the sky in triaxial orientation mode and deep scanning of selected celestial fields with an area of up to 150 square degrees. These modes of operation were tested during the Performance Verification phase. Every day, data from the SRG observatory are dumped onto the largest antennae of the Russian Deep Space Network in Bear Lakes and near Ussuriysk.

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Section: X-ray Maps Obtained During the First All-sky Survey And The ...mentioning

confidence: 99%

The SRG X-ray orbital observatory, its telescopes and first scientific results

Sunyaev,

Arefiev,

Babyshkin

et al. 2021

Preprint

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“…The main element of the science program of the SRG observatory is an all-sky survey that was planned to be carried out over a four-year time span consisting of eight surveys lasting six months each (i.e., two surveys each year) (Sunyaev et al 2021). An extensive program of optical identification of both eROSITA and ART-XC sources is underway (e.g., Khorunzhev et al 2020;Bikmaev et al 2020;Dodin et al 2021;Schwope et al 2022;Zaznobin et al 2022;Rodriguez et al 2023).…”

Section: Introductionmentioning

confidence: 99%

Optical identification and follow-up observations of SRGA J213151.5+491400

Balman,

Khamitov,

Kolbin

et al. 2024

A&A

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The paper is comprised of optical identification and multiwavelength studies of a new X-ray source discovered by the Spectrum Roentgen-Gamma ( observatory during the survey and its follow-up optical and X-ray observations. We aim to identify SRGA\,J213151.5+491400 in the optical wavelengths. We determine spectra and light curves in the optical high and low states to find periodicities in the light curves and resolve emission lines in the system using optical ground-based data. We intend to study the spectral and temporal X-ray characteristics of the new source using the surveys in the high and low states and data in the low state. I TAK National Observatory) and in Russia (6-m and 1-m at SAO RAS), together with the X-ray data obtained with and telescopes aboard and the observatory. Using the optical data, we performed astrometry, photometry, spectroscopy, and power spectral analysis of the optical time series. We present optical Doppler tomography along with X-ray data analysis producing light curves and spectra. We detected in a high state in 2020 (17.9 mag) that decreased by about 3 mag into a low state (21 mag) in 2021. We find only one significant period using optical photometric time series analysis, which reveals the white dwarf spin (orbital) period to be 0.059710(1) days (85.982 min). The long slit spectroscopy in the high state yields a power-law continuum increasing towards the blue with a prominent II line along with the Balmer line emissions with no cyclotron humps, which is consistent with a magnetic cataclysmic variable (MCV) nature. Doppler Tomography confirms the polar nature revealing ballistic stream accretion along with magnetic stream during the high state. These characteristics show that the new source is a polar-type MCV source. detections yield an X-ray flux of (4.0-7.0)times in the high state. detects a dominating hot plasma component max $ $>$ 21 keV in the high state) declining to (4.0-6.0)times 10$^ in 2021 (low state). The data obtained in the low state reveal a two-pole accretor showing a soft X-ray component at (6-7)sigma significance with a blackbody temperature of 15-18 eV. A soft X-ray component has never been detected for a polar in the low state before.

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“…The high performance of SRGz predictions was confirmed by a set of follow-up spectroscopic bservations of SRGz candidates: distant quasars at z ∼ 4 and quasars at lower redshifts z ∼ 1 ÷ 3 from deep X-ray survey of the Lockman Hole extragalactic field (observed by eROSITA during the Performance Verification phase) and from the first scan of eROSITA All-Sky Survey. The optical spectra of the candidates were obtained on AZT-33IK 1.6-m telescope of the Sayan Observatory (Khorunzhev et al, 2020), Russian-Turkish 1.5-m telescope (RTT-150, Bikmaev et al 2020) and 2.5-m KGO telescope of the Lomonosov Moscow State University (Dodin et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Discovery of the most X-ray luminous quasar SRGE J170245.3+130104 at redshift z$\approx5.5$

Khorunzhev,

Meshcheryakov,

Medvedev

et al. 2021

Preprint

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SRGE J170245.3+130104 was discovered by the eROSITA telescope aboard the SRG space observatory on March 13-15, 2020 during the first half-year scan of its all-sky X-ray survey. The optical counterpart of the X-ray source was photometrically identified as a distant quasar candidate at z ≈ 5.5. Follow-up spectroscopic observations, done in August/September 2020 with the SCORPIO-II instrument at the BTA 6-m telescope, confirmed that SRGE J170245.3+130104 is a distant quasar at redshift zspec = 5.466 ± 0.003. The X-ray luminosity of the quasar during the first half-year scan of the eROSITA all-sky survey was 3.6 +2.1 −1.5 × 10 46 erg/s (in the 2-10 keV energy range), whereas its X-ray spectrum could be described by a power law with a slope of Γ = 1.8 +0.9 −0.8 . Six months later (September 13-14, 2020), during the second half-year scan of the eROSITA all-sky survey, the quasar was detected again and its X-ray luminosity had decreased by a factor of 2 (at the ≈ 1.9σ confidence level). SRGE J170245.3+130104 proves to be the most X-ray luminous among all known X-ray quasars at z > 5. It is also one of the radio-loudest distant quasars (with radio-loudness R ∼ 10 3 ), which may imply that it is a blazar. In the Appendix, we present the list of all z > 5 quasars detected in X-rays to date.

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The First Distant X-ray Quasars ($$\boldsymbol{z\sim 4}$$) among the Sources Discovered by the eROSITA Telescope of the SRG Orbital Observatory during a Deep Lockman Hole Survey

Cited by 12 publications

References 24 publications

The SRG X-ray orbital observatory, its telescopes and first scientific results

The SRG X-ray orbital observatory, its telescopes and first scientific results

Optical identification and follow-up observations of SRGA J213151.5+491400

Discovery of the most X-ray luminous quasar SRGE J170245.3+130104 at redshift z$\approx5.5$

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