Discovery of the Most X-ray Luminous Quasar SRGE J170245.3+130104 at Redshift \boldsymbolz≈ 5.5

2021/03/01 by G. A. Khorunzhev, Г. А. Хорунжев, A. V. Meshcheryakov +21 · 1 citation
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Blazar #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma ray #Luminosity #Observatory #Physics #Quasar #Redshift #Sky #Telescope #acm:85-05 #astro-ph.GA #astro-ph.HE #msc:85-05

paper · pdf · doi:10.1134/s1063773721030026

published as Astronomy Letters 2021, volume 47,Number 3, pages 155-173 · Preprint: Original russian text: Pis'ma v Astronomichesky Zhurnal 2021, volume 47,Number 3, pages 155-173

openalex publication_date 2021/03/01 · arxiv created 2021/04/14 · openalex created_date 2021/04/26 · arxiv updated 2021/06/30 · openalex updated_date 2026/08/05

Abstract

During the first all-sky survey of the SRG orbital observatory, the X-ray source SRGE J170245.3+130104 was discovered with the eROSITA telescope on March 13–15, 2020. Its optical counterpart was identified by photometric attributes as a candidate for distant quasars at z≈ 5.5 . The spectroscopic observations of the object carried out in August and September 2020 at the 6-m BTA telescope with the SCORPIO-II instrument confirmed that SRGE J170245.3+130104 is a quasar at redshift z_\textrmspec=5.466± 0.003 . According to the eROSITA data obtained during the first sky survey, the X-ray luminosity of the quasar is 3.6^+2.1_-1.5× 10⁴⁶ erg s ^-1 in the 2–10 keV energy band, while its X-ray spectrum can be approximately fitted by a power law with a slope Γ=1.8^+0.9_-0.8 . The quasar was detected again with the eROSITA telescope half a year later (on September 13–14, 2020) during the second sky survey, with its X-ray luminosity, probably, having decreased approximately by a factor of 2 at a confidence level ≈1.9σ . SRGE J170245.3+130104 has turned out to be the most X-ray luminous quasar among all of the known quasars at redshifts z>5 . At the same time, it is also one of the radio loudest distant quasars (radio loudness R∼ 10³ ), which may imply that this is a blazar. We present a catalog of all the quasars at z>5 detected in X-rays to date.

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Cited by

• SRG X-ray orbital observatory