PKS 0537-286 (referred to QSO 0537-286), also known as QSO B0537-286, is a quasar located in the constellation Columba. With a redshift of 3.104, the object is located 11.4 billion light years away[1] and belongs to the flat spectrum radio quasar blazar subclass (FSQR).[2] It is one of the most luminous known high-redshift quasars.[3]
Observation history
First detected at radio frequencies in 1975, PKS 0537-286 was observed at X-rays by the Einstein observatory.[4] It was later studied by ASCA,[5]ROSAT,[6]XMM[7] and subsequently Swift.[8] These observations showed PKS 0537-286 as extremely luminous quasar ( Lx=1047erg s−1 in the 0.1-2 keV range) with a particularly hard spectrum (r = 1 measured by Swift/BAT), which in the γ-ray band, it shows an energy flux of (1.44 ± 0.006) × 10−11 erg cm−2 s−1 in the fourth catalogue of Fermi-LATactive galactic nuclei.[9] A weak iron K emission line and reflection features is also found in PKS 0537-286. Moreover, Sowards-Emmerd et al. (2004)[10] identified the quasar as probable counterpart of the EGRET source 3EG J0531-2940.[11]
Characteristics
PKS 0537-286 is the brightest blazar beyond z = 3.0.[2] It shows characteristic properties of blazars, such as (rapid variability, strong polarization and high brightness) which are widely attributed to a powerful relativistic jet oriented close to the line of sight.[12]
Moreover, in several occasions, γ-rayflares were observed when the daily flux was above 10−6 photon cm−2 s−1. This makes PKS 0537-286 the most distant γ-ray flaring blazar.[13] The broad-band emission from PKS 0537-286 was successfully modelled within a one-zone synchrotron and external inverseCompton scenario where the excess in optical and ultraviolet bands was interpreted as emission from bright thermal accretion disc.[2] Moreover, PKS 0537-286 shows an emission redshift of 3.11, a prominent absorption system at a redshift of 2.976, and a strong discontinuity at the Lyman-continuum edge in the absorption system.[3]