PKS 1402-012

PKS 1402-012, also known as UM 632, is a quasar located in the constellation of Virgo. With a redshift of 2.51, the object is located 10.7 billion light-years from Earth.

Characteristics
As one of the objects observed and noted by researchers analyzing the Parkes quarter-Jansky flat-spectrum sample at Parkes Observatory, PKS 1402-012 is classified a blazar. Optically variable, it is a type of active galaxy shooting out an astrophysical jet in the direction of Earth, PKS 1402-012 is found to emit large amounts radiation over the whole electromagnetic spectrum up to TeV energies. It was a target of prior X-ray observations mentioned in the Einstein quasar database and is a high redshift gamma ray loud quasar.

PKS 1402-012 is also a BL Lac object and such has a bolometric luminosity of 1044 ≲ L≲ 1048 erg s−1 with a weak emission-line showing EW(C iv)≲10 Å, with a high Eddington ratio, in relationship to the modified Baldwin effect. Like other quasars, PKS 1402-012 has a flux-density distribution and luminosity function stronger than 2.4 mJy The flux-density varies time to time. In 1972, the flux density was at 0.67 Jy with the flux-density decreasing to 0.15 Jy in 1989.

The host galaxy of PKS 1402-012 is a massive starburst early-type galaxy, located inside an overdense rich galaxy cluster at a >=2σ level. It is found amidst a violent star-forming event, producing a significant fraction of stars within 0.5 billion years and large quantities of high-density ionized gas in its regions. The quasar contains an extragalactic radio source, which is responsible for powering strong star formations with rates of ~500 M_sun per year, consistent with its "quasar mode" accretion in which cold gas flows fuel both the AGN and starburst.

According to the Hubble Space Telescope, PKS 1402-012 is a gravitational lensed quasar which researchers noted ground based direct imaging characterized by a good dynamical range is the best observational strategy in the long term.

Absorption-line system
PKS 1402-012 has an absorption-line. In a study of 821 quasars and 8558 absorption-line systems sampled in the quasar spectra, researchers found lines of heavy elements and neutral hydrogen in PKS 1402–012. Apart from that, the quasar also shows evidence of HI 21 cm absorption, is a strong C IV absorber stronger EWrest>=0.5 Å and a damped Lyman α (DLA) system, containing ~90 per cent of the neutral HI mass.

Through observation by researchers for its spectral line equivalent widths, the quasar also contains O [III] narrow lines and C IV λ1549 and Mg II λ2799 broad lines, correlating positively with R I at 4σ-8σ level but no strong depended on R suggesting the line-of-sight angle to the radio-jet axis of PKS 1402-012 decreases. Furthermore, they found Ca ii absorbers with a rest frame equaling to widths of Wr,3934 = 15-799 mÅ and column density of log N(Ca ii) = 11.25-13.04, following a steep power law pattern of, f(N) ∝ N - β and slope angle - β = -1.68.

Researchers also detected a 21-cm absorption in Mg ii absorbers of PKS 1402–012. Through results, they found the quasar has a linear size of LS < 100 pc, since its detection rate is higher at cm wavelengths. With a velocity width of ΔV > 100 km s−1, PKS 1402-012 also shows an extended radio morphology at arcsecond scales. Researchers noted the 21-cm detection rate in strong Mg ii systems is constant over 0.5 < zabs < 1.5; that is over ~30% of the total age of universe.

Black hole
According to researchers who used a mass estimator based on the Hβ, Mg II, and C IV emission lines, they found the supermassive black hole in PKS 1402-012 is found to grow at an exponentially rate with a solar mass range estimated 108.8-1010.7 Msolar and high luminosity of 1045.2<λLλ(5100 Å)<1047.3 ergs s−1.

The growth rate of the black hole is found longer compared to the age of the universe with a corresponding epoch, suggesting there was an earlier episode of faster growth at z >~3.