PKS 0805-07

PKS 0805-07 also known as PMN J0808-0751 and 4FGL J0808.2-0751, is a quasar located in the constellation of Monoceros. With a redshift of 1.83, light has taken at least 10 billion light-years to reach Earth.

Characteristics
Classified a high redshift blazar, a type of powerful radio-loud active galactic nuclei containing a relativistic jet, pointing towards the direction of Earth, PKS 0805-07 shows emitted radiation, mainly detected in gamma-rays (E>~100 MeV) as detected by Large Area Telescope. The quasar is known to have an extreme variability across its entire electromagnetic spectrum. Based on the strength of optical spectral lines, which the equivalent width (EW) of the spectral line is found greater or less than 5 Å, PKS 0805-07 is further classified a flat-spectrum radio quasar (FSRQ) containing strong emission-lines.

Like many other FSRQs, PKS 0805-07 contains characteristics like a high bolometric luminosity, and thermal activity that is related to an accretion disk in the quasar's optical and ultraviolet (UV) spectra. It is also known to have characteristic radio polarization at 1.4 GHz, P1.4 > 1% and a spinning black hole.

As studied by researchers for its emission properties, PKS 0805-07 exhibits lower electron energy (γ p ≲ 1.6 × 103) compared to BL Lacertae objects (BL Lacs) with a separation of Γ = -0.127 log ly + 8.18 in γ-ray luminosity versus photon index plane with a success rate of 88.6\%. It also has a stronger magnetic field (B) with smaller electron-to-magnetic energy ratio (U e/U B) than BL Lacs. Moreover, PKS 0805-07 shows a core-jet morphology with at least five observing epochs at 15 GHz between January 1996, and August 2019, observed by Very Long Baseline Array. The quasar also has a core-dominated source, showing asymmetric features than lobe-dominated sources, which is caused by modest relativistic motion (β ≡ 0.20) within its radio lobes.

Observations
Since April 2009, PKS 0805-07 was shown to have high levels of gamma-ray activity when detected by Large Area Telescope. Amongst other quasars, PKS 0805-07 has one of the fastest superluminal motions at that time.

Between 17 and 19, November 2022, an ongoing bright gamma-ray from PKS 0805-07 was observed by AGILE satellite. This source had a flux measured of F( > 100 MeV) = (2.7 +/- 0.8) x 10-6 photons/cm2/s and around 6 sigma.