PDS 456
PDS 456 is a relatively nearby radio-quiet quasar located in the constellation of Serpens. This is a luminous active galactic nucleus with a redshift of 0.184, first discovered by astronomers conducting the Pico dos Dias survey in 1997. The object is known to have prototypical ionized ultra-fast X-ray outflows and a bolometric luminosity value of 1047 erg s−1.
Description
An extremely bright X-ray flare was detected from PDS 456 in September 2018. Based on observations, it showed a flux increase by a factor 4, including its time-scale doubling and a high level of flare energy, exceeding 1051 erg. In addition, PDS 456 also displayed X-ray emission hardening following the flare. Radio images by very long baseline interferometry found PDS 456 has a complex nucleus described to be radio-emitting, an extended structure and a jet.In 2019, observations by the Atacama Large Millimeter Array found PDS 456 to contain kiloparsec-scale molecular outflows. The molecular outflows are estimated to have a mass of 2.5 x 108 Mʘ while a value of 290 Mʘ yr−1 was calculated for its outflow mass rate. Given its short depletion time, it is estimated the star-formation in PDS 456 would be quenched.
Additionally, disk wind from the accretion disk and signatures of highly ionized gas detected via X-ray broadband spectra of PDS 456, was also present. A supermassive [black hole] mass of 109.2±0.2 Mʘ was estimated for the object.