PDS 456
Quasar in the constellation Serpens
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PDS 456 is a relatively nearby radio-quiet quasar located in the constellation of Serpens.[1] This is a luminous active galactic nucleus (AGN) with a redshift of (z) 0.184, first discovered by astronomers conducting the Pico dos Dias survey in 1997.[2][3][4] The object is known to have prototypical ionized ultra-fast X-ray outflows[5] and a bolometric luminosity value of 1047 erg s−1.[6][7][8]
| PDS 456 | |
|---|---|
The quasar PDS 456. | |
| Observation data (J2000.0 epoch) | |
| Constellation | Serpens |
| Right ascension | 17h 28m 19.7906s |
| Declination | −14° 15′ 55.816″ |
| Redshift | 0.185000 |
| Heliocentric radial velocity | 55,462 km/s |
| Distance | 2.177 Gly |
| Apparent magnitude (V) | 14.03 |
| Apparent magnitude (B) | 14.69 |
| Characteristics | |
| Type | QSO |
| Other designations | |
| QSO B1725-142, IRAS 17254-1413, NVSS J172819-141555, 6dFGS J172819.8-141556 | |
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.[9] Radio images by very long baseline interferometry (VLBI) found PDS 456 has a complex nucleus described to be radio-emitting, an extended structure and a jet.[10]
In 2019, observations by the Atacama Large Millimeter Array (ALMA) 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.[11]
Additionally, disk wind from the accretion disk[12] and signatures of highly ionized gas detected via X-ray broadband spectra of PDS 456, was also present.[13] A supermassive black hole mass of 109.2±0.2 Mʘ was estimated for the object.[10]