Outflows from Active Galactic Nuclei
The centers of active galactic nuclei (AGNs) contain supermassive black holes, which actively grow by the accretion of surrounding material and drive near-relativistic outflows. Contemporary X-ray observations of AGNs in Seyfert galaxies at the low redshifts reveal the presemce of blueshifted absorption lines, which were interpreted as ionized gas outflows along the line of sight from accretion disks near supermassive black holes. Over half of Seyfert I AGNs were found to have blueshifted absorption lines attributed to ionized outflows in the range of several hundred km/sec commonly referred to as warm absorbers (WAs). A considerable fraction of AGNs showed ionized absorbing outflows with velocities upto of 0.1 to 0.4 times the speed of light, so called ultra-fast outflows (UFOs).
As a Postdoc Fellow at Smithsonian Astrophysical Observatory, Ashkbiz Danehkar has carried out X-ray data analysis and photoionization modeling of ionized absorbing outflows in Seyfert I AGNs since 2015. He studied time-averaged 433ks observations of the quasar PG 1211+143 in a Seyfert I galaxy taken with Chandra High Energy Transmission Grating Spectrometer. It is found that the velocity of X-ray ionized outflows reaches a mildly relativistic value of 0.06 times the speed of light, which is typical of UFOs in Seyfert 1 AGNs.