50% of quasar outflows are situated at least 100 parsecs from the central source

TYPEAstrophysics Seminar
Speaker:Nahum Arav
Affiliation:Virginia Tech
Time:14:30 - 15:30
Location:Lidow 620
Abstract:The most robust way for determining the distance of quasar absorption outflows is the use of troughs from excited states. Here we report the results of two surveys targeting outflows that show troughs from S iv. One survey includes 1091 SDSS and BOSS quasar spectra, and the other includes much higher quality spectra of 13 quasar observed with the Very Large Telescope. We demonstrate that the depth ratio of S iv* to S iv troughs is a powerful diagnostic for the distance of the outflows from the central source. Since S iv is formed in the same physical region of the outflow as the canonical outflow-identifying species Civ, the results of these surveys are applicable to the large majority of quasar outflows. We find that at least 50% of quasar outflows are at distances larger than 100 parsecs from the central source, and at least 12% are at distances larger than 1000 parsecs. These results have profound implications to the study of the origin and acceleration mechanism of quasar outflows, and their effects on the host galaxy.