The largest ever spectroscopic survey of [gamma]-ray blazars
Abstract/Contents
- Abstract
- This thesis reports on new optical spectroscopy of nearly 500 Fermi blazars---over 150 Flat Spectrum Radio Quasars (FSRQs) and over 300 BL Lacertae Objects (BL Lacs) drawn from the First and Second Fermi LAT AGN Catalogs. Including archival measurements (correcting several erroneous literature values) we have spectroscopic redshifts for 62% of the LAT AGN (46% of the BL Lacs). We establish firm lower redshift limits via intervening absorption systems and statistical lower limits via searches for host galaxies. This provides redshift constraints for an additional 49% of the BL Lac sample leaving only 5% of the BL Lacs unconstrained. Photometric monitoring and triggered large telescope spectroscopy is shown to improve these limits, but redshift identifications remain challenging. The new redshifts raise the median spectroscopic z of the BL Lacs from 0.23 to 0.33 and includes redshifts as large as z=2.2. Spectroscopic absorption limits have < z> = 0.70, showing a substantial fraction at large z and arguing against strong negative evolution. We find that detected BL Lac hosts are bright ellipticals with black hole masses ~ 10^{8.5-9} M_sun, substantially larger than the mean of optical AGN. The FSRQs have smaller virial estimates of black hole mass than the optical quasar sample. This appears to be largely due to a preferred (axial) view of the gamma-ray FSRQ and non-isotropic (H/R ~ 0.4) distribution of broad-line velocities. The power-law dominance of the optical spectrum extends to extreme values, but within the BL Lac class, this does not strongly correlate with the gamma-ray properties, suggesting that strong beaming is the primary cause of the range in continuum dominance. This substantially complete survey provides new opportunities for understanding the evolution of supermassive black holes and their spins over cosmic time; this LAT sample also helps elucidate the blazars' contribution to, and probes of, the cosmic extragalactic backgrounds.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Shaw, Michael S |
|---|---|
| Associated with | Stanford University, Department of Physics. |
| Primary advisor | Romani, Roger W. (Roger William) |
| Thesis advisor | Romani, Roger W. (Roger William) |
| Thesis advisor | Blandford, Roger D |
| Thesis advisor | Michelson, Peter F |
| Advisor | Blandford, Roger D |
| Advisor | Michelson, Peter F |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Michael S. Shaw. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Michael Shaw
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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