Rumbaugh, N;
Shen, Y;
Morganson, E;
Liu, X;
Banerji, M;
McMahon, RG;
Abdalla, FB;
... Wester, W; + view all
(2018)
Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey.
The Astrophysical Journal
, 854
(2)
, Article 160. 10.3847/1538-4357/aaa9b6.
Preview |
Text
Abdalla_Rumbaugh_2018_ApJ_854_160.pdf - Published Version Download (2MB) | Preview |
Abstract
We perform a systematic search for long-term extreme variability quasars (EVQs) in the overlapping Sloan Digital Sky Survey and 3 Year Dark Energy Survey imaging, which provide light curves spanning more than 15 years. We identified ~1000 EVQs with a maximum change in g-band magnitude of more than 1 mag over this period, about 10% of all quasars searched. The EVQs have L bol ~ 1045–1047 erg s−1 and L/L Edd ~ 0.01–1. Accounting for selection effects, we estimate an intrinsic EVQ fraction of ~30%–50% among all $g\lesssim 22$ quasars over a baseline of ~15 yr. We performed detailed multi-wavelength, spectral, and variability analyses for the EVQs and compared them to their parent quasar sample. We found that EVQs are distinct from a control sample of quasars matched in redshift and optical luminosity: (1) their UV broad emission lines have larger equivalent widths; (2) their Eddington ratios are systematically lower; and (3) they are more variable on all timescales. The intrinsic difference in quasar properties for EVQs suggests that internal processes associated with accretion are the main driver for the observed extreme long-term variability. However, despite their different properties, EVQs seem to be in the tail of a continuous distribution of quasar properties, rather than standing out as a distinct population. We speculate that EVQs are normal quasars accreting at relatively low rates, where the accretion flow is more likely to experience instabilities that drive the changes in flux by a factor of a few on multi-year timescales.
| Type: | Article |
|---|---|
| Title: | Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/aaa9b6 |
| Publisher version: | http://doi.org/10.3847/1538-4357/aaa9b6 |
| Language: | English |
| Additional information: | © 2018. The American Astronomical Society. All rights reserved. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, black hole physics, galaxies: active, line: profiles, quasars: general, surveys, ACTIVE GALACTIC NUCLEI, EMISSION-LINE PROPERTIES, BLACK-HOLE MASS, EDDINGTON RATIO, SEYFERT-1 GALAXIES, ACCRETION DISKS, DATA RELEASE, RADIO-LOUD, SDSS, TELESCOPE |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1562772 |
Archive Staff Only
 |
View Item |
