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A systematic search for changing-look quasars in SDSS
- Source :
- MacLeod, C L, Ross, N P, Lawrence, A, Goad, M, Horne, K, Burgett, W, Chambers, K C, Flewelling, H, Hodapp, K, Kaiser, N, Magnier, E, Wainscoat, R & Waters, C 2016, ' A systematic search for changing-look quasars in SDSS ', Monthly Notices of the Royal Astronomical Society, vol. 457, no. 1, pp. 389-404 . https://doi.org/10.1093/mnras/stv2997
- Publication Year :
- 2016
-
Abstract
- We present a systematic search for changing-look quasars based on repeat photometry from SDSS and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III BOSS. Objects with large, |\Delta g|>1 mag photometric variations in their light curves are selected as candidates to look for changes in broad emission line (BEL) features. Out of a sample of 1011 objects that satisfy our selection criteria and have more than one epoch of spectroscopy, we find 10 examples of quasars that have variable and/or "changing-look" BEL features. Four of our objects have emerging BELs; five have disappearing BELs, and one object shows tentative evidence for having both emerging and disappearing BELs. With redshifts in the range 0.20 < z < 0.63, this sample includes the highest-redshift changing-look quasars discovered to date. We highlight the quasar J102152.34+464515.6 at z = 0.204. Here, not only have the Balmer emission lines strongly diminished in prominence, including H$\beta$ all but disappearing, but the blue continuum $f_{\nu} \propto \nu^{1/3}$ typical of an AGN is also significantly diminished in the second epoch of spectroscopy. Using our selection criteria, we estimate that >15% of strongly variable luminous quasars display changing-look BEL features on rest-frame timescales of 8 to 10 years. Plausible timescales for variable dust extinction are factors of 2-10 too long to explain the dimming and brightening in these sources, and simple dust reddening models cannot reproduce the BEL changes. On the other hand, an advancement such as disk reprocessing is needed if the observed variations are due to accretion rate changes.<br />Comment: 15 pages, 8 Figures, 3 Tables, replaced with version accepted to MNRAS
- Subjects :
- ACTIVE GALACTIC NUCLEI
active [Galaxies]
Astrophysics::High Energy Astrophysical Phenomena
NDAS
Library science
FOS: Physical sciences
BROAD-LINE REGION
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
AGN DUSTY TORI
OSCILLATION SPECTROSCOPIC SURVEY
emission lines [Quasars]
7TH DATA RELEASE
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
QB Astronomy
010303 astronomy & astrophysics
RELATIVISTIC IRON LINE
BLACK-HOLES
Astrophysics::Galaxy Astrophysics
QC
QB
Physics
010308 nuclear & particles physics
Astronomy
Astronomy and Astrophysics
general [Quasars]
Astrophysics - Astrophysics of Galaxies
QC Physics
Accretion, accretion discs
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
X-RAY
SPECTRAL VARIABILITY
DIGITAL SKY SURVEY
Astrophysics::Earth and Planetary Astrophysics
Systematic search
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- MacLeod, C L, Ross, N P, Lawrence, A, Goad, M, Horne, K, Burgett, W, Chambers, K C, Flewelling, H, Hodapp, K, Kaiser, N, Magnier, E, Wainscoat, R & Waters, C 2016, ' A systematic search for changing-look quasars in SDSS ', Monthly Notices of the Royal Astronomical Society, vol. 457, no. 1, pp. 389-404 . https://doi.org/10.1093/mnras/stv2997
- Accession number :
- edsair.doi.dedup.....603d1904ce036616d0b6150ad31fec7c