Naslov
Periodically variable quasar candidates in SDSS Stripe 82 region

Autori
Fatović, Marta ; Palaversa, Lovro ; Tisanić, Krešimir ; Thanjavur, Karun ; Ivezić, Željko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, ostalo, znanstveni

Skup
European Astronomical Society Annual Meeting

Mjesto i datum
Valencia, Španjolska, 27.06.2022. - 01.07.2022

Vrsta sudjelovanja
Poster

Vrsta recenzije
Podatak o recenziji nije dostupan

Ključne riječi
Astronomy data analysis ; Period determination ; Time series analysis ; Quasars

Sažetak
We report the results of a search for small-amplitude (A less than 0.3 mag) long-period (P longer than 100 days) sources with periodic variability in SDSS Stripe 82 region. The SDSS coverage of Stripe 82 enables such a search because there are on average 20 observations per band in ugriz bands for about 1 million stars, collected over about 6 years, with a faint limit of r ∼ 22 mag and precisely calibrated 1-2% photometry. We calculated the periods of candidate variable sources in this sample using the LombScargle periodogram and considered the three highest periodogram peaks in each of the gri filters as relevant. Only those sources with gri periods consistent to within 0.1% were later studied. We focus our search on periodic variables with periods 100 < P < 600 days and uniform distribution of data points in phased light curves. We present 10 plausible candidates out of which seven have available archival spectra (two consistent with stars and five consistent with quasars). We have thoroughly analised the periodicity and photometry of the five plausibly periodically variable quasars, specifically focusing on possible false periods originating from the stochastic quasar variability. Furthermore, we extended the observational baseline of the SDSS with additional epochs from the ZTF and Pan-STARRS. The new data are in agreement with our model. Multiple explanations for the observed periodic behaviour are found in the literature: radio jet precession, tilted or warped accretion disks, but most of the explanations include binary super-massive black hole (BSMBH) systems. We single out one quasar with a period of P = 278 days whose X-ray variability is also detected by Chandra. This source is our pick for the most likely periodically variable quasar and follow-up efforts are in progress.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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