A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates

By M. Charisi, Imre Bartos, Zoltán Haiman, Adrian M. Price-Whelan, M. Graham, E. Bellm, R. Laher, Szabolcs Márka. 2016

179 citations recorded by the source corpus.

Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circum-binary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35 383 spectroscopically confirmed quasars in the photometric data base of the Palomar Transient Factory (PTF). We analysed Lomb–Scargle periodograms and assessed the significance of our findings by modelling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PTF and the Catalina Real-Time Transient Survey. Assuming that the observed periods correspond to the redshifted orbital periods of SMBHBs, we conclude that our findings are consistent with a population of unequal-mass SMBHBs, with a typical mass ratio as low as q ≡ M_2/M_1 ≈ 0.01.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/3b130c94dc102c72d7b919c9fad94eb314a00104

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Citations in the corpus

The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background (2023, result): “…et al. 2014; D’Orazio et al. 2015; Bowen et al. 2018; D’Orazio & Di Stefano 2018) have yielded a similar number of candidates (Graham et al. 2015; Charisi et al. 2016; Liu et al. 2019), though these samples are likely to also suffer significant contamination (Vaughan et al. 2016; Charisi et…”
False periodicities in quasar time-domain surveys (2016, unknown): “…stress that the precise number of phantom periods we find should not be directly compared to the survey of G15a, G15b, or of Liu et al. (2015), and Charisi et al. (2016) – our detection criteria are different, and our simulation experiment focuses on above-average data quality (a bright, variable…”
The quest for dual and binary supermassive black holes: A multi-messenger view (2019, background): “Additionally, Charisi et al. (2016) examined the candidates as a population and found a preference for low-mass ratio binaries (q = 0.”