Pulsar timing constraints on the Fermi massive black hole binary blazar population

Holgado, A. M.; Sesana, Alberto; Sandrinelli, A.; Covino, S.; Treves, A.; Liu, Xin; Ricker, P. M.

doi:10.1093/mnrasl/sly158

Cited by 47 publications

(33 citation statements)

References 55 publications

(62 reference statements)

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“…On the other hand, Sesana et al (2018) found that if all quasi-periodic quasars involved a SBBH system, then the expected gravitational wave background at frequencies corresponding to year timescales would be in conflict with that measured with pulsar timing arrays (Foster & Backer 1990). Holgado et al (2018) similarly concluded that binarity cannot uniquely explain quasi-periodicity in the Fermi blazar population on timescales of a few years.…”

Section: Discussionmentioning

confidence: 99%

Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38

Otero-Santos

Acosta–Pulido

González

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report on quasi-periodic variability found in two blazars included in the Steward Observatory Blazar Monitoring data sample: the BL Lac object 3C 66A and the Flat Spectrum Radio Quasar B2 1633+38. We collect optical photometric and polarimetric data in V and R bands of these sources from different observatories: St. Petersburg University, Crimean Astrophysical Observatory, WEBT-GASP, Catalina Real-Time Transient Survey, Steward Observatory, STELLA Robotic Observatory and Katzman Automatic Imaging Telescope. In addition, an analysis of the γ-ray light curves from Fermi-LAT is included. Three methods are used to search for any periodic behaviour in the data: the Z-transform Discrete Correlation Function, the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform. We find evidences of possible quasiperiodic variability in the optical photometric data of both sources with periods of ∼3 years for 3C 66A and ∼1.9 years for B2 1633+38, with significances between 3σ and 5σ. Only B2 1633+38 shows evidence of this behaviour in the optical polarized data set at a confidence level of 2σ-4σ. This is the first reported evidence of quasi-periodic behaviour in the optical light curve of B2 1633+38. Also a hint of quasi-periodic behaviour is found in the γ-ray light curve of B2 1633+38 with a confidence level 2σ, while no periodicity is observed for 3C 66A in this energy range. We propose different jet emission models that could explain the quasi-periodic variability and the differences found between these two sources.

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Section: Discussionmentioning

confidence: 99%

Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38

Otero-Santos

Acosta–Pulido

González

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Taylor et al 2017;Chen et al 2017;Middleton et al 2018) and make statements about SMBHB population statistics (e.g. Sesana et al 2018, Holgado et al 2018.…”

Section: Introductionmentioning

confidence: 99%

The NANOGrav 11 yr Data Set: Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Aggarwal¹,

Arzoumanian²,

Baker³

et al. 2019

ApJ

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157

183

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Observations indicate that nearly all galaxies contain supermassive black holes (SMBHs) at their centers. When galaxies merge, their component black holes form SMBH binaries (SMBHBs), which emit low-frequency gravitational waves (GWs) that can be detected by pulsar timing arrays (PTAs). We have searched the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 11-year data set for GWs from individual SMBHBs in circular orbits. As we did not find strong evidence for GWs in our data, we placed 95% upper limits on the strength of GWs from such sources. At f gw = 8 nHz, we placed a sky-averaged upper limit of h 0 < 7.3(3) × 10 −15 . We also developed a technique to determine the significance of a particular signal in each pulsar using "dropout" parameters as a way of identifying spurious signals. From these upper limits, we ruled out SMBHBs emitting GWs with f gw = 8 nHz within 120 Mpc for M = 10 9 M , and within 5.5 Gpc for M = 10 10 M at our most-sensitive sky location. We also determined that there are no SMBHBs with M > 1.6 × 10 9 M emitting GWs with f gw = 2.8 − 317.8 nHz in the Virgo Cluster. Finally, we compared our strain upper limits to simulated populations of SMBHBs, based on galaxies in Two Micron All-Sky Survey (2MASS) and merger rates from the Illustris cosmological simulation project, and found that only 34 out of arXiv:1812.11585v3 [astro-ph.GA] 21 May 2019 2 THE NANOGRAV COLLABORATION 75,000 realizations of the local Universe contained a detectable source.

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“…Unlike stellar mass binary black holes (which are advanced LIGO's primary targets, e.g., Abbott et al 2016) whose detection is largely limited to the local Universe, merging BSBHs would be detectable almost close to the edge of the observable Universe (e.g., Klein et al 2016). The more massive, low-redshift population (i.e., in the relatively nearby Universe) is being hunted by pulsar timing arrays (e.g., Zhu et al 2014 Guo et al 2016;Dvorkin & Barausse 2017;Kelley et al 2017b;Mingarelli et al 2017;Wang & Mohanty 2017;Aggarwal et al 2018;Holgado et al 2018;Sesana et al 2018), whereas the less massive, high-redshift population (i.e., in the earlier Universe) will be targeted by space-borne experiments in future (e.g., Babak et al 2011;.…”

Section: Introductionmentioning

confidence: 99%

Spectral energy distributions of candidate periodically variable quasars: testing the binary black hole hypothesis

Guo

Liu

Zafar

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Periodic quasars are candidates for binary supermassive black holes (BSBHs) efficiently emitting low frequency gravitational waves. Recently, ∼150 candidates were identified from optical synoptic surveys. However, they may be false positives caused by stochastic quasar variability given the few cycles covered (typically 1.5). To independently test the binary hypothesis, we search for evidence of truncated or gapped circumbinary accretion disks (CBDs) in their spectral energy distributions (SEDs). Our work is motivated by CBD simulations that predict flux deficits as cutoffs from central cavities opened by secondaries or notches from minidisks around both BHs. We find that candidate periodic quasars show SEDs similar to those of control quasars matched in redshift and luminosity. While seven of 138 candidates show a blue cutoff in the IR-optical-UV SED, which may represent CBDs with central cavities, the red SED fraction is similar to that in control quasars, suggesting no correlation between periodicity and SED anomaly. Alternatively, dust reddening may cause red SEDs. The fraction of extremely radio-loud quasars, i.e., blazars (with R > 100), is tentatively higher than that in control quasars (at 2.5σ). Our results suggest that, assuming most periodic candidates are robust, IR-optical-UV SEDs of CBDs are similar to those of accretion disks of single BHs, if the periodicity is driven by BSBHs; the higher blazar fraction may signal precessing radio jets. Alternatively, most current candidate periodic quasars identified from few-cycle light curves may be false positives. Their tentatively higher blazar fraction and lower Eddington ratios may both be caused by selection biases.

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Pulsar timing constraints on the Fermi massive black hole binary blazar population

Cited by 47 publications

References 55 publications

Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38

Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38

The NANOGrav 11 yr Data Set: Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Spectral energy distributions of candidate periodically variable quasars: testing the binary black hole hypothesis

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