# A possible close supermassive black-hole binary in a quasar with optical periodicity

@article{Graham2015APC,
title={A possible close supermassive black-hole binary in a quasar with optical periodicity},
author={Matthew J. Graham and S. George Djorgovski and Daniel Stern and Eilat Glikman and Andrew J. Drake and Ashish A. Mahabal and Ciro Donalek and Stephen M. Larson and Eric J. Christensen},
journal={Nature},
year={2015},
volume={518},
pages={74-76}
}
• Published 7 January 2015
• Physics
• Nature
Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the…
201 Citations
A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey
• Physics
• 2015
Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz
Toward the Unambiguous Identification of Supermassive Binary Black Holes through Bayesian Inference
• Physics
The Astrophysical Journal
• 2020
Supermassive binary black holes at sub-parsec orbital separations have yet to be discovered, with the possible exception of blazar OJ~287. In parallel to the global hunt for nanohertz gravitational
A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates
• Physics
• 2016
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
A Large Systematic Search for Close Supermassive Binary and Rapidly Recoiling Black Holes - II. Continued Spectroscopic Monitoring and Optical Flux Variability
• Physics
• 2015
We present new spectroscopic observations that are part of our continuing monitoring campaign of 88 quasars at z<0.7 whose broad H$\beta$ lines are offset from their systemic redshifts by a few
A large systematic search for close supermassive binary and rapidly recoiling black holes - III. Radial velocity variations
• Physics
• 2017
We have been spectroscopically monitoring 88 quasars selected to have broad H$\beta$ emission lines offset from their systemic redshift by thousands of km s$^{-1}$. By analogy with single-lined
A probable Milli-Parsec Supermassive Binary Black Hole in the Nearest Quasar Mrk 231
• Physics
• 2015
Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. Great effort has been made during the past several decades to
SPECTROSCOPIC INDICATION OF A CENTI-PARSEC SUPERMASSIVE BLACK HOLE BINARY IN THE GALACTIC CENTER OF NGC 5548
• Physics
• 2016
As a natural consequence of cosmological hierarchical structure formation, sub-parsec supermassive black hole binaries (SMBHBs) should be common in galaxies but thus far have eluded spectroscopic
Spectral energy distributions of candidate periodically variable quasars: testing the binary black hole hypothesis
• Physics
Monthly Notices of the Royal Astronomical Society
• 2019
Periodic quasars are candidates for binary supermassive black holes (BSBHs) efficiently emitting low-frequency gravitational waves. Recently, ∼150 candidates were identified from optical synoptic
A Periodically Varying Luminous Quasar at z=2 from the Pan-STARRS1 Medium Deep Survey: A Candidate Supermassive Black Hole Binary in the Gravitational Wave-Driven Regime
• Physics
• 2015
Supermassive black hole binaries (SMBHBs) should be an inevitable consequence of the hierarchical growth of massive galaxies through mergers, and the strongest sirens of gravitational waves (GWs) in
Infrared Time Lags for the Periodic Quasar PG 1302-102
• Physics
• 2015
The optical light curve of the quasar PG 1302-102 at $z = 0.278$ shows a strong, smooth 5.2 yr periodic signal, detectable over a period of $\sim 20$ yr. Although the interpretation of this

## References

SHOWING 1-10 OF 75 REFERENCES
Are the Variations in Quasar Optical Flux Driven by Thermal Fluctuations
• Physics
• 2009
We analyze a sample of optical light curves for 100 quasars, 70 of which have black hole mass estimates. Our sample is the largest and broadest used yet for modeling quasar variability. The sources
The FIRST-2MASS Red Quasar Survey
• Physics
• 2007
Combining radio observations with optical and infrared color selection, demonstrated in our pilot study to be an efficient selection algorithm for finding red quasars, we have obtained optical and
The Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Physics
• 2010
We model the time variability of ~9000 spectroscopically confirmed quasars in SDSS Stripe 82 as a damped random walk (DRW). Using 2.7 million photometric measurements collected over 10 yr, we confirm
TESTING THE 1995 BINARY BLACK HOLE MODEL OF OJ287
• Physics
• 2011
In 1995, a binary black hole model was proposed for the quasar OJ287, where the smaller secondary black hole impacts the accretion disk of the primary black hole twice during its 12 yr orbit and
Constraining Sub-parsec Binary Supermassive Black Holes in Quasars with Multi-epoch Spectroscopy. I. The General Quasar Population
• Physics
• 2013
We perform a systematic search for sub-parsec binary supermassive black holes (BHs) in normal broad-line quasars at z < 0.8, using multi-epoch Sloan Digital Sky Survey (SDSS) spectroscopy of the
A massive binary black-hole system in OJ 287 and a test of general relativity
• Physics
Nature
• 2008
The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system.
Optical monitoring of quasars — I. Variability
• Physics
• 1999
We present an analysis of quasar variability from data collected during a photometric monitoring of 50 objects carried out at CNPq/Laboratorio Nacional de Astrofisica, Brazil, between 1993 March and
Close supermassive binary black holes
It is proposed here instead that J1536+0441 is an example of line emission from a disk, and argues either that the merging of close SMBBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted.
THE POPULATION OF VISCOSITY- AND GRAVITATIONAL WAVE-DRIVEN SUPERMASSIVE BLACK HOLE BINARIES AMONG LUMINOUS ACTIVE GALACTIC NUCLEI
• Physics
• 2009
Supermassive black hole binaries (SMBHBs) in galactic nuclei are thought to be a common by-product of major galaxy mergers. We use simple disk models for the circumbinary gas and for the binary-disk
SUB-PARSEC SUPERMASSIVE BINARY QUASARS: EXPECTATIONS AT z < 1
• Physics, Computer Science
• 2009
The decreasing lifetime with SMBH binary mass suggests that lowering the luminosity threshold does not lead to a significant increase in the number of detectable sub-parsec binary quasars, and the theoretical expectations for detections of supermassive binary black holes that can be identified as sub- parsec luminous quasar are investigated.