Abstract
Binary supermassive black holes (BSBHs) are expected to be a generic byproduct from hierarchical galaxy formation. The final coalescence of BSBHs is thought to be the loudest gravitational wave (GW) siren, yet no confirmed BSBH is known in the GW-dominated regime. While periodic quasars have been proposed as BSBH candidates, the physical origin of the periodicity has been largely uncertain. Here, we report discovery of a periodicity (p = 1607 ± 7 d) at 99.95 per cent significance (with a global p value of ∼10-3 accounting for the look elsewhere effect) in the optical light curves of a redshift 1.53 quasar, SDSS J025214.67-002813.7. Combining archival Sloan Digital Sky Survey data with new, sensitive imaging from the Dark Energy Survey, the total ∼20-yr time baseline spans ∼4.6 cycles of the observed 4.4-yr (rest frame 1.7-yr) periodicity. The light curves are best fit by a bursty model predicted by hydrodynamic simulations of circumbinary accretion discs. The periodicity is likely caused by accretion rate modulation by a milli-parsec BSBH emitting GWs, dynamically coupled to the circumbinary accretion disc. A bursty hydrodynamic variability model is statistically preferred over a smooth, sinusoidal model expected from relativistic Doppler boost, a kinematic effect proposed for PG1302-102. Furthermore, the frequency dependence of the variability amplitudes disfavours Doppler boost, lending independent support to the circumbinary accretion variability hypothesis. Given our detection rate of one BSBH candidate from circumbinary accretion variability out of 625 quasars, it suggests that future large, sensitive synoptic surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time may be able to detect hundreds to thousands of candidate BSBHs from circumbinary accretion with direct implications for Laser Interferometer Space Antenna.
| Original language | English |
|---|---|
| Pages (from-to) | 4025-4041 |
| Number of pages | 17 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 500 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 1 2021 |
Funding
The DES data management system is supported by the National Science Foundation under grant numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Program (FP7/2007-2013) including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and the Brazilian Instituto Nacional de Ciênciae Tecnologia (INCT) e-Universe (CNPq grant 465376/2014-2). Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astroparticle Physics, Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundac¸ão Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desen-volvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovac¸ão, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS website is www.sdss.org. We thank the anonymous referee for helpful suggestions that improved the manuscript. XL thanks A. Barth, S. Dodelson, S. Gezari, and A. Palmese for comments; and B. Fields, C. Gammie, K. Gültekin, Z. Haiman, D. Lai, A. Loeb, D. D’Orazio, S. Tremaine, and X.-J. Zhu for discussions; and LCO director Tod Boroson for granting us DDT observation. W.-T. L is supported in part by the Gordon and Betty Moore Foundation’s Data-Driven Discovery Initiative through grant GBMF4561 to Matthew Turk and the government scholarship to study aboard from the ministry of education of Taiwan. YCC and XL acknowledge a Center for Advanced Study Beckman fellowship and support from the University of Illinois campus research board. YCC is supported by the government scholarship to study aboard from the ministry of education of Taiwan and the Illinois Survey Science Fellowship. AMH is supported by the DOE NNSA Stewardship Science Graduate Fellowship under grant number DE-NA0003864. YS acknowledges support from the Alfred P. Sloan Foundation and NSF grant AST-1715579. This work makes use of observations from the LCOGT network. This manuscript has been authored by Fermi Research Alliance, LLC under contract no. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
| Funders | Funder number |
|---|---|
| Australian Research Council Centre of Excellence for All-sky Astrophysics | CE110001020 |
| Brazilian Instituto Nacional de Ciênciae Tecnologia | |
| Collaborating Institutions in the Dark Energy Survey | |
| Conselho Nacional de Desen-volvimento Científico e Tecnológico | |
| European Union’s Seventh Framework Program | |
| FP7/2007 | |
| Fermi Research Alliance, LLC | DE-AC02-07CH11359 |
| INCT | |
| Kavli Institute of Cosmological Physics at the University of Chicago | |
| Ministry of Science and Education of Spain | |
| Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University | |
| National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign | |
| U.S. Department of Energy Office of Science | |
| U.S. National Science Foundation | |
| University of Illinois campus research board | DE-NA0003864 |
| National Science Foundation | AST-1715579, AST-1138766, AST-1536171 |
| U.S. Department of Energy | |
| Alfred P. Sloan Foundation | |
| Gordon and Betty Moore Foundation | GBMF4561 |
| Office of Science | |
| High Energy Physics | |
| Ohio State University | |
| Seventh Framework Programme | 1138766, 240672, 306478, 1715579, 291329 |
| Higher Education Funding Council for England | |
| Center for Cosmology and Astroparticle Physics, Ohio State University | |
| Engineering Research Centers | |
| Science and Technology Facilities Council | |
| European Commission | |
| European Research Council | |
| Deutsche Forschungsgemeinschaft | |
| Generalitat de Catalunya | |
| Ministerio de Economía y Competitividad | SEV-2016-0588, SEV-2016-0597, ESP2015-66861, MDM-2015-0509, FPA2015-68048, AYA2015-71825 |
| Conselho Nacional de Desenvolvimento Científico e Tecnológico | 465376/2014-2 |
| Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
| Financiadora de Estudos e Projetos | |
| Ministério da Ciência e Tecnologia | |
| European Regional Development Fund | |
| ministry of education of Taiwan |
Keywords
- Black hole physics
- Galaxies: Active
- Galaxies: High-redshift
- Galaxies: nuclei
- Quasars: General
- Surveys