ORCID Profile
0000-0002-0639-5141
Current Organisation
University of Southampton
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Publisher: Oxford University Press (OUP)
Date: 15-12-2015
Publisher: Oxford University Press (OUP)
Date: 23-03-2015
DOI: 10.1093/MNRAS/STV174
Publisher: American Astronomical Society
Date: 05-08-2016
Publisher: Oxford University Press (OUP)
Date: 10-10-2020
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 days) at 99.95% 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 (restframe 1.7-yr) periodicity. The light curves are best fit by a bursty model predicted by hydrodynamic simulations of circumbinary accretion disks. The periodicity is likely caused by accretion rate modulation by a milli-parsec BSBH emitting GWs, dynamically coupled to the circumbinary accretion disk. 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 litudes disfavors 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.
Publisher: Oxford University Press (OUP)
Date: 17-11-2016
Publisher: EDP Sciences
Date: 17-02-2015
Publisher: Oxford University Press (OUP)
Date: 02-07-2013
Publisher: Oxford University Press (OUP)
Date: 05-06-2019
Abstract: Black hole mass measurements outside the local Universe are critically important to derive the growth of supermassive black holes over cosmic time, and to study the interplay between black hole growth and galaxy evolution. In this paper, we present two measurements of supermassive black hole masses from reverberation mapping (RM) of the broad C iv emission line. These measurements are based on multiyear photometry and spectroscopy from the Dark Energy Survey Supernova Program (DES-SN) and the Australian Dark Energy Survey (OzDES), which together constitute the OzDES RM Program. The observed reverberation lag between the DES continuum photometry and the OzDES emission line fluxes is measured to be $358^{+126}_{-123}$ and $343^{+58}_{-84}$ d for two quasars at redshifts of 1.905 and 2.593, respectively. The corresponding masses of the two supermassive black holes are 4.4 × 109 and 3.3 × 109 M⊙, which are among the highest redshift and highest mass black holes measured to date with RM studies. We use these new measurements to better determine the C iv radius−luminosity relationship for high-luminosity quasars, which is fundamental to many quasar black hole mass estimates and demographic studies.
Publisher: Oxford University Press (OUP)
Date: 20-03-2013
DOI: 10.1093/MNRAS/STT320
Publisher: Oxford University Press (OUP)
Date: 25-04-2018
Publisher: SPIE
Date: 24-07-2014
DOI: 10.1117/12.2055826
Publisher: American Physical Society (APS)
Date: 30-08-2016
Publisher: Oxford University Press (OUP)
Date: 21-03-2016
DOI: 10.1093/MNRAS/STW641
Publisher: Oxford University Press (OUP)
Date: 26-08-2015
Publisher: Oxford University Press (OUP)
Date: 29-07-2015
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Manda Banerji.