Broad-line region configuration of the supermassive binary black hole candidate PG1302-102 in the relativistic Doppler boosting scenario

Abstract

PG1302-102 is thought to be a supermassive binary black hole (BBH) system according to the periodical variations of its optical and UV photometry, which may be interpreted as being due to the relativistic Doppler boosting of the emission mainly from the disk around the secondary black hole (BH) modulated by its orbital motion. In this paper, we investigate several broad emission lines of PG1302-102 using archived UV spectra obtained by IUE, GALEX, and Hubble, to reveal the broad-line region (BLR) emission properties of this BBH system under the Doppler boosting scenario. We find that the broad lines Ly$\alpha$, NV, CIV, and CIII] all show Gaussian profiles, and none of these lines exhibits obvious periodical variation. Adopting a simple model for the BLR, we perform Markov chain Monte Carlo fittings to these broad lines, and find that the BLR must be viewed at an orientation angle of $\sim 33^{\circ }$, close to face-on. If the Doppler boosting interpretation is correct, then the BLR is misaligned with the BBH orbital plane by an angle of $\sim 51^{\circ }$, which suggests that the Doppler boosted continuum variation has little effect on the broad-line emission and thus does not lead to periodical line variation. We further discuss the possible implications for such a BLR configuration with respect to the BBH orbital plane.

9 pages, 6 figures, matches A&A version (only minor changes)

References in corpus (10)

• A Catalog of Quasar Properties from SDSS DR7
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• A possible close supermassive black-hole binary in a quasar with optical periodicity
• Circumbinary Accretion from Finite and Infinite Disks
• Modeling reverberation mapping data I: improved geometric and dynamical models and comparison with cross-correlation results
• The Keck Baryonic Structure Survey: Using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at $z\sim 2$
• Minidisks in Binary Black Hole Accretion
• Dynamical evolution of cosmic supermassive binary black holes and their gravitational wave radiation
• Testing the relativistic Doppler boost hypothesis for supermassive binary black holes candidates via broad emission line profiles
• Predicting the broad lines polarization emitted by supermassive binary black holes

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• On Variation of Light Curves and Broad Emission Lines for Periodic QSOs from co-rotating Supermassive binary black holes in elliptical orbits
• The possible long-term periodic variability of the extremely luminous quasar WISE J090924.01+000211.1
• A Population Study for Searching Supermassive Binary Black Holes in Active Galactic Nuclei: Continuum Spectral Features and Periodic Variabilities