Discovery of a Quasar with Double-Peaked Broad Balmer Emission Lines

Abstract

Most massive galaxies contain a supermassive black hole (SMBH) at their center. When galaxies merge, their SMBHs sink to the center of the new galaxy where they are thought to eventually merge. During this process an SMBH binary is formed. The presence of two sets of broad emission lines in the optical spectrum of an active galactic nucleus (AGN) has been interpreted as evidence for two broad line regions (BLR), one surrounding each SMBH in a binary. We modeled the broad Balmer emission lines in SDSS spectra of 373 extreme variability AGNs using one broad and several narrow Gaussian components. We report on the discovery of SDSS J021647.53$-$011341.5 (hereafter J0216) as a double-peaked broad emission line source. Among the 373 AGNs there were five sources that are known double-peaked emission line sources. Three of these have been reported as candidate SMBH binaries in previous studies. We present all six objects and their double-peaked broad Balmer emission lines, and discuss the implications for a tidal disruption event (TDE) interpretation of the extreme variability assuming the double-peaked sources are SMBH binaries.

6 pages, 1 figure, 1 table. Accepted for publication in MNRAS

References in corpus (10)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Biases in Virial Black Hole Masses: An SDSS Perspective
• Massive binary black holes in galactic nuclei and their path to coalescence
• Active Galactic Nucleus Pairs from the Sloan Digital Sky Survey. I. The Frequency on ~ 5-100 kpc Scales
• Understanding extreme quasar optical variability with CRTS: I. Major AGN flares
• Long-Term Profile Variability of Double Peaked Emission Lines in Active Galactic Nuclei
• Double-peaked profiles: ubiquitous signatures of disks in the Broad Emission Lines of Active Galactic Nuclei
• Interactions between multiple supermassive black holes in galactic nuclei: a solution to the final parsec problem
• Extreme variability in an active galactic nucleus: Gaia16aax
• Properties of long-term optical variability of active galactic nuclei with double-peaked broad low-ionization emission lines