2025/01/17 by Jessie C. Runnoe, Michael Eracleous, Runnoe, Jessie C. +7 · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #Black Holes and Theoretical Physics #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Relativity and Gravitational Theory
paper · pdf · doi:10.48550/arxiv.2501.10574
openalex publication_date 2025/01/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present Hubble Space Telescope ultraviolet (UV) of 13 quasars at z<0.7, along with contemporaneous optical spectra from ground-based telescopes. The targets were selected to have broad H-beta emission lines with substantial velocity offsets relative to the rest frame of their host galaxy. By analogy to single-line spectroscopic binary stars, these objects have been regarded as supermassive black hole binary (SBHB) candidates where the offset emission lines may be caused by bulk orbital motion. The best alternative explanation is that the H-beta line profile is the result of non-axisymmetric emission from a disk-like broad-line region associated with a single supermassive black hole. We use the broad UV line profiles to discriminate between these two scenarios. We describe our methodology for isolating the broad optical and UV line profiles and the criteria we apply for comparing them. Of the 13 SBHB candidates, three have strong evidence in support of the SBHB hypothesis, five have tentative support, one is disfavored, and four have such severely absorbed UV line profiles that the results are inconclusive.