1997/11/30 by P. Romano, P. Marziani, D. Dultzin-Hacyan +1 · 7 citations
Mathematics · Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Balmer series #Doubly ionized oxygen #Emission spectrum #Full width at half maximum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Line (geometry) #Mathematics #Optics #Physics #Quasar #Redshift #Rest frame #Spectral line #astro-ph
paper · pdf · doi:10.1086/305293
published in The Astrophysical Journal 495(1), 222-226 (IOP Publishing) · 19 pages, 1 embedded figure (eps), to appear in ApJ 495
arxiv created 1997/11/30 · openalex publication_date 1998/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present spectroscopic observations of the quasar PG 1512+370, covering the Hβ line spectral range and collected at moderate resolution (2-7 Å FWHM) from 1988 to 1996. The observations show that the blue wing of the Hβ broad profile component has changed significantly in flux and shape between 1988 and 1990 and between 1995 and 1996. A displaced blue peak on the Hβ profile, visible in 1988, but not in the 1990-1995 spectra, is revealed again in one of the spectra obtained in 1996. The blue peak (in both the 1988 and 1996 spectra) is centered at Δ v r ≈ -3000 + 500 −500 km s -1 from the rest frame defined by the narrow component of Hβ, and the [O III] λλ4959, 5007 lines. We discuss several conflicting interpretations of the data. We find that the variability of the Hβ blue wing is consistent with Balmer line emission from regions whose motion is predominantly radial, if variations of the blue wing are a response to continuum changes. Alternatively, we note that observed Hβ line profile variations are consistent with a variable line component as in a "binary black hole" scenario. More frequent observations of Hβ are needed to distinguish among these hypotheses.