Toward a classification scheme for broad-line profiles in active galactic nuclei

Abstract

view Abstract Citations (56) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Toward a Classification Scheme for Broad-Line Profiles in Active Galactic Nuclei Sulentic, Jack W. Abstract A study has been made of the broad-line Hβ profile in quasars and Seyfert galaxies. All objects from the Palomar Bright Quasar Survey (PBQS; Schmidt and Green) catalog with published spectral scans have been included toward a goal of determining broad-line characteristics in a complete sample of active galactic nuclei (AGNs). The principal motivation for this study was to determine the range of spectral shifts exhibited by the broad lines relative to the narrow ones. We propose a simple classification scheme for broad-line Hβ that would note the presence of systematic line shifts and line asymmetries. We investigate two samples of AGNs: (1) 25 objects from the PBQS and (2) a less well defined sample of 36 objects selected from various literature sources. Together these samples represent virtually all published spectra accurate enough to be reliably classified in our system. Combining the two samples (n = 61) we find: (a) only nine objects show symmetric and unshifted profiles; (b) a large number (15) of displaced profiles are symmetric, with redshifts twice as common as blue ones; (c) 35 objects show a measurable wavelength shift relative to the narrow-line region [O III] (from 120 to 1900 km s^-1^), with redshifts (20) slightly more common than blueshifts; (d) a shifted profile is very unlikely to show a blue asymmetry (red asymmetries are 8 times more common); and (e) 37 objects show an asymmetric profile with red (27) ones almost three times as common as blue. The distribution of wavelength centroids at all four measured profile heights (allowing for a few outliers) is displaced ~100 km s^-1^ toward the red. This can be interpreted as evidence for a small gravitational redshift in most AGNs. Publication: The Astrophysical Journal Pub Date: August 1989 DOI: 10.1086/167684 Bibcode: 1989ApJ...343...54S Keywords: Active Galactic Nuclei; Astronomical Spectroscopy; Line Spectra; Spectrum Analysis; H Beta Line; Quasars; Red Shift; Seyfert Galaxies; Sky Surveys (Astronomy); Astrophysics; GALAXIES: SEYFERT; LINE PROFILES; QUASARS full text sources ADS | data products SIMBAD (59) NED (59)