Emergence of Double-peaked Emission Lines in the Broad-Line Radio Galaxy Pictor A
Abstract
A new optical spectrum of the nearby broad-line radio galaxy (BLRG) Pictor A reveals a prominent double-peaked component of the Balmer lines which does not appear in any historical spectra of this object. Carried out with the hope of obtaining exactly such a result, this observation is a key to the interpretation of double-peaked emitters. It bolsters our previous conclusion that there is a set of additional properties which are associated with the rare class of double-peaked emitters, namely F-R II radio morphology, strong low-ionization forbidden lines, weak UV continuum, and flat far-infrared spectrum. Furthermore, the low-velocity, "ordinary" broad Balmer lines in Pictor A remained relatively unchanged as the new twin peaks appeared, which justifies the practice of applying models that fit only the double peaks and not the low-velocity components that are often present in spectra of this type. We discuss the relative merits of accretion-disk models and other models for double-peaked emission lines in the light of this new observation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1994
- DOI:
- 10.1086/187537
- Bibcode:
- 1994ApJ...433L..17H
- Keywords:
-
- Accretion Disks;
- Active Galaxies;
- Astronomical Models;
- Balmer Series;
- Emission Spectra;
- Radio Galaxies;
- Visible Spectrum;
- Astronomical Spectroscopy;
- Continuums;
- Infrared Spectra;
- Mathematical Models;
- Radio Spectra;
- Spectrographs;
- Ultraviolet Spectra;
- Astronomy;
- ACCRETION;
- ACCRETION DISKS;
- GALAXIES: INDIVIDUAL NAME: PICTOR A;
- GALAXIES: ACTIVE;
- LINE: PROFILES;
- RADIO CONTINUUM: GALAXIES