2001/01/04 by Michael Eracleous, Jules P. Halpern, J. P. Halpern · 5 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/321331
To appear in the Astrophysical Journal. AASTeX v.5, using psfig.sty and emulateapj5.sty, 5 pages, including 2 figures and a table
arxiv created 2001/01/04 · openalex publication_date 2001/06/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Motivated by the X-ray properties of the galaxy NGC 3065, we have obtained new optical spectra that reveal that it has a low-ionization nuclear emission-line region (LINER) as well as broad Balmer emission lines, establishing it as an active galactic nucleus. We also examined an older spectrum from the CfA Redshift Survey that lacks broad Balmer lines, indicating that these lines appeared sometime after 1980. Thus NGC 3065 joins the set of LINERs with broad, variable Balmer lines, which includes such well-known galaxies as NGC 1097 and M81. Inspired by the sometimes double-peaked profiles of the variable Balmer lines in other LINERs, we speculate that the broad Balmer lines of NGC 3065 also come from an accretion disk. We illustrate the plausibility of this hypothesis by fitting a disk model to the observed Hα profile. We also estimate the mass of the central black hole to be (9 ± 4) × 10 7 M ☉ from the properties of the host galaxy, which leads to the conclusion that the accretion rate is only ~2 × 10 -4 times the Eddington value, a property that appears to be common among LINERs. At such a low relative accretion rate, the inner accretion disk can turn into a vertically extended ion torus, which can illuminate the outer thin disk and power the broad-line emission. The reason for the sudden appearance of broad Balmer lines is an open question, although we suggest two possible explanations: (1) tidal disruption of a star or (2) a sudden transition in the structure of the accretion disk.