Astronomy and Astrophysics – Astronomy
Scientific paper
May 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000aas...19511514f&link_type=abstract
American Astronomical Society, 195th AAS Meeting, #115.14; Bulletin of the American Astronomical Society, Vol. 32, p.878
Astronomy and Astrophysics
Astronomy
Scientific paper
We present results of an unbiased survey of neutral hydrogen (HI) in Seyfert galaxies to test theories designed to unify the Seyfert 1 (broad-emission line) and Seyfert 2 (narrow-line) classifications of active galaxies. These theories, which suggest that apparent differences in the two subclasses are due to orientation effects, can be examined by comparing various neutral hydrogen properties derived from 21-cm spectra. If the unification theory is correct and the accretion disks of Sy 1's are face-on and those of Sy 2's are edge-on, and if the HI disk is aligned with the accretion disk, then Sy 1 HI spectra should have narrower velocity widths but the total HI mass and surface density should be comparable for the two classes. During the summer of 1999, the newly upgraded Arecibo telescope was used to observe a sample of 71 Seyfert galaxies which had not been previously detected at 21-cm, all with redshifts < 0.044. We detected neutral hydrogen in 39 galaxies, of which 20 were classified as Sy 1 and 19 as Sy 2. The distributions of hydrogen mass and surface density were found to be similar for the two classes, thereby supporting the unification scheme. However, the distributions of the velocity widths were not significantly different, perhaps due to the nonalignment of the HI and accretion disks. DMF was supported by the NSF Research Experience for Undergraduates program.
Eder Josef
Frierson Dargan M.
Ghosh Tamal
Salter Chris
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