Circumnuclear molecular gas in Seyfert galaxies

Yoshiaki Taniguchi, Osamu Kameya, Naomasa Nakai, Kimiaki Kawara
1990 Astrophysical Journal  
In order to investigate ci uclear molecular gaseous contents and its relation to the nuclear activity, ade a search for circumnuclear 112C0 ( J = l -0) emission from 28 starbursts galaxies (SBNs) and 12 Seyfert galaxies with the recession velocities less than 5000 kmjs-', using the Nobeyama Radio Observatory 45-m telescope. The full half-power beam width of 17 arcsec covers a region of less than about 5 ameter for the sample galaxies. The circumnuclear CO emission h ected from twelve SBNs (one
more » ... s summarized .as follows. I. Starburst-Nucleus Galaxies (1) We study a relation between MH~/MHI and [OIII]/HP, where the latter ratio provides a measure of excitation condition of the ionized gas. It is indicated that the galaxies in which the circumnuclear gas is less abundant have higher-excitation emitting regions in general. This implies that molecular gas clouds are dissociated by strong radiation and/or supernova wind activity in such galaxies. Alternatively, we simply interpret that more intense starburst activity tends to h umed more molecular gas. results with previous CO studies made at radio observatories with 1 beam sizes, we investigated the radial distribution of s. We found that most of the SBNs show a tendency of central concentratjon of molecular gas in comparison to Seyfert galaxies. (3) We found tbat two of the SBNs (Mrk 52 and Mrk 708) have very narrow CO line widths although they look like significantly inclined galaxies. This strongly suggests that the circumnuclear molecular gas clouds in these galaxies are kinematically independent from the host galaxies. Since these galaxies have prominent bar structure, it is considered that the bar shock cause forcing gas infall toward the nuclear regions, triggering the nuclear starburst activities. i 1 marginal) and four Seyfert galaxies. Om main results an i 56 https://ntrs.nasa.gov/search.jsp?
doi:10.1086/168967 fatcat:yqd2spxhw5dljexiofo7csrrki