AGN Activity in Giant LSB Galaxies
A search of large, HI-rich disk galaxies finds a significantly higher
fraction of low luminosity AGN signatures compared to other late-type
galaxies. Approximately half of the galaxies selected in this sample
have AGN-like behavior in their cores, the rest have HII nuclei
resulting from simple star formation. Since AGN behavior is not
evident in all the sample galaxies, which where selected by high gas
mass, we speculate that it is the fuel flow rate that is the common
feature between late-type LSB disks and other active nuclear
galaxies.
The above spectra display the H_alpha/[N II]/[S II] and
[O I] features for six galaxies from the sample, all are classed as
giant
LSB systems except for UGC 12511. The arrow signifies H_alpha rest
frame. Note the strong [N II] and [S II] relative to H_alpha, the
signature of an active core.
A comparison plot of emission from the disk and core of UGC
4422. The core spectrum displays two of the most common features of
active classification in this study; strong [N II] and [S II] compared
to
H_alpha, a broad H_alpha width and [O I] emission. The disk spectrum
displays dominant and narrow H_alpha plus no indication of [O I],
indicative of ionized gas from star formation.