AGN Activity and Black Hole Masses in Low Surface Brightness Galaxies
  We present medium resolution optical spectroscopy of a sample of nine Low
Surface Brightness (LSB) galaxies. For those that show clear signatures of AGN
emission, we have disentangled the AGN component from stellar light and any Fe
I and Fe II contribution. We have decomposed the H_alpha line into narrow and
broad components and determined the velocities of the broad components; typical
values lie between 900--2500 km/s. Of the galaxies in our study, UGC 6614, UGC
1922, UGC 6968 and LSBC F568-6 (Malin~2) show clear signatures of AGN activity.
We have calculated the approximate black hole masses for these galaxies from
the H_alpha line emission using the virial approximation. The black hole masses
are ~3x10^{5} M_sun for three galaxies and lie in the intermediate mass black
holes domain rather than the supermassive range. UGC 6614 harbors a BH of mass
3.8x10^{6} M_sun; it also shows an interesting feature blueward of H_alpha and
H_beta implying outflow of gas or a one-sided jet streaming towards us. We have
also measured the bulge stellar velocity dispersions using the Ca II Triplet
lines and plotted these galaxies on the M-sigma plot. We find that all the
three galaxies UGC 6614, UGC 6968 and F568-6 lie below the M-sigma relation for
nearby galaxies. Thus we find that although the bulges of LSB galaxies may be
well evolved, their nuclear black hole masses are lower than those found in
bright galaxies and lie offset from the M-sigma correlation.
