The AGN and Gas Disk in the Low Surface Brightness Galaxy PGC045080
The AGN and Gas Disk in the Low Surface Brightness Galaxy PGC045080
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Date
2007
Authors
Das, M.
Kantharia, N.
Ramya, S.
Prabhu, T. P.
McGaugh, S. S.
Vogel, S. N.
Advisor
Citation
The AGN and Gas Disk in the Low Surface Brightness Galaxy PGC045080. Das, M., Kantharia, N., Ramya, S., Prabhu, T.P., McGaugh, S.S., & Vogel, S.N. 2007, MNRAS, 379, 11-20.
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Abstract
We present radio observations and optical spectroscopy of the giant low surface brightness
(LSB) galaxy PGC 045080 (or 1300+0144). PGC 045080 is a moderately distant
galaxy having a highly inclined optical disk and massive HI gas content. Radio continuum
observations of the galaxy were carried out at 320 MHz, 610 MHz and 1.4 GHz.
Continuum emission was detected and mapped in the galaxy. The emission appears extended
over the inner disk at all three frequencies. At 1.4 GHz and 610 MHz it appears
to have two distinct lobes. We also did optical spectroscopy of the galaxy nucleus; the
spectrum did not show any strong emission lines associated with AGN activity but
the presence of a weak AGN cannot be ruled out. Furthermore, comparison of the
H flux and radio continuum at 1.4 GHz suggests that a significant fraction of the
emission is non-thermal in nature. Hence we conclude that a weak or hidden AGN
may be present in PGC 045080. The extended radio emission represents lobes/jets
from the AGN. These observations show that although LSB galaxies are metal poor
and have very little star formation, their centers can host significant AGN activity.
We also mapped the HI gas disk and velocity field in PGC 045080. The HI disk extends
well beyond the optical disk and appears warped. In the HI intensity maps, the
disk appears distinctly lopsided. The velocity field is disturbed on the lopsided side
of the disk but is fairly uniform in the other half. We derived the HI rotation curve
for the galaxy from the velocity field. The rotation curve has a flat rotation speed of
190km s−1.