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Full-Text Articles in Physical Sciences and Mathematics
The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford
The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford
Macalester Journal of Physics and Astronomy
We present H I spectral line images of the nearby dwarf galaxy NGC 3239. The galaxy’s curious morphology suggests that it is a post-merger system. We propose that NGC 3239 is a merger because it has multiple tidal tails, an enhanced velocity dispersion throughout the disk, and widespread star formation. We have produced kinematic moment maps corresponding to the H I column density, radial velocity, and velocity dispersion. Further, position velocity (P-V) slices of the galaxy were taken and three-color images were made using the SDSS G, R, and I, filters for comparison with the moment maps. These slices illustrate …
The Role Of Cold Gas In Low-Level Supermassive Black Hole Activity, Erik D. Alfvin
The Role Of Cold Gas In Low-Level Supermassive Black Hole Activity, Erik D. Alfvin
Macalester Journal of Physics and Astronomy
The nature of the relationship between low-level supermassive black hole activity and galactic cold gas, if any, is currently unclear. It has been hypothesized that feedback may heat or expel gas and quench star formation; alternatively, central black holes may feed at higher rates (either directly or as a secondary effect from stellar winds) in gas-rich galaxies. We use a combination of radio data from the on-going ALFALFA survey and from the literature, along with archival X-ray flux measurements from the Chandra X-ray observatory, to investigate this potential relationship. We construct a sample of 136 late-type galaxies, with MB < −18 out to 50 Mpc, that have both HI masses and sensitive X-ray coverage. Of these, 76 host a nuclear X-ray source, a 56% detection fraction. There is a highly significant correlation between LX and Mstar with a slope of 1.5±0.2, and a tentative correlation (significant at the 2.5σ level) between LX and MHI. However, a joint fit to LX as a function of both Mstar and MHI finds no significant dependence on MHI, and similarly the residuals of LX − LX(Mstar) show no trend with MHI. We conclude that the galaxy-wide cold gas content in these spirals does not strongly influence their low-level supermassive black hole activity.