We present an analysis of the optical nuclear spectra from the activegalactic nuclei (AGN) in a sample of low surface brightness (LSB) galaxies.Using data from the Sloan Digital Sky Survey (SDSS), we derived the virialblack hole (BH) masses of 24 galaxies from their broad H$\alpha$ parameters. Wefind that our estimates of nuclear BH masses lie in the range$10^{5}-10^{7}~M_{\odot}$, with a median mass of 5.62 x 10$^{6}~M_{\odot}$. Thebulge stellar velocity dispersion $\sigma_{e}$ was determined from theunderlying stellar spectra. We compared our results with the existing BH mass -velocity dispersion ($M_{BH}-\sigma_{e}$) correlations and found that themajority of our sample lie in the low BH mass regime and below the$M_{BH}-\sigma_{e}$ correlation. We analysed the effects of any systematic biasin the M$_{BH}$ estimates, the effects of galaxy orientation in the measurementof $\sigma_e$ and the increase of $\sigma_e$ due to the presence of bars andfound that these effects are insufficient to explain the observed offset inM$_{BH}$ - $\sigma_e$ correlation. Thus the LSB galaxies tend to have low massBHs which probably are not in co-evolution with the host galaxy bulges. Adetailed study of the nature of the bulges and the role of dark matter in thegrowth of the BHs is needed to further understand the BH-bulge co-evolution inthese poorly evolved and dark matter dominated systems.

The Magellanic Clouds provide the only laboratory to study the effect ofmetallicity and galaxy mass on molecular gas and star formation at high (~20pc) resolution. We use the dust emission from HERITAGE Herschel data to map themolecular gas in the Magellanic Clouds, avoiding the known biases of COemission as a tracer of H$_{2}$. Using our dust-based molecular gas estimates,we find molecular gas depletion times of ~0.4 Gyr in the LMC and ~0.6 SMC at 1kpc scales. These depletion times fall within the range found for normal diskgalaxies, but are shorter than the average value, which could be due to recentbursts in star formation. We find no evidence for a strong intrinsic dependenceof the molecular gas depletion time on metallicity. We study the relationshipbetween gas and star formation rate across a range in size scales from 20 pc to~1 kpc, including how the scatter in molecular gas depletion time changes withsize scale, and discuss the physical mechanisms driving the relationships. Wecompare the metallicity-dependent star formation models of Ostriker, McKee, andLeroy (2010) and Krumholz (2013) to our observations and find that they bothpredict the trend in the data, suggesting that the inclusion of a diffuseneutral medium is important at lower metallicity.

Energetic feedback from active galactic nuclei (AGN) is an importantingredient for regulating the star-formation history of galaxies in models ofgalaxy formation, which makes it important to study how AGN feedback actuallyoccurs in practice. In order to catch AGNs in the act of quenching starformation we have used the interstellar NaD absorption lines to look forcold-gas outflows in a sample of 456 nearby galaxies for which we couldunambigously ascertain the presence of radio AGN activity, thanks to radioimaging at milli-arcsecond scales. While compact radio emission indicating aradio AGN was found in 103 galaxies (23% of the sample), and 23 objects (5%)exhibited NaD absorption-line kinematics suggestive of cold-gas outflows, notone object showed evidence of a radio AGN and of a cold-gas outflowsimultaneously. Radio AGN activity was found predominantly in early-typegalaxies, while cold-gas outflows were mainly seen in spiral galaxies withcentral star-formation or composite star-formation/AGN activity. Optical AGNsalso do not seem capable of driving galactic winds in our sample. Our work addsto a picture of the low-redshift Universe where cold-gas outflows in massivegalaxies are generally driven by star formation and where radio-AGN activityoccurs most often in systems in which the gas reservoir has already beensignificantly depleted.