Low Mass Galaxies and the Baryonic Tully Fisher Relation as a Distance Indicator

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It is difficult to understand an astronomical object unless its distance is known. That is why distance estimators are so precious. Scaling relations can be used to infer the distance to a galaxy. The Baryonic Tully Fisher Relation (BTFR) links the spin speed of a galaxy to its total mass in gas and stars. Astronomers are just beginning to ask if low mass galaxies obey the BTFR. These galaxies are sprinkled throughout the local universe and knowing their distances can open novel lines of inquiry. The team will use observations from NSF's Arecibo Observatory to measure the gas content, spin speed and recession speed of low mass galaxies. They will tally up the total masses in baryons to see if the galaxies obey the BTFR. If so, they will derive distances to galaxies near and inside the Pisces-Perseus Supercluster (PPS). They will compare the new distances and recession speeds to simulations to understand how the PSS formed. Senior team members will train junior team members. The Cornell team will continue to participate in the Undergraduate ALFALFA Team initiative, thereby involving students at 19 primarily undergraduate institutions in the research.The team will investigate the population of low-mass, HI-rich galaxies. Their goals are to (1) establish a robust BTFR for local star-forming disk galaxies, (2) use the BTFR as a distance estimator and to probe regimes where baryon deficiency becomes important, and (3) infer BTFR distances in the Pisces-Perseus Supercluster (PPS) and its foreground and background voids, to constrain simulations of PPS formation.