Date/Time
Date(s) - 14/03/2012
3:30 pm - 4:30 pm

Title: The ALFALFA Census of Gas-Bearing Galaxies at z=0

Speaker: Dr. Martha Haynes – Cornell University

Institute:

Location: ABB 102

Description:

Capitalizing on the huge collecting area of the Arecibo telescope and the survey capability of the 7-beam Arecibo L-band Feed Array (ALFA), the Arecibo Legacy Fast ALFA (ALFALFA) extragalactic HI 21cm line survey aims to produce a census of HI-bearing objects found over 7000 square degrees of the high galactic latitude sky out to z < 0.06. The survey observations are 95% complete and a catalog is available for about 50% of the final survey area. I will review the nature of the ALFALFA population and discuss some of its more enigmatic objects, including "dark galaxy" candidates and possible very low mass "mini-halos" in the Local Group. Most surprisingly, ALFALFA detects many more high HI mass objects than predicted by previous HI surveys, a result of particular importance since it directly impacts, in a positive sense, estimates of the expected HI detection rate at high z with the SKA and its pathfinders. With its completion, ALFALFA will provide the first robust census of gas-bearing halos over a cosmologically significant volume. Our coordinated multiwavelength program is yielding important insight into how some massive galaxies maintain huge gas reservoirs without converting their gas into stars and how isolated low mass halos are able to retain some HI gas despite their fragile thermal state and shallow potential wells.