ALFALFA: HI Cosmology in the Local Universe
Abstract
For the last 25 years, the 21 cm line has been used productively to investigate the large-scale structure of the Universe, its peculiar velocity field and the measurement of cosmic parameters. In February 2005 a blind HI survey that will cover 7074 square degrees of the high latitude sky was started at Arecibo, using the 7-beam feed L-band feed array (ALFA). Known as the Arecibo Legacy Fast ALFA (ALFALFA) Survey, the program is producing a census of HI-bearing objects over a cosmologically significant volume of the local Universe. With respect to previous blind HI surveys, ALFALFA offers an improvement of about one order of magnitude in sensitivity, 4 times the angular resolution, 3 times the spectral resolution, and 1.6 times the total bandwidth of HIPASS. ALFALFA can detect 7×104D2M⊙ of HI, where D is the source distance in Mpc. As of mid 2007, 44% of the survey observations and 15% of the source extraction are completed. We discuss the status of the survey and present a few preliminary results, in particular with reference to the proposed "dark galaxy" VirgoHI21.
- Publication:
-
Dark Galaxies and Lost Baryons
- Pub Date:
- May 2008
- DOI:
- 10.1017/S1743921307013853
- Bibcode:
- 2008IAUS..244...73G
- Keywords:
-
- galaxies: distances and redshifts;
- galaxies: dwarf;
- galaxies: evolution;
- galaxies: formation;
- galaxies: mass function;
- galaxies: spiral;
- cosmology: cosmological parameters;
- cosmology: observations;
- cosmology: large-scale structure of universe;
- radio lines: galaxies