DEEP ULTRAVIOLET LUMINOSITY FUNCTIONS AT THE INFALL REGION OF THE COMA CLUSTER
- Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States)
- Laboratory for X-ray Astrophysics, NASA GSFC, Code 662.0, Greenbelt, MD 20771 (United States)
- Department of Astronomy, Indiana University, Bloomington, IN 47404 (United States)
- Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom)
- Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
We have used deep GALEX observations at the infall region of the Coma cluster to measure the faintest ultraviolet (UV) luminosity functions (LFs) presented for a rich galaxy cluster thus far. The Coma UV LFs are measured to M{sub UV} = -10.5 in the GALEX FUV and NUV bands, or 3.5 mag fainter than previous studies, and reach the dwarf early-type galaxy population in Coma for the first time. The Schechter faint-end slopes ({alpha} Almost-Equal-To -1.39 in both GALEX bands) are shallower than reported in previous Coma UV LF studies owing to a flatter LF at faint magnitudes. A Gaussian-plus-Schechter model provides a slightly better parameterization of the UV LFs resulting in a faint-end slope of {alpha} Almost-Equal-To -1.15 in both GALEX bands. The two-component model gives faint-end slopes shallower than {alpha} = -1 (a turnover) for the LFs constructed separately for passive and star-forming galaxies. The UV LFs for star-forming galaxies show a turnover at M{sub UV} Almost-Equal-To -14 owing to a deficit of dwarf star-forming galaxies in Coma with stellar masses below M{sub *} = 10{sup 8} M{sub Sun }. A similar turnover is identified in recent UV LFs measured for the Virgo cluster suggesting this may be a common feature of local galaxy clusters, whereas the field UV LFs continue to rise at faint magnitudes. We did not identify an excess of passive galaxies as would be expected if the missing dwarf star-forming galaxies were quenched inside the cluster. In fact, the LFs for both dwarf passive and star-forming galaxies show the same turnover at faint magnitudes. We discuss the possible origin of the missing dwarf star-forming galaxies in Coma and their expected properties based on comparisons to local field galaxies.
- OSTI ID:
- 22011696
- Journal Information:
- Astrophysical Journal, Vol. 745, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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