MASS GROWTH AND MERGERS: DIRECT OBSERVATIONS OF THE LUMINOSITY FUNCTION OF LRG SATELLITE GALAXIES OUT TO z = 0.7 FROM SDSS AND BOSS IMAGES
- Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)
- Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)
- Apache Point Observatory, Apache Point Road, P.O. Box 59, Sunspot, NM 88349 (United States)
- Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)
We present a statistical study of the luminosity functions of galaxies surrounding luminous red galaxies (LRGs) at average redshifts (z) = 0.34 and (z) = 0.65. The luminosity functions are derived by extracting source photometry around more than 40,000 LRGs and subtracting foreground and background contamination using randomly selected control fields. We show that at both studied redshifts the average luminosity functions of the LRGs and their satellite galaxies are poorly fitted by a Schechter function due to a luminosity gap between the centrals and their most luminous satellites. We utilize a two-component fit of a Schechter function plus a log-normal distribution to demonstrate that LRGs are typically brighter than their most luminous satellite by roughly 1.3 mag. This luminosity gap implies that interactions within LRG environments are typically restricted to minor mergers with mass ratios of 1:4 or lower. The luminosity functions further imply that roughly 35% of the mass in the environment is locked in the LRG itself, supporting the idea that mass growth through major mergers within the environment is unlikely. Lastly, we show that the luminosity gap may be at least partially explained by the selection of LRGs as the gap can be reproduced by sparsely sampling a Schechter function. In that case LRGs may represent only a small fraction of central galaxies in similar mass halos.
- OSTI ID:
- 22011731
- Journal Information:
- Astrophysical Journal, Vol. 746, 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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