2005/06/29 by Andisheh Mahdavi, A. Mahdavi, Neil Trentham +3 · 89 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Biology #Demography #Dwarf galaxy #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy group #Halo #Local Group #Luminosity #Luminosity function #Physics #Population #Sky #Stellar, planetary, and galactic studies #Supercluster (genetic) #Surface brightness #Velocity dispersion #Virial mass #astro-ph
paper · pdf · doi:10.1086/444560
published in The Astronomical Journal 130(4), 1502-1515 (Institute of Physics) · 17 pages; accepted for publication in the Astronomical Journal
arxiv created 2005/06/29 · openalex publication_date 2005/09/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/08
We conduct a photometric and spectroscopic survey of a 10 deg 2 region surrounding the nearby NGC 5846 group of galaxies, using the Canada-France-Hawaii and Keck I telescopes to study the population of dwarf galaxies as faint as M R = -10. Candidates are identified on the basis of quantitative surface brightness and qualitative morphological criteria. Spectroscopic follow up and a spatial correlation analysis provide the basis for affirming group memberships. Altogether, 324 candidates are identified, and 83 have spectroscopic membership confirmation. We argue on statistical grounds that a total of 251 ± 10 galaxies in our sample are group members. The observations, together with archival Sloan Digital Sky Survey, ROSAT , XMM-Newton , and ASCA data, suggest that the giant ellipticals NGC 5846 and NGC 5813 are the dominant components of subgroups separated by 600 kpc in projection and embedded in a 1.6 Mpc diameter dynamically evolved halo. The galaxy population is overwhelmingly early type. The group velocity dispersion is 322 km s -1 , its virial mass is 8.4 × 10 13 M ⊙ , and M / L R = 320 M ⊙ L . The ratio of dwarfs to giants is large compared with other environments in the Local Supercluster studied, and, correspondingly, the luminosity function is relatively steep, with a faint-end Schechter function slope of α d = -1.3 ± 0.1 (statistical) ±0.1 (systematic) at our completeness limit of M R = -12.