Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-08-24
Mon.Not.Roy.Astron.Soc. 354 (2004) 851-869
Astronomy and Astrophysics
Astrophysics
16 pages, Latex, 17 figures, 6 tables, MNRAS in press
Scientific paper
10.1111/j.1365-2966.2004.08250.x
Isolated galaxies are important since they probe the lowest density regimes inhabited by galaxies. We define a sample of 36 nearby isolated early-type galaxies for further study. Our isolation criteria require them to have no comparable-mass neighbours within 2 B-band magnitudes, 0.67 Mpc in the plane of the sky and 700 km/s in recession velocity. New wide-field optical imaging of 10 isolated galaxies with the Anglo-Australian Telescope confirms their early-type morphology and relative isolation. We also present imaging of 4 galaxy groups as a control sample. The isolated galaxies are shown to be more gravitationally isolated than the group galaxies. We find that the isolated early-type galaxies have a mean effective colour of (B-R)_e = 1.54 +/- 0.14, similar to their high-density counterparts. They reveal a similar colour-magnitude relation slope and small intrinsic scatter to cluster ellipticals. They also follow the Kormendy relation of surface brightness versus size for luminous cluster galaxies. Such properties suggest that the isolated galaxies formed at a similar epoch to cluster galaxies, such that the bulk of their stars are very old. However, our galaxy modelling reveals evidence for dust lanes, plumes, shells, boxy and disk isophotes in four out of nine galaxies. Thus at least some isolated galaxies have experienced a recent merger/accretion event which may have induced a small burst of star formation. We derive luminosity functions for the isolated galaxies and find a faint slope of -1.2, which is similar to the `universal' slope found in a wide variety of environments. We examine the number density distribution of galaxies in the field of the isolated galaxies.
Beasley Michael A.
Forbes Duncan A.
Goudfrooij Paul
O'Sullivan Ewan J.
Reda Fatma M.
No associations
LandOfFree
The Photometric Properties of Isolated Early-Type Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Photometric Properties of Isolated Early-Type Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Photometric Properties of Isolated Early-Type Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-248617