WHAT DETERMINES THE SIZES OF RED EARLY-TYPE GALAXIES?
- Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
- Department of Astronomy, Yonsei University, Seoul 120-749 (Korea, Republic of)
The sizes of galaxies are known to be closely related with their masses, luminosities, redshifts, and morphologies. However, when we fix these quantities and morphology, we still find large dispersions in the galaxy size distribution. We investigate the origin of these dispersions for red early-type galaxies using two SDSS-based catalogs. We find that the sizes of faint galaxies (log (M{sub dyn}/M{sub Sun }) {approx}< 10.3 or {sup 0.1} M{sub r} {approx}> -19.5, where {sup 0.1} M{sub r} is the r-band absolute magnitude, k-corrected to z = 0.1) are affected more significantly by luminosity, while the sizes of bright galaxies (log (M{sub dyn}/M{sub Sun }) {approx}> 11.4 or {sup 0.1} M{sub r} {approx}< -21.4) are by dynamical mass. At fixed mass and luminosity, the sizes of low-mass galaxies (log (M{sub dyn}/M{sub Sun }) {approx} 10.45 and {sup 0.1} M{sub r} {approx} -19.8) are relatively less sensitive to their colors, color gradients, and axis ratios. On the other hand, the sizes of intermediate-mass (log (M{sub dyn}/M{sub Sun }) {approx} 10.85 and {sup 0.1} M{sub r} {approx} -20.4) and high-mass (log (M{sub dyn}/M{sub Sun }) {approx} 11.25 and {sup 0.1} M{sub r} {approx} -21.0) galaxies significantly depend on those parameters, in the sense that larger red early-type galaxies have bluer colors, more negative color gradients (bluer outskirts), and smaller axis ratios. These results indicate that the sizes of intermediate- and high-mass red early-type galaxies are significantly affected by their recent minor mergers or rotations, whereas the sizes of low-mass red early-type galaxies are affected by some other mechanisms. Major dry mergers also seem to have influenced on the size growth of high-mass red early-type galaxies.
- OSTI ID:
- 22078311
- Journal Information:
- Astrophysical Journal Letters, Vol. 762, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
A MULTIWAVELENGTH STUDY OF A SAMPLE OF 70 {mu}m SELECTED GALAXIES IN THE COSMOS FIELD. II. THE ROLE OF MERGERS IN GALAXY EVOLUTION
The Detailed Evolution of E+A Galaxies into Early Types