INSIGHTS ON THE FORMATION, EVOLUTION, AND ACTIVITY OF MASSIVE GALAXIES FROM ULTRACOMPACT AND DISKY GALAXIES AT z = 2-3
- Department of Astronomy, University of Texas at Austin, Austin, TX (United States)
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
- George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843 (United States)
- US Planck Data Center, MS220-6 Caltech, Pasadena, CA 91125 (United States)
- Gemini Observatory, Hilo, HI 96720 (United States)
- Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- NOAO, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)
- Australian Astronomical Observatory, P.O. Box 296, Epping, NSW 1710 (Australia)
We present our results on the structure and activity of massive galaxies at z = 1-3 using one of the largest (166 with M{sub *} {>=} 5 Multiplication-Sign 10{sup 10} M{sub Sun }) and most diverse samples of massive galaxies derived from the GOODS-NICMOS survey: (1) Sersic fits to deep NIC3 F160W images indicate that the rest-frame optical structures of massive galaxies are very different at z = 2-3 compared to z {approx} 0. Approximately 40% of massive galaxies are ultracompact (r{sub e} {<=} 2 kpc), compared to less than 1% at z {approx} 0. Furthermore, most ({approx}65%) systems at z = 2-3 have a low Sersic index n {<=} 2, compared to {approx}13% at z {approx} 0. We present evidence that the n {<=} 2 systems at z = 2-3 likely contain prominent disks, unlike most massive z {approx} 0 systems. (2) There is a correlation between structure and star formation rates (SFRs). The majority ({approx}85%) of non-active galactic nucleus (AGN) massive galaxies at z = 2-3, with SFR high enough to yield a 5{sigma} (30 {mu}Jy) 24 {mu}m Spitzer detection, have low n {<=} 2. Such n {<=} 2 systems host the highest SFR. (3) The frequency of AGNs is {approx}40% at z = 2-3. Most ({approx}65%) AGN hosts have disky (n {<=} 2) morphologies. Ultracompact galaxies appear quiescent in terms of both AGN activity and star formation. (4) Large stellar surface densities imply massive galaxies at z = 2-3 formed via rapid, highly dissipative events at z > 2. The large fraction of n {<=} 2 disky systems suggests cold mode accretion complements gas-rich major mergers at z > 2. In order for massive galaxies at z = 2-3 to evolve into present-day massive E/S0s, they need to significantly increase (n, r{sub e} ). Dry minor and major mergers may play an important role in this process.
- OSTI ID:
- 22004501
- Journal Information:
- Astrophysical Journal, Vol. 743, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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