CONSTRAINTS ON THE ASSEMBLY AND DYNAMICS OF GALAXIES. II. PROPERTIES OF KILOPARSEC-SCALE CLUMPS IN REST-FRAME OPTICAL EMISSION OF z {approx} 2 STAR-FORMING GALAXIES

Journal Article · Tue Sep 20 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/739/1/45; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587506

Foerster Schreiber, N M; Genzel, R; Davies, R; Genel, S; Lutz, D; Tacconi, L J ^[1]; Shapley, A E ^[2]; Bouche, N ^[3]; Cresci, G ^[4]; Erb, D K ^[5]; Newman, S; Shapiro, K L ^[6]; Steidel, C C ^[7]; Sternberg, A ^[8]

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1. Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany)
2. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)
3. Department of Physics, University of California Santa Barbara, Santa Barbara, California, CA 93106-9530 (United States)
4. INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)
5. Department of Physics, University of Wisconsin Milwaukee, Milwaukee, Wisconsin, WI 53211 (United States)
6. Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States)
7. California Institute of Technology, MS 105-24, Pasadena, CA 91125 (United States)
8. Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

We study the properties of luminous stellar 'clumps' identified in deep, high-resolution Hubble Space Telescope NIC2/F160W imaging at 1.6 {mu}m of six z {approx} 2 star-forming galaxies with existing near-infrared integral field spectroscopy from SINFONI at the Very Large Telescope. Individual clumps contribute {approx}0.5%-15% of the galaxy-integrated rest-frame {approx}5000 A emission, with median of {approx}2%; the total contribution of clump light ranges from 10% to 25%. The median intrinsic clump size and stellar mass are {approx}1 kpc and {approx}10{sup 9} M{sub sun}, in the ranges for clumps identified in rest-UV or line emission in other studies. The clump sizes and masses in the subset of disks are broadly consistent with expectations for clump formation through gravitational instabilities in gas-rich, turbulent disks given the host galaxies' global properties. By combining the NIC2 data with Advanced Camera for Surveys (ACS)/F814W imaging available for one source, and adaptive-optics-assisted SINFONI H{alpha} data for another, we infer modest color, M/L, and stellar age variations within each galaxy. In these two objects, sets of clumps identified at different wavelengths do not fully overlap; NIC2-identified clumps tend to be redder/older than ACS- or H{alpha}-identified clumps without rest-frame optical counterparts. There is evidence for a systematic trend of older ages at smaller galactocentric radii among the clumps, consistent with scenarios where inward migration of clumps transports material toward the central regions. From constraints on a bulge-like component at radii {approx}< 1-3 kpc, none of the five disks in our sample appears to contain a compact massive stellar core, and we do not discern a trend of bulge stellar mass fraction with stellar age of the galaxy. Further observations are necessary to probe the buildup of stellar bulges and the role of clumps in this process.

• OSTI ID: 21587506
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 739; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
EMISSION
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
GRAVITATIONAL INSTABILITY
INSTABILITY
PLASMA INSTABILITY