Ly{alpha}-EMITTING GALAXIES AT z = 2.1: STELLAR MASSES, DUST, AND STAR FORMATION HISTORIES FROM SPECTRAL ENERGY DISTRIBUTION FITTING

Journal Article · Wed Jun 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/733/2/114· OSTI ID:21576721

Guaita, Lucia; Padilla, Nelson ^[1]; Acquaviva, Viviana; Gawiser, Eric; Bond, Nicholas A; Kurczynski, Peter ^[2]; Ciardullo, Robin; Gronwall, Caryl ^[3]; Treister, Ezequiel ^[4]; Lira, Paulina ^[5]; Schawinski, Kevin ^[6]

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1. Departmento de Astronomia y Astrofisica, Universidad Catolica de Chile, Santiago (Chile)
2. Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)
3. Department of Astronomy and Astrophysics, Penn State University, State College, PA 16802 (United States)
4. Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States)
5. Departamento de Astronoma de la Universidad de Chile, Santiago (Chile)
6. Department of Astronomy, Yale University, New Haven, CT 06511 (United States)

We study the physical properties of 216 z {approx_equal} 2.1 Ly{alpha}-emitting galaxies (LAEs) discovered in an ultra-deep narrow- MUSYC image of the ECDF-S. We fit their stacked spectral energy distribution (SED) using Charlot and Bruzual templates. We consider star formation histories (SFHs) parameterized by the e-folding time parameter {tau}, allowing for exponentially decreasing ({tau} > 0), exponentially increasing ({tau} < 0), and constant star formation rates (SFRs). We estimated the average flux at 5015 A of our LAE sample, finding a non-detection, which translates into negligible He II line emission at z {approx_equal} 2.1. In addition to this, the lack of high equivalent width (EW) Ly{alpha} line objects ruled out the hypothesis of a top-heavy initial mass function in LAEs. The typical LAEs of our sample are characterized by best-fit parameters and 68% confidence intervals of log(M{sub *}/M{sub sun}) = 8.6[8.4-9.1], E(B - V) = 0.22[0.00-0.31], {tau} = -0.02[(- 4)-18] Gyr, and age{sub SF} = 0.018[0.009-3] Gyr. Thus, we obtain robust measurements of low stellar mass and dust content, but we cannot place meaningful constraints on the age or SFH of the LAEs. We also calculate the instantaneous SFR to be 35[0.003-170] M{sub sun} yr{sup -1}, with its average over the last 100 Myr before observation giving (SFR){sub 100} = 4[2-30] M{sub sun} yr{sup -1}. When we compare the results for the same SFH, typical LAEs at z {approx_equal} 2.1 appear dustier and show higher instantaneous SFRs than z {approx_equal} 3.1 LAEs, while the observed stellar masses of the two samples seem consistent. Because the majority are low-mass galaxies, our typical LAEs appear to occupy the low-mass end of the distribution of star-forming galaxies at z {approx} 2. We perform SED fitting on several sub-samples selected based on photometric properties and find that LAE sub-samples at z {approx_equal} 2.1 exhibit heterogeneous properties. The typical IRAC-bright, UV-bright, and red LAEs have the largest stellar mass and dust reddening. The typical UV-faint, IRAC-faint, and high EW LAE sub-samples appear less massive (<10{sup 9} M{sub sun}) and less dusty, with E(B - V) consistent with zero.

• OSTI ID: 21576721
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 733; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DUSTS
EMISSION
ENERGY SPECTRA
EVOLUTION
GALAXIES
LYMAN LINES
PHYSICAL PROPERTIES
SPECTRA
STAR EVOLUTION