RECENT STELLAR MASS ASSEMBLY OF LOW-MASS STAR-FORMING GALAXIES AT REDSHIFTS 0.3 < z < 0.9

Journal Article · Tue Jan 20 04:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/799/1/36· OSTI ID:22364525

Rodríguez-Muñoz, Lucía; Gallego, Jesús; De Paz, Armando Gil; Villar, Víctor ^[1]; Pacifici, Camilla ^[2]; Tresse, Laurence ^[3]; Charlot, Stéphane ^[4]; Barro, Guillermo ^[5]

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1. Dpto. de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Av. Complutense s/n. E-28040, Madrid (Spain)
2. Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of)
3. Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France)
4. UPMC-CNRS, UMR7095, Institut d'Astrophysique de Paris, F-75014 Paris (France)
5. UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

The epoch when low-mass star-forming galaxies (LMSFGs) form the bulk of their stellar mass is uncertain. While some models predict an early formation, others favor a delayed scenario until later ages of the universe. We present constraints on the star formation histories (SFHs) of a sample of LMSFGs obtained through the analysis of their spectral energy distributions using a novel approach that (1) consistently combines photometric (broadband) and spectroscopic (equivalent widths of emission lines) data, and (2) uses physically motivated SFHs with non-uniform variations of the star formation rate (SFR) as a function of time. The sample includes 31 spectroscopically confirmed LMSFGs (7.3 ≤ log M {sub *}/M {sub ☉} ≤ 8.0), at 0.3 < z {sub spec} < 0.9, in the Extended-Chandra Deep Field-South field. Among them, 24 were selected with photometric stellar mass log M {sub *}/M {sub ☉} < 8.0, 0.3 < z {sub phot} < 1.0, and m {sub NB816,} {sub AB} < 26 mag; the remaining 7 were selected as blue compact dwarfs within the same photometric redshift and magnitude ranges. We also study a secondary sample of 43 more massive spectroscopically confirmed galaxies (8.0 < log M {sub *}/M {sub ☉} ≤ 9.1), selected with the same criteria. The SFRs and stellar masses derived for both samples place our targets on the standard main sequence of star-forming galaxies. The median SFH of LMSFGs at intermediate redshifts appears to form 90% of the median stellar mass inferred for the sample in the ∼0.5-1.8 Gyr immediately preceding the observation. These results suggest a recent stellar mass assembly for LMSFGs, consistent with the cosmological downsizing trends. We find similar median SFH timescales for the more massive secondary sample.

• OSTI ID: 22364525
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 799; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ENERGY SPECTRA
GALAXIES
LIMITING VALUES
MASS
PHOTOMETRY
RED SHIFT
STAR EVOLUTION
STAR MODELS
STARS
TIME DEPENDENCE
UNIVERSE
VARIATIONS