A WIDE AREA SURVEY FOR HIGH-REDSHIFT MASSIVE GALAXIES. II. NEAR-INFRARED SPECTROSCOPY OF BzK-SELECTED MASSIVE STAR-FORMING GALAXIES
- CEA, Laboratoire AIM-CNRS-Universite Paris Diderot, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)
- National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo (Japan)
- INAF-Padova, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy)
- CfA, University of Science and Technology of China, Hefei 230026 (China)
- Dipartimento di Astronomia, Universita di Bologna, Via Ranzani 1, 40127 Bologna (Italy)
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)
Results are presented from near-infrared spectroscopic observations of a sample of BzK-selected, massive star-forming galaxies (sBzKs) at 1.5 < z < 2.3 that were obtained with OHS/CISCO at the Subaru telescope and with SINFONI at the Very Large Telescope. Among the 28 sBzKs observed, H{alpha} emission was detected in 14 objects, and for 11 of them the [N II] {lambda}6583 flux was also measured. Multiwavelength photometry was also used to derive stellar masses and extinction parameters, whereas H{alpha} and [N II] emissions have allowed us to estimate star formation rates (SFRs), metallicities, ionization mechanisms, and dynamical masses. In order to enforce agreement between SFRs from H{alpha} with those derived from rest-frame UV and mid-infrared, additional obscuration for the emission lines (that originate in H II regions) was required compared to the extinction derived from the slope of the UV continuum. We have also derived the stellar mass-metallicity relation, as well as the relation between stellar mass and specific SFR (SSFR), and compared them to the results in other studies. At a given stellar mass, the sBzKs appear to have been already enriched to metallicities close to those of local star-forming galaxies of similar mass. The sBzKs presented here tend to have higher metallicities compared to those of UV-selected galaxies, indicating that near-infrared selected galaxies tend to be a chemically more evolved population. The sBzKs show SSFRs that are systematically higher, by up to {approx}2 orders of magnitude, compared to those of local galaxies of the same mass. The empirical correlations between stellar mass and metallicity, and stellar mass and SSFR are then compared with those of evolutionary population synthesis models constructed either with the simple closed-box assumption, or within an infall scenario. Within the assumptions that are built-in such models, it appears that a short timescale for the star formation ({approx_equal}100 Myr) and large initial gas mass appear to be required if one wants to reproduce both relations simultaneously.
- OSTI ID:
- 21448750
- Journal Information:
- Astrophysical Journal, Vol. 715, Issue 1; Other Information: DOI: 10.1088/0004-637X/715/1/385; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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