Direct Measurements of the Stellar Continua and Balmer/4000 Angstrom Breaks of Red z>2 Galaxies: Redshifts and Improved Constraints on Stellar Populations

Abstract

We use near-infrared (NIR) spectroscopy obtained with GNIRS on Gemini, NIRSPEC on KECK, and ISAAC on the VLT to study the rest-frame optical continua of three `Distant Red Galaxies' (having Js - Ks > 2.3) at z>2. All three galaxy spectra show the Balmer/4000 Angstrom break in the rest-frame optical. The spectra allow us to determine spectroscopic redshifts from the continuum with an estimated accuracy dz/(1+z) ~ 0.001-0.04. These redshifts agree well with the emission line redshifts for the 2 galaxies with Halpha emission. This technique is particularly important for galaxies that are faint in the rest-frame UV, as they are underrepresented in high redshift samples selected in optical surveys and are too faint for optical spectroscopy. Furthermore, we use the break, continuum shape, and equivalent width of Halpha together with evolutionary synthesis models to constrain the age, star formation timescale, dust content, stellar mass and star formation rate of the galaxies. Inclusion of the NIR spectra in the stellar population fits greatly reduces the range of possible solutions for stellar population properties. We find that the stellar populations differ greatly among the three galaxies, ranging from a young dusty starburst with a small break and strong emission lines to an evolved galaxy with a strong break and no detected line emission. The dusty starburst galaxy has an age of 0.3 Gyr and a stellar mass of 1*10^11 Msun. The spectra of the two most evolved galaxies imply ages of 1.3-1.4 Gyr and stellar masses of 4*10^11 Msun. The large range of properties seen in these galaxies strengthens our previous much more uncertain results from broadband photometry. Larger samples are required to determine the relative frequency of dusty starbursts and (nearly) passively evolving galaxies at z~2.5.

Accepted for publication in the Astrophysical Journal. 12 pages, 6 figures

Cited by in corpus (34)

• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• EAZY: A Fast, Public Photometric Redshift Code
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• What do we learn from IRAC observations of galaxies at 2 < z < 3.5?
• A Significant Population of Very Luminous Dust-Obscured Galaxies at Redshift z ~ 2
• NICMOS Imaging of DRGs in the HDF-S: A Relation Between Star-Formation and Size at z ~ 2.5
• The Detection of a Red Sequence of Massive Field Galaxies at z~2.3 and its Evolution to z~0
• The Star Formation Epoch of the Most Massive Early-Type Galaxies
• A Near-Infrared Spectroscopic Survey of K-selected Galaxies at z~2.3: Redshifts and Implications for Broadband Photometric Studies
• The Multiwavelength Survey by Yale-Chile (MUSYC): Deep Near-Infrared Imaging and the Selection of Distant Galaxies
• Measuring the Average Evolution of Luminous Galaxies at z<3: The Rest-frame Optical Luminosity Density, Spectral Energy Distribution, and Stellar Mass Density
• Clustering of K-selected Galaxies at 2<z<3.5: Evidence for a Color-Density Relation
• A comparison among LBGs, DRGs and BzK galaxies: their contribution to the stellar mass density in the GOODS-MUSIC sample
• The Origin of Line Emission in Massive z~2.3 Galaxies: Evidence for Cosmic Downsizing of AGN Host Galaxies
• The VIMOS VLT Deep Survey: Tracing the galaxy stellar mass assembly history over the last 8Gyr
• Preventing Star Formation in Early-Type Galaxies with Late-Time Stellar Heating
• The SCUBA-2 Cosmology Legacy Survey: the submillimetre properties of Lyman break galaxies at z=3-5
• The Typical Massive Quiescent Galaxy at z$\sim$3 is a Post-starburst
• Presence of dust with a UV bump in massive, star-forming galaxies at 1 < z < 2.5
• Ultraviolet, Optical, and Infrared Constraints on Models of Stellar Populations and Dust Attenuation
• Extinction Corrected Star Formation Rates Empirically Derived from Ultraviolet-Optical Colors
• X-shooter Spectroscopy and HST Imaging of 15 Ultra Massive Quiescent Galaxies at $z\gtrsim 2$
• HST grism spectroscopy of z~3 massive quiescent galaxies: Approaching the metamorphosis
• The Color Magnitude Distribution of Field Galaxies to z~3: the evolution and modeling of the blue sequence
• The miniJPAS survey: the photometric redshift catalogue
• The Density and Spectral Energy Distributions of Red Galaxies at z~3.7
• An ancient massive quiescent galaxy found in a gas-rich z ~ 3 group
• The NIRSpec Wide GTO Survey
• Adaptive Optics Rest-Frame V-band Imaging of Lyman Break Galaxies at z~3: High-surface Density Disk-like Galaxies ?
• The interstellar medium and feedback in the progenitors of the compact passive galaxies at z~2
• A new sample of X-ray selected narrow emission-line galaxies. II. Looking for True Seyfert 2
• On the Stellar Populations in Faint Red Galaxies in the Hubble Ultra Deep Field
• Stellar populations of massive elliptical galaxies in very rich clusters
• Revealing the quiescent galaxy population in the Spiderweb protocluster at z=2.16 with deep HST/WFC3 slitless spectroscopy