Direct Measurements of the Stellar Continua and Balmer/4000 A Breaks of Redz> 2 Galaxies: Redshifts and Improved Constraints on Stellar Populations | Zendy

Mariska Kriek | Zendy; Pieter van Dokkum | Zendy; Marijn Franx | Zendy; N. M. Förster Schreiber | Zendy; Eric Gawiser | Zendy; G. D. Illingworth | Zendy; Ivo Labbé | Zendy; Danilo Marchesini | Zendy; Ryan Quadri | Zendy; HansWalter Rix | Zendy; Gregory Rudnick | Zendy; Sune Toft | Zendy; P. van der Werf | Zendy; Stijn Wuyts | Zendy

Open Access

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

Author(s) -

Mariska Kriek,

Pieter van Dokkum,

Marijn Franx,

N. M. Förster Schreiber,

Eric Gawiser,

G. D. Illingworth,

Ivo Labbé,

Danilo Marchesini,

Ryan Quadri,

HansWalter Rix,

Gregory Rudnick,

Sune Toft,

P. van der Werf,

Stijn Wuyts

Publication year - 2006

Publication title -

the astrophysical journal

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 2.376

H-Index - 489

eISSN - 1538-4357

pISSN - 0004-637X

DOI - 10.1086/504103

Subject(s) - physics , astrophysics , balmer series , galaxy , redshift , stellar population , star formation , astronomy , stellar mass , luminous infrared galaxy , emission spectrum , equivalent width , galaxy formation and evolution , population , spectral line , demography , sociology

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 continuaof three `Distant Red Galaxies' (having Js - Ks > 2.3) at z>2. All three galaxyspectra show the Balmer/4000 Angstrom break in the rest-frame optical. Thespectra allow us to determine spectroscopic redshifts from the continuum withan estimated accuracy dz/(1+z) ~ 0.001-0.04. These redshifts agree well withthe emission line redshifts for the 2 galaxies with Halpha emission. Thistechnique is particularly important for galaxies that are faint in therest-frame UV, as they are underrepresented in high redshift samples selectedin optical surveys and are too faint for optical spectroscopy. Furthermore, weuse the break, continuum shape, and equivalent width of Halpha together withevolutionary synthesis models to constrain the age, star formation timescale,dust content, stellar mass and star formation rate of the galaxies. Inclusionof the NIR spectra in the stellar population fits greatly reduces the range ofpossible solutions for stellar population properties. We find that the stellarpopulations differ greatly among the three galaxies, ranging from a young dustystarburst with a small break and strong emission lines to an evolved galaxywith a strong break and no detected line emission. The dusty starburst galaxyhas an age of 0.3 Gyr and a stellar mass of 1*10^11 Msun. The spectra of thetwo most evolved galaxies imply ages of 1.3-1.4 Gyr and stellar masses of4*10^11 Msun. The large range of properties seen in these galaxies strengthensour previous much more uncertain results from broadband photometry. Largersamples are required to determine the relative frequency of dusty starburstsand (nearly) passively evolving galaxies at z~2.5.Comment: Accepted for publication in the Astrophysical Journal. 12 pages, 6 figure

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