Spectral dating of high-redshift stellar populations

Abstract

(Abridged) Age derivation techniques for unresolved stellar populations at high redshifts are explored using the NUV spectrum of LBDS~53W091 and LBDS~53W069. The photometry and morphology of these galaxies suggest they are early-type systems,a feature that makes them ideal test beds for the analysis of their ages and metallicities. In the analysis that is based on simple stellar population models,we find a significant degeneracy between the derived ages and metallicities both in optical+NIR photometric and NUV spectroscopic analyses. This degeneracy is not so strong for LBDS~53W069. However even in this case the stellar age cannot be constrained better than to a range roughly encompassing one third of the age of the Universe at the observed redshift. We have explored several independent population synthesis models and consistently found similar results. Broadband photometry straddling the rest-frame 4000A break is also subject to a strong age-metallicity degeneracy. The use of realistic chemical enrichment assumptions significantly helps in disentangling the degeneracy. Based on this method, we derive the average stellar age for both galaxies around 3.6-3.8 Gyr with better constraints on the youngest possible ages. From the observational point of view, the most efficient (and feasible) way to set limits on unresolved stellar populations comprises a combination of Balmer absorption lines along with either low SNR rest frame NUV spectroscopy or accurate optical and NIR photometry.

8 pages, 8 figures, uses mn2e.cls. Accepted for publication in MNRAS

References in corpus (4)

• Early-type galaxies in the SDSS. IV. Colors and chemical evolution
• Uncertainties of Synthetic Integrated Colors as Age Indicators
• On the Assembly History of Early-Type Galaxies in the Hubble Deep Field North
• On breaking the age-metallicity degeneracy in early-type galaxies: infall versus star formation efficiency

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• Ages and Metallicities of Extragalactic Globular Clusters from Spectral and Photometric Fits of Stellar Population Synthesis Models
• Stellar populations of galaxies in the ALHAMBRA survey up to $z\sim 1$. IV. Properties of quiescent galaxies on the stellar mass$-$size plane
• The road to the red sequence: A detailed view of the formation of a massive galaxy at z~2
• Predicting spectral features in galaxy spectra from broad-band photometry
• Stellar populations of galaxies in the ALHAMBRA survey up to $z\sim 1$. III. The stellar content of the quiescent galaxy population during the last $8$ Gyr
• Open Issues on the Synthesis of Evolved Stellar Populations at Ultraviolet Wavelengths