Comparing six evolutionary population synthesis models by performing spectral synthesis for galaxies

Abstract

Aims. We compare six popularly used evolutionary population synthesis (EPS) models by fitting the full optical spectra of six representative types of galaxies (star-forming and composite galaxies, Seyfert 2s, LINERs, E+A, and early-type galaxies) taken from the Sloan Digital Sky Survey (SDSS). We explore the dependence of stellar population synthesis results on the main ingredients of the EPS models and study whether there is an age sequence among these types of galaxies. Methods. We use the simple stellar populations (SSPs) of each EPS model and the software STARLIGHT to perform our fits. Firstly, we explore the dependence of stellar population synthesis on EPS models by fixing the age, metallicity, and initial mass function (IMF) to construct a standard SSP group. We then use the standard SSP group of each EPS model (BC03, CB07, Ma05, GALEV, GRASIL, and Vazdekis/Miles) to fit the spectra of star-forming and E+A galaxies. Secondly, we fix the IMF and alter the age and metallicity to construct eight additional SSP groups. We then use these SSP groups to fit the spectra of star-forming and E+A galaxies to verify the effects of age and metallicity on stellar populations. Finally, we study the effect of stellar evolution tracks and stellar spectral libraries on our results, and present a possible age sequence among these types of galaxies. Results. Using different EPS models, the numerical values of contributing light fractions obviously change, even though the dominant populations are unaltered. The stellar population synthesis does depend on the selection of age and metallicity, but does not depend significantly on the stellar evolution track. The importance of young populations decreases from star-forming, composite, Seyfert 2, LINER, to early-type galaxies, and the properties of E+A galaxies are between composite galaxies and Seyfert 2s in most cases. Conclusions. Different EPS models infer different stellar population parameters, so that it is not reasonable to directly compare stellar populations estimated from different EPS models. To obtain reliable results, we should use the same EPS model to derive the parameter values that we compare.

Probing evolutionary population synthesis models in the near infrared with early-type galaxies

“…It is also fundamental to choose an adequate number of elements for such library in order to have nondegenerate solutions (Schmidt et al 1991;Cid Fernandes et al 2005;Dametto et al 2014). Chen et al (2010) presented a study in the optical region showing that different models may result in quite different SFHs for the same observed spectrum. Studying six different types of galaxies (star-forming galaxies, composite galaxies, Seyfert 2s, LINERs, E+A, and ETGs) using six different EPS models, they found that the differences found are significant, but the dominant populations are unaltered.…”

“…A major issue when characterizing the stellar population of a galaxy is attributed to the dependence of results in the model set used when fitting the underlying stellar features (Chen et al 2010). This happens because of all the uncertainties related to the construction of the SSPs.…”

Star-forming galaxies in intermediate-redshift clusters: stellar versus dynamical masses of luminous compact blue galaxies

“…of our cluster galaxies to those in the field sample of Guzmán et al (2003), employing the same SPS model in both cases will eliminate a potential source of systematic error (cf. Chen et al 2010). We therefore adopt the BC03-derived stellar masses in our subsequent analysis for consistency with previous studies.…”

A methodology to select galaxies just after the quenching of star formation

“…This is an interesting re- sult, since BC03 models are generally used only to describe more advanced evolutionary phases of galaxy evolution (e.g. Leitherer et al 1999, Bruzual & Charlot 2003, Chen et al 2010).…”