Ages of Elliptical Galaxies : Single versus Multi Population Interpretation
نویسنده
چکیده
New calibrations of spectrophotometric indices of elliptical galaxies as functions of spectrophotometric indices are presented, permitting estimates of mean stellar population ages and metallicities. These calibrations are based on evolutionary models including a two-phase interstellar medium, infall and a galactic wind. Free parameters were fixed by requiring that models reproduce the mean trend of data in the color-magnitude diagram as well as in the plane of indices Hβ-Mg2 and Mg2-< Fe >. To improve the location of faint ellipticals (MB > −20) in the Hβ-Mg2 diagram, down-sizing was introduced. An application of our calibrations to a sample of ellipticals and a comparison with results derived from single stellar population models is given. Our models indicate that mean population ages span an interval of 7-12 Gyr and are correlated with metallicities, which range from ∼ half up to three times solar.
منابع مشابه
Stellar Populations in the Central Galaxies of Fossil Groups
It is inferred from the symmetrical and luminous X-ray emission of fossil groups that they are mature, relaxed galaxy systems. Cosmological simulations and observations focusing on their dark halo and inter-galactic medium properties confirm their early formation. Recent photometric observations suggest that, unlike the majority of non-fossil brightest group galaxies (BGGs), the central early-t...
متن کاملBinary Stellar Population Synthesis Study of Elliptical Galaxies
We determine relative stellar ages and metallicities mainly for about 80 elliptical galaxies in low and high density environments via the latest binary stellar population (BSP) synthesis model and test a latest hierarchical formation model of elliptical galaxies which adopted the new ΛCDM cosmology for the first time. The stellar ages and metallicities of galaxies are estimated from two high-qu...
متن کاملCooling Flow Star Formation and the Apparent Stellar Ages of Elliptical Galaxies.
Simple theoretical arguments indicate that cooled interstellar gas in bright elliptical galaxies forms into a young stellar population having a bottom-heavy but optically luminous initial mass function extending to approximately 2 M middle dot in circle. When the colors and spectral features of this young population are combined with those of the underlying old stellar population, the apparent ...
متن کاملMid-UV Determination of Elliptical Galaxy Abundances and Ages
We investigate the effects of abundance and age on the mid-UV spectra and Mg2 strengths of stellar populations using simple population synthesis models. These models are used to constrain the star formation history of four nearby elliptical galaxies and spiral bulges. The mid-UV (1800 3200 Å) light of evolved stellar populations (> 1 Gyr) is dominated by the main sequence turn-off, unlike the o...
متن کاملThe Ages and Metallicities of Early Type Galaxies in the Fornax Cluster
We have measured central line strengths for a complete sample of early type galaxies in the Fornax cluster, comprising 11 elliptical and 11 lenticular galaxies, more luminous than MB = −17. In contrast to the elliptical galaxies in the sample studied by González (and recently revisited by Trager) we find that the Fornax ellipticals follow the locus of galaxies of fixed age in Worthey’s models a...
متن کامل