Lyman Break Galaxies: Are They Young Spheroids?

We have compared the results from a model for the chemical evolution of an elliptical galaxy with initial luminous mass of 2 × 1010 M☉ and effective radius of 2 kpc with the recent abundance determinations for the Lyman break galaxy MS 1512-cB58 at a redshift z = 2.7276. After correcting the iron abundance determination for the presence of dust, we concluded that the observed [Si/Fe], [Mg/Fe], and [N/Fe] are consistent with our model when a galactic age between 20 and 35 Myr is assumed. Moreover, the [N/O] ratio also suggests the same age. This age is in very good agreement with other independent studies based on the analysis of the spectral energy distribution suggesting that this object is younger than 35 Myr. Therefore, we suggest that MS 1512-cB58 is a truly young normal elliptical galaxy experiencing its main episode of star formation and galactic wind.

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