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A Revised Age for the z=1.55 Galaxy LBDS 53W091

Gustavo Bruzual·Gladis Magris
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Abstract

Empirical evidence suggests that the stellar population in LBDS 53W091 is significantly younger than that in M32. Population synthesis models indicate that the age of LBDS 53W091 is in the range from 1 to 2 Gyr and depends on the specific model. Older ages require sub-solar metallicity models. The estimates of the age of the dominant population in M32 range from 3 to 5 Gyr and depend not only on the model but also on the SED of this galaxy used in the fits. The same models predict an age of 11 to 13 Gyr for the stars in a typical old E/S0 galaxy. A 1 to 2 Gyr old galaxy at z = 1.55 poses no problem for the Lambda = 0, Omega = 1 universe, as long as h <= 0.8. The most likely reason for the difference between our age estimate and the value of 3.5 Gyr derived by Dunlop et al. (1996), is the fact that these authors did not require that the population synthesis models that they used fitted simultaneously the UV break amplitudes and the observed $R-J, R-H$, and $R-K$ colors of this galaxy. As we will discuss elsewhere, a comparison of our results with those by Spinrad et al. (1997) shows that our conclusions still hold. The paper by Spinrad et al. was unknown to us at the time of this Conference.

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Gustavo Bruzual, Gladis Magris. 1997-07-14. A Revised Age for the z=1.55 Galaxy LBDS 53W091. https://arxiv.org/abs/astro-ph/9707154

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