We present the discovery of a massive, quiescent galaxy at z = 2.99. We have obtained an Hubble Space Telescope WFC3 spectrum of this object and measured its redshift from the detection of a deep 4000 Å break consistent with an old population and a high metallicity. By stellar population modeling of both its grism spectrum and broadband photometry, we derive an age of ~0.7 Gyr, implying a formation redshift of z > 4, and a mass >1011 M ⊙. Although this passive galaxy is the most distant confirmed so far, we find that it is slightly less compact than other z > 2 early types of similar mass, being overall more analogous to those z ~ 1.6 field early-type galaxies. The discovery of this object shows that early-type galaxies are detectable to at least z = 3 and suggests that the diversity of structural properties found in z = 1.4-2 ellipticals to earlier epochs could have its origin in a variety of formation histories among their progenitors.
Gobat R., Strazzullo V., Daddi E., Onodera M., Renzini A., Béthermin M., et al. (2012). The Early Early Type: Discovery of a Passive Galaxy at z spec ~ 3. THE ASTROPHYSICAL JOURNAL, 759, L44-L48 [10.1088/2041-8205/759/2/L44].
The Early Early Type: Discovery of a Passive Galaxy at z spec ~ 3
CIMATTI, ANDREA
2012
Abstract
We present the discovery of a massive, quiescent galaxy at z = 2.99. We have obtained an Hubble Space Telescope WFC3 spectrum of this object and measured its redshift from the detection of a deep 4000 Å break consistent with an old population and a high metallicity. By stellar population modeling of both its grism spectrum and broadband photometry, we derive an age of ~0.7 Gyr, implying a formation redshift of z > 4, and a mass >1011 M ⊙. Although this passive galaxy is the most distant confirmed so far, we find that it is slightly less compact than other z > 2 early types of similar mass, being overall more analogous to those z ~ 1.6 field early-type galaxies. The discovery of this object shows that early-type galaxies are detectable to at least z = 3 and suggests that the diversity of structural properties found in z = 1.4-2 ellipticals to earlier epochs could have its origin in a variety of formation histories among their progenitors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.