The density of very massive evolved galaxies to z ? 1.7
Por:
Saracco P., Longhetti M., Severgnini P., Ceca R.D., Braito V., Mannucci F., Bender R., Drory N., Feulner G., Hopp U., Maraston C.
Publicada:
1 ene 2005
Resumen:
We spectroscopically identified seven massive, evolved galaxies with magnitudes 17.8 < K < 18.4 at 1.3 < z < 1.7 over an area of ~160 arcmin2 of the MUNICS survey. Their rest-frame K-band absolute magnitudes are -26.8 < MK < -26.1 (5L* < LK < 10L*) and the resulting stellar masses are in the range 3-6.5 × 1011 M?;. The analysis we performed unambiguously shows the early-type nature of their spectra. The seven massive, evolved galaxies account for a comoving density of (5.5 ± 2) × 10-5 Mpc-3 at (z) ? 1.5, a factor 1.5 lower than the density [(8.4 ± 1) × 10-5 Mpc-3] of early types with comparable masses at z = 0. The incompleteness (~30 per cent) of our spectroscopic observations accounts for this discrepancy. Thus, our data do not support a decrease of the comoving density of early-type galaxies with masses comparable to the most massive ones in the local Universe up to ? 1.7. This suggests that massive evolved galaxies do not play an important role in the evolution of the mass density outlined by recent surveys in this redshift range, evolution which instead has to be ascribed to the accretion of the stellar mass in late-type galaxies. Finally, the presence of such massive evolved galaxies at these redshifts suggests that the assembly of massive spheroids has taken place at z > 2 supporting a high efficiency in the accretion of the stellar mass in massive haloes in the early Universe. © 2005 RAS.
Filiaciones:
Saracco P.:
INAF, Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
Longhetti M.:
INAF, Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
Severgnini P.:
INAF, Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
Ceca R.D.:
INAF, Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
Braito V.:
INAF, Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
Mannucci F.:
Istitudo di Radioastronomia-CNR, Large E. Fermi 5, 5012 Firenze, Italy
Bender R.:
Universi?ats-Sternwarte M¨unchen, Scheiner Str. 1, 81679 München, Germany
Max-Plank-Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
Drory N.:
University of Texas at Austin, Austin, TX 78712, United States
Feulner G.:
Universi?ats-Sternwarte M¨unchen, Scheiner Str. 1, 81679 München, Germany
Hopp U.:
Universi?ats-Sternwarte M¨unchen, Scheiner Str. 1, 81679 München, Germany
Maraston C.:
Max-Plank-Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
Bronze
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