Journal ArticleDOI
The Epochs of Early-Type Galaxy Formation as a Function of Environment
TLDR
In this article, the authors derived ages, total metallicities, and element ratios of 124 early-type galaxies in high and low-density environments, and analyzed the data by comparison with mock galaxy samples created through Monte Carlo simulations taking the typical average observational errors into account.Abstract:
The aim of this paper is to set constraints on the epochs of early-type galaxy formation through the archaeology of the stellar populations in local galaxies. Using our models of absorption-line indices that account for variable abundance ratios, we derive ages, total metallicities, and element ratios of 124 early-type galaxies in high- and low-density environments. The data are analyzed by comparison with mock galaxy samples created through Monte Carlo simulations taking the typical average observational errors into account, in order to eliminate artifacts caused by correlated errors. We find that all three parameters, age, metallicity, and ?/Fe ratio, are correlated with velocity dispersion. We show that these results are robust against recent revisions of the local abundance pattern at high metallicities. To recover the observed scatter we need to assume an intrinsic scatter of about 20% in age, 0.08?dex in [Z/H], and 0.05?dex in [?/Fe]. All low-mass objects with M* 1010 M? (? 130 km s-1) show evidence for the presence of intermediate-age stellar populations with low ?/Fe ratios. About 20% of the intermediate-mass objects with 1010 M*/M? 1011 [110 ?/(km s-1) 230; both elliptical and lenticular galaxies] must have either a young subpopulation or a blue horizontal branch. On the basis of the above relationships, valid for the bulk of the sample, we show that the Mg-? relation is mainly driven by metallicity, with similar contributions from the ?/Fe ratio (23%) and age (17%). We further find evidence for an influence of the environment on the stellar population properties. Massive early-type galaxies in low-density environments seem on average ~2?Gyr younger and slightly (~0.05-0.1?dex) more metal-rich than their counterparts in high-density environments. No offsets in the ?/Fe ratios are instead detected. With the aid of a simple chemical evolution model, we translate the derived ages and ?/Fe ratios into star formation histories. We show that most star formation activity in early-type galaxies is expected to have happened between redshifts ~3 and 5 in high-density environments and between redshifts 1 and 2 in low-density environments. We conclude that at least 50% of the total stellar mass density must have already formed at z ~ 1, in good agreement with observational estimates of the total stellar mass density as a function of redshift. Our results suggest that significant mass growth in the early-type galaxy population below z ~ 1 must be restricted to less massive objects, and a significant increase of the stellar mass density between redshifts 1 and 2 should be present, caused mainly by the field galaxy population. The results of this paper further imply the presence of vigorous star formation episodes in massive objects at z ~ 2-5 and evolved elliptical galaxies around z ~ 1, both observationally identified as SCUBA galaxies and extremely red objects, respectively.read more
Citations
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Journal ArticleDOI
Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
John Kormendy,Luis C. Ho +1 more
TL;DR: In this paper, supermassive black holes (BHs) have been found in 85 galaxies by dynamical modeling of spatially resolved kinematics, and it has been shown that BHs and bulges coevolve by regulating each other's growth.
Journal ArticleDOI
Evolutionary population synthesis: models, analysis of the ingredients and application to high‐z galaxies
TL;DR: In this article, an evolutionary population synthesis model for a wide range of metallicities, ages, star formation histories, initial mass functions and horizontal branch morphologies, including blue morphologies at high metallicity, is presented.
Journal ArticleDOI
Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
Yingjie Peng,Simon J. Lilly,Katarina Kovac,Micol Bolzonella,Lucia Pozzetti,Alvio Renzini,G. Zamorani,Olivier Ilbert,C. Knobel,A. Iovino,Christian Maier,Olga Cucciati,Lidia Tasca,C. Marcella Carollo,John D. Silverman,P. Kampczyk,Loic de Ravel,David B. Sanders,Nick Scoville,Thierry Contini,Vincenzo Mainieri,Marco Scodeggio,Jean-Paul Kneib,Olivier Le Fevre,S. Bardelli,Angela Bongiorno,Karina Caputi,Graziano Coppa,Sylvain de la Torre,P. Franzetti,Bianca Garilli,F. Lamareille,Jean-Francois Le Borgne,Vincent Le Brun,M. Mignoli,Enrique Perez Montero,R. Pello,E. Ricciardelli,Masayuki Tanaka,Laurence Tresse,Daniela Vergani,Niraj Welikala,E. Zucca,Pascal Oesch,U. Abbas,Luke A. Barnes,Rongmon Bordoloi,D. Bottini,A. Cappi,Paolo Cassata,Andrea Cimatti,M. Fumana,Günther Hasinger,Anton M. Koekemoer,A. Leauthaud,D. Maccagni,Christian Marinoni,H. J. McCracken,P. Memeo,B. Meneux,Preethi Nair,Cristiano Porciani,V. Presotto,Roberto Scaramella +63 more
TL;DR: In this paper, the authors explore the simple interrelationships between mass, star formation rate, and environment in the SDSS, zCOSMOS, and other deep surveys.
Posted Content
Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies: Supplemental Material
John Kormendy,Luis C. Ho +1 more
TL;DR: Kormendy and Ho as mentioned in this paper proposed a method to estimate the BH masses for galaxies with active nuclei (AGNs) based on the observational criteria that are used to classify classical and pseudo bulges.
Journal ArticleDOI
The reversal of the star formation-density relation in the distant universe
David Elbaz,David Elbaz,Emanuele Daddi,Emanuele Daddi,D. Le Borgne,D. Le Borgne,Mark Dickinson,David M. Alexander,Ranga-Ram Chary,Jean-Luc Starck,W. N. Brandt,Manfred G. Kitzbichler,Emily MacDonald,Mario Nonino,Paola Popesso,Daniel Stern,Eros Vanzella +16 more
TL;DR: In this paper, the authors studied the relationship between the local environment of galaxies and their star formation rate (SFR) in the Great Observatories Origins Deep Survey, GOODS, at z∼1.
References
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The Evolution and Explosion of Massive Stars. II. Explosive Hydrodynamics and Nucleosynthesis
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TL;DR: In this paper, the nucleosynthetic yield of isotopes lighter than A = 66 (zinc) is determined for a grid of stellar masses and metallicities including stars of 11, 12, 13, 15, 18, 19, 20, 22, 25, 30, 35, and 40 M{sub {circle_dot}} and metals Z = 0, 10{sup {minus}4}, 0.01, 0.1, and 1 times solar (a slightly reduced mass grid is employed for non-solar metallicities).
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