A comparison of stellar populations in galaxy spheroids across a wide range of Hubble types

By R. Proctor, A. Sansom. 2002

145 citations recorded by the source corpus.

We present line-strengths and kinematics from the central regions of 32 galaxies with Hubble types ranging from E to Sbc. Spectral indices, based on the Lick system, are measured in the optical and near-infrared (NIR). The 24 indices measured, in conjunction with models of the effects of varying abundance ratios, permit the breaking of age/metallicity degeneracy, and allow estimation of enhancements in specific light elements (particularly C and Mg). The large range of Hubble types observed allows direct comparison of line-strengths in the centres of early-type galaxies (E and S0) with those in spiral bulges, free from systematic differences that have plagued comparisons of results from different studies. Our sample includes field and Virgo cluster galaxies. For early-type galaxies our data are consistent with previously reported trends of Mg2 and Mgb with velocity dispersion. In spiral bulges we find trends in all indices with velocity dispersion. We estimate luminosity-weighted ages, metallicities and heavy-element abundance ratios (enhancements) from optical indices. These show that bulges are less enhanced in light (α-capture) elements and have lower average age than early-type galaxies. Trends involving age and metallicity also differ sharply between early and late types. An anticorrelation exists between age and metallicity in early types, while, in bulges, metallicity is correlated with velocity dispersion. We consider the implications of these findings for models of the formation of these galaxies. We find that primordial collapse models of galaxy formation are ruled out by our observations, while several predictions of hierarchical clustering (merger) models are confirmed.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c5c491b36a40e31ee958ba7ecec314ae4424570e

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Citations in the corpus

The Millennium Galaxy Catalogue: the B-band attenuation of bulge and disc light and the implied cosmic dust and stellar mass densities (2007, result): “It therefore follows that they must be younger and/or metal-poorer which is consistent with the spectroscopic studies of Proctor & Sansom (2002) and Thomas & Davies (2006).”
Gas physics, disk fragmentation, and bulge formation in young galaxies (2003, background): “On the other hand, the abundance ratios in the centers of nearby bulges show only a moderate α overabundance ([α/Fe]≃ 0.2; Proctor & Sansom (2002)), arguing that these stars were formed from gas enriched by more extended star formation histories.”
The SAURON project – VIII. OASIS/CFHT integral-field spectroscopy of elliptical and lenticular galaxy centres (2006, methodology): “…log σ, (4) [α/Fe] = −0.45 + 0.26 log σ. (5) As found by many authors (e.g. Carollo, Danziger, & Buson 1993; Trager et al. 2000; Kuntschner et al. 2001; Proctor & Sansom 2002; Bernardi et al. 2005; Thomas et al. 2005), we find that the stellar population parameters correlate with velocity disper…”
A CATALOG OF BULGE, DISK, AND TOTAL STELLAR MASS ESTIMATES FOR THE SLOAN DIGITAL SKY SURVEY (2013, background): “More massive galaxies are found to be on average redder (e.g., Blanton et al. 2003; Baldry et al. 2006), older (Proctor & Sansom 2002; Kauffmann et al. 2003c; Gallazzi et al. 2005), more metalrich (Tremonti et al. 2004; Gallazzi et al. 2005), more strongly clustered (e.g., Beisbart & Kerscher 2000;…”
The SAURON project - VI. Line strength maps of 48 elliptical and lenticular galaxies (2006, result): “Similar trends have been noted by Proctor & Sansom (2002) in an analysis of spiral bulges and E/S0s.”
Population Synthesis in the Blue. IV. Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations (2007, methodology): “A method to address these difficulties was devised by Trager et al. (2000) and further developed by Proctor & Sansom (2002), Thomas, Maraston & Bender (2003a), and Thomas, Maraston & Korn (2004), and Korn, Maraston & Thomas (2005).”
Environment and self-regulation in galaxy formation (2009, methodology): “In particular, the latter could be further improved (Trager et al. 2000a; Proctor & Sansom 2002; Mehlert et al. 2003; T05) after element abundance ratio sensitive stellar population models were used (TMB; Trager et al. 2000b).”
THE CLUSTER LENSING AND SUPERNOVA SURVEY WITH HUBBLE: AN OVERVIEW (2011, background): “…as evidenced by the redshift at which their star formation peaks (e.g., Cowie et al. 1996; Guzman et al. 1997; Brinchmann & Ellis 2000; Juneau et al. 2005) and the old ages of their stellar populations at z = 0 (e.g., Faber et al. 1995; Worthey 1996; Proctor & Sansom 2002; Thomas et al. 2005).”
The SAURON project – XVII. Stellar population analysis of the absorption line strength maps of 48 early-type galaxies (2010, background): “In good agreement with the literature, we find a rather tight relation in the sense that more massive galaxies exhibit largerα/Fe ratios (see also Jørgensen 1999; Kuntschner et al. 2001; Proctor & Sansom 2002; Thomas et al. 2005, 2010).”
Spatially resolved spectroscopy of early-type galaxies over a range in mass (2007, methodology): “We derive Single Stellar Population (SSP)-equivalent parameters age, [Fe/H] and α-abundance ratios for all the galaxies of the sample using the χ2-minimization technique detailed in Proctor & Sansom (2002) and Proctor et al. (2004a,b).”
Extragalactic Globular Clusters and Galaxy Formation (2006, methodology): “…use more of the information available in a spectrum than is contained in a traditional index-index plot, Proctor, Forbes, & Beasley (2004; see also Proctor & Sansom 2002) developed a χ2 minimization routine that simultaneously fit all of the Lick indices to SSP models, exploiting the different…”
Stellar masses of SDSS-III/BOSS galaxies at z ∼ 0.5 and constraints to galaxy formation models (2012, background): “…et al. 1993; Carollo & Danziger 1994; Rose et al. 1994; Bender & Paquet 1995; Jorgensen et al. 1995; Greggio 1997; Trager et al. 2000; Kuntschner 2000; Proctor & Sansom 2002; Smith et al. 2009; Thomas et al. 2005, 2010), the total stellar metallicity andits dependence on stellar mass, which we…”
Empirical calibration of the near-infrared Ca II triplet — IV. The stellar population synthesis models (2003, background): “…Ellis 1992; Bender, Burstein & Faber 1993; Colless et al. 1999; Terlevich et al. 1999; Kuntschner 2000, hereafter K00; Trager et al. 2000b, hereafter T00; Proctor & Sansom 2002, hereafter PS02), are some of the main issues in the present debate about the evolutionary status of early-type galaxies.”
Spectral models for solar-scaled and α-enhanced stellar populations (2007, methodology): “…to observed spectra of massive early-type galaxies in 1 There is no consensus in the literature on whether it is more appropriate to fix the iron abundance [Fe/H] or the total metal abundance [Z/H] when exploring models with different α/Fe (see e.g. the different methods in Proctor & Sansom 2002).”
Star Formation Histories of Early-Type Galaxies. I. Higher Order Balmer Lines as Age Indicators (2003, background): “…is now beginning to simulate the effect of nonsolar abundance ratios (NSARs; Trager et al. 2000a; Kuntschner et al. 2001; Vazdekis et al. 2001b; Proctor & Sansom 2002), based on theoretical isochrones incorporating NSARs (Salaris & Weiss 1998; VandenBerg et al. 2000; Salasnich et al. 2000) and…”
The stellar masses of 25 000 galaxies at 0.2 ≤ z ≤ 1.0 estimated by the COMBO-17 survey (2006, background): “…observations of resolved stellar populations (e.g., Rocha-Pinto et al. 2000; Harris & Zaritsky 2004) and integrated spectra (e.g., Trager et al. 2000; Proctor & Sansom 2002; Panter et al. 2004) show that most galaxies have formed stars over extended periods — oftentimes over almost a Hubble time.”
Stellar population synthesis at the resolution of 2003 (2003, background): “Several recent studies have addressed the influence of changes in element abundance ratios on the strengths of Lick indices (Tripicco & Bell 1995; Tantalo, Chiosi & Bressan 1998; Trager et al. 2000; Vazdekis et al. 2001; Proctor & Sansom 2002; Thomas, Maraston & Bender 2003).”
Near-infrared line-strengths in elliptical galaxies: evidence for initial mass function variations? (2002, background): “However, as suggested by several authors, Ca seems to follow Fe (O’Connell 1976; Vazdekis et al. 1997; Worthey 1998; Mollá & GarćıaVargas 2000; Vazdekis et al. 2001; Proctor & Sansom 2002).”
The ages and metallicities of galaxies in the local universe (2005, background): “…that the trends of log(Z/Z ) residuals with the strengths of D4000 and HδA+HγA are not caused by any bias in our estimates of stellar metallicity (see Section 2.4.2). galaxies (Jablonka, Martin & Arimoto 1996; Goudfrooij, Gorgas & Jablonka 1999; Proctor & Sansom 2002; Terlevich & Forbes 2002).”
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) (2007, unknown): “In early-type galaxies (Worthey et al. 1992) and, to a lesser extent, in the bulges of spirals (Proctor & Sansom 2002) magnesium is found to be enhanced relative to iron, which is commonly interpreted as due to a short timescale for star formation in those systems.”