Bars in early- and late-type discs in COSMOS

Ewan Cameron ,M Salvato,D B Sanders,O Ilbert,S J Lilly,P Cerulo,C M Carollo,H Aussel,H J Mccracken,P Capak,Alexie Leauthaud ,N Z Scoville ,Jason Rhodes ,T J Bschorr ,Anton M Koekemoer ,Kartik Sheth ,Yoshiaki Taniguchi ,Richard Massey ,M Aller ,E Le Floc’h ,Pascal Oesch ,Jean-Paul Kneib ,D J Thompson

doi:10.1111/j.1365-2966.2010.17314.x

Abstract

We investigate the (large-scale) bar fraction in a mass-complete sample of M > 10^10.5 Msun disk galaxies at 0.2 < z < 0.6 in the COSMOS field. The fraction of barred disks strongly depends on mass, disk morphology, and specific star formation rate (SSFR). At intermediate stellar mass (10^10.5 < M < 10^11 Msun) the bar fraction in early-type disks is much higher, at all redshifts, by a factor ~2, than that in late-type disks. This trend is reversed at higher stellar mass (M > 10^11 Msun), where the fraction of bars in early-type disks becomes significantly lower, at all redshifts, than that in late-type disks. The bar fractions for galaxies with low and high SSFRs closely follow those of the morphologically-selected early-type and late-type populations, respectively. This indicates a close correspondence between morphology and SSFR in disk galaxies at these earlier epochs. Interestingly, the total bar fraction in 10^10.5 < M < 10^11 Msun disks is built up by a factor of ~2 over the redshift interval explored, while for M > 10^11 Msun disks it remains roughly constant. This indicates that, already by z ~ 0.6, spectral and morphological transformations in the most massive disk galaxies have largely converged to the familiar Hubble sequence that we observe in the local Universe, while for intermediate mass disks this convergence is ongoing until at least z ~ 0.2. Moreover, these results highlight the importance of employing mass-limited samples for quantifying the evolution of barred galaxies. Finally, the evolution of the barred galaxy populations investigated does not depend on the large-scale environmental density (at least, on the scales which can be probed with the available photometric redshifts).

Highlights

IntroductionNumerous observational studies have demonstrated that large-scale stellar bars are remarkably common amongst local disc galaxies (e.g. de Vaucouleurs et al 1991; Eskridge et al 2000; MenendezDelmestre et al 2007; Aguerri, Mendez-Abreu & Corsini 2009), and that a substantial population of barred discs exists out to at least redshift unity (e.g. Abraham et al 1999; Elmegreen, Elmegreen & Hirst 2004; Jogee et al 2004; Elmegreen et al 2007; Sheth et al 2008)
Numerous observational studies have demonstrated that large-scale stellar bars are remarkably common amongst local disc galaxies, and that a substantial population of barred discs exists out to at least redshift unity (e.g. Abraham et al 1999; Elmegreen, Elmegreen & Hirst 2004; Jogee et al 2004; Elmegreen et al 2007; Sheth et al 2008)
We investigate the bar fraction in a mass-complete sample of M > 1010.5 M disc galaxies at 0.2 < z < 0.6 in the Cosmological Evolution Survey (COSMOS) field

Summary

Introduction

Numerous observational studies have demonstrated that large-scale stellar bars are remarkably common amongst local disc galaxies (e.g. de Vaucouleurs et al 1991; Eskridge et al 2000; MenendezDelmestre et al 2007; Aguerri, Mendez-Abreu & Corsini 2009), and that a substantial population of barred discs exists out to at least redshift unity (e.g. Abraham et al 1999; Elmegreen, Elmegreen & Hirst 2004; Jogee et al 2004; Elmegreen et al 2007; Sheth et al 2008). Marinova et al (2009) and Barazza et al (2009) have identified a minimal dependence of the bar fraction on environment (see Mendez-Abreu, Sanchez-Janssen & Aguerri 2010), except perhaps in cluster centres, where bar formation appears to be enhanced. Both studies recovered a rise in the bar fraction towards later morphological types, or bluer, increasingly disc-dominated systems, while Sheth et al (2008) recovered an enhanced bar fraction in redder, increasingly bulge-dominated systems at high redshifts. A further complication is introduced by the various methods of disc selection employed, whether spectral energy distribution (SED) fit type and visual inspection (Sheth et al 2008), visual inspection alone (Barazza et al 2009), or colour, global Sersic index and visual inspection (Marinova et al 2009)

Methods

Results

Conclusion