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Paper: Bars in Local Galaxies: Evidence for a Higher Optical Bar Fraction in Disk-Dominated Galaxies
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 351
Authors: Barazza, F.D.; Jogee, S.; Marinova, I.
Abstract: We present a study of large-scale bars in the local Universe, based on a large sample of ∼ 3692 galaxies, with −18.5 ≤ Mg < −22.0 mag and redshift 0.01 ≤ z < 0.03, drawn from the SDSS. Our sample includes many galaxies that are disk-dominated and of late Hubble types. Both color cuts and Sérsic cuts yield a similar sample of ∼ 2000 disk galaxies. We characterize bars and disks by ellipse-fitting r−band images and applying quantitative criteria. After excluding highly inclined (> 60°) systems, we find the following results. (1) The optical r-band fraction (fopt−r) of barred galaxies is ∼ 48% − 52%. (2) When galaxies are separated according to normalized half light radius (re/R24), a remarkable result is seen: fopt−r rises sharply, from ∼ 40% in galaxies that have small re/R24 and visually appear to host prominent bulges, to ∼ 70% for galaxies that have large re/R24 and appear disk-dominated. (3) fopt−r rises for galaxies with bluer colors and higher central surface brightness. A weaker rise is seen toward lower masses. (4) We find that ∼ 20% of our sample of disk galaxies appear to be ‘quasi-bulgeless’. (5) If we restrict our sample to bright galaxies and only consider bars that are strong (ellipticity ≥ 0.4) and large enough (semi-major axis ≥ 1.5 kpc) to be reliably characterized via ellipse-fitting out to z ∼ 0.8, we get an optical r-band fraction for strong bars fopt−s of ∼ 34%. This value is higher only by a modest factor of 1.4, compared to the value of ∼ 24% ± 4% reported at z ∼ 0.7 − 1.0. If one assumes that the increasing obscuration by dust and star formation over z ∼ 0 to 1.0 causes a further artificial loss of bars, the data even allow for a constant or rising fraction of strong bars with redshift.
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