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Erwin, Peter (2018): The dependence of bar frequency on galaxy mass, colour, and gas content - and angular resolution - in the local universe. In: Monthly Notices of the Royal Astronomical Society, Vol. 474, No. 4: pp. 5372-5392
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I use distance- and mass-limited subsamples of the Spitzer Survey of Stellar Structure in Galaxies (S(4)G) to investigate how the presence of bars in spiral galaxies depends on mass, colour, and gas content and whether large, Sloan Digital Sky Survey (SDSS)-based investigations of bar frequencies agree with local data. Bar frequency reaches a maximum of f(bar) approximate to 0.70 at M-* similar to 10(9.7)M(circle dot), declining to both lower and higher masses. It is roughly constant over a wide range of colours (g-r approximate to 0.1-0.8) and atomic gas fractions (log(M-III/M-circle dot) approximate to -2.5 to 1). Bars are thus as common in blue, gas-rich galaxies are they are in red, gas-poor galaxies. This is in sharp contrast to many SDSS-based studies of z similar to 0.01-0.1 galaxies, which report fbar increasing strongly to higher masses (from M-* similar to 10(10) to 10(11)M(circle dot)), redder colours, and lower gas fractions. The contradiction can be explained if SDSS-based studies preferentially miss bars in, and underestimate the bar fraction for, lower mass (bluer, gas-rich) galaxies due to poor spatial resolution and the correlation between bar size and stellar mass. Simulations of SDSS-style observations using the S(4)G galaxies as a parent sample, and assuming that bars below a threshold angular size of twice the point spread function full width at half-maximum cannot be identified, successfully reproduce typical SDSS f(bar) trends for stellar mass and gas mass ratio. Similar considerations may affect high-redshift studies, especially if bars grow in length over cosmic time;simulations suggest that high-redshift bar fractions may thus be systematically underestimated.