A Near‐Infrared Study of 2MASS Bars in Local Galaxies: An Anchor for High‐Redshift Studies

We have measured the fraction of bars in nearby spiral galaxies usingnear-infrared J, H, and K_s images of 151 spiral galaxies from 2MASS. Thislocal sample provides an anchor for the study of the evolution of the barfraction and bar properties with redshift. We identify bars by analyzing thefull two-dimensional light distribution and requiring a combined ellipticityand position angle signature. The combined bar signature is found in 59% of thegalaxies. The bar fraction increases to 67% when we include "candidate" bars,where only the ellipticity signature is present. We also measure the change inthe bar fraction as a function of bar size; the bar fraction drops to 36% forbars with a semi-major axis larger than 4 kpc. We find that infrared barstypically extend to one-third of the galactic disk, with a deprojected relativesize of ~ 0.3 +/- 0.2. Early-type spirals host significantlylarger bars, consistent with earlier studies. The is two timeslarger in early-types than in late-types. The typical bar axial ratio (b/a) is\~0.5, with a weak trend of higher axial ratios for larger bars.