Gas inflow and nuclear star formation in galaxies with non-axisymmetric bulges

摘要

We present the dependence of the amount of nuclear star formation on the non-axisymmetry of a bulge of disk galaxies. For this, we use a volume-limited sample of spiral galaxies at 0.02 <= z < 0.055 from the SDSS DR7. Among 3173 final sample galaxies with an axis ratio b/a > 0.6 and a bulge fraction ranged in B/T <= 0.41, nuclear starburst galaxies are 10 %. We find that a fraction of the nuclear starburst galaxies become higher when ellipticity of a bulge increases in early type galaxies. Also, the fraction increases clearly when early type galaxies are isolated and in low density region. Our results indicate that the non-axisymmetry of bulges assists gas to fall inside and affects the nuclear starburst process in disk galaxies.