Kavli Affiliate: Luis C. Ho
| First 5 Authors: Ze-Zhong Liang, Jing Wang, Hua Gao, Luis C. Ho, E. Athanassoula
| Summary:
Non-axisymmetric structures, such as bars and spiral arms, are known to
concentrate molecular gas and star formation in galaxy centers, actively
building up the pseudo-bulges. However, a direct link between the neutral
(i.e., molecular and atomic) gas distribution and the exerted torque forces
over a broader radial range of galactic disks still remains to be explored. In
the present work, we investigate this link by carefully evaluating the torque
force field using the $3.6, mathrm{mu m}$ images for 17 The H I Nearby
Galaxy Survey (THINGS) galaxies, and measuring neutral gas distribution on
resolved atomic and molecular line maps. We find that galaxies with stronger
torque forces show a more concentrated neutral gas distribution over the
disk-scale, defined as half the isophotal radius at $25.5, mathrm{mag,
arcsec^{-2}}$. The correlation holds regardless of whether the neutral gas
fraction, or the effective stellar mass surface density is controlled for. In
addition, $mathrm{kpc}$-scale neutral gas over-densities tend to be located
close to the local maxima of torque forces. Most of these correlations
involving the torque forces are comparatively stronger than those using the
traditional Fourier amplitudes to quantify the non-axisymmetric structures.
These results are consistent with the scenario that non-axisymmetric structures
exert torque forces, and trigger dissipative processes to transport gas inward,
not only to build the pseudo-bulges, but also fuel the inner disk growth. In
this regard, non-axisymmetric structures inducing stronger torque forces appear
to be more efficient in these processes.
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