On the neutral gas distribution and kinematics in the dwarf irregular galaxy IC 1613

Abstract

We study the neutral hydrogen distribution and kinematics in the Local Group dwarf irregular galaxy IC 1613 and compare them with the ionized gas distribution and stellar content of the galaxy. We discuss several mechanisms which may be responsible for the origin of the observed complicated HI morphology and compare parameters of the most prominent kpc-scale HI structure with the multiple SNe scenario. The observations were performed with the Vary Large Array of NRAO with a linear resolution ~23 pc at the adopted distance of 725 kpc and the spectral channel width of 2.57 km/s. The numerical calculations have been provided with our 2.5D Lagrangian scheme based on the thin layer approximation. We found that the ISM of the galaxy is highly inhomogeneous and identified a number of intermediate-scale (200 pc - 300 pc in diameter) HI arcs and shells having expansion velocities of 10 to 20 km/s. Besides these shells, several giant holes and arc-shaped structures have been revealed, whose radii exceed several hundred parsecs. We found that parameters of the most prominent (M_HI = 2.8 x 10^7 Msol) kpc-scale structure and the level of the detected star formation activity are inconsistent with the multiple SNe hypothesis.