HI imaging of dwarf star-forming galaxies: Masses, morphologies and gas deficiencies

Abstract

The GMRT observations of the HI 21~cm-line emission from 13~nearby dwarf star-forming galaxies are presented. The ranges of star formation rates and stellar masses of the sample galaxies are 0.03 -- 1.7~$M_\odot~{\rm yr}^{-1}$ and 0.04 -- 22.3~$\times 10^8~M_\odot$, respectively. The HI channel images, moment images, global profiles and mass surface density profiles are presented here. The average value of the peak HI mass surface density is estimated to be $\sim$2.5~M$_{\odot}$~pc$^{-2}$, which is significantly less compared to that in massive spiral galaxies. The scaling relations of $(M_{stars} + M_{\rm H\,I} + M_{\rm He})$ vs $M_{dyn}$, gas fraction vs $M_B$, $M_{\rm H\,I}$ vs $M_{stars}$, \ion{H}{i}-to-stellar mass ratio vs $M_{stars}$, and $M_{\rm H\,I}$ vs $D_{\rm H\,I}$ for the sample galaxies are estimated. These scaling relations can be used to constraint the key parameters in the galaxy evolution models. These galaxies are residing in group environment with galaxy density up to 8~galaxy~Mpc$^{-3}$. A HI mass deficiency (with $DEF_{\rm HI} > 0.3$) is noticed in majority of galaxies for their optical diameters as compared to galaxies in field environments. Clear signatures of tidal interactions in these galaxies could be inferred using the HI images. Isolated HI clouds without known optical counterparts are seen in the vicinity of several galaxies. HI emission envelope is found to be having an offset from the optical envelope in several galaxies. Consistent with the previous studies on galaxy evolution in group environments, tidal interactions seem to play an important role in triggering recent star formation.