Kinematics and Feedback in H II regions in the Dwarf Starburst Galaxy IC 10

Abstract

We present a survey of the central region of the nearest starburst galaxy, IC 10, using the W. M. Keck Observatory Keck Cosmic Web Imager (KCWI) at high spectral and spatial resolution. We map the central starburst of IC 10 to sample the kinematic and ionization properties of the individual star-forming regions. Using the low spectral resolution mode of KCWI we map the oxygen abundance and with the high spectral resolution mode we identify 46 individual H II regions. These H II regions have an average radius of 4.0 pc, star formation rate $\sim 1.3\times 10^{-4}$ M${}_{\odot }$ yr${}^{-1}$, and velocity dispersion $\sim$16 km s${}^{-1}$. None of the H II regions appear to be virialized (${\alpha }_{\mathrm{vir}}>>1$), and, on average, they show evidence of ongoing expansion. IC 10's H II regions are offset from the star forming region size-luminosity scaling relationships, as well as Larson's Law that relates size and velocity dispersion. We investigate the balance of inward and outward pressure, ${\mathrm{P}}_{\mathrm{in}}$ and ${\mathrm{P}}_{\mathrm{out}}$, finding ${\mathrm{P}}_{\mathrm{out}}>{\mathrm{P}}_{\mathrm{in}}$ in 89% of H II regions, indicating feedback driven expansion even in these low mass H II regions. We find warm gas pressure (${\mathrm{P}}_{\mathrm{gas}}$) provides the dominant contribution to the outward pressure (${\mathrm{P}}_{\mathrm{out}}$). This counteracts the inward pressure which is dominated by turbulence in the surrounding gas rather than self-gravity. Five H II regions show evidence of outflows which are most likely supported by either stellar winds (2 regions) or champagne flows (3 regions). These observations provide new insights into the state of the star-forming regions in IC 10 and negative feedback from low mass clusters.

57 pages, 35 figures, 9 tables, accepted for publication in The Astrophysical Journal

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