Investigating the Spectral Energy Distribution within the Dwarf Irregular Galaxy IC 10
Parkin, Tara Jill
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We present new submillimetre images of the dwarf irregular galaxy IC 10, taken with the Submillimeter Bolometer Common-User Array, mounted on the James Clerk Maxwell Telescope. Combining this new data with archival data from the 2MASS survey, ISO, Spitzer IRAC and MIPS, and the VLA, we plot the observed spectral energy distributions from 1.24 μm to 850 μm for two star forming regions within IC 10, namely IC 10 SE and IC 10 NW. The spectral energy distributions were subsequently modelled using a dust model with PAHs, and silicate and graphite dust grain components. This is the first time that well-constrained spectral energy distribution models of two individual regions within IC 10 have been presented. From our results, we find that IC 10 SE and IC 10 NW share the same physical characteristics in most cases, such as the gas-to-dust mass ratio, the mass fraction of PAHs comprising the total dust mass, and the fraction of PAHs that are ionised. The most significant difference is seen in the peak wavelengths of the SEDs, which are ~70 μm and ~45 μm for IC 10 SE and IC 10 NW, respectively. From this we conclude that the primary dust component within IC 10 NW is warmer than that of IC 10 SE, due to the hot young stars at the heart of the star forming region within IC 10 NW having a larger heating effect on the nearby dust than the interstellar radiation field. The similar environments of these two regions lead us to suggest that the star formation taking place within them was triggered by the same starburst, and that both stellar populations evolved together. We also find that IC 10 has physical conditions that are common amongst other low-metallicity, dwarf irregular galaxies, implying that IC 10 does not have an abnormal interstellar medium in these regions.