AzTEC Survey of the Central Molecular Zone: Increasing Spectral Index of Dust with Density. (arXiv:2008.12361v1 [astro-ph.GA])

AzTEC Survey of the Central Molecular Zone: Increasing Spectral Index of Dust with Density. (arXiv:2008.12361v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tang_Y/0/1/0/all/0/1">Yuping Tang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Q/0/1/0/all/0/1">Q. Daniel Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilson_G/0/1/0/all/0/1">Grant W. Wilson</a>

The Central Molecular Zone (CMZ) of our Galaxy hosts an extreme environment
analogous to that found in typical starburst galaxies in the distant universe.
In order to understand dust properties in environments like our CMZ, we present
results from a joint SED analysis of our AzTEC/Large Millimeter Telescope
survey, together with existing textit{Herschel} far-IR data on the CMZ, from a
wavelength range of $160$ $mu m$ to $1.1$ $mm$. We include global foreground
and background contributions in a novel Bayesian modeling that incorporates the
Point Spread Functions (PSFs) of the different maps, which enables the full
utilization of our high resolution ($10.5”$) map at 1.1 $mm$ and reveals
unprecedentedly detailed information on the spatial distribution of dusty gas
across the CMZ. There is a remarkable trend of increasing dust spectral index
$beta$, from $2.0-2.4$, toward dense peaks in the CMZ, indicating a deficiency
of large grains or a fundamental change in dust optical properties. This
environmental dependence of $beta$ could have a significant impact on the
determination of dust temperature in other studies. Depending on how the
optical properties of dust deviate from the conventional model, dust
temperatures could be underestimated by $10-50%$ in particularly dense
regions.

The Central Molecular Zone (CMZ) of our Galaxy hosts an extreme environment
analogous to that found in typical starburst galaxies in the distant universe.
In order to understand dust properties in environments like our CMZ, we present
results from a joint SED analysis of our AzTEC/Large Millimeter Telescope
survey, together with existing textit{Herschel} far-IR data on the CMZ, from a
wavelength range of $160$ $mu m$ to $1.1$ $mm$. We include global foreground
and background contributions in a novel Bayesian modeling that incorporates the
Point Spread Functions (PSFs) of the different maps, which enables the full
utilization of our high resolution ($10.5”$) map at 1.1 $mm$ and reveals
unprecedentedly detailed information on the spatial distribution of dusty gas
across the CMZ. There is a remarkable trend of increasing dust spectral index
$beta$, from $2.0-2.4$, toward dense peaks in the CMZ, indicating a deficiency
of large grains or a fundamental change in dust optical properties. This
environmental dependence of $beta$ could have a significant impact on the
determination of dust temperature in other studies. Depending on how the
optical properties of dust deviate from the conventional model, dust
temperatures could be underestimated by $10-50%$ in particularly dense
regions.

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