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How hot is the molecular gas in the Galactic Center?

Published online by Cambridge University Press:  09 February 2017

Katharina Immer
Affiliation:
European Southern Observatory Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany email: [email protected]
Jens Kauffmann
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Thushara Pillai
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Adam Ginsburg
Affiliation:
European Southern Observatory Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany email: [email protected]
Karl M. Menten
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
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Abstract

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The molecular clouds in the Central Molecular Zone of our Galaxy (CMZ; inner ~200 pc) show systematically higher gas than dust temperatures (>50 K vs <30 K) in recent H2CO line and dust continuum surveys. This discrepancy is puzzling since gas and dust temperatures should become equal over short times at the high densities observed in these clouds. In deep H2CO(3–2) and (4–3) observations of seven clouds in the CMZ, we detected not only large temperature differences between the clouds but also large gradients within the clouds. Comparing the temperatures and the main H2CO lines at 218 and 291 GHz, we found a positive correlation between those two parameters, indicating that turbulence plays an important role in the heating of the gas. As a follow-up, we mapped the temperature tracers CH3CCH and CH3CN in these seven clouds to derive multiple temperature estimates and test the accuracy of high gas temperatures.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2017 

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