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Paper: SMA CO J = 3 − 2 Observations of the Antennae (NGC4038/39)
Volume: 375, From Z-Machines to ALMA: (Sub)Millimeter Spectroscopy of Galaxies
Page: 267
Authors: Petitpas, G.; Iono, D.; Peck, A.; Wilson, C.; Matsushita, S.; Sakamoto, K.; Wang, J.; Ho, P.; Zhang, Q.; Rots, A.; Wang, Z.; Yun, M.; Surace, J.
Abstract: The Submillimeter Array (SMA) is currently the only interferometer capable of studying molecular gas warmer than ∼ 30K in nearby and high-redshift sources. We present high angular resolution 12CO J = 3 − 2 observations of the Antennae merging galaxy system made with the SMA. We find that the peaks in the warm molecular gas emission do not necessarily correspond to the peaks seen in the cooler CO J = 1 − 0 gas. This suggests the existence of temperature and/or density gradients in the molecular gas in this interacting system. To study this effect in more detail, we have created a data cube comprising the CO J = 3 − 2/J = 1 − 0 line ratio for every 20 kms−1 channel in this galaxy. With this cube, we can trace the temperature gradients across the spatial and dynamical range of this system. We find excellent spatial agreement between elevated CO J = 3 − 2/J = 1 − 0 ratio and bright spots in the Spitzer 8 μm map, suggesting that the star formation that is heating the dust is also actively heating the molecular gas. With this correlation, it is possible to trace the dynamics of the warm and cold dust in this system using the CO line ratio, whereas it is not possible to do this with dust measurements alone. The techniques used in this study of a nearby interacting system have strong implications for and analogies to future studies of higher-redshift galaxies that will be studied when ALMA comes online.
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