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The jet and arc molecular clouds toward Westerlund 2, RCW 49, and HESS J1023-575; 12CO and 13CO (J = 2-1 and J = 1-0) observations with NANTEN2 and Mopra telescope


Furukawa, N and Ohama, A and Fukuda, T and Torii, K and Hayakawa, T and Sano, H and Okuda, T and Yamamoto, H and Moribe, N and Mizuno, A and Maezawa, H and Onishi, T and Kawamura, A and Mizuno, N and Dawson, JR and Dame, TM and Yonekura, Y and Aharonian, F and De Ona Wilhelmi, E and Rowell, GP and Matsumoto, R and Asahina, Y and Fukui, Y, The jet and arc molecular clouds toward Westerlund 2, RCW 49, and HESS J1023-575; 12CO and 13CO (J = 2-1 and J = 1-0) observations with NANTEN2 and Mopra telescope, Astrophysical Journal, 781, (2) Article 70. ISSN 0004-637X (2014) [Refereed Article]


Copyright Statement

Copyright 2014 The American Astronomical Society

DOI: doi:10.1088/0004-637X/781/2/70


We have made new CO observations of two molecular clouds, which we call "jet" and "arc" clouds, toward the stellar cluster Westerlund 2 and the TeV γ-ray source HESS J1023-575. The jet cloud shows a linear structure from the position of Westerlund 2 on the east. In addition, we have found a new counter jet cloud on the west. The arc cloud shows a crescent shape in the west of HESS J1023-575. A sign of star formation is found at the edge of the jet cloud and gives a constraint on the age of the jet cloud to be ~Myr. An analysis with the multi CO transitions gives temperature as high as 20 K in a few places of the jet cloud, suggesting that some additional heating may be operating locally. The new TeV γ-ray images by H.E.S.S. correspond to the jet and arc clouds spatially better than the giant molecular clouds associated with Westerlund 2. We suggest that the jet and arc clouds are not physically linked with Westerlund 2 but are located at a greater distance around 7.5 kpc. A microquasar with long-term activity may be able to offer a possible engine to form the jet and arc clouds and to produce the TeV γ-rays, although none of the known microquasars have a Myr age or steady TeV γ-rays. Alternatively, an anisotropic supernova explosion which occurred ~Myr ago may be able to form the jet and arc clouds, whereas the TeV γ-ray emission requires a microquasar formed after the explosion.

Item Details

Item Type:Refereed Article
Keywords:ISM: clouds, ISM: individual objects (jet and arc molecular clouds, HESS J1023-575), stars: individual (Westerlund 2)
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Dawson, JR (Dr Joanne Dawson)
ID Code:98562
Year Published:2014
Web of Science® Times Cited:8
Deposited By:Mathematics and Physics
Deposited On:2015-02-19
Last Modified:2017-11-03
Downloads:232 View Download Statistics

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