The jet and arc molecular clouds toward Westerlund 2, RCW 49, and HESS J1023–575; {sup 12}CO and {sup 13}CO (J = 2-1 and J = 1-0) observations with NANTEN2 and Mopra telescope
- Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
- Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan)
- Department of Astrophysics, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)
- National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)
- School of Mathematics and Physics, University of Tasmania, Sandy Bay Campus, Churchill Avenue, Sandy Bay, TAS 7005 (Australia)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Center for Astronomy, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan)
- Dublin Institute for Advanced Studies, 31 Fitzwiliam Place, Dublin 2 (Ireland)
- Max-Planck-Institut für Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany)
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.
- OSTI ID:
- 22348139
- Journal Information:
- Astrophysical Journal, Vol. 781, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Magnetohydrodynamic Simulations of the Formation of Molecular Clouds toward the Stellar Cluster Westerlund 2: Interaction of a Jet with a Clumpy Interstellar Medium
Probing the hadronic nature of the gamma-ray emission associated with Westerlund 2