An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site?
Sgr B2 is a well-known star-forming molecular cloud complex in the Galactic center region showing evidence of high energy activity as traced by the Kα neutral Fe I line at 6.4 keV, as well as GeV and TeV γ-ray emission. Here, we present Very Large Array and GMRT observations with respective resoluti...
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| Format: | Journal Article |
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Institute of Physics Publishing
2016
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| Online Access: | http://hdl.handle.net/20.500.11937/74665 |
| _version_ | 1848763338922655744 |
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| author | Yusef-Zadeh, F. Cotton, W. Wardle, M. Intema, Hubertus |
| author_facet | Yusef-Zadeh, F. Cotton, W. Wardle, M. Intema, Hubertus |
| author_sort | Yusef-Zadeh, F. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Sgr B2 is a well-known star-forming molecular cloud complex in the Galactic center region showing evidence of high energy activity as traced by the Kα neutral Fe I line at 6.4 keV, as well as GeV and TeV γ-ray emission. Here, we present Very Large Array and GMRT observations with respective resolutions of approx. 3.”5 x 1.”2 and 25” x 25” and report the detection of an OH(1720 MHz) maser, with no accompanying OH 1665, 1667, and 1612 MHz maser emission. The maser coincides with a 150 MHz nonthermal radio source in Sgr B2(M). This rare class of OH(1720 MHz) masers or the so-called supernova remnant (SNR) masers, with no main line transitions, trace shocked gas and signal the interaction of an expanding SNR with a molecular cloud. We interpret the 150 MHz radio source as either the site of a SNR–molecular gas interaction or a wind–wind collision in a massive binary system. The interaction of the molecular cloud and the nonthermal source enhances the cosmic-ray ionization rate, allows the diffusion of cosmic rays into the cloud, and produces the variable 6.4 keV line, GeV, and TeV γ-ray emission from Sgr B2(M). The cosmic-ray electron interaction with the gas in the Galactic center can not only explain the measured high values of cosmic-ray ionization and heating rates but also contribute to nonthermal bremsstrahlung continuum emission, all of which are consistent with observations. |
| first_indexed | 2025-11-14T11:01:53Z |
| format | Journal Article |
| id | curtin-20.500.11937-74665 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T11:01:53Z |
| publishDate | 2016 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-746652019-06-25T01:32:47Z An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? Yusef-Zadeh, F. Cotton, W. Wardle, M. Intema, Hubertus Sgr B2 is a well-known star-forming molecular cloud complex in the Galactic center region showing evidence of high energy activity as traced by the Kα neutral Fe I line at 6.4 keV, as well as GeV and TeV γ-ray emission. Here, we present Very Large Array and GMRT observations with respective resolutions of approx. 3.”5 x 1.”2 and 25” x 25” and report the detection of an OH(1720 MHz) maser, with no accompanying OH 1665, 1667, and 1612 MHz maser emission. The maser coincides with a 150 MHz nonthermal radio source in Sgr B2(M). This rare class of OH(1720 MHz) masers or the so-called supernova remnant (SNR) masers, with no main line transitions, trace shocked gas and signal the interaction of an expanding SNR with a molecular cloud. We interpret the 150 MHz radio source as either the site of a SNR–molecular gas interaction or a wind–wind collision in a massive binary system. The interaction of the molecular cloud and the nonthermal source enhances the cosmic-ray ionization rate, allows the diffusion of cosmic rays into the cloud, and produces the variable 6.4 keV line, GeV, and TeV γ-ray emission from Sgr B2(M). The cosmic-ray electron interaction with the gas in the Galactic center can not only explain the measured high values of cosmic-ray ionization and heating rates but also contribute to nonthermal bremsstrahlung continuum emission, all of which are consistent with observations. 2016 Journal Article http://hdl.handle.net/20.500.11937/74665 10.3847/2041-8205/819/2/L35 Institute of Physics Publishing restricted |
| spellingShingle | Yusef-Zadeh, F. Cotton, W. Wardle, M. Intema, Hubertus An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? |
| title | An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? |
| title_full | An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? |
| title_fullStr | An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? |
| title_full_unstemmed | An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? |
| title_short | An oh(1720 MHZ) maser and a nonthermal radio source insgr b2(m): An snr-molecular cloud interaction site? |
| title_sort | oh(1720 mhz) maser and a nonthermal radio source insgr b2(m): an snr-molecular cloud interaction site? |
| url | http://hdl.handle.net/20.500.11937/74665 |