Very Large Array Observations of Galactic Center OH 1720 MHz Masers in Sagittarius A East and in the Circumnuclear Disk - AstrophysicsReportar como inadecuado




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Abstract: We present Very Large Array VLA radio interferometry observations of the1720 MHz OH masers in the Galactic Center GC. Most 1720 MHz OH masers arisein regions where the supernova remnant Sgr A East is interacting with theinterstellar medium. The majority of the newly found 1720 MHz OH masers arelocated to the northeast, independently indicating and confirming an area ofshock interaction with the +50 km-s molecular cloud M-0.02-0.07 on the farside of Sgr A East. The previously known bright masers in the southeast aresuggested to be the result of the interaction between two supernova remnants,instead of between Sgr A East and the surrounding molecular clouds as generallyfound elsewhere in the Galaxy. Together with masers north of the circumnucleardisk CND they outline an interaction on the near side of Sgr A East. Incontrast to the interaction between the +50 km-s cloud and Sgr A East, OHabsorption data do not support a direct interaction between the CND materialand Sgr A East. We also present three new high-negative velocity masers,supporting a previous single detection. The location and velocities of thehigh-negative and high-positive velocity masers are consistent with being nearthe tangent points of, and physically located in the CND. We argue that thehigh velocity masers in the CND are pumped by dissipation between densityclumps in the CND instead of a shock generated by the supernova remnant. Thatis, the CND masers are not coupled to the supernova remnant and are sustainedindependently.



Autor: L. O. Sjouwerman, Y. M. Pihlstrom

Fuente: https://arxiv.org/







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