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Unusually Wide, High-Velocity Radio Recombination Lines from G0.15–0.05 in the Radio Arc

Published online by Cambridge University Press:  23 September 2016

F. Yusef-Zadeh ,
Mark Morris  and
J. H. van Gorkom
F. Yusef-Zadeh
Affiliation:
LASP, Goddaxd Space Flight Center and Northwestern University
Mark Morris
Affiliation:
Astronomy Department, University of California, Los Angeles
J. H. van Gorkom
Affiliation:
Columbia University and National Radio Astronomy Observatory

Abstract

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The H92α recombination line was observed at 8 GHz toward the “pistol-shaped” HII region G0.15–0.05 using the VLA2 in its most compact configuration. The line profiles of individual components of this source peak at VLSR=123 km/s and have total line widths of ~90 km/s. The kinematical structure of the “pistol” is unusual in that much of the neutral and ionized gas in this region is seen predominantly at either +50 or +20 km/s. The line width and radial velocity are the largest found in the Galactic center region with the exception of Sgr A West. We also found gas at VLSR=140 km/s associated with G0.18–0.04: the sickle-shaped feature which surrounds G0.15–0.05. The kinematic properties of G0.18–0.04 and G0.15–0.05 suggest that these two features are components of a single, but complex thermal system interacting with the nonthermal filaments of the radio Arc. In this regard, the width of the broad recombination line from G0.15–0.05, and its large radial velocity, might be explained as the interaction of streaming relativistic particles in the nonthermal filaments of the Arc impacting upon ambient gas clouds lying in the Galactic plane.

Type
The Arc
Information
Symposium - International Astronomical Union , Volume 136: The Galactic Center , 1989 , pp. 275 - 280
Copyright
Copyright © Kluwer 1989 

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