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Interstellar Scintillation of Radio Sources as a Probe for Investigations of the Local Interstellar Medium

Published online by Cambridge University Press:  12 April 2016

N. Bochkarev  and
M. Ryabov
N. Bochkarev
Affiliation:
Sternberg Astronomical Institute, Universitetskij prosp. 13, Moscow, 119899, Russia
M. Ryabov
Affiliation:
Odessa Observatory URAN-4 ofRadioastronomical Institute of National Academy of Science, Pushkinskaya str. 37, Odessa, 270011, Ukraine

Abstract

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A possibility of obtaining information on small scale inhomogeneities of the electron component of the local interstellar medium (LISM) is investigated using interstellar scintillations of extragalactic radio sources. We analyse Culgoora array observational data on variability of 190 extragalactic radio sources, covering most of the sky, at 80 and 160 MHz. The variability at time scales from 1 month to 15 years is interpreted as refractive interstellar scintillations in fast-moving nearby (less than 150 pc) hot gas near shock waves in the LISM. All-sky map of scintillation indices m averaged over 3–5 sources closest to one another shows several m maxima. Two of the 3 most pronounced maxima are probably connected with Loop I; the third one coincides with the soft X-ray (0.1–0.3 keV) background maximum near the South Galactic Pole. Other, less certain, m maxima probably correspond to the Orion star-formation region and to a soft X-ray maximum near the North Galactic Pole. The ”free-of-gas” tunnel in the direction l = 240° corresponds to low values of m. The estimated time scale of interstellar scintillations on the above-mentioned LISM structures is in agreement with that of the observed radio-source variations.

Type
Part IV Clouds, Ionized Gas, and Particles in the Local ISM
Information
International Astronomical Union Colloquium , Volume 166: The Local Bubble and Beyond , 1997 , pp. 215 - 218
Copyright
Copyright © Springer-Verlag 1998

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