Issue |
A&A
Volume 440, Number 1, September II 2005
|
|
---|---|---|
Page(s) | 171 - 177 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20042537 | |
Published online | 19 August 2005 |
A multi-frequency study of the spectral index distribution in the SNR CTB 80
Instituto de Astronomía y Física del Espacio (IAFE), CC 67, Suc. 28, 1428 Buenos Aires, Argentina e-mail: gcastell@iafe.uba.ar
Received:
14
December
2004
Accepted:
4
May
2005
We have conducted a study at radio wavelengths of the spectral behaviour
of the supernova remnant (SNR) CTB 80.
Based on an homogenised data set of integrated flux densities, we calculated
for the whole SNR a radio index . The shape of the
global spectrum suggests absorption by ionized gas in the
interstellar medium (ISM) along the line of sight. Spatial spectral variations across the
SNR are investigated
based on high-angular resolution data at 240, 324, 610, and 1380 MHz using
different techniques. The three extended arms associated with this SNR
show a clear indication of spectral steepening when moving
outwards from the central nebula, with variations of up to
. However, while the spectral steepening is smooth
along the eastern arm, the northern and soutwestern arms include locally
flatter structures, which in all cases coincide with radio, IR and optical
emission enhancements. We interpret this spectral property as the result
of the combination of two different particle populations: aging relativistic
electrons injected by PSR B1951+32 and particles accelerated at the sites
where the SNR shock front encounters interstellar gas inhomogeneities.
Concerning the central nebula, the angular resolution of the available
database does not permit a detailed spectral study of the core region, i.e. the 45″ region around PSR B1951+32, where we can only confirm
an average spectral index
. The surrounding 8′ plateau nebula has an
, with a peak of
coincident with a secondary maximun located at the
termination of a twisted filament that trails to the east, behind the pulsar.
Key words: ISM: individual objects: CTB 80 / pulsar: individual: PSR B1951+32 / ISM: supernova remnants / radio continuum: ISM
© ESO, 2005
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