Open AccessGlobal very long‐baseline interferometry observations of compact radio sources in M82
Author(s) -
McDonald A. R.,
Muxlow T. W. B.,
Pedlar A.,
Garrett M. A.,
Wills K. A.,
Garrington S. T.,
Diamond P. J.,
Wilkinson P. N.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04109.x
Subject(s) - physics , very long baseline interferometry , astrophysics , supernova remnant , supernova , very long baseline array , astronomy , galaxy , interferometry , cassiopeia a , angular resolution (graph drawing) , active galactic nucleus , mathematics , combinatorics
Observations of the starburst galaxy, M82, have been made with a 20‐station global very long‐baseline interferometry (VLBI) array at λ 18 cm. Maps are presented of the brightest young supernova remnants (SNR) in M82 and the wide‐field mapping techniques used in making images over a field of view of ∼1 arcmin with 3‐milliarcsecond resolution are discussed. A limit has been placed on the power‐law deceleration of the young supernova remnant (SNR) 43.31+592 with an index greater than 0.73±0.11 from observations with the European VLBI Network. Using the global array we have resolved compact knots of radio emission in the source which, with future global observations, will enable better constraints to be placed on the expansion parameters of this SNR. The latest global observations have also provided high‐resolution images of the most compact radio source in M82, 41.95+575. We determine an upper limit to the radial expansion rate along the major axis of 2000 km s −1 . However, the new images also show structure resembling that of collimated ejection which brings into question the previous explanation of the source as being a result of the confinement of a supernova by a high‐density circumstellar medium. It is apparent that we are now able to image the brightest supernova remnants in M82 with a linear scale which allows direct comparison with galactic SNR such as Cassiopeia A.