Department
Physics
Document Type
Article
Publication Date
1-2000
Abstract
We present a wide-field, high dynamic range, high-resolution, long-wavelength (lambda = 90 cm) VLA image of the Galactic center region. The image is centered on Sgr A, covers an area of 4 degrees x 5 degrees with an angular resolution of 43 ", and has a rms sensitivity of approximate to 5 mJy beam-l. The image was constructed from archival (1989 and 1991) VLA data of Pedlar et al. and Anantharamaiah et al. using new three-dimensional image restoration techniques. These three-dimensional imaging techniques resolve the problem of non-coplanar baselines encountered at long wavelengths and yield distortion-free imaging of far-field sources with improved sensitivity. At lambda = 90 cm the VLA is sensitive to both thermal and nonthermal emission and the resulting image gives an unprecedented contextual perspective of the large-scale radio structure in this unique and complicated region. We have catalogued over a hundred sources from this image and present for each source its 90 cm flux density, position, and size. For many of the small- diameter sources, we also derive the 20/90 cm spectral index. The spectral index as a function of length along several of the isolated nonthermal filaments has been estimated and found to be constant. We have found six new small-diameter sources, as well as several extended regions of emission, which are clearly distinct sources that have not been previously identified at higher frequencies. These data are presented as a first epoch of VLA observations that can be used to search for source variability in conjunction with a second epoch of observations that were recently initiated.
Journal Title
The Astrophysical Journal
Journal ISSN
0004-637X
Volume
119
First Page
207
Last Page
240