A Wide-Field 90 Centimeter VLA Image of the Galactic Center Region
Abstract
We present a wide-field, high dynamic range, high-resolution, long-wavelength (lambda = 90 cm) Very Large Array (VLA) image of the Galactic center region. The image is centered on Sgr A, covers an area of 4 deg. x 5 deg. with an angular resolution of 43", and has a rms sensitivity of approx. 5 mJy beam(expo. -1). 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2000
- Accession Number
- ADA464575
Entities
People
- Namir E. Kassim
- S. D. Hyman
- T. J. Lazio
- T. N. Larosa
Organizations
- Kennesaw State University