PdfCLEAN, AGNs, and Interstellar Scattering Toward the Galactic Center

Details PdfCLEAN, AGNs, and Interstellar Scattering Toward the Galactic Center PdfCLEAN, AGNs, and Interstellar Scattering Toward the Galactic Center

Mar 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995aas...186.5004l&link_type=abstract

American Astronomical Society, 186th AAS Meeting, #50.04; Bulletin of the American Astronomical Society, Vol. 27, p.884

Mathematics

Probability

1

Scientific paper

Observations of Sgr A(*) and OH/IR stars toward the Galactic center have revealed a region of enhanced and anisotropic angular broadening. However, the radial distance of the scattering material from the Galactic center is as yet unconstrained. If the scattering region is an unrelated superposition with the Galactic center and distant, e.g. 1 kpc, extragalactic sources seen through the region should be broadened to roughly double the size of the OH/IR sources, i.e. ~ 1arcsec . If the scattering region is local to the Galactic center, e.g. 50 pc, and a consequence of the extreme properties of the Galactic center, extragalactic source sizes should be much larger, e.g. ~ 2 arcmin. We have observed 10 fields toward the Galactic center using the VLA in the BnA configuration. We identify potential AGNs in these fields using pdfCLEAN, a procedure of source detection amidst noise with a known probability distribution (Zepka et al. 1994, ApJ, 427, 438): Image pixels whose intensity deviates from the expected intensity distribution for a noise-only image indicate the presence of sources in the image. Our current catalog has a sensitivity of 2--10 mJy and contains nearly 100 sources with fluxes between 2 and 500 mJy. A comparison against a previous Galactic plane survey with similar resolution and a sensitivity of 10--50 mJy (Zoonematkermani et al. 1990, ApJS, 74, 181; Helfand et al. 1992, ApJS, 80, 211) indicates that a significant fraction of our catalog is new. A surprisingly large number of these sources is compact, though not all of these are AGN, as the catalog also includes ultra-compact Hii regions, supernova remnants, and possibly pulsars and transient sources. However, fields within ~ 1deg of Sgr A(*) appear to show a deficit of sources. Such a deficit is consistent with a scattering region local to the Galactic center, resulting in source sizes so large as to be resolved out by our observations.

Affiliated with

Also associated with

No associations

Rating

PdfCLEAN, AGNs, and Interstellar Scattering Toward the Galactic Center does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with PdfCLEAN, AGNs, and Interstellar Scattering Toward the Galactic Center, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and PdfCLEAN, AGNs, and Interstellar Scattering Toward the Galactic Center will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-882754