AUSTRALIA TELESCOPE COMPACT ARRAY RADIO CONTINUUM 1384 AND 2368 MHz OBSERVATIONS OF SAGITTARIUS B

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/141/3/82· OSTI ID:21583212

Jones, David I; Protheroe, Raymond J ^[1]; Crocker, Roland M ^[2]; Ott, Juergen ^[3]

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1. Department of Physics, School of Chemistry and Physics, University of Adelaide, South Australia 5000 (Australia)
2. Max Planck Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg (Germany)
3. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

We present images of the Sagittarius (Sgr) B giant molecular cloud at 1384 and 2368 MHz obtained using new, multi-configuration Australia Telescope Compact Array observations. We have combined these observations with archival single-dish observations yielding images at resolutions of 47'' x 14'' and 27'' x 8'' at 1384 and 2368 MHz, respectively. These observations were motivated by our theoretical work indicating the possibility that synchrotron emission from secondary electrons and positrons created in hadronic cosmic ray (CR) collisions with the ambient matter of the Sgr B2 cloud could provide a detectable (and possibly linearly polarized) non-thermal radio signal. We find that the only detectable non-thermal emission from the Sgr B region is from a strong source to the south of Sgr B2, which we label Sgr B2 Southern Complex (SC). We find Sgr B2(SC) integrated flux densities of 1.2 {+-} 0.2 Jy at 1384 MHz and 0.7 {+-} 0.1 Jy at 2368 MHz for a source of FWHM size at 1384 MHz of {approx}54''. Despite its non-thermal nature, the synchrotron emission from this source is unlikely to be dominated due to secondary electrons and positrons. Failing to find clear evidence of non-thermal emission due to secondary electrons and positrons, we use polarization data to place 5{sigma} upper limits on the level of polarized intensity from the Sgr B2 cloud of 3.5 and 3 mJybeam{sup -1} at 1384 and 2368 MHz, respectively. We also use the angular distribution of the total intensity of archival 330 MHz Very Large Array and the total intensity and polarized emission of our new 1384 and 2368 MHz data to constrain the diffusion coefficient for transport of the parent hadronic CRs into the dense core of Sgr B2 to be no larger than about 1% of that in the Galactic disk. Finally, we have also used the data to perform a spectral and morphological study of the features of the Sgr B cloud and compare and contrast these to previous studies.

• OSTI ID: 21583212
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 141, Issue 3; Other Information: DOI: 10.1088/0004-6256/141/3/82; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANGULAR DISTRIBUTION
ASTROPHYSICS
COSMIC RADIATION
ELECTRON EMISSION
ELECTRONS
FLUX DENSITY
GALAXIES
GALAXY NUCLEI
GHZ RANGE 01-100
HADRONS
IMAGES
PHOTON COLLISIONS
POSITRONS
TELESCOPES
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
COLLISIONS
DISTRIBUTION
ELEMENTARY PARTICLES
EMISSION
FERMIONS
FREQUENCY RANGE
GHZ RANGE
IONIZING RADIATIONS
LEPTONS
MATTER
PHYSICS
RADIATIONS