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Abstract: We present images of the Sagittarius Sgr B giant molecular cloud at 2368and 1384 MHz obtained using new, multi-configuration Australia TelescopeCompact Array ATCA observations. We have combined these observations witharchival single-dish observations yielding images at resolutions of 47- by 14-and 27- by 8- at 1384 and 2368 MHz respectively. These observations weremotivated by our theoretical work Protheroe et al. 2008 indicating thepossibility that synchrotron emission from secondary electrons and positronscreated in hadronic cosmic ray CR collisions with the ambient matter of theSgr B2 cloud could provide a detectable and possibly linearly polarizednon-thermal radio signal. We find that the only detectable non-thermal emissionfrom the Sgr B region is from a strong source to the south of Sgr B2, which welabel Sgr B2 Southern Complex SC. We find Sgr B2SC integrated fluxdensities of 1.2+-0.2 Jy at 1384 MHz and 0.7+-0.1 Jy at 2368 MHz for a sourceof FWHM size at 1384 MHz of ~54-. Despite its non-thermal nature, thesynchrotron emission from this source is unlikely to be dominantly due tosecondary electrons and positrons. We use polarization data to place 5-sigmaupper limits on the level of polarized intensity from the Sgr B2 cloud of 3.5and 3 mJy-beam at 1384 and 2368 MHz respectively. We also use the angulardistribution of the total intensity of archival 330 MHz VLA and the totalintensity and polarized emission of our new 1384 MHz and 2368 MHz data toconstrain the diffusion coefficient for transport of the parent hadronic CRsinto the dense core of Sgr B2 to be no larger than about 1% of that in theGalactic disk. Finally, we have also used the data to perform a spectral andmorphological study of the features of the Sgr B cloud and compare and contrastthese to previous studies.



Author: David I. Jones 1,2,3, Roland M. Crocker 4,3, Juergen Ott 5,6, Raymond J. Protheroe 1, Ron D. Ekers 2 1 University of Adelaide, 2

Source: https://arxiv.org/



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