Nonthermal Continuum toward Sagittarius B2(N-LMH)

An analysis of continuum antenna temperatures observed in the Green BankTelescope (GBT) spectrometer bandpasses is presented for observations towardSgrB2(N-LMH). Since 2004, we have identified four new prebiotic moleculestoward this source by means of rotational transitions between low energylevels; concurrently, we have observed significant continuum in the GBTspectrometer bandpasses centered at 85 different frequencies in the range of 1to 48 GHz. The continuum heavily influences the molecular spectral featuressince we have observed far more absorption lines than emission lines for eachof these new molecular species. Hence, it is important to understand thenature, distribution, and intensity of the underlying continuum in the GBTbandpasses for the purposes of radiative transfer, i.e. the means by whichreliable molecular abundances are estimated. We find that the GBT spectrometerbandpass continuum is consistent with optically-thin, non thermal (synchrotron)emission with a flux density spectral index of -0.7 and a Gaussian source sizeof ~143" at 1 GHz that decreases with increasing frequency as nu^(-0.52). Somesupport for this model is provided by high frequency Very Large Array (VLA)observations of SgrB2.Comment: Accepted for Publication in the Astrophysical Journal Letter