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C.M. Brunt (DRAO - HIA - NRC (Canada) and Dept.of Phys. and Astron., Univ. of Calgary), J. Ontkean, L.B.G. Knee (DRAO - HIA - NRC (Canada))
We have completed a reprocessing of the FCRAO 12CO(J=1-0) Outer Galaxy Survey (Heyer et al ApJS 115, 241, 1998), using techniques that (1) suppress correlated noise induced by reference-sharing and (2) isolate and remove contaminating emission present in the reference positions. The accuracy of the reprocessing technique and the inferred emission in the reference positions have been confirmed by follow-up observations. We report the discovery of a widespread distribution of faint CO emission in the Outer Galaxy.
The typical sensitivity of the reference spectra is ~ 0.04 K (1\sigma TR* scale), a factor of 15 below that of the OGS spectra. Spectral lines are identifiable all the way down to the (variable) sensitivity limit of the reference spectra, and are generally bounded from above by the nominal sensitivity limit to which the reference positions were originally checked (5\sigma TR* ~ 0.7K).
The faint emission is spatially and kinematically associated with known structures in the Outer Galaxy. Contaminating emission around vLSR ~ 0 kms-1 occurs at a range of peak line temperatures, has narrow linewidths (generally < 1 kms-1) and is widely but not uniformly distributed, while Perseus Arm contamination is rarer and spatially compact, having higher peak temperatures and slightly broader linewidths. Contaminating emission beyond the Perseus Arm follows the warp of the Galactic Plane and has similar characteristics to the Perseus Arm contamination, but at lower peak temperatures.
The reprocessed Outer Galaxy Survey is part of the Canadian Galactic Plane Survey. This work was supported by NRC (Canada), grants from NSERC (Canada) and NSF (USA) Grant AST 97-25951 to FCRAO.
The author(s) of this abstract have provided an email address for comments about the abstract: chris.brunt@hia.nrc.ca