Astronomy and Astrophysics – Astrophysics
Scientific paper
May 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011iaus..280p.310r&link_type=abstract
The Molecular Universe, Posters from the proceedings of the 280th Symposium of the International Astronomical Union held in Tole
Astronomy and Astrophysics
Astrophysics
Scientific paper
While spectral line surveys are indispensible tools for exploring the physical and chemical evolution of astrophysical environments, they also provide a substantial challenge for traditional spectral analysis software. These surveys are extremely useful due to the vast amount of raw data that can be obtained in a very short amount of time, however, this large amount of data can take years to fully analyze. Our recent CSO survey of Orion-KL at λ=1.3 mm, for example, required only four nights of observations to reach a noise level of 30 mK across a spectral window of ˜30 GHz. Over 2900 spectral lines with intensities >3σ above the rms noise are observed in this spectrum. The traditional method of assigning one molecule at a time, one line at a time has proven to be inadequate for fully interpreting this broadband line survey. We have therefore developed a new spectral analysis program that can be used to analyze such complicated observational spectra. This program globally fits the spectrum for each molecule through a least-squares comparison of the spectral line catalog to the observational spectrum using the approximation of local thermodynamic equilibrium (LTE). We are now upgrading this software to allow simultaneous fitting for multiple species and molecules with multiple temperature components. Ultimately we will also incorporate radiative transfer/statistical equilibrium analysis capabilities in addition to the LTE approximation. We have demonstrated that even this first attempt at a global fitting approach makes assignment and determination of physical conditions more reliable than traditional methods. Through comparison to publicly-available spectral line catalogs, we have now assigned ˜1200 lines in the Orion-KL survey, corresponding to slightly less than half of the observed lines. We will present the results of our analysis, the current state of the software development, and our future plans for the line survey analysis software.
Blake Geoffrey A.
Kroll Jay A.
Radhuber Mary L.
Sumner Matthew. C.
Widicus Weaver Susanna L.
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