Christer Watson edited Analysis.tex  over 9 years ago

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\section{Analysis}  In order to calculate the abundance of CS, we first must estimate the total gas column density along each line of sight. We used FIR imaging taken as part of the HiGal survey. This survey imaged the galactic plane, including all sources observed here, in wavelengths between 60 $\mu$m and 600 $\mu$m. We used Level 2 data products (FITS files), which have been fully calibrated. Within CASA, we measured the integrated emission in all five survey bands in regions exactly coincident with the GBT beamsize, centered at each source of CS emission. The emission was then modeled as a modified blackbody:  \begin{equation}  B_\nu B_{mod}  = \frac{h^2\nu^{3+\beta}}{c^3}\frac{1}{e^{\frac{h\nu}{kT}}-1} \end{equation}  where $\beta$ is assumed to be 2. The total column density is then:  \begin{equation}  N = \frac{I}{B_\nu \mu_H m_H \kappa R_d}\\  B_\nu = \frac{2 h \nu^3}{c^2 (e^\frac{h\nu}{kT}-1)\\  I = flux(at 350 \mu m)1.085\times 10^{-18} \left(\frac{18.6"}{\theta}\right)^2  \end{equation}