ReverseRADEX: a tool to quickly gauge global physical conditions of a gas cloud

Mooren, Filip, van der (2021) ReverseRADEX: a tool to quickly gauge global physical conditions of a gas cloud. Bachelor's Thesis, Astronomy.

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Abstract

Molecular emission line observations of interstellar gas clouds harbor information about the global physical components like kinetic temperature and densities. Current software to extract this information in a quick and practical manner is scarce and due for improvement. RADEX is used as the underlying radiative transfer code based on escape probability methodology, requiring molecular collision data following the format of the Leiden Atomic and Molecular Database (LAMDA). RADEX input consist of physical components and outputs line spectra and required inversion. Accordingly, a set of python wrappers for Fortran written RADEX was compared and SpectralRadex chosen. ReverseRADEX takes molecular spectral lines as input and optimizes for physical components using an algorithm chain consisting of three parts; a Brute-force method to estimate initial physical parameters, subsequently the Levenberg-Marquardt (LM) algorithm refines the parameter estimates, culminated by an Monte Carlo Markov Chain (MCMC) algorithm in order to determine parameter uncertainties. ReverseRADEX is available online and the design of ReverseRADEX is described here, with exemplifying tests showcasing the software’s capabilities and limitations as a practical program to obtain physical parameter and uncertainty estimates quickly.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Tak, F.F.S. van der
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	09 Jul 2021 11:53
Last Modified:	09 Jul 2021 11:53
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/25088

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