Disentangling Multiple Emitting Components in Molecular Observations with Non-negative Matrix Factorization

arXiv (Cornell University)

Abstract

Molecular emission from the galactic and extragalactic interstellar medium (ISM) is often used to determine the physical conditions of the dense gas. However, even from spatially resolved regions, the observed molecules are not necessarily arising from a single component. Disentangling multiple gas components is often a degenerate problem in radiative transfer studies. In this paper we investigate the use of the non-negative matrix factorization (NMF) approach as a means to recover gas components from a set of blended line intensity maps of molecular transitions which may trace different physical conditions. We run a series of experiments on synthetic datasets designed to replicate conditions in two very different environments: galactic pre-stellar cores and the ISM in high redshift galaxies. We find that the NMF algorithm often recovers the multiple components resembling those used in the data-generating process, provided that the different components have similar column densities. When NMF fails to recover all the individual components it does however group together the most similarly emitting ones. We further found that initialisation and regularisation are key factors in the efficiency of the NMF algorithm.

Authors 4

1. Damien de Mijolla

   University College London

   Affiliation as printed

   Department of Physics and Astronomy , University College London , Gower Street , London WC1E 6BT

2. Jonathan Holdship Aachen Leiden Observatory

   Leiden University · Leiden Observatory · University College London

   Affiliation as printed

   Department of Physics and Astronomy , University College London , Gower Street , London WC1E 6BT

   Leiden Observatory , Leiden University , PO Box 9513 , NL-2300 RA Leiden , The Netherlands

3. S. Viti Aachen Leiden Observatory

   Leiden University · Leiden Observatory · University College London

   Affiliation as printed

   Department of Physics and Astronomy , University College London , Gower Street , London WC1E 6BT

   Leiden Observatory , Leiden University , PO Box 9513 , NL-2300 RA Leiden , The Netherlands

4. Johannes Heyl

   University College London

   Affiliation as printed

   Department of Physics and Astronomy , University College London , Gower Street , London WC1E 6BT