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On the shape of the mass-function of dense clumps in the Hi-GAL fields II. Using Bayesian inference to study the clump mass function

Olmi, L. and Anglés-Alcázar, D. and Elia, D. and Molinari, S. and Pestalozzi, M. and Pezzuto, S. and Schisano, E. and Testi, L. and Thompson, M. (2014) On the shape of the mass-function of dense clumps in the Hi-GAL fields II. Using Bayesian inference to study the clump mass function. Astronomy and Astrophysics, 564 . Art. No. A87. ISSN 0004-6361. http://resolver.caltech.edu/CaltechAUTHORS:20140529-084834980

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Abstract

Context. Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin, their evolution, and their detailed physical properties. In particular, the relationship between the mass distribution of these clumps (also known as the “clump mass function”, or CMF) and the stellar initial mass function (IMF) is still poorly understood. Aims. To better understand how the CMF evolve toward the IMF and to discern the “true” shape of the CMF, large samples of bona-fide pre- and proto-stellar clumps are required. Two such datasets obtained from the Herschel infrared GALactic Plane Survey (Hi-GAL) have been described in Paper I. Robust statistical methods are needed to infer the parameters describing the models used to fit the CMF and to compare the competing models themselves. Methods. In this paper, we apply Bayesian inference to the analysis of the CMF of the two regions discussed in Paper I. First, we determine the posterior probability distribution for each of the fitted parameters. Then, we carry out a quantitative comparison of the models used to fit the CMF. Results. We have compared several methods of sampling posterior distributions and calculating global likelihoods, and we have also analyzed the impact of the choice of priors and the influence of various constraints on the statistical conclusions for the values of model parameters. We find that both parameter estimation and model comparison depend on the choice of parameter priors. Conclusions. Our results confirm our earlier conclusion that the CMFs of the two Hi-GAL regions studied here have very similar shapes but different mass scales. Furthermore, the lognormal model appears to better describe the CMF measured in the two Hi-GAL regions studied here. However, this preliminary conclusion is dependent on the choice of parameter priors.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1051/0004-6361/201323035DOIArticle
http://www.aanda.org/articles/aa/abs/2014/04/aa23035-13/aa23035-13.htmlPublisherArticle
http://arxiv.org/abs/1311.2736arXivDiscussion Paper
Additional Information:© 2014 ESO. Article published by EDP Sciences. Received 12 November 2013; accepted 18 February 2014. L.O. would like to thank L. Pericchi for fruitful discussions on various issues related to Bayesian inference and parameter priors.
Subject Keywords:stars: formation; ISM: clouds; methods: data analysis; methods: statistical
Record Number:CaltechAUTHORS:20140529-084834980
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140529-084834980
Official Citation:On the shape of the mass-function of dense clumps in the Hi-GAL fields - II. Using Bayesian inference to study the clump mass function L. Olmi, D. Anglés-Alcázar, D. Elia, S. Molinari, M. Pestalozzi, S. Pezzuto, E. Schisano, L. Testi and M. Thompson A&A 564 A87 (2014) DOI: http://dx.doi.org/10.1051/0004-6361/201323035
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45959
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:29 May 2014 19:12
Last Modified:29 May 2014 19:12

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