Fitting density models to observational data. The local Schmidt law in molecular clouds

Author(s)

Marco Lombardi, Charles J. Lada, João Alves

Abstract

We consider the general problem of fitting a parametric density model to

discrete observations, taken to follow a non-homogeneous Poisson point

process. This class of models is very common, and can be used to

describe many astrophysical processes, including the distribution of

protostars in molecular clouds. We give the expression for the

likelihood of a given spatial density distribution of protostars and

apply it to infer the most probable dependence of the protostellar

surface density on the gas surface density. Finally, we apply this

general technique to model the distribution of protostars in the Orion

molecular cloud and robustly derive the local star formation scaling

(Schmidt) law for a molecular cloud. We find that in this cloud the

protostellar surface density, ΣYSO, is directly

proportional to the square gas column density, here expressed as

infrared extinction in the K-band, AK: more precisely,

ΣYSO = (1.65 ± 0.19)

(AK/mag)2.03 ± 0.15 stars pc-2.

Organisation(s)

Department of Astrophysics

External organisation(s)

Harvard-Smithsonian Center for Astrophysics, Universitá degli Studi di Milano

Journal

Astronomy & Astrophysics

Volume

559

No. of pages

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/201321827

Publication date

11-2013

Peer reviewed

Yes

Austrian Fields of Science 2012

103004 Astrophysics, 103003 Astronomy

Keywords

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