Journal Article

From light to mass: accessing the initial and present-day Galactic globular cluster mass functions

C. Bonatto and E. Bica

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 2, pages 1390-1396
Published in print June 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20963.x
From light to mass: accessing the initial and present-day Galactic globular cluster mass functions

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The initial and present-day mass functions (ICMFs and PDMFs, respectively) of the Galactic globular clusters (GCs) are constructed based on their observed luminosities, the stellar evolution and dynamical mass-loss processes, and the mass-to-light ratio (M/L). Under these conditions, a Schechter-like ICMF is evolved for approximately a Hubble time and converted into a luminosity function (LF), which requires finding the values of five free parameters: the mean GC age (), the dissolution time-scale of a 105-M cluster (τ5), the exponential truncation mass () and two M/L parametrizing constants. This is achieved by minimizing the residuals between the evolved and observed LFs, with the minimum residuals and realistic parameters obtained with M/Ls that increase with luminosity (or mass). The optimum PMDFs indicate a total stellar mass of ∼4 × 107 M still bound to GCs, representing ∼15 per cent of the mass in clusters at the beginning of the gas-free evolution. The corresponding ICMFs resemble the scale-free MFs of young clusters and molecular clouds observed in the local Universe, while the PDMFs follow closely a lognormal distribution with a turnover at M. For most of the GC mass range, we find an M/L lower than usually adopted, which explains the somewhat low . Our results confirm that the M/L increases with cluster mass (or luminosity), and suggest that GCs and young clusters share a common origin in terms of physical processes related to formation.

Keywords: globular clusters: general

Journal Article.  5554 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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