The mass function of young star clusters in spiral galaxies

By S. Larsen. 2008

175 citations recorded by the source corpus.

Aims. The initial cluster mass function (ICMF) in spiral discs is constrained and compared with data for old globular clusters and young clusters in starbursts. Methods. For a given absolute magnitude, the cluster age distribution depends on the ICMF. Here, the behaviour of the median age-magnitude relation is analysed in detail for Schechter ICMFs with various cut-off masses, Mc. The calculated relations are com- pared with observations of the brightest clusters in spiral galaxies. Schechter functions are also fitted directly to observed mass functions (MFs). Results. A single Schechter ICMF with an Mc of a few times 10 5 Mcan reproduce the observed ages and luminosities of the brightest (and 5th brightest) clusters in the spirals if disruption of optically visible clusters is dominated by relatively slow secular evolution. A Schechter function fit to the combined cluster MF for all spirals in the sample yields Mc = (2.1 ± 0.4) × 10 5 M� .T he MFs in cluster-poor and cluster-rich spirals are statistically indistinguishable. An Mc = 2.1 × 10 5 MSchechter function also fits the MF of young clusters in the Large Magellanic Cloud. If the same ICMF applies in the Milky Way, a bound cluster with M > 10 5 Mwill form about once every 10 7 years, while an M > 10 6 Mcluster will form only once every 50 Gyr. Luminosity functions (LFs) of model cluster populations drawn from an Mc = 2.1 × 10 5 MSchechter ICMF generally agree with LFs observed in spiral galaxies. Conclusions. The ICMF in present-day spiral discs can be modelled as a Schechter function with Mc ≈ 2 × 10 5 M� .H owever, the presence of significant numbers of M > 10 6 M� (and even M > 10 7 M� ) clusters in some starburst galaxies makes it unlikely that the Mc value derived for spirals is universal. In high-pressure environments, such as those created by complex gas kinematics and feedback in mergers, Mc can shift to higher masses than in quiescent discs.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e506c48bb7a55728532b7a20f663416d7b294e23

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Citations in the corpus

The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, background): “Some authors also report a non-powerlaw cutoff at the highest masses (Bastian 2008; Larsen 2009; Bastian et al. 2012a), though the reality of this feature is disputed (Fall & Chandar 2012).”
CO-EVOLUTION OF GALACTIC NUCLEI AND GLOBULAR CLUSTER SYSTEMS (2013, background): “The masses of individual clusters are drawn from the power-law distribution dN/dM ∝ M−β , Mmin < M < Mmax, (2) that is observed for young massive star clusters in nearby galaxies (e.g., Zhang & Fall 1999; Gieles 2009; Larsen 2009; Chandar et al. 2010a,b, 2011).”
Stellar-mass black holes in star clusters: implications for gravitational-wave radiation (2009, methodology): “We take the mass function of the IMCs to be a power law with index α = −2 which is the approximate index of the ICMF in spiral and starburst galaxies (see e.g. Gieles et al. 2004; Larsen 2009a).”
On the fraction of star formation occurring in bound stellar clusters (2012, background): “21 A possibly more relevant (and currently unanswered) question is whether there are any physical mechanisms that limit the maximum cluster mass, and how these would evolve with the galactic environment (e.g. Gieles et al. 2006a; Bastian 2008; Larsen 2009).”
Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation (2016, background): “By nature, MonteCarlo calculations are restricted to massive clusters, initially ∼ 105M −106M , that are more representatives (or progenitors) of classical globular clusters (hereafter GC), although young clusters of up to ∼ 107M are observed in nearby starburst galaxies (e.g., in the Antennae Larse”
Young Massive Star Clusters (2010, background): “For Milky-Way type spiral galaxiesM∗ ≈ 2×105M⊙ (Gieles et al. 2006b, Larsen 2009a).”
THE ANTENNAE GALAXIES (NGC 4038/4039) REVISITED: ADVANCED CAMERA FOR SURVEYS AND NICMOS OBSERVATIONS OF A PROTOTYPICAL MERGER (2010, background): “A version of this diagram for cluster populations in entire galaxies was first shown – 23 – by Whitmore (2003) and has been subsequently studied by several other authors (Larsen 2002; WCF07; Bastian 2008; Larsen 2009).”
Globular clusters as the relics of regular star formation in ‘normal’ high-redshift galaxies (2015, background): “(ii) Only some fraction of all star formation occurs in bound stellar clusters (Lada & Lada 2003), which is referred to as the the cluster formation efficiency (CFE orΓ, Bastian 2008).”
Probing the role of the galactic environment in the formation of stellar clusters, using M83 as a test bench (2015, methodology): “With a similar argument, Larsen (2009) noticed that the maximum GMC mass observed in the Antennae system is larger than the GMC mass found in local spiral galaxies.”