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Many observed globular clusters (GCs) seem to show a central overabundance of mass whose nature has not yet fully understood. Indeed, it is not clear whether it is due to a central intermediate mass black hole (IMBH) or to a massive stellar…

Astrophysics of Galaxies · Physics 2016-06-23 Manuel Arca-Sedda

Clustering is a fundamental problem in machine learning and operations research. Therefore, given the fact that fairness considerations have become of paramount importance in algorithm design, fairness in clustering has received significant…

Machine Learning · Computer Science 2024-06-25 John Dickerson , Seyed A. Esmaeili , Jamie Morgenstern , Claire Jie Zhang

Statistical sampling from the stellar initial mass function (IMF) for all star-forming regions in the Galaxy would lead to the prediction of ~1000 Msun stars unless there is a rapid turn-down in the IMF beyond several hundred solar masses.…

Astrophysics · Physics 2009-10-31 Bruce G. Elmegreen

Binary population synthesis provides a direct way of studying the effects of different choices of binary evolution models and initial parameter distributions on present-day binary compact merger populations, which can then be compared to…

High Energy Astrophysical Phenomena · Physics 2023-04-05 L. M. de Sá , A. Bernardo , R. R. A. Bachega , L. S. Rocha , J. E. Horvath

It has been shown before that the high mass-to-light ratios of ultra compact dwarf galaxies (UCDs) can be explained if their stellar initial mass function (IMF) was top-heavy, i.e. that the IMF was skewed towards high mass stars. In this…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Jörg Dabringhausen , Pavel Kroupa , Jan Pflamm-Altenburg , Steffen Mieske

We propose that the stellar initial mass function (IMF) is universal in the sense that its functional form arises as a consequence of the statistics of random supersonic flows. A model is developed for the origin of the stellar IMF, that…

Astrophysics · Physics 2015-06-24 Paolo Padoan , Ake Nordlund , Bernard J. T. Jones

We examine the gravitational lensing effect of a foreground galaxy cluster on the number count statistics of background X-ray sources. The lensing produces a deficit in the number of resolved sources in a ring close to the critical radius…

Astrophysics · Physics 2007-05-23 Alexandre Refregier , Abraham Loeb

The astrophysical origins of the binary black hole systems seen with gravitational waves are still not well understood. However, features in the distribution of black-hole masses, spins, redshifts, and eccentricities provide clues into how…

High Energy Astrophysical Phenomena · Physics 2024-03-25 Christian Adamcewicz , Paul D. Lasky , Eric Thrane

This contribution describes the difficult task of inferring the IMF from local star-count data, by discussing the mass-luminosity relation, unresolved binary, triple and quadruple systems, abundance and age spreads and Galactic structure,…

Astrophysics · Physics 2007-05-23 Pavel Kroupa

Two of the dominant channels to produce the black-hole binary mergers observed by LIGO and Virgo are believed to be the isolated evolution of stellar binaries in the field and dynamical formation in star clusters. Their relative efficiency…

High Energy Astrophysical Phenomena · Physics 2020-08-31 Vishal Baibhav , Davide Gerosa , Emanuele Berti , Kaze W. K. Wong , Thomas Helfer , Matthew Mould

It is surprising to find dust around B type stars, as in the case of B[e] stars. These stars exhibit a dense, dusty environment witnessed by their infrared-excess and many emission lines from permitted and forbidden transitions. Given the…

Solar and Stellar Astrophysics · Physics 2009-09-15 Michaela Kraus , Marcelo Borges Fernandes , Olivier Chesneau

The determination of the mass of galaxy clusters from observations is subject to systematic uncertainties. Beyond the errors due to instrumental and observational systematic effects, in this work we investigate the bias introduced by…

We introduce a new method to measure the dispersion of mmax values of star clusters and show that the observed sample of mmax is inconsistent with random sampling from an universal stellar initial mass function (IMF) at a 99.9% confidence…

Astrophysics of Galaxies · Physics 2015-06-16 Carsten Weidner , Pavel Kroupa , Jan Pflamm-Altenburg

One of the greatest challenges facing gravitational wave astronomy in the low frequency band is the confusion noise generated by the vast numbers of unresolved galactic and extra galactic binary systems. Estimates of the binary confusion…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Neil J. Cornish

From time to time, and quite more frequently in recent years, claims appear favoring a variable Initial Mass Function (IMF), one way or another, either in time or space. In this chapter we add our two pennies of wisdom, illustrating how the…

Astrophysics of Galaxies · Physics 2020-07-17 Laura Greggio , Alvio Renzini

Massive stars can be found in wide (hundreds to thousands AU) binaries with other massive stars. We use $N$-body simulations to show that any bound cluster should always have approximately one massive wide binary: one will probably form if…

Astrophysics of Galaxies · Physics 2018-03-14 Daniel W. Griffiths , Simon P. Goodwin , Saida M. Caballero-Nieves

The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Pavel Kroupa , Carsten Weidner , Jan Pflamm-Altenburg , Ingo Thies , Joerg Dabringhausen , Michael Marks , Thomas Maschberger

We present a new study of H{\alpha}/FUV flux ratios of star forming regions within a sample of nearby spiral galaxies. We search for evidence of the existence of a cluster mass dependent truncation in the underlying stellar initial mass…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-14 Maciej T. Hermanowicz , Robert C. Kennicutt , John J. Eldridge

I discuss an issue arising in analyzing data from astronomical surveys: accounting for measurement uncertainties in the properties of individual sources detected in a survey when making inferences about the entire population of sources.…

Astrophysics · Physics 2009-11-10 Thomas J. Loredo

It is frequently debated in literature whether a "standard" Initial Mass Function (IMF) - meaning an IMF of the kind usually adopted to explain the chemical evolution in the local Solar Neighbourhood - can account for the observed metal…

Astrophysics · Physics 2009-11-10 L. Portinari , A. Moretti , C. Chiosi , J. Sommer-Larsen