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Some ultra-compact dwarf galaxies have large dynamical mass to light (M/L) ratios and also appear to contain an overabundance of LMXB sources, and some Milky Way globular clusters have a low concentration and appear to have a deficit of…

Astrophysics of Galaxies · Physics 2020-03-18 Pavel Kroupa

Increasingly, software is making autonomous decisions in case of criminal sentencing, approving credit cards, hiring employees, and so on. Some of these decisions show bias and adversely affect certain social groups (e.g. those defined by…

Machine Learning · Computer Science 2021-07-12 Joymallya Chakraborty , Suvodeep Majumder , Tim Menzies

We explore the assumption, widely used in many astrophysical calculations, that the stellar initial mass function (IMF) is universal across all galaxies. By considering both a canonical Salpeter-like IMF and a non-universal IMF, we are able…

Globular clusters display an anticorrelation between the fraction of the first generation of stars ($N({\rm G1})/N({\rm tot})$) and the slope of the present-day mass function of the clusters ($\alpha_{pd}$), which is particularly…

Astrophysics of Galaxies · Physics 2023-02-10 Sami Dib , Valery V. Kravtsov , Hosein Haghi , Akram Hasani Zonoozi , José Antonio Belinchón

As most if not all stars are born in stellar clusters the shape of the mass function of the field stars is not only determined by the initial mass function of stars (IMF) but also by the cluster mass function (CMF). In order to quantify…

Astrophysics · Physics 2015-11-11 Carsten Weidner , Pavel Kroupa

Negative binomial regression is commonly employed to analyze overdispersed count data. With small to moderate sample sizes, the maximum likelihood estimator of the dispersion parameter may be subject to a significant bias, that in turn…

Methodology · Statistics 2020-11-06 Euloge Clovis Kenne Pagui , Alessandra Salvan , Nicola Sartori

The star discrepancy is a quantitative measure of the uniformity of a point set in the unit cube. A central quantity of interest is the inverse of the star discrepancy, $N(\varepsilon, s)$, defined as the minimum number of points required…

Numerical Analysis · Mathematics 2026-03-06 Josef Dick , Friedrich Pillichshammer

Gravitational microlensing depends primarily on the lens mass and presents a larger occurrence rate in crowded regions, which makes it the best tool to uncover the initial mass function (IMF) of low-mass stars in the Galactic bulge. The…

Most structural and evolutionary properties of galaxies strongly rely on the stellar initial mass function (IMF), namely the distribution of the stellar mass formed in each episode of star formation. As the IMF shapes the stellar population…

Astrophysics of Galaxies · Physics 2023-01-31 Jiadong Li , Chao Liu , Zhi-Yu Zhang , Hao Tian , Xiaoting Fu , Jiao Li , Zhi-Qiang Yan

Several methods for identifying Be star candidates are reviewed for observational bias with respect to system inclination, that is the angle between the stellar/disk rotation axis and the observer's line of sight, with focus on two…

Solar and Stellar Astrophysics · Physics 2026-01-30 B. D. Lailey , T. A. A. Sigut

Histograms are convenient non-parametric density estimators, which continue to be used ubiquitously. Summary quantities estimated from histogram-based probability density models depend on the choice of the number of bins. We introduce a…

Data Analysis, Statistics and Probability · Physics 2013-09-17 Kevin H. Knuth

Observations of external galaxies and of local star-forming clouds in the Milky Way have suggested a variety of star formation laws, i.e., simple direct relations between the column density of star formation (Sigma_SFR: the amount of gas…

Astrophysics of Galaxies · Physics 2013-12-12 Christoph Federrath

We present the new technique for the determination of the low-mass slope of the stellar mass function from the pixel-space fitting of integrated light spectra. This technique is the extension of the NBursts full spectral fitting technique.…

Instrumentation and Methods for Astrophysics · Physics 2013-01-25 N. Podorvanyuk , I. Chilingarian , I. Katkov

Star formation has been observed to occur at globally low yet locally varying efficiencies. As such, accurate capture of star formation in numerical simulations requires mechanisms that can replicate both its smaller-scale variations and…

Astrophysics of Galaxies · Physics 2023-11-23 Eden Girma , Romain Teyssier

The first building block to use galaxy clusters in astrophysics and cosmology is the accurate determination of their mass. Two of the most well regarded direct mass estimators are based on weak lensing (WL) determinations or X-ray analyses…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-15 Mauro Sereno , Stefano Ettori

Two varieties of the universal stellar initial mass function (IMF) viz., the Kroupa and the Chabrier IMF, have emerged over the last decade to explain the observed distribution of stellar masses. The possibility of the universal nature of…

Astrophysics of Galaxies · Physics 2015-06-05 S. Anathpindika

We present the results of a study performed with the goal to investigate whether low-mass pre-main sequence binary stars are formed by multiple fragmentation or via stellar capture. If binaries form preferentially by fragmentation, we…

Astrophysics · Physics 2007-05-23 Sebastian Wolf , Bringfried Stecklum , Thomas Henning

We give independent proof of the deficit of stars in the in-plane central disc with respect to the predictions of a pure exponential density distribution. We use three different methods: 1) the inversion of the red clump giant distribution…

Astrophysics · Physics 2009-11-10 M. Lopez-Corredoira , A. Cabrera-Lavers , O. Gerhard , F. Garzon

Least-squares fits are an important tool in many data analysis applications. In this paper, we review theoretical results, which are relevant for their application to data from counting experiments. Using a simple example, we illustrate the…

Data Analysis, Statistics and Probability · Physics 2019-06-07 Hans Dembinski , Michael Schmelling , Roland Waldi

Knowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments (see, e.g., Blaauw 1991, and references therein). Binarity is also a key…