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Using homogeneous CCD photometric data from the 105-cm Kiso Schmidt telescope covering a 50' x 50' field, we study the mass functions (MFs) of nine open clusters. The ages and Galactocentric distances of the target clusters vary from 16 -…

Astrophysics · Physics 2009-11-13 Saurabh Sharma , A. K. Pandey , K. Ogura , T. Aoki , Kavita Pandey , T. S. Sandhu , R. Sagar

Standard evolutionary synthesis models rely on the assumption of a fully sampled stellar initial mass function (IMF). Under this assumption, the age, chemical composition, and IMF uniquely define the predicted absorption spectra. However,…

Predictive mean matching (PMM) is a popular imputation strategy that imputes missing values by borrowing observed values from other cases with similar expectations. We show that, unlike other imputation strategies, PMM is not guaranteed to…

Methodology · Statistics 2025-07-01 Paul T. von Hippel

A wealth of observations recently challenged the notion of a universal stellar initial mass function (IMF) by showing evidences in favour of a variability of this statistical indicator as a function of galaxy properties. I present…

Astrophysics of Galaxies · Physics 2020-06-17 Fabio Fontanot

A Bayesian statistical formalism is developed to quantify the level at which the mass function slope (alpha) and the projected cumulative mass fraction (f) of (CDM) substructure in strong gravitational-lens galaxies, with arcs or Einstein…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 S. Vegetti , L. V. E. Koopmans

Star formation rates (SFR) larger than 1000 Msun/ yr are observed in extreme star bursts. This leads to the formation of star clusters with masses > 10^6 Msun in which crowding of the pre-stellar cores may lead to a change of the stellar…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Carsten Weidner , Pavel Kroupa , Jan Pflamm-Altenburg

We present the core mass function (CMF) of the massive star-forming clump G33.92+0.11 using 1.3 mm observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). With a resolution of 1000 au, this is one of the highest…

A robust stellar initial mass function (IMF) is crucial in any studies related to star formation. However, the direct measurement of the stellar IMF is confined to the local universe, limited by the resolving power of telescopes. Recently,…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-12 Sung Kei Li

Binary population synthesis (BPS) is an essential tool for extracting information about massive binary evolution from gravitational-wave (GW) detections of compact object mergers. It has been successfully used to constrain the most likely…

High Energy Astrophysical Phenomena · Physics 2024-11-27 L. M. de Sá , A. Bernardo , L. S. Rocha , R. R. A. Bachega , J. E. Horvath

We perform spatially-resolved, pixel-by-pixel SED fitting on galaxies up to $z\sim2.5$ in the Hubble Extreme Deep Field (XDF). Comparing stellar mass estimates from spatially resolved and spatially unresolved photometry we find that…

Astrophysics of Galaxies · Physics 2018-02-14 Robert Sorba , Marcin Sawicki

The production rate of ionizing photons in young < 8 Myr, unresolved stellar clusters in the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize the ionizing photon rate by the…

In many data analyses, each measurement may come with a simple yes/no correction; for example, belonging to one of two populations or being contaminated or not. Ignoring such binary effects may bias the results, while accounting for them…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-13 Marcus Högås , Edvard Mörtsell

An all-sky sample of 1227 visual binaries based on Washington Double Star catalogue is constructed to infer the IMF, mass ratio, and projected distance distribution with a dedicated population synthesis model. Parallaxes from Gaia DR2 and…

Solar and Stellar Astrophysics · Physics 2020-12-02 Dmitry Chulkov

The accuracy of position measurements on stellar targets with the future Space Interferometry Mission (SIM) will be limited not only by photon noise and by the properties of the instrument (design, stability, etc.) and the overall…

Astrophysics · Physics 2009-11-13 R. Sridharan , Ronald J. Allen

Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Crescenzo Tortora , Aaron J. Romanowsky , Nicola R. Napolitano

The high-mass slope of the stellar initial mass function (IMF), first measured by E. Salpeter in 1955, appears universal across star-forming environments. Its origin remains a central unsolved problem in astrophysics. Using $getsf$, we…

Astrophysics of Galaxies · Physics 2026-05-22 Guo-Yin Zhang , Alexander Men'shchikov , Jin-Zeng Li

AIMS. The maximum-likelihood method is the standard approach to obtain model fits to observational data and the corresponding confidence regions. We investigate possible sources of bias in the log-likelihood function and its subsequent…

Astrophysics · Physics 2009-11-11 J. Hartlap , P. Simon , P. Schneider

We conduct a detailed lensing, dynamics and stellar population analysis of nine massive lens early-type galaxies (ETGs) from the X-Shooter Lens Survey (XLENS). Combining gravitational lensing constraints from HST imaging with…

Astrophysics of Galaxies · Physics 2015-05-28 C. Spiniello , M. Barnabè , L. V. E. Koopmans , S. C. Trager

An excess up-scattering mass bias on a weak lensing cluster mass estimate is a statistical bias that an observed weak lensing mass ($M_{\rm obs}$) of a cluster of galaxies is, in a statistical sense, larger than its true mass ($M_{\rm…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-09 Takashi Hamana

Strong gravitational lensing offers constraints on the Hubble constant that are independent of other methods. However, those constraints are subject to uncertainties in lens models. Previous studies suggest that using an elliptical power…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-02 Dilys Ruan , Charles R. Keeton