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A detailed study of stellar populations in Milky Way (MW) satellite galaxies remains an observational challenge due to their faintness and fewer spectroscopically confirmed member stars. We use unsupervised machine learning methods to…

Instrumentation and Methods for Astrophysics · Physics 2023-11-27 Devika K Divakar , Pallavi Saraf , Sivarani Thirupathi , Vijayakumar H Doddamani

We study the stellar mass-to-halo mass relation at $z=0$ in 30 Milky Way-like systems down to the ultra-faint ($M_* < 10^5 M_\odot$) regime using the semi-analytic model A-SLOTH. A new model allows us to follow star formation and the…

Astrophysics of Galaxies · Physics 2022-04-22 Li-Hsin Chen , Mattis Magg , Tilman Hartwig , Simon C. O. Glover , Alexander P. Ji , Ralf S. Klessen

[Abridged] A specialized data mining algorithm has been developed using wide-field photometry catalogues, enabling systematic and efficient searches for resolved, extremely low surface brightness satellite galaxies in the halo of the Milky…

Astrophysics · Physics 2009-11-13 Shane Walsh , Beth Willman , Helmut Jerjen

We use the Millennium Simulation, a 10 billion particle simulation of the growth of cosmic structure, to construct a new model of galaxy clustering. We adopt a methodology that falls midway between the traditional semi-analytic approach and…

Astrophysics · Physics 2009-11-11 Lan Wang , Cheng Li , Guinevere Kauffmann , Gabriella De Lucia

The semi-analytical model A-SLOTH (Ancient Stars and Local Observables by Tracing Halos) is the first public code that connects the formation of the first stars and galaxies to observables. After several successful projects with this model,…

Many observable properties of globular clusters (GCs) provide valuable insights for unveiling the hierarchical assembly of their host galaxy. For the Milky Way (MW) in particular, GCs from different accreted satellite galaxies show distinct…

Astrophysics of Galaxies · Physics 2024-04-05 Yingtian Chen , Oleg Y. Gnedin

In this paper, a similarity-driven cluster merging method is proposed for unsuper-vised fuzzy clustering. The cluster merging method is used to resolve the problem of cluster validation. Starting with an overspecified number of clusters in…

Machine Learning · Computer Science 2012-07-19 Xuejian Xiong , Kap Chan , Kian Lee Tan

We employ unsupervised machine learning to enhance the accuracy of our recently presented scaling method for wave confinement analysis [1]. We employ the standard k-means++ algorithm as well as our own model-based algorithm. We investigate…

Joint analyses of small-scale cosmological structure probes are relatively unexplored and promise to advance measurements of microphysical dark matter properties using heterogeneous data. Here, we present a multidimensional analysis of dark…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-10 Ethan O. Nadler , Simon Birrer , Daniel Gilman , Risa H. Wechsler , Xiaolong Du , Andrew Benson , Anna M. Nierenberg , Tommaso Treu

We combine a series of high-resolution simulations with semi-analytic galaxy formation models to follow the evolution of a system resembling the Milky Way and its satellites. The semi-analytic model is based on that developed for the…

Astrophysics of Galaxies · Physics 2010-01-18 Yang-Shyang Li , Gabriella De Lucia , Amina Helmi

The accretion of satellites onto central galaxies along vast cosmic filaments is an apparent outcome of the anisotropic collapse of structure in our Universe. Numerical work (based on gravitational dynamics of N-body simulations) indicates…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 E. Tempel , Q. Guo , R. Kipper , N. I. Libeskind

In the $\Lambda$-Cold Dark Matter model of the Universe, galaxies form in part through accreting satellite systems. Previous work have built an understanding of the signatures of these processes contained within galactic stellar halos. This…

We present a modified adaptive matched filter algorithm designed to identify clusters of galaxies in wide-field imaging surveys such as the Sloan Digital Sky Survey. The cluster-finding technique is fully adaptive to imaging surveys with…

Astrophysics · Physics 2009-11-13 Feng Dong , Elena Pierpaoli , James E. Gunn , Risa H. Wechsler

Making mock simulated catalogs is an important component of astrophysical data analysis. Selection criteria for observed astronomical objects are often too complicated to be derived from first principles. However the existence of an…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Amir Hajian , Marcelo Alvarez , J. Richard Bond

We measure the angular clustering of galaxies from the Sloan Digital Sky Survey Data Release 7 in order to probe the spatial distribution of satellite galaxies within their dark matter halos. Specifically, we measure the angular correlation…

Astrophysics of Galaxies · Physics 2015-06-29 Jennifer A. Piscionere , Andreas A. Berlind , Cameron K. McBride , Roman Scoccimarro

Ultra-faint dwarf galaxies, which can be detected as resolved satellite systems of the Milky Way, are critical to understanding galaxy formation, evolution, and the nature of dark matter, as they are the oldest, smallest, most metal-poor,…

The chemical abundances of Milky Way's satellites reflect their star formation histories (SFHs), yet, due to the difficulty of determining the ages of old stars, the SFHs of most satellites are poorly measured. Ongoing and upcoming surveys…

We propose a new method for measuring the spatial density distribution of the stellar halo of the Milky Way. Our method is based on a pairwise statistic of the distribution of stars on the sky, the angular two-point correlation function…

Astrophysics of Galaxies · Physics 2023-08-09 Anda Chen , Zhigang Li , Yougang Wang , Yan Gong , Xuelei Chen , Richard J. Long

We develop a comprehensive and flexible model for the connection between satellite galaxies and dark matter subhalos in dark matter-only zoom-in simulations of Milky Way (MW)--mass host halos. We systematically identify the physical and…

Astrophysics of Galaxies · Physics 2019-03-04 Ethan O. Nadler , Yao-Yuan Mao , Gregory M. Green , Risa H. Wechsler

A new clustering accuracy measure is proposed to determine the unknown number of clusters and to assess the quality of clustering of a data set given in any dimensional space. Our validity index applies the classical nonparametric…

Methodology · Statistics 2022-02-15 Soumita Modak
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