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We measure the clustering of dark matter halos in a large set of collisionless cosmological simulations of the flat LCDM cosmology. Halos are identified using the spherical overdensity algorithm, which finds the mass around isolated peaks…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Jeremy L. Tinker , Brant E. Robertson , Andrey V. Kravtsov , Anatoly Klypin , Michael S. Warren , Gustavo Yepes , Stefan Gottlober

We present the framework of slowly varying regression under sparsity, allowing sparse regression models to exhibit slow and sparse variations. The problem of parameter estimation is formulated as a mixed-integer optimization problem. We…

Machine Learning · Computer Science 2023-11-14 Dimitris Bertsimas , Vassilis Digalakis , Michael Linghzi Li , Omar Skali Lami

Cosmological galaxy formation simulations are still limited by their spatial/mass resolution and cannot model from first principles some of the processes, like star formation, that are key in driving galaxy evolution. As a consequence they…

Astrophysics of Galaxies · Physics 2022-03-02 Andrea V. Macciò , Mohamad Ali-Dib , Pavle Vulanović , Hind Al Noori , Fabian Walter , Nico Krieger , Tobias Buck

We present a new method to estimate redshift distributions and galaxy-dark matter bias parameters using correlation functions in a fully data driven and self-consistent manner. Unlike other machine learning, template, or correlation…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-09 Ben Hoyle , Markus Michael Rau

Reward models (RMs) are a core component in the post-training of large language models (LLMs), serving as proxies for human preference evaluation and guiding model alignment. However, training reliable RMs under limited resources remains…

Artificial Intelligence · Computer Science 2025-11-12 Dengcan Liu , Jiahao Li , Zheren Fu , Yi Tu , Jiajun Li , Zhendong Mao , Yongdong Zhang

We investigate the contentious issue of the presence, or lack thereof, of satellites mass segregation in galaxy groups using the Galaxy And Mass Assembly (GAMA) survey, the GALFORM semi-analytic and the EAGLE cosmological hydrodynamical…

The abundance of satellite galaxies is set by the hierarchical assembly of their host halo. We leverage this to investigate the low mass end ($M_{\mathrm{H}} < 10^{11} M_{\odot}$) of the Stellar-to-Halo Mass Relation (SHMR), which is key to…

Astrophysics of Galaxies · Physics 2024-10-10 J. Sebastian Monzon , Frank C. van den Bosch , Kaustav Mitra

We study the performance of sparse regression methods and propose new techniques to distill the governing equations of dynamical systems from data. We first look at the generic methodology of learning interpretable equation forms from data,…

Machine Learning · Computer Science 2019-03-25 Chinmay S. Kulkarni

We have studied the galaxy-group cross-correlations in redshift space for the Galaxy And Mass Assembly (GAMA) Survey. We use a set of mock GAMA galaxy and group catalogues to develop and test a novel 'halo streaming' model for…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-21 Qianjun Hang , John A. Peacock , Shadab Alam , Yan-Chuan Cai , Katarina Kraljic , Marcel van Daalen , M. Bilicki , B. W. Holwerda , J. Loveday

We present halo model predictions for the expected angular clustering and associated errors from the completed Sloan Digital Sky Survey (SDSS) photometric galaxy sample. These results are used to constrain halo model parameters under the…

Astrophysics · Physics 2009-11-07 Ryan Scranton

The classification of galaxies as spirals or ellipticals is a crucial task in understanding their formation and evolution. With the arrival of large-scale astronomical surveys, such as the Sloan Digital Sky Survey (SDSS), astronomers now…

Computer Vision and Pattern Recognition · Computer Science 2023-12-04 Anusha Guruprasad

The Luminous Convolution Model (LCM) demonstrates that it is possible to predict the rotation curves of spiral galaxies directly from estimates of the luminous matter. We consider two frame-dependent effects on the light observed from other…

Astrophysics of Galaxies · Physics 2014-07-30 S. Cisneros , N. S. Oblath , J. A. Formaggio , R. A. Ott , D. Chester , D. J. Battaglia , A. Ashley , R. Robinson , A. Rodriguez

We investigate the evolution of galaxy masses and star formation rates in the Evolution and Assembly of Galaxies and their Environment (EAGLE) simulations. These comprise a suite of hydrodynamical simulations in a $\Lambda$CDM cosmogony…

Satellite galaxies in galaxy clusters represent a significant fraction of the global galaxy population. Because of the unusual dense environment of clusters, their evolution is driven by different mechanisms than the ones affecting field or…

Astrophysics of Galaxies · Physics 2019-05-22 Anna Niemiec , Eric Jullo , Carlo Giocoli , Marceau Limousin , Mathilde Jauzac

We develop an explicit model for the formation of the stellar halo from tidally disrupted, accreted dwarf satellites in the cold dark matter (CDM) framework, focusing on predictions testable with the Sloan Digital Sky Survey (SDSS) and…

Astrophysics · Physics 2009-10-31 James S. Bullock , Andrey V. Kravtsov , David H. Weinberg

Halo merger trees describe the hierarchical mass assembly of dark matter haloes, and are the backbone for modeling galaxy formation and evolution. Merger trees constructed using Monte Carlo algorithms based on the extended Press-Schechter…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Fangzhou Jiang , Frank C. van den Bosch

A simple, fully connected neural network with a single hidden layer is used to estimate stellar masses for star-forming galaxies. The model is trained on broad-band photometry - from far-ultraviolet to mid-infrared wavelengths - generated…

Instrumentation and Methods for Astrophysics · Physics 2025-07-15 E. Elson

The relative roles of mergers and star formation in regulating galaxy growth are still a matter of intense debate. We here present our DECODE, a new Discrete statistical sEmi-empiriCal mODEl specifically designed to predict rapidly and…

Low-rank matrix approximation (LRMA) is a powerful technique for signal processing and pattern analysis. However, its potential for data compression has not yet been fully investigated in the literature. In this paper, we propose sparse…

Multimedia · Computer Science 2016-02-22 Junhui Hou , Lap-Pui Chau , Nadia Magnenat-Thalmann , Ying He

Using N-body simulations and galaxy formation models, we study the galaxy stellar mass correlation and the two-point auto-correlation. The simulations are run with cosmological parameters from the WMAP first, third and seven year results,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 X. Kang , M. Li , W. P. Lin , P. J. Elahi