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Dark matter haloes play a fundamental role in cosmological structure formation. The most common approach to model their assembly mechanisms is through N-body simulations. In this work we present an innovative pathway to predict dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-15 Mauro Bernardini , Lucio Mayer , Darren Reed , Robert Feldmann

We propose the HI 21-cm power spectrum from the post-reionization epoch as a probe of a cosmological model with decaying dark matter particles. The unstable particles are assumed to undergo a 2-body decay into a massless and massive…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-12 Mohit Yadav , Tapomoy Guha Sarkar

We explore the possibility of retrieving cosmological information from 21-cm tomographic data at intermediate redshift. The first step in our approach consists of training an encoder, composed of several three dimensional convolutional…

Instrumentation and Methods for Astrophysics · Physics 2025-07-30 Sambatra Andrianomena

In this chapter, the use of machine learning (ML) in redshifted 21 cm cosmology is discussed, especially for the cosmic dawn, the Epoch of Reionization, and the scientific program of SKA-Low. The 21 cm signal is useful because it can…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-18 Hayato Shimabukuro

We carried out synthetic observations of interstellar atomic hydrogen at 21cm wavelength by utilizing the magneto-hydrodynamical numerical simulations of the inhomogeneous turbulent interstellar medium (ISM) Inoue and Inutsuka (2012). The…

Modelling the distribution of neutral hydrogen (HI) in dark matter halos is important for studying galaxy evolution in the cosmological context. We use a novel approach to infer the HI-dark matter connection at the massive end ($m_{\rm HI}…

Astrophysics of Galaxies · Physics 2018-06-12 Niladri Paul , Tirthankar Roy Choudhury , Aseem Paranjape

21-cm intensity mapping (IM) is a powerful technique to probe the large-scale distribution of neutral hydrogen (HI) and extract cosmological information such as the baryon acoustic oscillation feature. A key challenge lies in recovering the…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-24 Zitong Wang , Feng Shi , Le Zhang , Yanming Liu , Xiaoping Li , Shulei Ni , Ming Jiang , Xiaofan Ma

Machine learning (ML) has demonstrated significant promise in various physical design (PD) tasks. However, model generalizability remains limited by the availability of high-quality, large-scale training datasets. Creating such datasets is…

Machine Learning · Computer Science 2025-07-16 Bing-Yue Wu , Vidya A. Chhabria

Low-frequency radio observations of neutral hydrogen during and before the epoch of cosmic reionization will provide ~ 1000 quasi-independent source planes, each of precisely known redshift, if a resolution of ~1 arcminutes or better can be…

Astrophysics · Physics 2017-03-15 R. Benton Metcalf , S. D. M. White

Dark matter (DM) halo properties are extensively studied in cosmological simulations but are very challenging to estimate from observations. The DM halo density profile of observed galaxies is modelled using multiple probes that trace the…

Astrophysics of Galaxies · Physics 2023-04-19 Sioree Ansar , Sandeep Kumar Kataria , Mousumi Das

We present the first and so far the only simulations to follow the fine-grained phase-space structure of galaxy haloes formed from generic LCDM initial conditions. We integrate the geodesic deviation equation in tandem with the N-body…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Mark Vogelsberger , Simon D. M. White

We extend the results of previous analyses towards constraining the abundance and clustering of post-reionization ($z \sim 0-5$) neutral hydrogen (HI) systems using a halo model framework. We work with a comprehensive HI dataset including…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-23 Hamsa Padmanabhan , Alexandre Refregier , Adam Amara

This white paper envisions a revolutionary post-DESI, post-LSST dark energy program based on intensity mapping of the redshifted 21cm emission line from neutral hydrogen at radio frequencies. The proposed intensity mapping survey has the…

The redshifted 1420 MHz emission from the HI in unresolved damped Lyman-\alpha clouds at high z will appear as a background radiation in low frequency radio observations. This holds the possibility of a new tool for studying the universe at…

Astrophysics · Physics 2009-10-31 Somnath Bharadwaj , Biman B. Nath , Shiv K. Sethi

We use a large N-body simulation to examine the detectability of HI in emission at redshift z ~ 1, and the constraints imposed by current observations on the neutral hydrogen mass function of galaxies at this epoch. We consider three…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Nishikanta Khandai , Shiv K. Sethi , Tiziana Di Matteo , Rupert A. C. Croft , Volker Springel , Anirban Jana , Jeffrey P. Gardner

The detection of microlensing has opened the way for the development of new methods in galactic astronomy. This series of papers investigates what microlensing can teach us about the structure and shape of the dark halo. In this paper we…

Large inhomogeneities in neutral hydrogen in the universe can be detected at redshifts $z \leq 10$ using the redshifted 21 cm line emission. We use cosmological N-Body simulations for dark matter and a simple model for baryonic collapse to…

Astrophysics · Physics 2015-06-24 J. S. Bagla , Biman Nath , T. Padmanabhan

For many analyses in cosmology it is necessary to reconstruct the likely distribution of unobserved fields, such as dark matter or non-luminous baryons, from observed luminous tracers. The dominant approach in cosmology has been to use the…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-16 Jordan Krywonos , Yurii Kvasiuk , Matthew C. Johnson , Moritz Münchmeyer

We use observations of the neutral atomic hydrogen (HI) 21-cm emission line to study the spatial distribution of the HI gas in a 80$\degree\times~$90$\degree$ region of the Galaxy halo. The HI column densities in the range of…

Astrophysics of Galaxies · Physics 2017-09-20 Ericson López , Jairo Armijos , Mario Llerena , Franklin Aldás

Hydrogen 21-cm Line Intensity Mapping offers the unique opportunity to access the Dark Ages and trace the formation and evolution of the large scale structure of the Universe prior to star and galaxy formation. In this work we investigate…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-22 Elena Vanetti , Eleonora Vanzan , Nicola Bellomo , Alvise Raccanelli