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We assess the performance of the multipole expansion formalism in the case of single-dish HI intensity mapping, including instrumental and foreground removal effects. This formalism is used to provide MCMC forecasts for a range of HI and…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-13 Paula S. Soares , Steven Cunnington , Alkistis Pourtsidou , Chris Blake

The future of precision cosmology could benefit from cross-correlations between intensity maps of unresolved neutral hydrogen (HI) and more conventional optical galaxy surveys. A major challenge that needs to be overcome is removing the…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-17 Steven Cunnington , Laura Wolz , Alkistis Pourtsidou , David Bacon

One of the most promising probes to complement current standard cosmological surveys is the HI intensity map, i.e. the distribution of temperature fluctuations in neutral hydrogen. In this paper we present calculations of the 2-point…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-24 Anut Sangka , David Bacon

We model a 21 cm intensity mapping survey in the redshift range 0.01<z<1.5 designed to simulate the skies as seen by future radio telescopes such as the Square Kilometre Array (SKA), including instrumental noise and Galactic foregrounds. In…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-27 L. Wolz , F. B. Abdalla , C. Blake , J. R. Shaw , E. Chapman , S. Rawlings

We use full sky simulations, including the effects of foreground contamination and removal, to explore multi-tracer synergies between a SKA-like 21cm intensity mapping survey and a LSST-like photometric galaxy redshift survey. In particular…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-27 Amadeus Witzemann , David Alonso , José Fonseca , Mario G. Santos

\textsc{Hi} intensity mapping will provide maps of the large-scale distribution of neutral hydrogen (\textsc{Hi}) in the universe. These are prime candidates to be used to constrain primordial non-Gaussianity using the Large Scale Structure…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-03 José Fonseca , Michele Liguori

Neutral hydrogen intensity mapping can in principle deliver rapid and large-volume cosmological surveys with exquisitely accurate redshifts that are determined directly from imaging. However, intensity maps suffer from very strong…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-30 Rahul Kothari , Roy Maartens

The bispectrum is a 3-point statistic with the potential to provide additional information beyond power spectra analyses of survey datasets. Radio telescopes which broadly survey the 21cm emission from neutral hydrogen (HI) are a promising…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-11 Steven Cunnington , Catherine Watkinson , Alkistis Pourtsidou

Neutral hydrogen (HI) $21$-cm intensity mapping (IM) is a promising probe of the large-scale structures in the Universe. However, a few orders of magnitude brighter foregrounds obscure the IM signal. Here we use the Tapered Gridded…

Mapping the unresolved intensity of the 21-cm emission of neutral hydrogen (HI) is now regarded as one the most promising tools for cosmological investigation in the coming decades. Here, we investigate, for the first time, extensions of…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-05 Stefano Camera , Hamsa Padmanabhan

The cross-correlation of a foreground density field with two different background convergence fields can be used to measure cosmographic distance ratios and constrain dark energy parameters. We investigate the possibility of performing such…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-11 Alkistis Pourtsidou , David Bacon , Robert Crittenden

Intensity mapping of the HI brightness temperature provides a unique way of tracing large-scale structures of the Universe up to the largest possible scales. This is achieved by using a low angular resolution radio telescopes to detect…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-02 Obinna Umeh

21cm tomography promises to be a powerful tool for estimating cosmological parameters, constraining the epoch of reionization, and probing the so-called dark ages. However, realizing this promise will require the extraction of a…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-02 Adrian Liu , Max Tegmark

We use an analytical forward model based on perturbation theory to predict the neutral hydrogen (HI) overdensity maps at low redshifts. We investigate its performance by comparing it directly at the field level to the simulated HI from the…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-01 Andrej Obuljen , Marko Simonović , Aurel Schneider , Robert Feldmann

Potential evidence for primordial non-Gaussianity (PNG) is expected to lie in the largest scales mapped by cosmological surveys. Forthcoming 21cm intensity mapping experiments will aim to probe these scales by surveying neutral hydrogen…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-20 Steven Cunnington , Stefano Camera , Alkistis Pourtsidou

The Cosmological Principle states that the universe is statistically isotropic and homogeneous on large length scales, typically $\gtrsim 70$Mpc. A detection of significant deviation would help us falsify the simplest models of inflation.…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-26 Bhuwan Joshi , Rahul Kothari

Intensity mapping of 21cm emission from neutral hydrogen promises to be a powerful probe of large-scale structure in the post-reionisation epoch. However, HI intensity mapping (IM) experiments will suffer the loss of long-wavelength…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-30 Kavilan Moodley , Warren Naidoo , Heather Prince , Aurelie Penin

The 21-cm intensity mapping (IM) of neutral hydrogen (HI) is a promising tool to probe the large-scale structures. Sky maps of 21-cm intensities can be highly contaminated by different foregrounds, such as Galactic synchrotron radiation,…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-01 Elimboto Yohana , Yin-Zhe Ma , Di Li , Xuelei Chen , Wei-Ming Dai

Mapping of the neutral hydrogen (HI) 21-cm intensity fluctuations across redshifts promises a novel and powerful probe of cosmology. The neutral hydrogen gas mass density, $\Omega_{\rm HI}$ and bias parameter, $b_{\rm HI}$ are key…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-10 Hamsa Padmanabhan , T. Roy Choudhury , Alexandre Refregier

21 cm intensity mapping has arisen as a powerful probe of the high-redshift universe, but its potential is limited by extremely bright foregrounds and high source confusion. In this Letter, we propose a new analysis which can help solve…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-11 Patrick C. Breysse , Christopher J. Anderson , Philippe Berger
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