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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

It is shown that 21 cm intensity mapping could be used in the near term to make cosmologically useful measurements. Large scale structure could be detected using existing radio telescopes, or using prototypes for dedicated redshift survey…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-13 Kiyoshi Wesley Masui , Patrick McDonald , Ue-Li Pen

The Internal Linear Combination (ILC) method has been extensively used to extract the cosmic microwave background (CMB) anisotropy map from foreground contaminated multi-frequency maps. However, the performance of simple ILC is limited and…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-01 Debabrata Adak

The Tianlai Pathfinder is designed to demonstrate the feasibility of using a wide field of view radio interferometers to map the density of neutral hydrogen in the Universe after the Epoch of Reionizaton. This approach, called 21~cm…

The neutral hydrogen (HI) signal is a crucial probe for astrophysics and cosmology, but it is quite challenging to measure from raw data because of bright foreground contaminants at radio wavelengths. Cross-correlating the radio…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-27 Alessandro Marins , Chang Feng , Filipe B. Abdalla

Radio observation of the large-scale structure (LSS) of our Universe faces major challenges from foreground contamination, which is many orders of magnitude stronger than the cosmic signal. While other foreground removal techniques struggle…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-27 Tian-Cheng Luan , Xin Wang , Jiacheng Ding , Qian Li , Xiao-Dong Li , Weishan Zhu

We analyze synthetic neutral hydrogen (HI) absorption and emission spectral lines from a high- resolution, three-dimensional hydrodynamical simulation to quantify how well observational methods recover the physical properties of…

Line-intensity mapping (LIM) offers an approach to obtain three-dimensional maps of the large-scale structure by collecting the aggregate emission from all emitters along the line of sight. The procedure hinges on reconstructing the radial…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-15 José Luis Bernal , Antón Baleato Lizancos

Ground-based observations at thermal infrared wavelengths suffer from large background radiation due to the sky, telescope and warm surfaces in the instrument. This significantly limits the sensitivity of ground-based observations at…

Instrumentation and Methods for Astrophysics · Physics 2018-03-16 Silvan Hunziker , Sascha P. Quanz , Adam Amara , Michael R. Meyer

We use the full-mission $\textit{Planck}$ PR4 data to construct maps of the thermal Sunyaev$--$Zel'dovich effect (Compton-$y$ parameter) in our Universe. To do so, we implement a custom needlet internal linear combination (NILC) pipeline in…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-19 Fiona McCarthy , J. Colin Hill

The sky-averaged (global) highly redshifted 21-cm spectrum from neutral hydrogen is expected to appear in the VHF range of $\sim20-200$ MHz and its spectral shape and strength are determined by the heating properties of the first stars and…

Instrumentation and Methods for Astrophysics · Physics 2018-10-24 Keith Tauscher , David Rapetti , Jack O. Burns , Eric R. Switzer

21-cm Intensity Mapping (IM) is a promising approach to detecting information about the large-scale structure beyond the local universe. One of the biggest challenges for an IM observation is the foreground removal procedure. In this paper,…

Signal Processing · Electrical Eng. & Systems 2025-06-10 Lin-Cheng Li , Jia-Yu Lin , Yuan-Gen Wang , Lister Staveley-Smith

The Cosmic Microwave Background (CMB) primordial B-modes signal is predicted to be much lower than the polarized Galactic emission (foregrounds) in any region of the sky pointing to the need for sophisticated component separation methods.…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-26 Alessandro Carones , Marina Migliaccio , Giuseppe Puglisi , Carlo Baccigalupi , Domenico Marinucci , Nicola Vittorio , Davide Poletti

We forecast the cosmological constraints of the neutral hydrogen (HI) intensity mapping (IM) technique with radio telescopes by assuming 1-year of observational time. The current and future radio telescopes we consider here are FAST (Five…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-15 Elimboto Yohana , Yi-Chao Li , Yin-Zhe Ma

This study investigates the sensitivity of the radio interferometers to identify imprints of spatially inhomogeneous dark matter annihilation signatures in the 21-cm signal during the pre-reionization era. We focus on the upcoming low-mode…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-28 Pravin Kumar Natwariya , Kenji Kadota , Atsushi J. Nishizawa

Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe the large scale structure of the Universe. In this paper, we demonstrate that using the 64-dish MeerKAT radio telescope as a connected interferometer, it is…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-28 Sourabh Paul , Mario G. Santos , Junaid Townsend , Matt J. Jarvis , Natasha Maddox , Jordan D. Collier , Bradley S. Frank , Russ Taylor

Foreground removal remains an ongoing challenge in radio cosmology, and increasingly sensitive experiments necessitate more robust analysis techniques. In this work, we model simulated data from a single-dish intensity mapping experiment,…

Instrumentation and Methods for Astrophysics · Physics 2026-04-30 Geoff G. Murphy , Philip Bull , Mario G. Santos , Zheng Zhang , Steven Cunnington

I update the SKA key science program (KSP) on first light and cosmic reionization. The KSP has two themes: (i) Using the 21cm line of neutral hydrogen as the most direct probe into the evolution of the neutral intergalactic medium during…

Astrophysics · Physics 2008-02-14 C. L. Carilli

AIMS: One of the most challenging and important problem of digital signal processing in Cosmology is the separation of foreground contamination from cosmic microwave background (CMB). This problem becomes even more difficult in situations,…

Astrophysics · Physics 2008-02-05 Robertio Vio , Paola Andreani

We investigate the prospects of measuring the cosmic magnification effect by cross-correlating neutral hydrogen intensity mapping (HI IM) maps with background optical galaxies. We forecast the signal-to-noise ratio for HI IM data from…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Amadeus Witzemann , Alkistis Pourtsidou , Mario G. Santos
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