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21-cm intensity surveys aim to map neutral hydrogen atoms in the universe through hyper-fine emission. Unfortunately, long-wavelength (low-wavenumber) radial modes are highly contaminated by smooth astrophysical foregrounds that are six…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-21 Naim Goksel Karacayli , Nikhil Padmanabhan

Near-surface atmospheric conditions can differ sharply over tens to hundreds of meters due to land cover and topography, yet this variability is absent from current weather analyses and forecasts. It is unclear whether such meter-scale…

The 21-cm forest is a promising probe of the Epoch of Reionization. The local state of the intergalactic medium (IGM) is encoded in the spectrum of a background source (radio-loud quasars or gamma ray burst afterglow) by absorption at the…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-18 Benoit Semelin

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

Studying the redshifted 21-cm signal from the the neutral hydrogen during the Epoch of Reionization and Cosmic Dawn is fundamental for understanding the physics of the early universe. One of the challenges that 21-cm experiments face is the…

Many applications in computational and experimental fluid mechanics require effective methods for reconstructing the flow fields from limited sensor data. However, this task remains a significant challenge because the measurement operator,…

Fluid Dynamics · Physics 2024-11-22 Phong C. H. Nguyen , Joseph B. Choi , Quang-Trung Luu

The main challenge of 21 cm cosmology experiments is astrophysical foregrounds which are difficult to separate from the signal due to telescope systematics. An earlier study has shown that foreground residuals induced by antenna gain errors…

A critical challenge in the observation of the redshifted 21-cm line is its separation from bright Galactic and extragalactic foregrounds. In particular, the instrumental leakage of polarized foregrounds, which undergo significant Faraday…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-18 C. D. Nunhokee , G. Bernardi , S. A. Kohn , J. E. Aguirre , N. Thyagarajan , J. S. Dillon , G. Foster , T. L. Grobler , J. Z. E. Martinot , A. R. Parsons

We investigate the effect of radio-frequency interference (RFI) excision in estimating the cosmological \hi\ 21 cm power spectrum. Flagging of RFI-contaminated channels results in a non-uniform sampling of the instrumental bandpass…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-27 Arnab Chakraborty , Abhirup Datta , Aishrila Mazumder

At redshifts beyond $z \gtrsim 30$, the 21cm line from neutral hydrogen is expected to be essentially the only viable probe of the 3D matter distribution. The lunar far-side is an extremely appealing site for future radio arrays that target…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-26 Philip Bull , Caroline Guandalin , Chris Addis

We introduce a new implementation of the FastICA algorithm on simulated LOFAR EoR data with the aim of accurately removing the foregrounds and extracting the 21-cm reionization signal. We find that the method successfully removes the…

A first statistical detection of the 21-cm Epoch of Reionization (EoR) is on the horizon, as cosmological volumes of the Universe become accessible via the adoption of low-frequency interferometers. We explore the impact which non-identical…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-01 A. Chokshi , N. Barry , J. L. B. Line , C. H. Jordan , B. Pindor , R. L. Webster

The EDGES collaboration reported the finding of an unexpectedly deep absorption in the radio background at 78 MHz and interpreted the dip as a first detection of redshifted 21-cm from Cosmic Dawn. We have attempted an alternate analysis,…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-31 Saurabh Singh , Ravi Subrahmanyan

Observations of the high-redshift Universe with the 21 cm hyperfine line of neutral hydrogen promise to open an entirely new window onto the early phases of cosmic structure formation. Here we review the physics of the 21 cm transition,…

Astrophysics · Physics 2009-11-11 Steven Furlanetto , S. Peng Oh , Frank Briggs

We present the first of two papers dedicated to verifying the Australian Epoch of Reionisation pipeline (AusEoRPipe) through simulation. The AusEoRPipe aims to disentangle 21-cm radiation emitted by gas surrounding the very first stars from…

Instrumentation and Methods for Astrophysics · Physics 2024-04-09 J. L. B. Line , C. M. Trott , J. H. Cook , B. Greig , N. Barry , C. H. Jordan

Context. Filamentary structures appear to be ubiquitous in the interstellar medium. Being able to detect and characterize them is the first step toward understanding their origin, their evolution, and their role in the Galactic cycle of…

Astrophysics of Galaxies · Physics 2022-12-14 J. -S. Carrière , L. Montier , K. Ferrière , I. Ristorcelli

During cosmic reionization, the 21-cm brightness fluctuations were highly non-Gaussian, and complementary statistics can be extracted from the distribution of pixel brightness temperatures that are not derivable from the 21-cm power…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-27 Tony Pan , Rennan Barkana

Experiments aimed at detecting highly-redshifted 21 centimeter emission from the Epoch of Reionization (EoR) are plagued by the contamination of foreground emission. A potentially important source of contaminating foregrounds may be…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-13 David F. Moore , James E. Aguirre , Aaron R. Parsons , Daniel C. Jacobs , Jonathan C. Pober

The precise characterization and mitigation of systematic effects is one of the biggest roadblocks impeding the detection of the fluctuations of cosmological 21cm signals. Missing data in radio cosmological experiments, often due to radio…

The 21-cm absorption feature reported by the EDGES collaboration is several times stronger than that predicted by traditional astrophysical models. If genuine, a deeper absorption may lead to stronger fluctuations on the 21-cm signal on…