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Since 2003, significant efforts have been devoted to the understanding of the radio emission of extensive air showers above 20 MHz. Despite some studies led until the early nineties, the band available below 20 MHz has remained unused for…

Instrumentation and Methods for Astrophysics · Physics 2019-05-29 Didier Charrier , Richard Dallier , Antony Escudie , Daniel García-Fernández , Alain Lecacheux , Lilian Martin , Benoît Revenu

Discovery of the cosmic reionization epoch would represent a significant milestone in cosmology. We present Keck spectroscopy of the quasar SDSS 1044-0125, at z = 5.73. The spectrum shows a dramatic increase in the optical depth at observed…

Astrophysics · Physics 2009-11-07 S. G. Djorgovski , S. M. Castro , D. Stern , A. Mahabal

The redshifted $21$\,cm signal of neutral hydrogen can be used as a direct probe of the intergalactic medium during Cosmic Dawn\,(CD) and Epoch of Reionization\,(EoR). However, detecting this inherently weak signal has numerous challenges.…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-28 Samit Kumar Pal , Abhirup Datta , Aishrila Mazumder

The sky-averaged redshifted 21-cm signal from Cosmic Dawn is expected to provide a unique view of the first compact objects. However, its measurement remains daunting. Difficulties are driven by the large dynamic contrast between the…

Experiments designed to measure the redshifted 21~cm line from the Epoch of Reionization (EoR) are challenged by strong astrophysical foreground contamination, ionospheric distortions, complex instrumental response and other different types…

A near-future detection of the 21cm signal from the epoch of reionization will provide unique opportunities to probe the underlying cosmology, provided that such cosmological information can be extracted with precision. To this end, we…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-28 Wenzer Qin , Katelin Schutz , Aaron Smith , Enrico Garaldi , Rahul Kannan , Tracy R. Slatyer , Mark Vogelsberger

Precise instrument calibration is critical to the success of 21 cm Cosmology experiments. Unmitigated errors in calibration contaminate the Epoch of Reionization (EoR) signal, precluding a detection. Barry et al. 2016 characterizes one…

Instrumentation and Methods for Astrophysics · Physics 2019-04-24 Ruby Byrne , Miguel F. Morales , Bryna Hazelton , Wenyang Li , Nichole Barry , Adam P. Beardsley , Ronniy Joseph , Jonathan Pober , Ian Sullivan , Cathryn Trott

Recently the EDGES experiment has claimed the detection of an absorption feature centered at 78 MHz. When interpreted as a signature of cosmic dawn, this feature appears at the correct wavelength (corresponding to a redshift range of…

High Energy Astrophysical Phenomena · Physics 2018-08-15 Prateek Sharma

Radio Frequency Interference (RFI) presents a significant challenge for carrying out precision measurements in radio astronomy. In particular, RFI can be a showstopper when looking for faint cosmological signals such as the red-shifted…

The 21-cm line emitted by neutral hydrogen is the most promising probe of the Epoch of Reionization (EoR). Multiple radio interferometric instruments are on the cusp of detecting its power spectrum. It is therefore essential to deliver…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-15 Anshuman Acharya , Enrico Garaldi , Benedetta Ciardi , Qing-bo Ma

Digital radio arrays are widely used for the low-frequency radio astronomy as well as for detection of air-showers induced by high-energy cosmic rays and neutrinos. Since the radio emission from air-showers forms short broadband pulses with…

Several ongoing and upcoming radio telescopes aim to detect either the global 21 cm signal or the 21 cm power spectrum. The extragalactic radio background, as detected by ARCADE-2 and LWA-1, suggests a strong radio background from cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-24 Sudipta Sikder , Anastasia Fialkov , Rennan Barkana

The properties of the first galaxies, expected to drive the Cosmic Dawn (CD) and the Epoch of Reionization (EoR), are encoded in the 3D structure of the cosmic 21-cm signal. Parameter inference from upcoming 21-cm observations promises to…

Astrophysics of Galaxies · Physics 2019-01-24 Jaehong Park , Andrei Mesinger , Bradley Greig , Nicolas Gillet

The SKA will build upon early detections of the EoR by precursor instruments, such as MWA, PAPER, and LOFAR, and planned instruments, such as HERA, to make the first high signal-to-noise measurements of fluctuations in the 21 cm brightness…

The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-alpha radiation from some of the…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-20 Rennan Barkana

We investigate a number of potential foregrounds for an ambitious goal of future radio telescopes such as the Square Kilometer Array (SKA) and Low Frequency Array (LOFAR): spatial tomography of neutral gas at high redshift in 21cm emission.…

Astrophysics · Physics 2009-11-07 S. Peng Oh , Katherine J. Mack

Predicting the 21cm signal from the epoch of reionization and cosmic dawn is a complex and challenging task. Various simplifying assumptions have been applied over the last decades to make the modeling more affordable. In this paper, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-25 Timothée Schaeffer , Sambit K. Giri , Aurel Schneider

During the Epoch of Reionization (EoR), the ultraviolet radiation from the first stars and galaxies ionised the neutral hydrogen of the intergalactic medium, which can emit radiation through its 21 cm hyperfine transition. This 21 cm signal…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-27 Ivelin Georgiev , Adélie Gorce , Garrelt Mellema

Dispersion measures (DM) of fast radio bursts (FRBs) probe the density of electrons in the intergalactic medium (IGM) along their lines-of-sight, including the average density versus distance to the source and its variations in direction.…