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Related papers: Detecting Early Galaxies Through Their 21-cm Signa…

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The 21 cm signal appears to be a treasure trove to provide an insight into the period when the first generation of luminous objects formed in the Universe. Hydrogen is the predominating fraction of the total baryonic matter during cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-09 Pravin Kumar Natwariya

The cosmological 21cm signal is a physics-rich probe of the early Universe, encoding information about both the ionization and the thermal history of the intergalactic medium (IGM). The latter is likely governed by X-rays from…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-17 Fabio Pacucci , Andrei Mesinger , Stefano Mineo , Andrea Ferrara

One of the next decade's most exciting prospects is to explore the cosmic "dark ages," during which the first stars in the Universe formed, with the 21 cm line of neutral hydrogen. At z>6, this light redshifts into the low-frequency radio…

Investigating the properties of the first stars in the universe is essential, yet it remains an open question. One way to explore these stars is by examining their effects on the surrounding gas during the epoch of reionization. In this…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-06 Sho Ukai , Hayato Shimabukuro , Kenji Hasegawa , Kiyotomo Ichiki

The 21-cm signal in the vicinity of the first stars is expected to reflect properties of the first stars. In this study we pay special attention to tracing the time evolution of the ionizing photons' escape fraction, which affects the…

Astrophysics of Galaxies · Physics 2018-08-08 Toshiyuki Tanaka , Kenji Hasegawa , Hidenobu Yajima , Masato I. N. Kobayashi , Naoshi Sugiyama

Understanding the formation and evolution of the first stars and galaxies represents one of the most exciting frontiers in astronomy. Since the universe was filled with neutral hydrogen at early times, the most promising method for…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Rennan Barkana

The hydrogen 21-cm signal is predicted to be the richest probe of the young Universe including eras known as the cosmic Dark Ages, the Cosmic Dawn when the first star and black hole formed, and the Epoch of Reionization. This signal holds…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-01 Anastasia Fialkov , Thomas Gessey-Jones , Jiten Dhandha

We review our current understanding of how the first galaxies formed at the end of the cosmic dark ages, a few 100 million years after the Big Bang. Modern large telescopes discovered galaxies at redshifts greater than seven, whereas…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Volker Bromm , Naoki Yoshida

X-rays emitted by high mass X-ray binaries (HMXBs) and supernovae-driven winds in the first galaxies during Cosmic Dawn are expected to warm the intergalactic medium prior to its reionization. While most of the heating will be uniform on…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-26 Ka-Hou Leong , Avery Meiksin

The 21cm line refers to a forbidden transition in neutral hydrogen associated with alignment of spins of the proton and electron. It is a very low energy transition that is emitted whenever there is neutral hydrogen in the Universe. Since…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-12 Adrian Liu , Laura Newburgh , Benjamin Saliwanchik , Anže Slosar

The cosmic dark ages and the epoch of reionization, during which the first generations of stars and galaxies formed, are among the most compelling frontiers of extragalactic astrophysics and cosmology. Here we describe an exciting new probe…

Probing statistical distribution of the neutral hydrogen (\HI) using the redshifted 21-cm hyperfine-transition spectral line holds the key to understand the formation and evolution of the matter density in the universe. The two-point…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-24 Urvashi Arora , Prasun Dutta

Observations of the 21cm line of neutral hydrogen are poised to revolutionize our knowledge of cosmic reionization and the high-redshift population of galaxies. However, harnessing such information requires robust and comprehensive…

Astrophysics of Galaxies · Physics 2023-12-19 Joseph S. W. Lewis , Annalisa Pillepich , Dylan Nelson , Ralf S. Klessen , Simon C. O. Glover

Observations of 21-cm radio emission by neutral hydrogen at redshifts z ~ 0.5 to ~ 2.5 are expected to provide a sensitive probe of cosmic dark energy. This is particularly true around the onset of acceleration at z ~ 1, where traditional…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-22 Tzu-Ching Chang , Ue-Li Pen , Kevin Bandura , Jeffrey B. Peterson

The first generation of galaxies is expected to form in minihalos, accreting gas through ${\rm H}_2$ cooling, and possessing unique properties. Although unlikely to be directly detected in UV/infrared surveys, the radiation from these…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-11 Yuxiang Qin , Andrei Mesinger , Bradley Greig , Jaehong Park

Observations of the 21-cm signal are opening a window to the cosmic-dawn epoch, when the first stars formed. These observations are usually interpreted with semi-numerical or hydrodynamical simulations, which are often computationally…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-03 Hector Afonso G. Cruz , Julian B. Munoz , Nashwan Sabti , Marc Kamionkowski

The redshifted 21-cm monopole is expected to be a powerful probe of the epoch of the first stars and galaxies ($10<z<35$). The global 21-cm signal is sensitive to the thermal and ionization state of hydrogen gas and thus provides a tracer…

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

We describe how the high-redshift 21-cm background can be used to improve both our understanding of the fundamental cosmological parameters of our Universe and exotic processes originating in the dark sector. The 21-cm background emerging…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-30 Steven R. Furlanetto

Prior to the epoch of full reionization, the intergalactic medium and gravitationally collapsed systems will be detectable in 21-cm radiation. Physical mechanisms that would produce a 21-cm signature are discussed. These include Lya…

Astrophysics · Physics 2007-05-23 A Meiksin