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The classical radiometer equation is commonly used to calculate the detectability of the 21cm emission by diffuse cosmic hydrogen at high redshifts. However, the classical description is only valid in the regime where the occupation number…

Astrophysics · Physics 2009-06-23 Abraham Loeb

We investigate the interaction of Lyman alpha photons produced by the first stars in the universe with the intergalactic medium (IGM) prior to reionization. The background Lyman alpha spectral profile is obtained by solving a Fokker-Planck…

Astrophysics · Physics 2009-11-07 Xuelei Chen , Jordi Miralda-Escude

The rate of photon absorption in warm dense matter (WDM) induced by free-free electron-ion collisions is derived from Sommerfeld's cross-section for non-relativistic bremsstrahlung emission, making use of detailed balance relations. Warm…

Plasma Physics · Physics 2020-01-08 Jürgen Meyer-ter-Vehn , Rafael Ramis

Photons are a penetrating probe of the hot medium formed in heavy-ion collisions, but they are emitted from all collision stages. At photon energies below 2-3 GeV, the measured photon spectra are approximately exponential and can be…

Nuclear Theory · Physics 2014-05-02 Chun Shen , Ulrich W. Heinz , Jean-Francois Paquet , Charles Gale

The extraction of information carried by light plays an increasingly important role in optical communication, imaging, and detection. However, the information can only be successfully extracted when the light pulse is comparably strong,…

Optics · Physics 2026-05-25 Zhen Yang , Zeng-Quan Yan , Li Wang , Xiao-Wei Wang , Ka-Di Zhu , Xian-Min Jin

We study the prospects for extracting cosmological and astrophysical parameters from the low radio frequency 21-cm background due to the spin-flip transition of neutral Hydrogen during and prior to the reionization of the Universe. We make…

Astrophysics · Physics 2009-11-11 Mario G. Santos , Asantha Cooray

The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of processes, still finding potentially measurable…

Astrophysics · Physics 2010-11-11 R. A. Sunyaev , J. Chluba

The sky-averaged redshifted 21 cm signal from Cosmic Dawn is a uniquely sensitive tracer of early heating and ionisation, but it remains challenging to measure directly. The Sunyaev-Zel'dovich effect of the 21 cm background (SZE-21cm)…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-29 Charles Mpho Takalana

Lyman-alpha photons from the first radiating sources in the Universe play a pivotal role in 21-cm radio detections of Cosmic Dawn and the Epoch of Reionization. Comments are provided on the effect of the hyperfine structure of hydrogen on…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-01 A. Meiksin

Aiming to correctly restore the redshifted 21 cm signals emitted by the neutral hydrogen during the cosmic reionization processes, we re-examine the separation approaches based on the quadratic polynomial fitting technique in frequency…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jingying Wang , Haiguang Xu , Tao An , Junhua Gu , Xueying Guo , Weitian Li , Yu Wang , Chengze Liu , Olivier Martineau-Huynh , Xiang-Ping Wu

We study the impact of thermal inflation on the formation of cosmological structures and present astrophysical observables which can be used to constrain and possibly probe the thermal inflation scenario. These are dark matter halo…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-16 Sungwook E. Hong , Heeseung Zoe , Kyungjin Ahn

We determine the limit of the lowest achievable photoemitted electron temperature, and therefore the maximum achievable electron brightness, due to heating just after emission into vacuum, applicable to dense relativistic or nonrelativistic…

Accelerator Physics · Physics 2015-06-15 Jared Maxson , Ivan Bazarov , Christopher Coleman-Smith , Weishi Wan , Howard Padmore

Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21 cm line signal. If dark matter (DM) decays or annihilates the corresponding energy input affects the hydrogen kinetic temperature and ionized…

Astrophysics · Physics 2008-11-26 M. Valdes , A. Ferrara , M. Mapelli , E. Ripamonti

In generic particle physics models, the inflaton field is coupled to other bosonic and fermionic fields that acquire large masses during inflation and may decay into light degrees of freedom. This leads to dissipative effects that modify…

High Energy Physics - Phenomenology · Physics 2015-06-05 Mar Bastero-Gil , Arjun Berera , Rudnei O. Ramos , Joao G. Rosa

We present a statistical method for measuring the average HI spin temperature in distant galaxies using the expected detection yields from future wide-field 21cm absorption surveys. As a demonstrative case study we consider a simulated…

Astrophysics of Galaxies · Physics 2016-08-17 J. R. Allison , M. A. Zwaan , S. W. Duchesne , S. J. Curran

We study $e^{\pm}$ pair plasmas in pair equilibrium, which emit high energy radiation by thermal Comptonization of soft photons. We find that the maximum luminosity to size ratio of the source (i.e. the compactness) depends not only on the…

Astrophysics · Physics 2009-10-22 Gabriele Ghisellini , Francesco Haardt

While limited to low spatial resolution, the next generation low-frequency radio interferometers that target 21 cm observations during the era of reionization and prior will have instantaneous fields-of-view that are many tens of square…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 M. G. Santos , L. Ferramacho , M. B. Silva , A. Amblard , A. Cooray

Observations of redshifted 21-cm signal from neutral hydrogen (HI) appear to be the most promising probe of the cosmic dark ages. The signal carries information about the thermal state along with density distribution of the intergalactic…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-12 Sioree Ansar , Kanan K. Datta , Dhruba Dutta Chowdhury

The long spin coherence times in ambient conditions of color centers in solids, such as nitrogen-vacancy (NV$^{-}$) centers in diamond, make these systems attractive candidates for quantum sensing. Quantum sensing provides remarkable…

Quantum Physics · Physics 2019-06-06 N. J. Harmon , M. E. Flatté

We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure…

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