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Patchy reionization leaves a number of imprints on the small-scale cosmic microwave background (CMB) temperature fluctuations, the largest of which is the kinematic Sunyaev-Zel'dovich (kSZ), the Doppler shift of CMB photons scattering off…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-26 Simone Ferraro , Kendrick M. Smith

We investigate the constraints on the reionization history of the Universe from a joint analysis of the cosmic microwave background and neutral hydrogen fraction data. The $\tanh$ parametrization and principal component analysis methods are…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-27 Wei-Ming Dai , Yin-Zhe Ma , Zong-Kuan Guo , Rong-Gen Cai

We show that by jointly fitting cosmic microwave background (CMB) and astrophysical data - a compilation of UV luminosity data from the Hubble Frontier Field and neutral hydrogen data from distant sources-, we can infer on the shape of the…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-16 Daniela Paoletti , Dhiraj Kumar Hazra , Fabio Finelli , George F. Smoot

We study the constraints on reionization from five years of WMAP data, parametrizing the evolution of the average fraction of ionized hydrogen with principal components that provide a complete basis for describing the effects of…

Astrophysics · Physics 2009-11-13 Michael J. Mortonson , Wayne Hu

The simple assumption of an instantaneous reionization of the Universe may bias estimates of cosmological parameters. In this paper a model-independent principal component method for the reionization history is applied to give constraints…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-21 Wei-Ming Dai , Zong-Kuan Guo , Rong-Gen Cai

Cosmic Microwave Background temperature and polarization anisotropies from Planck have estimated a lower value of the optical depth to reionization ($\tau$) compared to WMAP. A significant period in the reionization history would then fall…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-19 Dhiraj Kumar Hazra , Daniela Paoletti , Fabio Finelli , George F. Smoot

Given that the reionization history of cosmic hydrogen is yet to be stringently constrained, it is worth checking the prospects of doing so using physically motivated models and available observational data. For this purpose, we use an…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-04 Barun Maity , Tirthankar Roy Choudhury

With a simple power-law approximation of high-redshift ($\gtrsim3.5$) star formation history, i.e., $\dot{\rho}_*(z)\propto [(1+z)/4.5]^{-\alpha}$, we investigate the reionization of intergalactic medium (IGM) and the consequent Thomson…

Cosmology and Nongalactic Astrophysics · Physics 2012-08-07 Yun-Wei Yu , K. S. Cheng , M. C. Chu , S. Yeung

The epoch of reionisation is a key phase in cosmic history, characterised by the ionisation of the intergalactic medium by the first luminous sources. In this work, we constrain the reionisation history of the Universe using data from the…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-18 S. Ilić , M. Tristram , M. Douspis , A. Gorce , S. Henrot-Versillé , L. T. Hergt , M. Langer , L. McBride , M. Muñoz-Echeverría , E. Pointecouteau , L. Salvati

Massive neutrinos modify the expansion history of the universe and suppress the structure formation below their free streaming scale. Cosmic microwave background (CMB) observations at small angular scales can be used to constrain the total…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-15 Gali Shmueli , Debanjan Sarkar , Ely D. Kovetz

On large angular scales, the polarization of the CMB contains information about the evolution of the average ionization during the epoch of reionization. Interpretation of the polarization spectrum usually requires the assumption of a fixed…

Astrophysics · Physics 2010-11-11 Michael J. Mortonson , Wayne Hu

The study of reionization history plays an important role in understanding the evolution of our universe. It is commonly believed that the intergalactic medium (IGM) in our universe are fully ionized today, however the reionizing process…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-09 Yang Liu , Hong Li , Si-Yu Li , Yong-Ping Li , Xinmin Zhang

The recent observations of cross temperature-polarization power spectra of the Cosmic Microwave Background (CMB) made by the WMAP satellite are in better agreement with a high value of the Thomson scattering optical depth \tau \approx 0.17.…

Astrophysics · Physics 2009-11-13 A. Melchiorri , T. Roy Choudhury , P. Serra , A. Ferrara

The Epoch of Reionization (EoR) depends on the complex astrophysics governing the birth and evolution of the first galaxies and structures in the intergalactic medium. EoR models rely on cosmic microwave background (CMB) observations, and…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-30 Yuxiang Qin , Vivian Poulin , Andrei Mesinger , Bradley Greig , Steven Murray , Jaehong Park

We present a fast Markov Chain Monte-Carlo exploration of cosmological parameter space. We perform a joint analysis of results from recent CMB experiments and provide parameter constraints, including sigma_8, from the CMB independent of…

Astrophysics · Physics 2008-11-26 Antony Lewis , Sarah Bridle

Recent studies report a mild discrepancy between baryon acoustic oscillation (BAO) and cosmic microwave background (CMB) measurements within the $\Lambda$CDM framework. This discrepancy could be explained if the optical depth $\tau$…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-15 Yuta Kageura , Masami Ouchi , Fumihiro Naokawa , Hiroya Umeda , Akinori Matsumoto , Yuichi Harikane , Minami Nakane , Tran Thi Thai

Neutral hydrogen around high-z QSO and an optical depth tau ~ 0.17 can be reconciled if reionization is more complex than a single transition at z ~ 6-8. Tracing its details could shed a new light on the first sources of radiation. Here we…

We study the optical depth to reionization in a cosmological setting that includes backreaction from matter inhomogeneities, using the Buchert averaging formalism. We construct a spacetime model consisting of multiple inhomogeneous domains,…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-16 Shashank Shekhar Pandey , Ruchika , Subhadeep Mukherjee , A. S. Majumdar

Cosmic Reionization imprints its signature on the temperature and polarization anisotropies of the cosmic microwave background (CMB). Advances in CMB telescopes have already placed a significant constraint on the history of reionization. As…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-18 Hina Sakamoto , Kyungjin Ahn , Kiyotomo Ichiki , Hyunjin Moon , Kenji Hasegawa

We highlight recent progress in the sophistication and diversification of cosmic dawn and reionization simulations. The application of these modeling tools to current observations has allowed us narrow down the timing of reionization, which…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-22 Andrei Mesinger