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A detection of the predicted anticorrelation between 21cm and either Ly-alpha or H-alpha from the Epoch of Reionization (EOR) would be a powerful probe of the first galaxies. While 3D intensity maps isolate foregrounds in low k_\parallel…

宇宙学与河外天体物理 · 物理学 2017-11-06 Abraham R. Neben , Brian Stalder , Jacqueline N. Hewitt , John L. Tonry

Measurements of the cosmic 21 cm signal need to achieve a high dynamic range to isolate it from bright foreground emissions. Calibration inaccuracies can compromise the spectral fidelity of the smooth foreground continuum, thereby limiting…

宇宙学与河外天体物理 · 物理学 2026-02-06 Pascal M. Keller , Bojan Nikolic , Nithyanandan Thyagarajan

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)…

宇宙学与河外天体物理 · 物理学 2026-04-29 Charles Mpho Takalana

The power spectrum of the two-degree Field Galaxy Redshift Survey (2dFGRS) sample is estimated with the discrete wavelet transform (DWT) method. The DWT power spectra within $0.04 <k< 2.3 h$Mpc$^{-1}$ are measured for three volume-limited…

天体物理学 · 物理学 2008-11-26 Yan-Chuan Cai , Jun Pan , Yong-Heng Zhao , Long-Long Feng , Li-Zhi Fang

Cross-correlating 21cm and Ly$\alpha$ intensity maps of the Epoch of Reionization (EoR) promises to be a powerful tool for exploring the properties of the first galaxies. Next-generation intensity mapping experiments such as the Hydrogen…

宇宙学与河外天体物理 · 物理学 2022-03-02 Tyler A. Cox , Daniel C. Jacobs , Steven G. Murray

A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way,…

宇宙学与河外天体物理 · 物理学 2015-12-23 Hannes Jensen , Suman Majumdar , Garrelt Mellema , Adam Lidz , Ilian T. Iliev , Keri L. Dixon

The redshifted 21cm signal from the Cosmic Dawn is expected to provide unprecedented insights into early Universe astrophysics and cosmology. Here we explore how dark matter can heat the intergalactic medium before the first galaxies,…

宇宙学与河外天体物理 · 物理学 2024-09-17 Gaétan Facchinetti , Laura Lopez-Honorez , Yuxiang Qin , Andrei Mesinger

We investigate the impact that warm dark matter (WDM) has in terms of 21cm intensity mapping in the post-reionization Universe at z = 3 - 5. We perform hydrodynamic simulations for 5 different models: cold dark matter and WDM with 1,2,3,4…

宇宙学与河外天体物理 · 物理学 2015-07-31 Isabella P. Carucci , Francisco Villaescusa-Navarro , Matteo Viel , Andrea Lapi

We describe a survey in the ELAIS N2 region with the VLA at 43.4 GHz, carried out with 1627 independent snapshot observations in D-configuration and covering about 0.5 square degrees. One certain source is detected, a previously-catalogued…

宇宙学与河外天体物理 · 物理学 2015-05-19 Jasper Wall , Rick Perley , Robert Laing , Sean Stotyn , Angela Taylor , Joe Silk

We report the first direct detection of the cosmological power spectrum using the intensity signal from 21-cm emission of neutral hydrogen (HI), derived from interferometric observations with the L-band receivers of the new MeerKAT radio…

宇宙学与河外天体物理 · 物理学 2023-01-31 Sourabh Paul , Mario G. Santos , Zhaoting Chen , Laura Wolz

The Tianlai Dish Pathfinder Array (TDPA) is a radio interferometer designed to test techniques for 21 cm intensity mapping in the post-reionization universe as a means of measuring large-scale cosmic structure. Using 9 nights of…

We have proposed a method for measuring weak lensing using the Lyman-alpha forest. Here we estimate the noise expected in weak lensing maps and power spectra for different sets of observational parameters. We find that surveys of the size…

宇宙学与河外天体物理 · 物理学 2018-06-21 R. Benton Metcalf , Rupert A. C. Croft , Alessandro Romeo

During Cosmic Dawn, Pop III stars could be formed in minihalos through molecular hydrogen (H$_2$) cooling. The minimum halo mass required for H$_2$ cooling is highly sensitive to Lyman-Werner (LW) radiation, which dissociates H$_2$ and…

宇宙学与河外天体物理 · 物理学 2026-04-21 Xi Du , Bin Yue , Furen Deng , Yidong Xu , Yan Gong , Ely D. Kovetz , Xuelei Chen

We present methods and results from "21-cm Spectral Line Observations of Neutral Gas with the EVLA" (21-SPONGE), a large survey for Galactic neutral hydrogen (HI) absorption with the Karl G. Jansky Very Large Array (VLA). With the upgraded…

We present the data analysis and the X-ray source counts for the first season of XMM-Newton observations in the COSMOS field. The survey covers ~2 deg^2 within the region of sky bounded by 9^h57.5^m<R.A.<10^h03.5^m; 1^d27.5^m<DEC<2^d57.5^m…

We report the first results of a systematic investigation to characterize blazar variability power spectral densities (PSDs) at optical frequencies using densely sampled (5--15 minutes integration time), high photometric accuracy…

高能天体物理现象 · 物理学 2021-03-10 Arti Goyal

Measurements of the 21cm line emission by residual cosmic hydrogen after reionization can be used to trace the power spectrum of density perturbations through a significant fraction of the observable volume of the Universe. We show that a…

天体物理学 · 物理学 2009-06-23 Abraham Loeb , Stuart Wyithe

We present observations of the region between 5deg < l < 45deg and |b| < 3deg, in the OH 1612 MHz line, taken from 1993 to 1995 with the VLA. These observations are the last part of a larger survey, covering |l| < 45deg and |b| < 3deg, with…

天体物理学 · 物理学 2019-08-17 M. Sevenster , H. v. Langevelde , R. Moody , J. Chapman , H. Habing , N. Killeen

The first station of the Long Wavelength Array (LWA1) was completed in April 2011 and is currently performing observations resulting from its first call for proposals in addition to a continuing program of commissioning and characterization…

The recent detection of an anomalously strong 21-cm signal of neutral hydrogen from Cosmic Dawn by the EDGES Low-Band radio experiment can be explained if cold dark matter particles scattered off the baryons draining excess energy from the…

宇宙学与河外天体物理 · 物理学 2018-07-11 Anastasia Fialkov , Rennan Barkana , Aviad Cohen