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One of the most promising probes to complement current standard cosmological surveys is the HI intensity map, i.e. the distribution of temperature fluctuations in neutral hydrogen. In this paper we present calculations of the 2-point…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-24 Anut Sangka , David Bacon

The cross-correlation of optical galaxies with the neutral hydrogen (HI) radiation intensity can enhance the signal-to-noise ratio (SNR) of the HI intensity measurement. In this paper, we investigate the cross-correlation of the galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-21 Furen Deng , Yan Gong , Yougang Wang , Shuting Dong , Ye Cao , Xuelei Chen

We conduct the first case study towards developing optimal foreground mitigation strategies for neutral hydrogen (HI) intensity mapping using radio interferometers at low redshifts. A pipeline for simulation, foreground mitigation and power…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-08 Zhaoting Chen , Laura Wolz , Richard Battye

We investigate the prospects of measuring the cosmic magnification effect by cross-correlating neutral hydrogen intensity mapping (HI IM) maps with background optical galaxies. We forecast the signal-to-noise ratio for HI IM data from…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Amadeus Witzemann , Alkistis Pourtsidou , Mario G. Santos

We present a new halo model of neutral hydrogen (HI) calibrated to galaxy formation simulations at redshifts $z\sim0.1$ and $z\sim1.0$ that we employ to investigate the constraining power of interferometric HI intensity mapping on HI…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-23 Zhaoting Chen , Laura Wolz , Marta Spinelli , Steven G. Murray

The effective redshift distribution $n(z)$ of galaxies is a critical component in the study of weak gravitational lensing. Here, we introduce a new method for determining $n(z)$ for weak lensing surveys based on high-quality redshifts and…

The future of precision cosmology could benefit from cross-correlations between intensity maps of unresolved neutral hydrogen (HI) and more conventional optical galaxy surveys. A major challenge that needs to be overcome is removing the…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-17 Steven Cunnington , Laura Wolz , Alkistis Pourtsidou , David Bacon

Obtaining accurately calibrated redshift distributions of photometric samples is one of the great challenges in photometric surveys like LSST, Euclid, HSC, KiDS, and DES. We present an inference methodology that combines the redshift…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-09 M. M. Rau , C. B. Morrison , S. J. Schmidt , S. Wilson , R. Mandelbaum , Y. Y. Mao

HI intensity mapping (IM) is a novel technique capable of mapping the large-scale structure of the Universe in three dimensions and delivering exquisite constraints on cosmology, by using HI as a biased tracer of the dark matter density…

The next generation of proposed galaxy surveys will increase the number of galaxies with photometric redshifts by two orders of magnitude, drastically expanding both redshift range and detection threshold from the current state of the art.…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 A. E. Schulz

Visbal & Loeb (2010) have shown that it is possible to measure the clustering of galaxies by cross correlating the cumulative emission from two different spectral lines which originate at the same redshift. Through this cross correlation,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Eli Visbal , Hy Trac , Abraham Loeb

The first direct measurements of the HI intensity mapping power spectrum were recently made using the MeerKAT telescope. These measurements are on nonlinear scales, at redshifts 0.32 and 0.44. We develop a formalism for modelling…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-17 Hamsa Padmanabhan , Roy Maartens , Obinna Umeh , Stefano Camera

While most purpose-built 21cm intensity mapping experiments are close-packed interferometer arrays, general-purpose dish arrays should also be capable of measuring the cosmological 21cm signal. This can be achieved most efficiently if the…

We discuss a method aiming to use photometric redshifts in lensing clusters to access the population of distant background sources. The amplification provided by gravitational lensing allows to calibrate photometric redshifts 1 to 3…

Astrophysics · Physics 2007-05-23 Roser Pello , Jean-Paul Kneib , Micol Bolzonella , Joan-Marc Miralles

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…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-31 Sourabh Paul , Mario G. Santos , Zhaoting Chen , Laura Wolz

We propose an innovative method for measuring the neutral hydrogen (HI) content of an optically-selected spectroscopic sample of galaxies through cross-correlation with HI intensity mapping measurements. We show that the HI-galaxy…

Astrophysics of Galaxies · Physics 2017-07-26 L. Wolz , C. Blake , J. S. B. Wyithe

We present a new scheme, $\it{galtag}$, for refining the photometric redshift measurements of faint galaxies by probabilistically tagging them to observed galaxy groups constructed from a brighter, magnitude-limited spectroscopy survey.…

Astrophysics of Galaxies · Physics 2018-07-04 P. R. Kafle , A. S. G. Robotham , S. P. Driver , S. Deeley , P. Norberg , M. J. Drinkwater , L. J. Davies

We discuss cosmological inference from galaxy surveys at low and high redshifts. Studies of optical and IRAS redshift surveys with median redshift ${\bar z} \sim 0.02$ yield measurements of the density parameter $\Omega$ and the…

Astrophysics · Physics 2007-05-23 Ofer Lahav

The accurate determination of the true redshift distributions in tomographic bins is critical for cosmological constraints from photometric surveys. The proposed redshift self-calibration method, which utilizes the photometric galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-10 Hui Peng , Yu Yu