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We consider the evolution of the sky-averaged 21 cm background during the early phases of structure formation. Using simple analytic models, we calculate the thermal and ionization histories, assuming that stellar photons dominate the…

Astrophysics · Physics 2009-11-11 Steven Furlanetto

Predictions for the ability of 21-cm interferometric experiments to discriminate Epoch of Reionization (EoR) signal models are typically limited by the simplicity of data models, whereby foreground signals and characteristics of the…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-29 Ainulnabilah Nasirudin , Steven Murray , Cathryn Trott , Bradley Greig , Ronniy Joseph , Chris Power

Radio interferometric (RI) data are noisy under-sampled spatial Fourier components of the unknown radio sky affected by direction-dependent antenna gains. Failure to model these antenna gains accurately results in a radio sky estimate with…

Instrumentation and Methods for Astrophysics · Physics 2021-07-14 Arwa Dabbech , Audrey Repetti , Rick A. Perley , Oleg M. Smirnov , Yves Wiaux

The fluctuations generated by Inflation are nearly Gaussian in the simplest models, but may be non-Gaussian in more complex models, potentially leading to signatures in the late Universe. In particular, local type primordial non-Gaussianity…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-03 Mponeng Kopana , Sheean Jolicoeur , Roy Maartens

By listening to gravity in the low frequency band, between 0.1 mHz and 1 Hz, the future space-based gravitational-wave observatory LISA will be able to detect tens of thousands of astrophysical sources from cosmic dawn to the present. The…

General Relativity and Quantum Cosmology · Physics 2019-07-24 Quentin Baghi , Ira Thorpe , Jacob Slutsky , John Baker , Tito Dal Canton , Natalia Korsakova , Nikos Karnesis

Many adaptive optics systems operate by measuring the distortion of the wavefront in one wavelength range and performing the scientific observations in a second, different wavelength range. One common technique is to measure wavefront…

Astrophysics · Physics 2009-11-07 Henry G. Roe

Inferring sky surface brightness distributions from noisy interferometric data in a principled statistical framework has been a key challenge in radio astronomy. In this work, we introduce Imaging for Radio Interferometry with Score-based…

Instrumentation and Methods for Astrophysics · Physics 2025-01-07 Noé Dia , M. J. Yantovski-Barth , Alexandre Adam , Micah Bowles , Laurence Perreault-Levasseur , Yashar Hezaveh , Anna Scaife

We report characterization results for an engineering prototype of a next-generation low-frequency radio astronomy array. This prototype, which we refer to as the Aperture Array Verification System 0.5 (AAVS0.5), is a sparse pseudo-random…

The recovery of an exoplanet's atmospheric parameters from its spectrum requires accurate knowledge of the spectral errors and covariances. Unfortunately, the complex image processing used in high-contrast integral-field spectrograph (IFS)…

Earth and Planetary Astrophysics · Physics 2016-12-14 Johnny P. Greco , Timothy D. Brandt

The low-frequency radio sky is dominated by the diffuse synchrotron emission of our Galaxy and extragalactic radio sources related to Active Galactic Nuclei and star-forming galaxies. This foreground emission is much brighter than the…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-30 Emma Chapman , Vibor Jelić

The highly-accurate optical reference frame GCRF (Gaia Celestial Reference Frame) is expected to be available in several years. By the same time, a new version of radio reference frame ICRF (International Celestial Reference Frame) will be…

Instrumentation and Methods for Astrophysics · Physics 2015-10-06 Zinovy Malkin

Estimating a distance by inverting a parallax is only valid in the absence of noise. As most stars in the Gaia catalogue will have non-negligible fractional parallax errors, we must treat distance estimation as a constrained inference…

Instrumentation and Methods for Astrophysics · Physics 2016-11-30 Tri L. Astraatmadja , Coryn A. L. Bailer-Jones

We re-examine the effects of redshift space distortion in all-sky galaxy redshift surveys in the formalism of spherical harmonics. Within this framework we show how one can treat both the large-scale linear effects, and the small-scale…

Astrophysics · Physics 2015-06-24 A. F. Heavens , A. N. Taylor

Observation of redshifted 21-cm signals from neutral hydrogen holds the key to understanding the structure formation and its evolution during the reionization and post-reionization era. Apart from the presence of orders of magnitude larger…

Instrumentation and Methods for Astrophysics · Physics 2022-03-02 Jais Kumar , Prasun Dutta , Samir Choudhuri , Nirupam Roy

We consider a possibility of detecting the jitter effect of apparent celestial positions of distant sources due to local fluctuations of the Galaxy gravitational field. It is proposed to observe two samples of extragalactic sources (target…

Astrophysics of Galaxies · Physics 2020-07-29 Tatiana I. Larchenkova , Natalia Lyskova , Leonid Petrov , Alexander A. Lutovinov

We describe a tool we improved to detect excess noise in the gravitational wave (GW) channel arising from its bilinear or nonlinear coupling with fluctuations of various components of a GW interferometer and its environment. We also…

Instrumentation and Methods for Astrophysics · Physics 2016-06-22 Sukanta Bose , Bernard Hall , Nairwita Mazumder , Sanjeev Dhurandhar , Anuradha Gupta , Andrew Lundgren

Density inhomogeneities along the line-of-sight distort fluctuations in the cosmic microwave background. Usually, this effect is thought of as a small second-order effect that mildly alters the statistics of the microwave background…

Astrophysics · Physics 2009-10-30 Maki Suginohara , Tatsushi Suginohara , David N. Spergel

Atmospheric refraction affects to various degrees exoplanet transit, lunar eclipse, as well as stellar occultation observations. Exoplanet retrieval algorithms often use analytical expressions for the column abundance along a ray traversing…

Earth and Planetary Astrophysics · Physics 2017-03-23 Yan Betremieux , Lisa Kaltenegger

We present an analysis of errors on the tensor-to-scalar ratio due to residual diffuse foregrounds. We use simulated observations of a CMB polarization satellite, the Cosmic Origins Explorer, using the specifications of the version proposed…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-31 Carlos Hervías-Caimapo , Anna Bonaldi , Michael L. Brown

A simple model is presented to explain the high Galactic latitude anomalies in the WMAP data recently reported by Diego et al (2009). It is suggested that the anomalous deviation from a thermal spectrum could be caused by the propagation of…

Astrophysics of Galaxies · Physics 2009-04-14 H. N. Sharpe