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Hydrogen intensity mapping is a new field in astronomy that promises to make three-dimensional maps of the matter distribution of the Universe using the redshifted $21\,\textrm{cm}$ line of neutral hydrogen gas (HI). Several ongoing and…

Instrumentation and Methods for Astrophysics · Physics 2022-03-14 Anh Phan , Santanu Das , Albert Stebbins , Peter Timbie , Reza Ansari , Shifan Zuo , Jixia Li , Trevor Oxholm , Fengquan Wu , Xuelei Chen , Shijie Sun , Yougang Wang , Jiao Zhang

Accurately accounting for spectral structure in spectrometer data induced by instrumental chromaticity on scales relevant for detection of the 21-cm signal is among the most significant challenges in global 21-cm signal analysis. In the…

One of the main unsolved problems of cosmology is how to maximize the extraction of information from nonlinear data. If the data are nonlinear the usual approach is to employ a sequence of statistics (N-point statistics, counting statistics…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-07 Uros Seljak , Grigor Aslanyan , Yu Feng , Chirag Modi

A simple, yet general, formalism for the optimized linear combination of astrophysical images is constructed and demonstrated. The formalism allows the user to combine multiple undersampled images to provide oversampled output at high…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Barnaby Rowe , Christopher Hirata , Jason Rhodes

Radio interferometers suffer from the problem of missing information in their data, due to the gaps between the antennas. This results in artifacts, such as bright rings around sources, in the images obtained. Multiple deconvolution…

Instrumentation and Methods for Astrophysics · Physics 2021-03-24 Michelle Lochner , Bruce A. Bassett , Martin Kunz , Iniyan Natarajan , Nadeem Oozeer , Oleg Smirnov , Jon Zwart

An innovative inverse scattering (IS) method is proposed for the quantitative imaging of pixel-sparse scatterers buried within a lossy half-space. On the one hand, such an approach leverages on the wide-band nature of ground penetrating…

Information Theory · Computer Science 2021-08-04 Marco Salucci , Nicola Anselmi

We present two estimators to quantify the angular power spectrum of the sky signal directly from the visibilities measured in radio interferometric observations. This is relevant for both the foregrounds and the cosmological 21-cm signal…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-11 Samir Choudhuri , Somnath Bharadwaj , Abhik Ghosh , SK. Saiyad Ali

Upcoming radio surveys will probe the sky with unprecedented depth and sky coverage, enabling a broad range of cosmological and astrophysical applications, as well as powerful synergies with experiments at other wavelengths. The preparation…

Constraints on cosmological parameters from large-scale structure have traditionally been obtained from two-point statistics. However, non-linear structure formation renders these statistics insufficient in capturing the full information…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-22 Alex Hall , Alexander Mead

The arrival time distribution of cosmic ray events is well suited to extract information regarding sky anisotropies. For an experiment with nearly constant exposure, the frequency resolution one can achieve is given by the inverse of the…

Astrophysics · Physics 2009-06-23 Pierre Billoir , Antoine Letessier-Selvon

We present Global MOdel for the radio Sky Spectrum (GMOSS) -- a novel, physically motivated model of the low-frequency radio sky from 22 MHz to 23 GHz. GMOSS invokes different physical components and associated radiative processes to…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-19 Mayuri Sathyanarayana Rao , Ravi Subrahmanyan , N Udaya Shankar , Jens Chluba

Ground-based radio astronomical observation at frequencies below 30 MHz is hampered by the Ionosphere and radio frequency interference (RFI). The Discovering Sky at the Longest wavelength (DSL) mission, also known as the Hongmeng mission,…

Instrumentation and Methods for Astrophysics · Physics 2025-11-25 Furen Deng , Yidong Xu , Fengquan Wu , Yanping Cong , Bin Yue , Xuelei Chen

This paper proposes a novel approach to robust radar detection of range-spread targets embedded in Gaussian noise with unknown covariance matrix. The idea is to model the useful target echo in each range cell as the sum of a coherent signal…

Signal Processing · Electrical Eng. & Systems 2022-10-04 Angelo Coluccia , Alessio Fascista , Giuseppe Ricci

Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of nearby galaxies, but many of their properties are not well-constrained. Gamma-ray observations provide a powerful tool in this respect, allowing us to constrain both the…

High Energy Astrophysical Phenomena · Physics 2023-07-19 Maria Werhahn , Philipp Girichidis , Christoph Pfrommer , Joseph Whittingham

We present a method for coherently combining short data segments from gravitational-wave detectors to improve the sensitivity of semi-coherent searches for continuous gravitational waves. All-sky searches for continuous gravitational waves…

General Relativity and Quantum Cosmology · Physics 2016-04-13 Evan Goetz , Keith Riles

Computing accurate estimates of the Fourier transform of analog signals from discrete data points is important in many fields of science and engineering. The conventional approach of performing the discrete Fourier transform of the data…

Machine Learning · Statistics 2017-12-08 Luca Ambrogioni , Eric Maris

We derive and implement a full Bayesian large scale structure inference method aiming at precision recovery of the cosmological power spectrum from galaxy redshift surveys. Our approach improves over previous Bayesian methods by performing…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Jens Jasche , Benjamin D. Wandelt

The CLEAN deconvolution algorithm has well-known limitations due to the restriction of locating point source model components on a discretized grid. In this letter we demonstrate that these limitations are even more pronounced when applying…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 M. R. Bell , N. Oppermann , A. Crai , T. A. Enßlin

The disconnected part of the power spectrum covariance matrix (also known as the "Gaussian" covariance) is the dominant contribution on large scales for galaxy clustering and weak lensing datasets. The presence of a complicated sky mask…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-02 Carlos García-García , David Alonso , Emilio Bellini