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We provide a new methodology for statistical recovery of single linear mixtures of piecewise constant signals (sources) with unknown mixing weights and change points in a multiscale fashion. We show exact recovery within an…

统计方法学 · 统计学 2017-08-31 Merle Behr , Chris Holmes , Axel Munk

Faraday rotation studies of distant radio sources can constrain the evolution and the origin of cosmic magnetism. We use data from the LOFAR Two Metre Sky Survey: Data Release 2 (LoTSS DR2) to study the dependence of the Faraday rotation…

Wide-band radio polarization observations offer the possibility to recover information about the magnetic fields in synchrotron sources, such as details of their three-dimensional configuration, that has previously been inaccessible. The…

宇宙学与河外天体物理 · 物理学 2015-06-18 Cathy Horellou , Andrew Fletcher

Faraday rotation has been seen at millimeter wavelengths in several low luminosity active galactic nuclei, including Event Horizon Telescope (EHT) targets M87* and Sgr A*. The observed rotation measure (RM) probes the density, magnetic…

高能天体物理现象 · 物理学 2020-10-07 Angelo Ricarte , Ben S. Prather , George N. Wong , Ramesh Narayan , Charles Gammie , Michael Johnson

The design and performance of a wide bandwidth linear polarization modulator based on the Faraday effect is described. Faraday Rotation Modulators (FRMs) are solid-state polarization switches that are capable of modulation up to ~10 kHz.…

We present new 6 and 20 cm Very Large Array (VLA) observations of polarized continuum emission of roughly 0.5 square degrees of the Galactic center (GC) region. The 6 cm observations detect diffuse linearly-polarized emission throughout the…

星系天体物理 · 物理学 2015-05-27 C. J. Law , M. A. Brentjens , G. Novak

We present the first Faraday rotation measure (RM) grid study of an individual low-mass cluster -- the Fornax cluster -- which is presently undergoing a series of mergers. Exploiting commissioning data for the POlarisation Sky Survey of the…

Low-frequency radio observatories are reaching unprecedented levels of sensitivity in an effort to detect the 21 cm signal from the Cosmic Dawn. High precision is needed because the expected signal is overwhelmed by foreground…

天体物理仪器与方法 · 物理学 2022-03-14 Adam E. Lanman , Steven G. Murray , Daniel C. Jacobs

We investigate the distribution of Faraday rotation measure (RM) in the M87 jet at arc-second scales by using archival polarimetric VLA data at 8, 15, 22 and 43 GHz. We resolve the structure of the RM in several knots along the jet for the…

高能天体物理现象 · 物理学 2016-06-01 Juan-Carlos Algaba , Keiichi Asada , Masanori Nakamura

Unveiling the intergalactic magnetic field (IGMF) in filaments of galaxies is a very important and challenging subject in modern astronomy. In order to probe the IGMF from rotation measures (RMs) of extragalactic radio sources, we need to…

宇宙学与河外天体物理 · 物理学 2015-06-18 Takuya Akahori , Kohei Kumazaki , Keitaro Takahashi , Dongsu Ryu

A tomography method is proposed to image magnetic anomaly sources buried below a non-flat ground surface, by developing the expression of the total power associated with a measured magnetic field. By discretising the integral relating a…

地球物理 · 物理学 2011-12-30 Paolo Mauriello , Domenico Patella

We present the first detailed case study using quadratic estimators (QE) to diagnose and remove systematics present in observed Cosmic Microwave Background (CMB) maps. In this work we focus on the temperature to polarization leakage. We use…

宇宙学与河外天体物理 · 物理学 2021-07-13 Joel Williams , Nialh McCallum , Aditya Rotti , Daniel Thomas , Richard Battye , Michael L. Brown

Aims - We report new Very Large Array polarimetric observations of Compact Steep-Spectrum (CSS) sources at 8.4, 15, and 23GHz. Methods - Using multi-frequency VLA observations we have derived sub-arcsecond resolution images of the total…

宇宙学与河外天体物理 · 物理学 2015-06-15 F. Mantovani , A. Rossetti , W. Junor , D. J. Saikia , C. J. Salter

We derive an algorithm for computing a classic nonlinearity correction -- applicable to constant and uniform illumination -- in the presence of read noise and photon noise. The algorithm operates simultaneously on many nondestructive ramps…

天体物理仪器与方法 · 物理学 2026-01-21 Timothy D. Brandt

Multipath propagation in the interstellar medium distorts radio pulses, an effect predominant for distant pulsars observed at low frequencies. Typically, broadened pulses are analyzed to determine the amount of propagation-induced pulse…

天体物理学 · 物理学 2009-11-07 N. D. R. Bhat , J. M. Cordes , S. Chatterjee

Current mm/submm interferometers, like the Atacama Large mm/submm Array (ALMA), use receivers that register the sky signal in a linear polarization basis. In the case of observations performed in full-polarization mode (where the…

天体物理仪器与方法 · 物理学 2016-09-21 I. Marti-Vidal , W. H. T. Vlemmings , S. Muller

Rotation measure (RM) grids of extragalactic radio sources have been widely used for studying cosmic magnetism. But their potential for exploring the intergalactic magnetic field (IGMF) in filaments of galaxies is unclear, since other…

宇宙学与河外天体物理 · 物理学 2015-06-22 Takuya Akahori , B. M. Gaensler , Dongsu Ryu

We determined Faraday rotation measures (RMs) towards 137 pulsars in the northern sky, using Low-Frequency Array (LOFAR) observations at 110-190 MHz. This low-frequency RM catalogue, the largest to date, improves the precision of existing…

The parsec-scale Faraday rotation measure (RM) distribution of six "blazars" is investigated using multi-frequency (4.6--43 GHz) polarization observations taken on 2006 July 2 with the VLBA. Analysis of the RM provides the direction of the…

天体物理学 · 物理学 2009-02-11 Shane P. O'Sullivan , Denise C. Gabuzda

We introduce a new cross-correlation method to detect and verify the astrophysical origin of Faraday Rotation (FR) in multiwavelength surveys. FR is well studied in radio astronomy from radio point sources but the $\lambda^{2}$ suppression…

天体物理仪器与方法 · 物理学 2018-01-18 Matthew Kolopanis , Philip Mauskopf , Judd Bowman