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We present a detailed depolarization analysis of the radio galaxy \texttt{ILTJ012215.21+254334.8} using polarimetric data from the \textit{LOFAR Two-metre Sky Survey} (LoTSS) Data Release 2 (DR2) catalogue. This source, with \textit{RM}…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-12 Samantha Sneha Paul , Abhik Ghosh

We used archival very long baseline interferometry (VLBI) data of active galactic nuclei (AGN) observed from 1.4 GHz to 86 GHz to measure the angular size of VLBI radio cores in 8959 AGNs. We analysed their sky distributions, frequency…

Astrophysics of Galaxies · Physics 2022-08-15 T. A. Koryukova , A. B. Pushkarev , A. V. Plavin , Y. Y. Kovalev

We present the "C4 Cluster Catalog", a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster--finding algorithm identifies…

Polarized synchrotron emission from ultra-relativistic electrons spiraling the Galactic magnetic field has become one of the most relevant emissions in the Interstellar medium these last years due to the improvement in the quality of…

We compiled a catalog of Faraday rotation measures (RMs) for 4553 extragalactic radio point sources ublished in literature. These RMs were derived from multi-frequency polarization observations. The RM data are compared to those in the NRAO…

Astrophysics of Galaxies · Physics 2014-07-30 J. Xu , J. L. Han

This thesis reports on the application of new wide-field Very Long Baseline Interferometry (VLBI) imaging techniques using real data for the first time. These techniques are used to target three specific science areas: (i) a…

Astrophysics of Galaxies · Physics 2014-06-19 Emil Lenc

We use linear estimators to determine the magnitude and direction of the cosmic radio dipole from the NRAO VLA Sky Survey (NVSS) and the Westerbork Northern Sky Survey (WENSS). We show that special attention has to be given to the issues of…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-25 Matthias Rubart , Dominik J. Schwarz

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…

The third iteration of the International Celestial Reference Frame (ICRF3) is made up of 4536 quasars observed at S/X bands using Very Long baseline Interferometry (VLBI). These sources are high redshift quasars, typically between $1<z<2$,…

Astrophysics of Galaxies · Physics 2021-09-08 Lucas R. Hunt , Megan C. Johnson , Phillip J. Cigan , David Gordon , John Spitzak

We investigate the correlations in galaxy shapes between optical and radio wavelengths using archival observations of the COSMOS field. Cross-correlation studies between different wavebands will become increasingly important for precision…

Astrophysics of Galaxies · Physics 2016-12-19 Ben Tunbridge , Ian Harrison , Michael L. Brown

Researchers routinely characterize optical samples by computing the scattering cross-section. However, the experimental determination of this magnitude requires the measurement and integration of the components of the scattered field in all…

The goal of this work is to characterize the polarization effects of the VLTI and GRAVITY. This is needed to calibrate polarimetric observations with GRAVITY for instrumental effects and to understand the systematic error introduced to the…

Proper modelling of astronomical receivers is vital: it describes the systematic errors in the raw data, guides the receiver design process, and assists data calibration. In this paper we describe a method of analytically modelling the full…

Instrumentation and Methods for Astrophysics · Physics 2015-06-23 O. G. King , Michael E. Jones , C. Copley , R. J. Davis , J. P. Leahy , J. Leech , S. J. C. Muchovej , T. J. Pearson , Angela C. Taylor

Measuring the quasar distance through joint analysis of spectroastrometry (SA) and reverberation mapping (RM) observations is a new method for driving the development of cosmology. In this paper, we carry out detailed simulation and…

High Energy Astrophysical Phenomena · Physics 2022-03-14 Ying-Ke Huang , Yue-Dong Fang , Kai-Xing Lu , Zhi-Xiang Zhang , Ji-Lin Liu , Sha-sha Li , Bao-Rui Luo , Qin Lin , Zhuo-Xi Huo

Polarization calibration of interferometric observations is a costly procedure and, in some cases (e.g., a limited coverage of parallactic angle for the calibrator), it may not be possible to be performed. To avoid this worst-case scenario…

Instrumentation and Methods for Astrophysics · Physics 2023-04-05 E. Albentosa-Ruiz , I. Marti-Vidal

The two-point correlation function of the galaxy distribution is a key cosmological observable that allows us to constrain the dynamical and geometrical state of our Universe. To measure the correlation function we need to know both the…

Observations of polarization position angle ($\theta$) standards made from 2014 to 2023 with the High Precision Polarimetric Instrument (HIPPI) and other HIPPI-class polarimeters in both hemispheres are used to investigate their…

Observed cyclotron resonant scattering features (CRSFs) in X-ray pulsars (XRPs) exhibit strong variability. In the subcritical luminosity regime, the centroid energy ($E_{CRSF}$) and line width ($\sigma_{CRSF}$) often show positive…

High Energy Astrophysical Phenomena · Physics 2026-05-27 Prodromos Fotiadis , Nick Loudas , Nikolaos D. Kylafis , Joachim Trümper

Distributed calibration based on consensus optimization is a computationally efficient method to calibrate large radio interferometers such as LOFAR and SKA. Calibrating along multiple directions in the sky and removing the bright…

Instrumentation and Methods for Astrophysics · Physics 2021-10-29 Sarod Yatawatta

In this paper we study the joint determination of source and background flux for point sources as observed by digital array detectors. We explicitly compute the two-dimensional Cram\'er-Rao absolute lower bound (CRLB) as well as the…

Instrumentation and Methods for Astrophysics · Physics 2023-11-22 Mario L. Vicuña , Jorge F. Silva , Rene A. Mendez , Marcos E. Orchard , Sebastian Espinosa , Jeremy Tregloan-Reed
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