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Context: The timescale of a microlensing event scales as a square root of a lens mass. Therefore, long-lasting events are important candidates for massive lenses, including black holes. Aims: Here we present the analysis of the Gaia18cbf…

Positions and proper motions of Gaia sources are expressed in a reference frame that ideally should be non-rotating relative to distant extragalactic objects, coincident with the International Celestial Reference System (ICRS), and…

Instrumentation and Methods for Astrophysics · Physics 2020-05-15 Lennart Lindegren

We present a new calculation of the intergalactic $\gamma$-ray pair-production absorption coefficient as a function of both energy and redshift up to the redshift of 3C279, z = 0.54. In reexamining this problem, we make use of new…

Astrophysics · Physics 2009-10-28 F. W. Stecker , O. C. de Jager

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…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Takuya Akahori , B. M. Gaensler , Dongsu Ryu

We study the alignment of radio galaxies axes using the FIRST catalogue. we impose several cuts in order to select the candidates which are most likely to be free of systematic bias. In our study we primarily focus on testing for alignment…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-07 Mohit Panwar , Prabhakar , Pritpal Kaur Sandhu , Yogesh Wadadekar , Pankaj Jain

We extend previous works by considering two additional radio frequencies (K band and X/Ka band) with the aim to study the frequency dependence of the source positions and its potential connection with the physical properties of the…

Instrumentation and Methods for Astrophysics · Physics 2021-08-18 Niu Liu , Sebastien Lambert , Patrick Charlot , Zi Zhu , Jia-Cheng Liu , Nan Jiang , Xiao-Sheng Wan , Cheng-Yu Ding

Spectrographs nominally contain a degree of quasi-static optical aberrations resulting from the quality of manufactured component surfaces, imperfect alignment, design residuals, thermal effects, and other other associated phenomena…

Instrumentation and Methods for Astrophysics · Physics 2021-07-28 Eric B. Bechter , Andrew J. Bechter , Justin R. Crepp , Jonathan Crass

The global astrometric observations of a GAIA-like satellite were modeled within the PPN formulation of Post-Newtonian gravitation. An extensive experimental campaign based on realistic end-to-end simulations was conducted to establish the…

There are by now ten published detections of fast radio bursts (FRBs), single bright GHz-band millisecond pulses of unknown origin. Proposed explanations cover a broad range from exotic processes at cosmological distances to atmospheric and…

This paper discusses the effects of gravitational waves on high-accuracy astrometric observations such as those delivered by Gaia. Depending on the frequency of gravitational waves, two regimes for the influence of gravitational waves on…

High Energy Astrophysical Phenomena · Physics 2018-02-14 Sergei A. Klioner

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…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Takuya Akahori , Kohei Kumazaki , Keitaro Takahashi , Dongsu Ryu

OCARS (Optical Characteristics of Astrometric Radio Sources) is a compiled catalog of various additional data associated with astrometric radio sources whose coordinates have been determined from very long baseline interferometry (VLBI)…

Instrumentation and Methods for Astrophysics · Physics 2025-05-20 Zinovy Malkin

We estimate the biases caused by the coherent deflection of cosmic rays due to the Galactic magnetic field (GMF) in maximum-likelihood analysis for searches of ultrahigh-energy cosmic ray (UHECR) sources in the literature. We simulate mock…

High Energy Astrophysical Phenomena · Physics 2023-06-14 Ryo Higuchi , Takashi Sako , Toshihiro Fujii , Kazumasa Kawata , Eiji Kido

Spectrophotometric distances to stars observed by large spectroscopic surveys offer a crucial complement to parallax distances that remain very important also after the future Gaia data releases. Here we present a probabilistic approach to…

Astrophysics of Galaxies · Physics 2018-09-11 Johanna Coronado , Hans-Walter Rix , Wilma H. Trick

In this study, we compared results of determination of the orientation angles between celestial reference frames realized by radio source position catalogues using three methods of accounting for correlation information: using the position…

Instrumentation and Methods for Astrophysics · Physics 2019-07-30 Yulia Sokolova , Zinovy Malkin

The Gaia mission has been designed to perform absolute astrometric measurements with unprecedented accuracy; the end-of-mission parallax standard error is required to be 30 micro-arcseconds for a G2V type star of magnitude 15. These…

Instrumentation and Methods for Astrophysics · Physics 2015-05-30 Thibaut Prod'homme , Berry Holl , Lennart Lindegren , Anthony G. A. Brown

In this paper, we propose to use the scatter of celestial pole offset (CPO) series obtained from VLBI observations as a measure of the accuracy of the celestial reference frame (CRF) realizations. Several scatter indices (SIs) including…

Geophysics · Physics 2013-01-03 Zinovy Malkin

ESA's Global Astrometric Interferometer for Astrophysics (GAIA) holds the promise of mapping out the detailed phase space structure of the Galactic halo by providing unprecedented annual proper motion and parallax of $1-10\muas$ astrometric…

Astrophysics · Physics 2007-05-23 HongSheng Zhao , Kathryn Johnston , Lars Hernquist , David Spergel

The ESA Gaia mission uses two telescopes to create the most ambitious survey of the Galaxy. The angle between them must be known with exquisite precision and accuracy. An interferometer: the Basic Angle Monitoring system measures its…

Instrumentation and Methods for Astrophysics · Physics 2017-07-03 Alcione Mora , Ulrich Bastian , Michael Biermann , François Chassat , Lennart Lindegren , Iñaki Serraller , Edmund Serpell , Wouter van Reeven

The infrared-radio correlation (IRRC) offers a way to assess star formation from radio emission. Multiple studies found the IRRC to decrease with increasing redshift. This may in part be due to the lack of knowledge about the possible radio…