LG

L. Gurvits

126 records found

The Black Hole Explorer

Astrophysics Mission Concept Engineering Study Report

The Black Hole Explorer (BHEX) mission will enable the study of the fine photon ring structure, aiming to reveal the clear universal signatures of multiple photon orbits and true tests of general relativity, while also giving astronomers access to a much greater population of bla ...
We present an overview of the operations and engineering interface for Planetary Radio Interferometry and Doppler Experiment (PRIDE) radio astronomy observations as a scientific component of the ESA’s Jupiter Icy Moons Explorer (JUICE) mission, as well as other prospective planet ...
Context. High-redshift blazars provide valuable input to studies of the evolution of active galactic nuclei (AGN) jets and provide constraints on cosmological models. Detections at high energies (0.1a< Ea< 100 GeV) of these distant sources are rare, but when they exhibit br ...
In the coming decade, JUICE and Europa Clipper radio-science will yield the most accurate estimation to date of the Galilean moons’ physical parameters and ephemerides. JUICE's PRIDE (Planetary Radio Interferometry and Doppler Experiment) will help achieve such a solution by prov ...
There is still a limited number of high-redshift (z > 3) active galactic nuclei (AGNs) whose jet kinematics have been studied with very long baseline interferometry (VLBI). Without a dedicated proper motion survey, regularly conducted astrometric VLBI observations of bright ra ...
Context. The existence of accreting supermassive black holes of up to billions of solar masses at early cosmological epochs (in the context of this work, redshifts z & 6) requires very fast growth rates that are challenging to explain. The presence of a relativistic jet can b ...

A Gamma-Ray Flare from TXS 1508+572

Characterizing the Jet of a z = 4.31 Blazar in the Early Universe

Blazars can be detected from very large distances due to their high luminosity. However, the detection of γ-ray emission of blazars beyond z = 3 has only been confirmed for a small number of sources. Such observations probe the growth of supermassive black holes close to the peak ...
We present the state of the art on the study of surfaces and tenuous atmospheres of the icy Galilean satellites Ganymede, Europa and Callisto, from past and ongoing space exploration conducted with several spacecraft to recent telescopic observations, and we show how the ESA JUIC ...
The JUpiter ICy moons Explorer (JUICE) of ESA was launched on 14 April 2023 and will arrive at Jupiter and its moons in July 2031. In this review article, we describe how JUICE will investigate the interior of the three icy Galilean moons, Ganymede, Callisto and Europa, during it ...
We present total intensity and linear polarization images of OJ 287 at 1.68 GHz, obtained through space-based very long baseline interferometry (VLBI) observations with RadioAstron on April 16, 2016. The observations were conducted using a ground array consisting of the Very Long ...
This paper introduces the first results of observations with the Ultra-Long-Wavelength (ULW) —- Low Frequency Interferometer and Spectrometer (LFIS) on board the selenocentric satellite Longjiang-2. We present a brief description of the satellite and focus on the LFIS payload. Th ...
Recent advances in technology coupled with the progress of observational radio astronomy methods resulted in achieving a major milestone of astrophysics - a direct image of the shadow of a supermassive black hole, taken by the Earth-based Event Horizon Telescope (EHT). The EHT wa ...
Context. Stellar occultations currently provide the most accurate ground-based measurements of the positions of natural satellites (down to a few kilometres for the Galilean moons). However, when using these observations in the calculation of satellite ephemerides, the uncertaint ...
We present results from the first 22 GHz space very long baseline interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of the Nearby AGN Key Science Program, the source was observed in 2014 February at 22 GHz with 21 ground stations, reaching projected (u, ...

J2102+6015

An intriguing radio-loud active galactic nucleus in the early universe

The powerful high-redshift quasar J2102+6015 (at z = 4.575) may provide useful information for studying supermassive black hole growth, galaxy evolution and feedback in the early Universe. The source has so far been imaged with very-long-baseline interferometry (VLBI) at 2/8 GHz ...
Arecibo excelled in three separate, major scientific areas, planetary science, space and atmospheric sciences, and astronomy. We envision a new, unparalleled facility, We present a concept for the Next Generation Arecibo Telescope (NGAT) — an innovative combination of a compact, ...
Supermassive black holes at the centre of active galactic nuclei power some of the most luminous objects in the Universe. Typically, very-long-baseline interferometric observations of blazars have revealed only funnel-like morphologies with little information on the internal stru ...
Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a multi-purpose experimental technique aimed at enhancing the science return of planetary missions. The technique exploits the science payload and spacecraft service systems without requiring a dedicated onboard ins ...
Over the past several years a number of high-resolution studies conducted with Earth-based and spaceborne very long baseline interferometry systems provided a large volume of experimental data on the phenomenon of supermassive black hole binaries. These objects manifest themselve ...
Radio-loud quasars at high redshift (z ≥ 4) are rare objects in the universe and rarely observed with Very Long Baseline Interferometry (VLBI). But some of them have flux density sufficiently high for monitoring of their apparent position. The instability of the astrometric posit ...