ﻻ يوجد ملخص باللغة العربية
We performed multi-frequency studies on the gigahertz-peaked spectrum high-redshift quasar 0858-279. Initially, the source presented itself at early VLBI images as a very peculiar resolved blob. We observed the quasar with the VLBA at 1.4-24 GHz in dual-polarization mode. The high spatial resolution and spectral index maps enabled us to resolve the core-jet structure and locate a weak and compact core by its inverted spectrum. The dominant jet component 20 parsecs away from the core was found to be optically thin above 10 GHz and opaque below it. We also estimated an uncommonly strong magnetic field in the bright jet feature which turned out to be around 3 G. Faraday rotation measure maps revealed high RM values over 6000 rad/m^2. Additionally, these maps allowed us to follow the magnetic field direction in the bright jet feature being perpendicular to the propagation direction of the jet. All the results strongly indicated the formation of a shock wave in the dominant component arising from an interaction with the surrounding matter. Using the proposed hypothesis as well as the core shift approach, we discovered that the magnetic field in the core region is of the order of 0.1 G.
The high redshift GPS quasar PKS 0858-279 exhibits the following properties which make the source unusual. Our RATAN-600 monitoring of 1-22 GHz spectrum has detected broad-band radio variability with high amplitude and relatively short time scale. In
The quasar 3C~286 is one of two compact steep spectrum sources detected by the {it Fermi}/LAT. Here, we investigate the radio properties of the parsec(pc)-scale jet and its (possible) association with the $gamma$-ray emission in 3C~286. The Very Long
We present broadband observations and spectral modeling of PKS B0008-421, and identify it as an extreme gigahertz-peaked spectrum (GPS) source. PKS B0008-421 is characterized by the steepest known spectral slope below the turnover, close to the theor
We investigate the sample of 213 GPS sources selected from simultaneous multi-frequency 1-22 GHz observations obtained with RATAN-600 radio telescope. We use publicly available data to characterize parsec-scale structure of the selected sources. Amon
Pulsars orbiting the Galactic center black hole, Sgr A*, would be potential probes of its mass, distance and spin, and may even be used to test general relativity. Despite predictions of large populations of both ordinary and millisecond pulsars in t