Features of Secular Changes in the Flux Density of the Cas a Supernova Remnant, from Centimeter to Decameter Wavelengths

Galaxies

Artem Gorbynov¹  Michail Ryabov²  Vladislavs Bezrukovs³  Arturs Orbidans³  Artem Sukharev³ 

[1] Department of Theoretical Physics and Astronomy, Odessa I.I. Mechnikov National University, Pastera Str. 42, 65023 Odessa, Ukraine;Odessa Observatory “URAN-4” of the Institute of Radio Astronomy NAS of Ukraine, Marazlievskaya Str. 1V, 65014 Odessa, Ukraine;Ventspils International Radio Astronomy Centre (VIRAC), Inzenieru Str. 101, LV-3601 Ventspils, Latvia;

关键词: secular radio flux decrease;    Cassiopeia A;    supernova remnant;   

DOI  :  10.3390/galaxies9020030

来源: DOAJ

【 摘 要 】

The purpose of this work is to summarize a large amount of observational data about the secular decrease of Cas A flux in the radio range, as an indicator of physical processes both in the source itself and as a consequence of the influence of the propagation medium. This paper presents results of observations Cas A and Cyg A on radio telescopes of International Radio Astronomy Center (Latvia), and URAN-4 phased array antenna (Institute of Radio Astronomy NAS of Ukraine). According to URAN-4 observations, there were seasonal–diurnal changes in Cas A/Cyg A flux ratios due to the effects of solar activity on the ionosphere, and there may be no secular decrease in Cas A flux density, or a weak tendency to decrease it. The significant influence of the ionosphere makes it difficult to use Cyg A as a reference source in the decameter radio range. In the centimeter radio range, there were episodic intra-day variations at the level 8–10% of Cas A averaged flux. Additionally, in the period January–February 2021, Cas A flux was about 1.7 times that of Cyg A. Taking into account the observed complex type of secular decrease in Cas A flux against the background of changes in space weather variations, further observations of Cas A were planned at radio observatories in Latvia and Ukraine.

【 授权许可】

Unknown