Scientific achievements in 2021
Detection of close periodicities due to orbital and precession modulation of radio emission from jets in the microquasar LSI+61d303
The RATAN-600 radio telescope monitored the radio emission from a microquasar, a gamma source, an X-ray optical binary star LSI+61d303, which includes a Be star and a black hole (BH). For over a hundred consecutive orbital periods (26.5 days) during 2013-2021, periodic flares were detected at frequencies of 4.8 and 11.2 GHz, 3-4 days after the closest approach of the components. As a result of the intense matter flow accreting on the BH, powerful jet ejections (jets) are formed, in which radio emission and, probably, gamma rays are generated. It was found from the orbital light curve averaged over many periods that the radio emission evolves from an optically thick state at the beginning of the flare to an optically thin state, when the radio spectrum becomes steepest; then the system returns to the flat spectrum characteristic of a compact jet. This process is due to the generation of relativistic electrons in strong shock waves traveling along the gas flow of a jet and is in good agreement with the theory of the evolution of synchrotron radiation. A noticeable shift in the moments of the maximum radio flux of flares was found, as the phase of the visible 4.6-year period changed, which is easily explained in the model of precessing jets.
But the main result of many years of research was the discovery in the power spectrum of the light curves of two close periods, equal to 26.49 and 26.93 days. The first harmonic exactly corresponds to the previously found orbital period of the system; the second harmonic is due to the modulation of the radio flux due to the precessional motion of the jet. It is precisely the beating of close frequencies of these periods that explains the super-orbital 4.6-year period in the system, and the model of precessing relativistic jets in LSI+61d303 was unambiguously confirmed.
Authors: Trushkin S.A., Shevchenko A.V., Nizhelskij N.A., Tsybulev P.G. (SAO RAS)
1. Trushkin et al. Long-term multi-frequency studies of flaring activity from microquasars. Open Astronomy, 2021, 4pp, in press.
2. Trushkin et al. Monitoring of Microquasars with RATAN-600 Ground-Based Astronomy in Russia. 21st Century, Proceedings of the All-Russian Conference held 21-25 September, 2020 in Nizhny Arkhyz, Russia. Edited by I.I. Romanyuk, I.A. Yakunin, A.F. Valeev, D.O. Kudryavtsev, 2020, p.351-354.
3. Trushkin et al. The Jets of Microquasars during Giant Flares and Quiet State. 2017, Galaxies, vol.5, issue 4, p.84
Interactive catalog of blazar measurements at RATAN-600
In 2021, an interactive catalog of multifrequency (1.1-22.3 GHz) measurements of blazars at the RATAN-600 was developed: "RATAN-600 multi-frequency catalog of blazars". The catalog is hosted in www.sao.ru/blcat and is a modernized version of the electronic catalog of BL Lacertae objects (Mingaliev et al., 2014). The new catalog contains all types of blazars (blazars, flat-spectrum quasars, and blazars of an undetermined type) from the BZCAT blazar catalog (Massaro et al., 2009) and includes measurements of more than 1600 objects. The catalog contains the radio spectra and light curves of blazars obtained with the RATAN-600 SAO RAS in 2004-2021; measurements in the radio continuum from external sources connected from the CATS and NED databases are available for export. Basic information about objects (the coordinates, redshifts, blazar type, magnitude, and radio luminosity) is presented in the main table. Radio luminosities, spectral and variability indices, statistics on the main parameters of the sample are interactively calculated and available for export; objects with a radio emission variability of 200% at a frequency of 11 GHz on a scale of two years are indicated. The catalog is systematically updated with new measurements and is an effective tool for studying the statistical properties of large samples of blazars and for studying individual objects using long-term light curves.
Authors: Sotnikova Yu.V., Mufakharov T.V., Mingaliev M.G., Udovitskiy R.Yu., Semenova T.A., Erkenov A.K., Bursov N.N., Mikhailov A.G. (SAO RAS)
1. Mufakharov T., Sotnikova Y., et al., The RATAN-600 multi-frequency catalogue of blazars, 2021, MNRAS, submitted
2. Sotnikova Yu., Udovitsky R., Mufakharov T., state registration of the database "RATAN-600 multi-frequency data for blazars, edition 1.3", Certificate No. 2021621910 dated 09.09.2021.
3. Sotnikova Yu., Mufakharov T., Udovitsky R. et al., Filing of an international application for the invention "Method of compiling a catalog of measurements of radio emission parameters of blazars", Application No. PCT/RU2021/000473 dated 29.10.2021.
4. Mingaliev M., Sotnikova Yu., Udovitskiy R., et al., RATAN-600 multi-frequency data for the BL Lacertae objects, Astronomy & Astrophysics, 572, id.A59, 4 pp., 2014.