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Current projects 2021-2022

Monitoring of the Galactic X-ray binaries with relativistic jets (SAO RAS, Russia). Regular measurements of flux densities, construction and study of light curves and instantaneous spectra of the microquasars - X-ray binary systems with relativistic jets - at the frequencies 1.25-30 GHz. The main tasks are detection and study of the radio flare properties, research of periodicities via light curve measurements, and relationships with other ranges of the electromagnetic spectrum (X-rays, optics, IR and gamma rays with energies from GeV to TeV). The sample includes the brightest microquasars: SS433, Cyg X-3, GRS1915+105, LSI+63d303, and rare transient sources V404 Cyg. 

The radio properties of OH Megamaser galaxies (Guizhou University, China). The OHM emission is found in luminous infrared galaxies (LIRGS) or ultra luminous infrared galaxies (ULIRGs). The dominant energy source in the central regions of LIRGs and ULIRGs are either starburst or an active galactic nucleus, and they very likely represent an important link between starburst galaxies and the AGN phenomena. In this project the RATAN quasi-simultaneous measurements are used to study the multi-band radio properties of OHM galaxies in order to understand the fraction of thermal and non-thermal emission and present a rough classification of each source. 

Radio properties of the Narrow-Line Seyfert 1 Galaxies (Metsahovi Radio Observatory, Finland). Narrow Line Seyfert type 1 galaxies are a type of non-Doppler beamed active galaxies, in contrast to highly beamed and variable blazars. They have exceptionally small widths of the broad hydrogen Balmer lines (FWHM (H_{β}) < 2000 km s^-1) and are seemingly very different objects than blazars; they have lower black hole masses (10^6-10^7 M_ʘ), higher accretion rates and a different host galaxy morphology. Most NLS1 galaxies are also radio quiet and only roughly 7% of them are radio loud. A strong candidate to explain the radio loudness was from the beginning relativistic beaming occurring in the prospective jets. Before jets have been associated with objects with elliptical host galaxies, while NLS1 galaxies were predominantly spiral. A major breakthrough in the field occurred in 2008, when the first NLS1 galaxy was detected at gamma-rays. The long-term radio monitoring is needed to obtain the broadband radio spectra and variability properties. Knowing the type of the radio spectrum could help to select gamma-ray-emitting NLS1 candidates and samples of NLS1 to identify and study their jets with VLBI.

IceCube trigger: monthly monitoring of the new high-energy neutrino candidates (Institute for Nuclear Research, Russia). Analysis of radio data (Plavin et al. 2020, 2021) revealed that high-energy neutrinos can be produced in the nuclei of active galaxies (AGNs) with radio-bright compact jets, and several such events have been identified. To continue the research, we propose to regularly monitor AGNs falling into the coordinate error ellipses of new neutrino detections with the IceCube observatory. Each new neutrino candidate will be observed monthly for a year after the neutrino discovery. This will allow us to check the found correlation for AGN radio outbursts with neutrino events, to refine and significantly limit the models of the high-energy neutrinos origin, and to significantly increase the number of confirmed identifications of neutrino events with AGNs.

RATAN-600 in multichannel astronomy: a complete sample of AGNs with VLBI-compact jets as indicators of high-energy neutrinos (ASC, Russia). A complete VLBI sample of 600 active galactic nuclei as possible sources of high-energy neutrinos is studied. The RATAN-600 radio spectra, VLBI structure, their variability and relationship with current neutrino events detected with Ice Cube observatory are being studied using new methods of analysis (Plavin et al., 2020, 2021; Kovalev et al., 2000, 2020). The research is based on IceCube neutrino events and their cross-identification with the VLBI catalogue objects, continuous AGN radio spectra at wavelengths 1.4-24 cm and their analysis. It is planned to check and further study the recently discovered connection of neutrino events with compact nuclei of active galaxies, to assess the significance of the connection between neutrinos and active galaxies. Purpose: determination of the characteristics of relativistic jets and study of the nature of AGN, localization of the zone of protons acceleration to relativistic velocities and generation of high-energy neutrinos, joint analysis of spectra, VLBI structure of active galaxies and neutrino events.

Spectra of FR0 galaxies in the centimeter range (SAO RAS, Russia). FR0 radio galaxies with a compact radio structure are the dominant population of radio-loud AGNs in the nearby Universe. Relativistic jets were found on parsec scales in most of the objects. For FR0 galaxies, a flat spectrum is characteristic; however, few quasi-simultaneous data have been obtained. Within the framework of the program, it is planned to obtain continual radio spectra of objects in the 1.25-22.3 GHz frequency range, to study the features of variability. The program will also clarify the possible relationship between FR0 galaxies and GPS sources.

Monitoring SRGE J170245.3 + 130104 - the most powerful X-ray quasar at z> 5 (IKI RAS, Russia). The first supermassive black holes in the early Universe and the relationship between their growth and the first galaxies formation is a topical issue in astrophysics. In this study the radio properties of the X-ray quasar SRGE J170245.3+130104 at z~5.5 is planned. The object was discovered using the SRG X-ray observatory and the 6-m BTA telescope and turned out to be the most powerful in X-rays among the known objects at z> 5, as well as one of the most powerful in radio. Systematic measurements with RATAN-600 will make it possible to measure the continuum radio spectrum of the quasar, to establish the presence and level of variability at radio frequencies. Radio data combined with measurements from other electromagnetic spectrum ranges can reveal the object nature.

Multifrequency monitoring of blazar variability on long time scales (Shanghai Astronomical Observatory, China). Long-term monitoring of BZCAT blazars with the RATAN-600 at 1.3-22 GHz, the total number of objects is 1650. Objectives: comparative analysis of the blazar subclasses properties based on their SED features (spectral energy distribution); variability analysis of bright and faint representatives at different time scales by cross-correlating light curves in different ranges; monitoring of the WEBT blazars list for which both archive measurements and operative observations are relevant; light curves analysis, expansion of the interactive BLcat catalogue.

Radio spectra and variability of quasars at z4 (SAO RAS, Russia). High redshift quasars are important to study because they provide information about the growth of supermassive black holes and the evolution of active galactic nuclei (AGNs). Discovery of the most distant radio loud blazar PSOJ047.4478+27.2992 at z = 6.1 (Belladitta et al., 2020), which is also the brightest radio source in gamma rays, reveals the compact objects at z>6 can have a relativistic jet. Observations with RATAN (Mufakharov et al. 2021) and VLA (Spingola et al. 2020) in 2020 confirmed a flat radio spectra at 1.4-8.2 GHz (α =-0.4±0.1) and we consider J0309+27 as a compact steep-spectrum or a megahertz-peaked spectrum (CSS/MPS) object. The purpose of our observations is a study of non thermal radio emission of distant quasars at z>4, estimation of their flux density variability at the time scale of several years at the frequency range of 1.2-22 GHz, study of radio loudness and a relation between redshift and some radio parameters.

Joint studies of the chromosphere and the transition region of sunspots on the ALMA and RATAN-600 interferometer (New Jersey Institute of Technology, USA). The application is for the Sun multi-azimuth observations as part of joint solar observations in December 2021 at the Atacama Large Millimeter / Submillimeter Array (ALMA). The use of observations at millimeter (ALMA) and centimeter (RATAN-600) wavelengths will make it possible to carry out a detailed study of the thermal structure of the chromosphere and the transition region to the corona in sunspots. The use of data from the optical and UV wavelengths will facilitate the integration of the results obtained in the radio range into the complete picture of the structure of the sunspot atmosphere from the lowest photospheric layers to coronal heights. The requested observation period corresponds to the ALMA interferometer configuration period for solar observations.

Supplementing the Coronal-like jet events extended catalogue with RATAN-600 observational data (SAO RAS, Russia). In the near future, observations of individual regions of the Sun due to the modernized Spectral Polarization Complex (SPC) of RATAN-600 and the newly mastered methodology for long term tracking will supplement the Coronal-like jet events extended catalogue. The catalog in its primitive form is available on the SPbF SAO website at http://prognoz2.sao.ru/coronal-jets-catalog and summarize data obtained with the Solar dynamics observatory (SDO) and ground-based optical and radio telescopes and spectrometers, including RATAN-600, SRG and NoRH. For some events, data on the reconstructed magnetic field are also provided. The Catalog of hot jets in the solar corona was developed with the aim of providing a unified multiwavelength information for further statistical analysis, determination of characteristic jet parameters, and for further in-depth study of individual events by all the interested researchers.

Structure and evolution of solar active regions (University of Ioannina, Greece). Daily observations of the Sun with RATAN-600 at five azimuths in order to study the structure and the evolution of solar active regions (AR) and the inversion of the circular polarization are proposed. At the same time, we are analyzing RATAN-600 observations of AR plages in conjunction with ALMA full-disk images at 1.3 and 3 mm, as well as Nobeyama (NoRH) images at 1.7 cm. The analysis of the observations will provide improved information on the electron density, the electron temperature and the magnetic field as a function of height and their variation with the AR development. RATAN-600/ALMA/NoRH observations will enable us to propose improved models of AR plages from the low chromosphere to the transition region. It is expected to reveal small-scale energy release events relevant to the heating of the upper solar atmosphere.

Development of the determining physical conditions methods on the Sun flare-active regions (St. Petersburg State University, Russia). Development of methods for determining the electron temperature, density, and magnetic fields in active regions from the parameters of microwave emission measured with RATAN-600: revealing the features of the magnetic fields and its structure and dynamics in flare-active regions, improving the direct method for determining the topology of magnetic fields in active regions using spectral measurements data, determination of atmospheric parameters over active regions in the non-flare period.

Investigation of coronal plasma parameters during solar flares in the decimeter wavelength range (SAO RAS, Russia). The comletion of the planned technical modernization work is facilitating the realization of decimeter wavelength observations with high temporal and spectral resolutions. In the last two years, the southern sector with the periscopic flat mirror in conjunction with the feed cabin №-3 was used to demonstrate a new way of tracking the selected active regions of the Sun for a much longer period. Such tracking has tremendous applicability given the high spectral resolution of RATAN-600 as it opens a new possibility for registering the quasiperiodic pulsations and other transient coronal processes during solar flares. However further testing and analysis during actual observations will be conducted in order to assess the important characteristics of the spectral complex which will help to finalize the optimal methodology for long term tracking of the select regions of the Sun. The data obtained in such observations will help us diagnose the coronal plasma parameters and help us stimulate research in the field of quasiperiodic pulsations, which is one of the intensely studied phenomena in the context of coronal seismology.

Investigation of weak solar activity using the microwave solar observations (ISTP SB RAS, Russia). Study of background quasi-stationary processes in the solar atmosphere that form solar wind streams that constantly affect the Earth's magnetosphere and a detailed research of explosive processes in the solar atmosphere, leading to the ejection of accelerated particles, plasma fluxes and hard X-rays. The emphasis is supposed to be made on the study of ultra-weak manifestations of solar activity - events of class A, B on the GOES scale, which became available as a result of the modernization of the SSRT.

Correlational analysis between preflare CaII K and radio plages (SAO RAN, Kislovodsk Solar Station Ras, Kalmyk State University, Russia). Kislovodsk’s Solar Optical Patrol Telescope (SPOT) regularly monitors the solar chromosphere on a daily basis with a time cadence of 3 minutes. The observations are made in CaII K line and they show an interesting preflare spectral line evolution. As the solar chromosphere and corona are radio permeable, we must proceed with patrol radio observations of the associated radio plages for understanding the nature of such a preflare evolution. Using the RATAN-600‘s Solar Spectral Polarization Complex (SSPC), we can make Sun tracking radio observations with a time cadence similar to that of SPOT which in conjunction with the SPOT will help us make comparative analysis of the data. Such a comparative analysis will provide a better idea of physical mechanisms responsible for the observed transformation of the CaII K line before the onset of a solar flare.
Call for Proposals
Observational proposals are accepted via an interactive form twice a year: from February 1 to March 10 and from August 1 to September 10.