Copper (II) Speciation in a Freshwater Ecosystem

Results of chemico-biological experiments in a natural water body with the use of model systems with Cu (II) introduced in them at different proportions of its chemical forms (natural and simulated) in the solution. The model forms used in the experiments were Cu complexes with benzyl- and hexadecylmalonic acids, simulating low-molecular dissolved organic substances. The experimental conditions were chosen based on a preliminary calculation using WATEQ–4f program. The complexes of Cu with hexadecylmalonic acid are found to be absorbed by suspensions and removed into bottom sediment more actively than other Cu forms. The toxicity of introduced Cu for the phyto- and zooplanktonic communities is found to depend on the concentration of Cu²⁺ aqua-ions in the solution, in the presence of which the higher concentrations of complexes with malonic acids do not exert their toxic effect.     

Particle acceleration test with Cas A multiwavelength emission

The investigation of supernova remnants (SNRs) across the electromagnetic spectrum from radio up to very high energy gamma-rays can serve as a test of the particle acceleration and touches on one of the unresolved problems of modern astrophysics, namely the origin of cosmic rays and the Galaxy's contribution to the overall cosmic ray spectrum. The multiwavelength observations of Cas A SNR demonstrated that structure and spectral features have clear signs of young SNRs and its overall properties make this object the best target to test a hypothesis of cosmic ray origin in SNRs. Studies of Cas A at very high energies by SHALON telescope showed the location of TeV gamma-ray emission region relative to the position of reveres shock. Also, the spectral energy distribution was obtained at high and very high energies. To describe the spectral and structural features of this SNR viewed in non-thermal emission, two approaches involving reverse and also both reverse and forward shocks to the mechanism of diffusive shock acceleration of cosmic rays in Cas A were applied. It is demonstrated that the observational properties of Cas A are well reproduced by the hadronic model with significant contribution of both the forward and reverse shocks in the generation of broadband emission. Calculation results suggest that the very high efficiency of particle acceleration in Cas A, which value is up to 25% of the supernova explosion energy with energy of accelerated particles not exceeding of $$ eV. Whereas, the forward shock model predicts the spectral characteristics of the TeV-gamma-emission corresponding to ones detected at 800 GeV–40 TeV that are the evidence of acceleration of the hadronic cosmic rays in shells of SNRs up to $$ eV     

Manifestation of the gothenburg geomagnetic field excursion in sediments on the northwestern Central Russian Upland

A paleomagnetic study of sediments at the Baranova Gora and Podol III/1 archaeological sites, located near Lake Volgo on the northwestern Central Russian Upland (56.9°N, 33.2°E), was performed. The paleomagnetic studies at both sites for the first time revealed the development of the Gothenburg geomagnetic excursion (dated 13000-12350 BP) in this region. This made it possible to specify the time interval when the Alleroed climatic phase started developing on the Central Russian Upland.     

Numerical studies on alluvia settlement, considering hydrodynamic interaction

The paper addresses the model problem on the motion of alluvia clouds in an infinite fluid. Deposition fractions are described in close relationship with one another. For this type of calculation, only the finiteness of particles dimensions is taken into consideration. The motion of alluvia has been found to be closely dependent on the ratio between the size of granules. Time dependence of separation periods of fractions on the dimensionless radius for different densities of samples has been studied. It has been established that for particles of similar dimensions, calculation of the rate of sedimentation using Stokes's formula is not possible. Translated by Vladimir A. Puchkin.     

Very High Energy Emission from the Binary System Cyg X-3

Cyg X-3 is actively studied in the entire range of the electromagnetic spectrum from the radio band to ultrahigh energies. Based on the detection of ultrahigh-energy gamma-ray emission, it has been suggested that Cyg X-3 could be one of the most powerful sources of charged cosmic-ray particles in the Galaxy. We present the results of long-term observations of the Cygnus Х-3 region at energies 800 GeV–100 TeV by the SHALON mirror Cherenkov telescope. In 1995 the SHALON observations revealed a new Galactic source of very high energy gamma-ray emission coincident in its coordinates with the microquasar Cyg X-3. To reliably identify the detected source with Cyg X-3, an analysis has been performed and an orbital period of 4.8 h has been found, which is a signature of Cyg X-3. A series of flares in Cyg X-3 at energies >800 GeV and their correlation with the activity in the X-ray and radio bands have been observed. The results obtained in a wide energy range for Cyg X-3, including those during the periods of relativistic jet events, are needed to find the connection and to understand the different components of an accreting binary system.     

Emission from the galaxy NGC 1275 at high and very high energies and its origin

The Seyfert galaxy NGC 1275 is the central, dominant galaxy in the Perseus cluster of galaxies. NGC1275 is known as a powerful source of radio and X-ray emission. The well-known extragalactic object NGC 1275 has been observed by the SHALON high-altitude mirror Cherenkov telescopes within the framework of long-term studies of metagalactic gamma-ray sources. In 1996, the SHALON observations revealed a new metagalactic source of very high energy gamma-ray emission coincident in its coordinates with the galaxy NGC 1275. Having analyzed the SHALON data, we have determined such characteristics of NGC 1275 as the spectral energy distributions and images at energies >800 GeV for the first time. The results obtained at high and very high energies are needed for understanding the emission generation processes in an entire wide energy range.     

Supernova remnants: The Crab Nebula,Cassiopeia A,and Tycho as sources of cosmic rays in our galaxy

We present the results of our observations of two types of Galactic supernova remnants with the ShALON mirror Cherenkov telescope: the plerion Crab Nebula and the shell-type supernova remnants Cassiopeia A and Tycho. The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (0.8–100 TeV) gamma rays in Tycho’s supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is different in origin.     

Studies of bright flat-spectrum radio quasar 3C 454.3 at high and very-high-energies

Blazars are the subclass of active galactic nuclei (AGNs) which includes the Flat Spectrum Radio Quasars (FSRQ) and BL Lacertae (BL Lac) objects. Variability on the short- and long-time scale in all the wide energy ranges from radio up to gamma-ray emission is a special characteristic of blazars. Multi-wavelength studies of the flaring activity and variability of blazars can serve as a tool to probe the physical properties of the near the core regions and processes responsible for the observed features. 3C 454.3 is a bright FSRQ that is intensively studied through the wide range of electromagnetic spectrum. It has shown remarkably high activity since 2000. The long-term observations of 3C 454.3 at 800 GeV–100 TeV energies with the SHALON telescope were started in 1998 year. A number of activity periods were found. The most significant flaring state of 3C 454.3 at TeV energies was detected in the SHALON observational period of November–December 2010. This increase is correlated with the flares at a lower energy range in observations of Fermi-LAT. The direct association of the significant changes of gamma-ray flux with strong core radio flares are not clear but observed correlations and lags in multi-wavelength activity may point to the complexity of the emission processes in blazars connected with disturbance propagating in the jet.     

The Gothenburg geomagnetic excursion as a chronological marker for the Allerød interstadial in the Central Russian Upland

Palaeomagnetic investigations of deposits at the Baranova Gora archaeological site located near Volgo Lake (56.9°N, 33.2°E) in the Central Russian Upland have been carried out. The palaeomagnetic studies have revealed the development of the Gothenburg geomagnetic excursion dated at 13000–12350 BP. Revealing the Gothenburg excursion allowed us to use the findings of the palaeomagnetic investigations as a chronological benchmark, in addition to the results of palynological and archaeological (comparative analysis of archaeological artifacts) methods of dating the cultural layers of this archaeological monument, as well as to refine the time frame of the climatic Allerød interstadial in the Central Russian Upland. The data obtained in our study indicate that the Allerød interstadial in the Central Russian Upland began several hundred years before 12000 BP, the date commonly believed to be the beginning of the Allerød interstadial.