Том 63, № 1 (2019)

The scenario of a merger of two black holes surrounded by an accretion disk is considered. As a result of the emission of gravitational waves, the mass of the central object decreases, and the accretion disk is perturbed. Computational results show that the main consequence of this perturbation is the formation of a shock propagating from the center to the periphery of the disk. The light curve is calculated and the duration of the flare estimated, assuming that the flare ends when the luminosity decreases to its initial value. If themass of the merging binary is 55M_⊙ (as in the case ofGW170814), the flare from the shock will lead to an increase in the disk’s bolometric luminosity by four to six orders of magnitude, up to 10⁴⁵ erg/s (an absolute magnitude of −23.8^m). With a source distance of 540Mpc and reasonable assumptions about the parameters of the accretion disk, the apparent brightness of the flare at the maximum of the spectral flux density should be 12.8^m−14.2^m, and the duration of the flare should be several minutes. The main radiation flux from the shock lies in the X-ray and gamma-ray ranges. In the spectral band of the XMM-Newton EPIC instrument or the eROSITA telescope of the Spectr-RG Observatory (0.3−10 keV), the luminosity will increase by three to four orders of magnitude (7.5^m−10^m), up to 10⁴⁴ erg/s, corresponding to an apparent magnitude of approximately 17^m. The luminosity is maximum in the observing band of the INTEGRAL IBIS instrument (20 keV−10 MeV), where it is 10⁴⁴−10⁴⁵ erg/s, corresponding to an apparent flux of 10⁻⁴ photons cm⁻² s⁻¹ keV⁻¹ at 100 keV. There is almost no brightening starting from the far ultraviolet and continuing towards longer wavelengths: the lumnosity at 10 eV grows by about a factor of two, corresponding to an absolute magnitude of −6^m and a visual magnitude of 32^m.

A means of generating the radio emission of polars is proposed, based on cyclotron radiation of thermal electrons in a fluctuating magnetic field. The source of these fluctuations is Alfvén turbulence. Expressions for the radiation spectrum and degree of polarization are obtained. The radio flux from the accretion flow is computed, using the polar AM Her as an example. The proposed model for the emission can reproduce the observed fluxes in the VLA frequency range with realistic plasma characteristics.

The results of long-term monitoring of the Galactic maser source IRAS 18316–0602 (G25.65+1.05) in the water-vapor line at frequency f = 22.235 GHz (6₁₆–5₂₃ transitioin) carried out on the 22-m Simeiz, 26-m HartRAO, and 26-m Torun radio telescopes are reported. The source has been episodically observed on the Simeiz telescope since 2000, with more regular observations beginning in 2017. A double flare was observed beginning in September 2017 and continuing to February 2018, which was the most powerful flare registered over the entire history of observations of this object. Most of the monitoring of the flare was carried out in a daily regime. Detailed analysis of the variations of the flux density, which reached a maximum value P ≈ 1.3 × 10⁵ Jy, have led to important scientific conclusions about possible mechanisms for the emission in this water line. The exponential growth in the flux density in this double flare testifies that it was associated with a maser that was unsaturated right up to the maximum flux densities observed. An additional argument suggesting the maser was unsaturated is the relatively moderate degree of linear polarization (≈30%), nearly half the value displayed by the Galactic kilomasers in Orion KL. The accurate distance estimate for IRAS 18316–0602 (12.5 kpc) and the flux density at the flare maximum (≈1.3 × 10⁵ Jy) makes this the most powerful Galactic kilomaser known. The double form of the flare with exponential rises in flux density rules out the possibility that the flare is the effect of directivity of a radiation beam relative to the observer. The physical nature of the flare is most likely related to internal parameters of the medium in which the maser clumps radiating in the water line are located. A rapid, exponential growth in the flux density of a kilomaser and associated exponential decays requires the presence of an explosive increase in the density of the medium and the photon flux, leading to an increase in the temperature by 10–40 K above the initial base level. A mechanism for the primary energy release in IRAS 18316–0602 is proposed, which is associated with a multiple massive star system located in a stage of evolution preceding its entry onto the main sequence. A flare in this object could initiate gravitational interaction between the central star and a massive companion at its periastron. The resulting powerful gravitational perturbation could lead to the ejection of the envelope of the central supermassive star, which gives rise to an explosive increase in the density and temperature of the associate gas–dust medium when it reaches the disk, where the maser clumps are located.