A. Biryukov

Monotonic and cyclic components of radio pulsar spin-down

In this article we revise the problem of anomalous values of pulsars’ braking indices nobs and frequency second derivatives ¨ ν arising in observations. The intrinsic evolutionary braking is buried deep under the superimposed irregular processes, that prevent direct estimations of its parameters for the majority of pulsars. We re-analyze the distribution of “ordinary” radio pulsars on a ¨ ν u ν, ¨ ν, u ν ν and nobs τch diagrams assuming their spin-down to be a superposition of a “true” monotonous and a symmetric oscillatory terms. We demonstrate that their effects may be clearly separated using simple ad hoc arguments. Using maximum likelihood estimator we derive the parameters of both components. We find characteristic timescales of such oscillations to be of order of 10 3 ...10 4 years, while its amplitudes are large enough to modulate the observed spin-down rate up to 0.5...5 times and completely dominate the second frequency derivatives. On the other hand, pulsars’ secular evolution is consistent with classical magnetodipolar model with braking index n � 3 So, observed pulsars’ characteristic ages (and similar estimators that depend on the observed u ν) are biased up to 0.5...5 times. This fact naturally resolves the discrepancy of characteristic and independently estimated physical ages of several objects, as well as explains very large, up to 10 8 years, characteristic ages of some pulsars. We suggest that these oscillations are caused by the long-term precession of neutron stars around its magnetic axis, probably driven by the anomalous braking torque.

Search for pairs of isolated radio pulsars—Components in disrupted binary systems

We have developed a method for analyzing the kinematic association of isolated relativistic objects-possible remnants of disrupted close binary systems. We investigate pairs of fairly young radio pulsars with known proper motions and estimated distances (dispersion measures) that are spaced no more than 2–3 kpc apart. Using a specified radial velocity distribution for these objects, we have constructed 100–300 thousand trajectories of their possible motion in the Galactic gravitational field on a time scale of several million years. The probabilities of their close encounters at epochs consistent with the age of the younger pulsar in the pair are analyzed. When these probabilities exceed considerably their reference values obtained by assuming a purely random encounter between the pulsars under consideration, we conclude that the objects may have been gravitationally bound in the past. As a result, we have detected six pulsar pairs (J0543+2329/J0528+2200, J1453-6413/J1430-6623, J2354+6155/J2321+6024, J1915+1009/J1909+1102, J1832-0827/J1836-1008, and J1917+1353/J1926+1648) that are companions in disrupted binary systems with a high probability. Estimates of their kinematic ages and velocities at binary disruption and at the present epoch are provided.

Wide-field optical monitoring with Mini-MegaTORTORA (MMT-9) multichannel high temporal resolution telescope

We describe the properties of Mini-MegaTORTORA (MMT-9) nine-channel wide-field optical sky monitoring system with subsecond temporal resolution. This instrument can observe sky areas as large as 900 deg2, perform photometry in three filters close to Johnson BV R system and polarimetry of selected objects or areas with 100–300 deg2 sizes. The limiting magnitude of the system is up to V = 11m for 0.1 s temporal resolution, and reaches V = 15m in minute-long exposures. The system is equipped with a powerful computing facility and dedicated software pipeline allowing it to perform automatic detection, real-time classification, and investigation of transient events of different nature located both in the near- Earth space and at extragalactic distances. The objects routinely detected by MMT-9 include faint meteors and artificial Earth satellites.We discuss astronomical tasks that can be solved using MMT-9, and present the results of the first two years of its operation. In particular, we report the parameters of the optical flare detected on June 25, 2016, which accompanied the gamma-ray burst GRB160625B.

The LYRA-B Space Experiment: Goals and Principles for Its Realization

We describe goals and principles for the realization the Lyra-B space experiment onboard the International Space Station, which is currently being prepared at the Sternberg Astronomical Institute. The main goal of the experiment is to carry out a high-accuracy, multicolor all-sky survey of stars down to 16m–17m. The detailed structure of the expected observational data, their possible scientific use, and a number of technical problems are discussed.

The first light of Mini-MegaTORTORA wide-field monitoring system

Abstract We describe the first light of a new 9-channel wide-field optical monitoring system with sub-second temporal resolution, Mini-MegaTORTORA, which is being tested now at the Special Astrophysical Observatory in Russian Caucasus. The system is able to observe the sky simultaneously in either wide (~900 deg2) or narrow (~100 deg2) fields of view, either in clear light or with any combination of color (Johnson B, V or R) and polarimetric filters installed, with exposure times ranging from 100 ms to 100 s. The primary goal of the system is the detection of rapid (with sub-second characteristic time scales) optical transients, but it may be also used for studying variability of sky objects over longer time scales.

Search for fast optical activity of SGR 1806-20 at the SAO RAS 6-m telescope

The region of SGR 1806-20 localization was observed during its gamma-ray activity in 2001. The observations have been performed on the 6-meter telescope of the Special Astrophysical Observatory, using the Panoramic Photometer-Polarimeter (PPP). The search for variability was performed on the

Search for the event horizon by means of optical observations with high temporal resolution

10^{-6}

Observational appearances of isolated stellar-mass black hole accretion – Theory and observations

- 10 s time scale, and its results were compared to the properties of corresponding x-ray flares.

On the peculiarities in the rotational frequency evolution of isolated neutron stars

The critical property of the black hole is the presence of the event horizon. It may be detected only by means of the detailed study of the emission features of its surroundings. The temporal resolution of such observations has to be better than ∼ rg/c, and it lies in the 10−6–10 s range depending on the black hole mass. In SAO RAS we have developed the MANIA hardware and software complex based on the panoramic photon counter and use it in observations on 6m telescope for the search and investigation of the optical variability on the time scales of 10−6–103 s of various astronomical objects. We present the hardware and methods used for these photometrical, spectroscopic and polarimetrical observations, the principles and criteria of the object selection. The list of the latter includes objects with featureless optical spectra (DC white dwarfs, blazars) and long microlensing events. We present the results of the observations of two objects-candidates – long MACHO event MACHO-1999-BLG-22 and radio-loud x-ray source with featureless optical spectrum J1942+10 – on the 6-m telescope in June-July 2006.

Wide Field Optical Camera for Search and Investigation of Fast Cosmic Transients

Abstract General properties of accretion onto isolated stellar-mass black holes in the Galaxy are discussed. An analysis of plasma internal energy growth during the infall is performed. Adiabatic heating of collisionless accretion flow due to magnetic adiabatic invariant conservation is 25% more efficient than in the standard non-magnetized gas case. It is shown that magnetic field line reconnections in discrete current sheets lead to significant nonthermal electron component formation, which leads to a formation of a hard (UV, X-ray, up to gamma), highly variable spectral component in addition to the standard synchrotron optical component first derived by Shvartsman generated by thermal electrons in the magnetic field of the accretion flow. Properties of accretion flow emission variability are discussed. Observation results of two single black hole candidates – gravitational lens MACHO-1999-BLG-22 and radio-loud X-ray source with featureless optical spectrum J1942+10 – in optical band with high temporal resolution are presented and interpreted in the framework of the proposed model.