Gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges: elliptical orbits on a cone

Extending the electromagnetic and gravitational radiations from binary black holes with electric and magnetic charges in circular orbits in Liu et al. (Phys. Rev. D 102:103520, 2020), we calculate the total emission rates of energy and angular momentum due to gravitational and electromagnetic radiations from dyonic binary black holes in precessing elliptical orbits. It is shown that the emission rates of energy and angular momentum due to gravitational and electromagnetic radiations have the same dependence on the conic angle for different orbits. Moreover, we obtain the evolutions of orbits and find that a circular orbit remains circular while an elliptic orbit becomes quasi-circular due to electromagnetic and gravitational radiations. Using the evolution of orbits, we derive the waveform models for dyonic binary black hole inspirals and show the amplitudes of the gravitational waves for dyonic binary black hole inspirals differ from those for Schwarzschild binary black hole inspirals, which can be used to test electric and magnetic charges of black holes.

Black Hole Spin and Stellar Flyby Periastron Shift

For a scenario of a close flyby of a compact star near a spinning black hole, we provide analytical and numerical estimates for the shift of trajectory periastron due to relativistic (beyond post-Newtonian) effects. More specifically, we derived a generalized expression (not limited to quasi-circular or elliptical orbits) directly linking the periastron shift and the spin of the black hole. The expression permits the estimation of black hole spin based on astronomical tracking of locations of stars traveling along highly eccentric (parabolic and hyperbolic) trajectories in close vicinity of a black hole. We also demonstrate how stars traveling on hyperbolic or parabolic trajectories may be (temporarily) captured onto quasi-circular orbits around black holes, and we quantitatively examine conditions for such scenarios.

Сomparative study of the accuracy of Earth observation by satellite constellations in high elliptical orbits

The paper provides results of estimated accuracy comparisons for applied satellite constellations (ASC) in Molniya-type high elliptical orbits based on a previously presented criterion for analysis of accuracy parameters of ASC that observe targets on the Earth surface and/or in the layer above the surface, which is not dependent on specific features of the onboard equipment, but rather on the structure and dynamics of the ASC. The paper provides an algorithm for numerical simulations of ASC. The paper discusses accuracy parameters for ASC in high elliptical orbits in various orbital configurations, as well as a combined option involving spacecraft in geostationary orbit. It defines key trajectory design parameters driving the ASC accuracy. The results can be used for selecting the initial ASC configuration in high elliptical orbits during preliminary design phase. Key words: observation satellite systems, high elliptical orbits, accuracy criterion, satellite constellation analysis.

COMPARATIVE STUDY OF THE ACCURACY OF EARTH OBSERVATION BY SATELLITE CONSTELLATIONS IN HIGH ELLIPTICAL ORBITS

The paper provides results of estimated accuracy comparisons for applied satellite constellations (ASC) in Molniya-type high elliptical orbits based on a previously presented criterion for analysis of accuracy parameters of ASC that observe targets on the Earth surface and/or in the layer above the surface, which is not dependent on specific features of the onboard equipment, but rather on the structure and dynamics of the ASC. The paper provides an algorithm for numerical simulations of ASC. The paper discusses accuracy parameters for ASC in high elliptical orbits in various orbital configurations, as well as a combined option involving spacecraft in geostationary orbit. It defines key trajectory design parameters driving the ASC accuracy. The results can be used for selecting the initial ASC configuration in high elliptical orbits during preliminary design phase. Key words: observation satellite systems, high elliptical orbits, accuracy criterion, satellite constellation analysis.

THE USE OF NEAR-EARTH ORBITS BY SATELLITE SYSTEMS IN DIFFERENT FREQUENCY BANDS

Выполнен анализ интенсивности использования геостационарной орбиты (ГСО) и негеостационарных орбит (НГСО) современными системами спутниковой связи фиксированной спутниковой службы в Ки-, Ка- и Q/V-диапазонах частот. Исследование охватывает ГСО, а также два наиболее используемых сегмента НГСО с высотой апогея до 1500 км и выше 8000 км. Представлены также результаты исследований для высокоэллиптических орбит (ВЭО). Сделан вывод о дефиците орбитально-частотного ресурса на ГСО и НГСО для рассматриваемых диапазонов частот. The paper analyzes the intensity of the use of geostationary orbit (GSO) and non-geostationary orbits (non-GSO) by modern satellite communication systems of the fixed-satellite service in the Ku-, Ka- and Q/V-bands. The analysis is made for geostationary orbit and two most used segments of non-GSO orbits with apogee altitudes up to 1500 km and above 8000 km. Results for highly inclined elliptical orbits (HEO) are also presented. The analysis results show a shortage of orbital and frequency resources in GSOs and non-GSOs for the considered frequency bands.