Synchro-curvature radiation of charged particles in the strong curved magnetic fields

It is generally believed that the radiation of relativistic particles in a curved magnetic field proceeds in either the synchrotron or the curvature radiation modes. In this paper we show that in strong curved magnetic fields a significant fraction of the energy of relativistic electrons can be radiated away in the intermediate, the so-called synchro-curvature regime. Because of the persistent change of the trajectory curvature, the radiation varies with the frequency of particle gyration. While this effect can be ignored in the synchrotron and curvature regimes, the variability plays a key role in the formation of the synchro-curvature radiation. Using the Hamiltonian formalism, we find that the particle trajectory has the form of a helix wound around the drift trajectory. This allows us to calculate analytically the intensity and energy distribution of prompt radiation in the general case of magnetic bremsstrahlung in the curved magnetic field. We show that the transition to the limit of the synchrotron and curvature radiation regimes is determined by the relation between the drift velocity and the component of the particle velocity perpendicular to the drift trajectory. The detailed numerical calculations, which take into account the energy losses of particles, confirm the principal conclusions based on the simplified analytical treatment of the problem, and allow us to analyze quantitatively the transition between different radiation regimes for a broad range of initial pitch angles. We argue that in the case of realization of specific configurations of the electric and magnetic fields, the gamma-ray emission of the pulsar magnetospheres can be dominated by the component radiated in the synchro-curvature regime.Comment: this article supersedes arXiv:1207.6903 and arXiv:1305.078

Mechanics and kinetics in the Friedmann-Lemaitre-Robertson-Walker space-times

Using the standard canonical formalism, the equations of mechanics and kinetics in the Friedmann-Lemaitre-Robertson-Walker (FLRW) space-times in Cartesian coordinates have been obtained. The transformation law of the generalized momentum under the shift of the origin of the coordinate system has been found, and the form invariance of the Hamiltonian function relative to the shift transformation has been proved. The general solution of the collisionless Boltzmann equation has been found. In the case of the homogeneous distribution the solutions of the kinetic equation for several simple, but important for applications, cases have been obtained

On transition of propagation of relativistic particles from the ballistic to the diffusion regime

A stationary distribution function that describes the entire processes of propagation of relativistic particles, including the transition between the ballistic and diffusion regimes, is obtained. The spacial component of the constructed function satisfies to the first two moments of the Boltzmann equation. The angular part of the distribution provides accurate values for the angular moments derived from the Boltzmann equation, and gives a correct expression in the limit of small-angle approximation. Using the derived function, we studied the gamma-ray images produced through the $pp$ interaction of relativistic particles with gas clouds in the proximity of the accelerator. In general, the morphology and the energy spectra of gamma-rays significantly deviate from the "standard" results corresponding to the propagation of relativistic particles strictly in the diffusion regime

TeV gamma rays from blazars beyond z=1?

At TeV energies, the gamma-ray horizon of the universe is limited to redshifts z<<1, and, therefore, any observation of TeV radiation from a source located beyond z=1 would call for a revision of the standard paradigm. While robust observational evidence for TeV sources at redshifts z>1 is lacking at present, the growing number of TeV blazars with redshifts as large as z~0.5 suggests the possibility that the standard blazar models may have to be reconsidered. We show that TeV gamma rays can be observed even from a source at z>1, if the observed gamma rays are secondary photons produced in interactions of high-energy protons originating from the blazar jet and propagating over cosmological distances almost rectilinearly. This mechanism was initially proposed as a possible explanation for the TeV gamma rays observed from blazars with redshifts z~0.2, for which some other explanations were possible. For TeV gamma-ray radiation detected from a blazar with z>1, this model would provide the only viable interpretation consistent with conventional physics. It would also have far-reaching astronomical and cosmological ramifications. In particular, this interpretation would imply that extragalactic magnetic fields along the line of sight are very weak, in the range 0.01 < fG < 10 fG, assuming random fields with a correlation length of 1 Mpc, and that acceleration of E> 0.1 EeV protons in the jets of active galactic nuclei can be very effective.Comment: 8 pages, 4 figure

Synchrotron-to-curvature transition regime of radiation of charged particles in a dipole magnetic field

The details of trajectories of charged particles become increasingly important for proper understanding of processes of formation of radiation in strong and curved magnetic fields. Because of damping of the perpendicular component of motion, the particle's pitch angle could be decreased by many orders of magnitude leading to the change of the radiation regime -- from synchrotron to the curvature mode. To explore the character of this transition, we solve numerically the equations of motion of a test particle in a dipole magnetic field, and calculate the energy spectrum of magnetic bremsstrahlung self-consistently, i.e. without a priori assumptions on the radiation regime. In this way we can trace the transitions between the synchrotron and curvature regimes, as well as study the third (intermediate or the so-called synchro-curvature) regime. We briefly discuss three interesting astrophysical scenarios, the radiation of electrons in the pulsar magnetosphere in the polar cap and outer gap models, as well as the radiation of ultrahigh energy protons in the magnetosphere of a massive black hole, and demonstrate that in these models the synchrotron, synchro-curvature and curvature regimes can be realized with quite different relative contributions to the total emission

Angular, spectral, and time distributions of highest energy protons and associated secondary gamma-rays and neutrinos propagating through extragalactic magnetic and radiation fields

The angular, spectral and temporal features of the highest energy protons and accompanying them secondary neutrinos and synchrotron gamma-rays propagating through the intergalactic magnetic and radiation fields are studied using the analytical solutions of the Boltzmann transport equation obtained in the limit of the small-angle and continuous-energy-loss approximation.Comment: 21 pages, 13 figure

Non-variable cosmologically distant gamma-ray emitters as an imprint of propagation of ultra-high-energy protons

The acceleration cites of ultra-high-energy (UHE) protons can be traced by the footprint left by these particles propagating through cosmic microwave background (CMB) radiation. Secondary electrons produced in extended region of several tens of Mpc emit their energy via synchrotron radiation predominantly in the initial direction of the parent protons. It forms a non-variable and compact (almost point-like) source of high energy gamma rays. The importance of this effect is increased for cosmologically distant objects; because of severe energy losses, UHE protons cannot achieve us even in the case of extremely weak intergalactic magnetic fields. Moreover, at high redshifts the energy conversion from protons to secondary particles becomes significantly more effective due to the denser and more energetic CMB in the past. This increases the chances of UHE cosmic rays to be traced by the secondary synchrotron gamma radiation. We discuss the energy budget and the redshift dependence of the efficiency of energy transfer from UHE protons to synchrotron radiation. The angular and spectral distributions of radiation in the gamma- and X-ray energy bands are calculated and discussed in the context of their detectability by Fermi LAT and Chandra observatories

The Effect of Dehydration on the Development of Endothelial Dysfunction in Young Athletes: a Comparative Analysis of the Effectiveness of a New Honey Isotonic Drink and Standard Means of Restoring Hydro-Electrolytic Balance

Aim of the research. To prove the effectiveness of using isotonic honey drink “Gold F25 IsoDrink Light” (IsoDrink-L) based on the study of the hydration process and endothelial function in young athletes. Materials and methods. A randomized controlled study was performed in young athletes under the age of 18 years. Athletes of the main group (n = 40) consumed IsoDrink-L for a month; athletes of the control group (n = 34) consumed water and isotonic drink “X”. A bioimpedance-based device was used to determine the total amount of water, the absolute and relative proportions of intra- and extracellular water, as well as the ratio of extracellular water to the total amount of water. Hematocrit, specific gravity and color of morning urine, samples with reactive hyperemia and hyperventilation in the brachial artery, including the determination of the endothelial sensitivity index were assessed.Results. All athletes had dehydration in the form of extracellular dehydration, cellular hyperhydration, “blood  thickening”, hyponatremia, increased specific gravity and urine color, as well as endothelial dysfunction. All  symptoms disappeared after using IsoDrink-L for 1 month. No dynamics was observed in the control group,  where 95 % of the athletes took water and 5 % – isotonic drink “X”. ROC analysis showed that the endothelial sensitivity index with a sensitivity of 95.8 % and a specificity of 99.4 % detects endothelial dysfunction. The canonical correlation coefficient between the set of hydration-dependent and endothelium-dependent signs was R = 0.71 (p &lt; 0.0001). We established the danger of uncontrolled water consumption for rehydration in young athletes, as well as the high efficiency of isotonic honey drink and the evidence for its use for the correction of dehydration and endothelial dysfunction. A low awareness of athletes, doctors and coaches about the importance of using effective methods of rehydration in children’s sports was revealed.Conclusion. It was found that water imbalance in young athletes directly or indirectly contributes to the development of endothelial dysfunction, thereby increasing cardiovascular risk. Original approaches to the development of honey isotonic drink for young athletes with proven hydrating and endothelium-protective properties are proposed

Endothelial dysfunction as a major cardiovascular risk factor limiting the performance of young athletes: assessment and correction with specialized food products based on apian and herbal components

Objective: to assess with exercise tests the endothelial dysfunction (ED) and performance before and after the treatment with specialized athlete’s nutrition product (SANP) with apian and herbal components. Materials and methods: 88 athletes aged 16-18 we tested. The main group included 58 athletes, who took SANP (candy bar «Gold F25 ApiSpeis Light») for 2 months. The control group-1 included 32 schoolchildren and students, non-athletes, with normal endothelium-dependent vasodilatation function of the brachial artery (EDVD BA) at the peak of the reactive hyperemia test (RHT). Control group-2, 30 athletes who did not take SANP, was formed for the comparison with the main group after taking SANP. For all individuals, we evaluated the level of EDVD, endothelium-dependent vasoconstriction (EDVC BA) at the peak of the hyperventilation test (HVT), the coefficients (C) of the endothelial sensitivity to shear stress and the blood flow velocity (Vps) of the BA at the peak of the RHT and HVT, the endothelial sensitivity index (ESI), and the maximum load (Wmax), the anaerobic threshold time (ATT). We also did general and biochemical blood tests. Results: the earliest manifestation of endothelial dysfunction is a decrease in sensitivity to shear stress during RHT and HVT resulting from endotheliocyte overstrain which can be assessed with ESI (sensitivity 80.9%, specificity 99.4 The EDVD diagnostic significance was 5.6 times lower than that of EIS, while 10.5% of athletes with over 10% EDVD actually had ED, with a predominant vasospasm and high cardiovascular risk. After the course of SANP in the main group, EDVD increased by 70%, EDVC decreased by 2.2 times, and the ESI increased by 2.3 times, against the background of improved performance. Total cholesterol decreased by 13%, triglycerides by 17%, cortisol by 14%, lactate by 25%. Red blood cell and mineral levels increased. A correlation was found between an increase in ATT a decrease in cortisol (r=-0.53; p&lt;0.0001), an increase in red blood cells (r=0.62; p&lt;0.0001), and an increase in Vps in BA during of hyperventilation with an increase in Wmax (r=0.52; p&lt;0.0001). Conclusions: ED is the main factor of cardiovascular risk, limiting working capacity and forming a spastic type of regional hemodynamics of young athletes. The ESI criterion enables the detection of a decrease in the endothelial sensitivity to shear stress during a hyperventilation test, which causes the predominant vasospasm. Th e tested SANP can be used in the system of biomedical support for young athletes