Energy Density Of Particles Research Articles

Testing the magnetic flux paradigm for AGN radio loudness with a radio-intermediate quasar

For understanding the diversity of jetted active galactic nuclei (AGN) and especially the puzzling wide range in their radio loudness, it is important to understand what role the magnetic fields play in setting the power of relativistic jets in AGN. We have performed VLBA phase-referencing observations of the radio-intermediate quasar IIIZw 2 to estimate jet magnetic flux by measuring the core-shift effect. Multi-frequency observations at 4 GHz, 8 GHz, 15 GHz, and 24 GHz were made using three nearby calibrators as reference sources. By combining the self-referencing core shift of each calibrator with the phase-referencing core shifts, we obtained an upper limit of 0.16 mas for the core shift between 4 and 24 GHz in IIIZw 2. By assuming equipartition between magnetic and particle energy densities and adopting the flux-freezing approximation, we further estimated the upper limit for both the magnetic field strength and poloidal magnetic flux threading the black hole. We find that the upper limit to the measured magnetic flux is smaller by at least a factor of five compared to the value predicted by the magnetically arrested disk (MAD) model. An alternative way to derive the jet magnetic field strength from the turnover of the synchrotron spectrum leads to an even smaller upper limit. Hence, the central engine of IIIZw 2 has not reached the MAD state, which could explain why it has failed to develop a powerful jet even though the source harbours a fast-spinning black hole. However, it generates an intermittent jet, which is possibly triggered by small-scale magnetic field fluctuations, as predicted by the magnetic flux paradigm. We propose here that combining black hole spin measurements with magnetic field measurements from the very-long-baseline-interferometry core-shift observations of AGN over a range of jet powers could provide a strong test for the dominant factor that sets the jet power relative to the available accretion power.

X-Ray Diffraction Analysis by Williamson-Hall, Size-Strain, Halder-Wagner Plot Methods for Ni Doped CdS Nanoparticles

Cadmium sulfide (CdS) doped with different concentrations of Ni (2, 4, 6, 8, and 10 %) nanoparticles have been synthesized by chemical co-precipitation method. X-ray diffraction (XRD) studies confirm the crystalline nature of Ni doped CdS nanoparticles had a hexagonal wurtzite structure. Williamson-Hall (W–H), Size-Strain Plot (SSP), and Halder-Wagner (H–W) methods have been used to investigate the average particle size, lattice strain, stress, and energy density from the XRD peak broadening analysis. In W–H method, the models of uniform deformation, uniform deformation stress, and uniform deformation energy density have been implemented to determine the elastic parameters.

Implementation of Cosmic Ray Energy Spectrum (CRESP) Algorithm in PIERNIK MHD Code. I. Spectrally Resolved Propagation of Cosmic Ray Electrons on Eulerian Grids

Abstract We present an efficient algorithm to follow spectral evolution of cosmic rays (CR) coupled with an MHD system on Eulerian grids. The algorithm is designed for studies of CR energy spectrum evolution in MHD simulations of a galactic interstellar medium. The base algorithm for CR transport relies on the two-moment piece-wise power-law method, known also as coarse-grained momentum finite volume (CGMV), for solving the Fokker–Planck CR transport equation, with a low number of momentum bins extending over several decades of the momentum coordinate. We propose an extension of the CGMV with a novel feature that allows momentum boundaries to change in response to CR momentum gains or losses near the extremes of the population distribution. Our extension involves a special treatment of momentum bins containing spectral cutoff. Contrary to the regular bins of fixed width, those bins have variable width, and their outer edges coincide with spectral cutoffs. The cutoff positions are estimated from the particle number density and energy density in the outer bins for an assumed small value of an additional parameter representing the smallest physically significant level of CR spectral energy density. We performed a series of elementary tests to validate the algorithm and demonstrated, whenever possible, that results of the test simulations correspond, with a reasonable accuracy, to the results of analogous analytical solutions. In a more complex test of the galactic CR-driven wind problem, we obtained results consistent with expectations regarding the effects of advection, diffusion, adiabatic, and synchrotron cooling of a CR population.

Koide Lepton Relation Explained by Lepton Radius (Compton Wavelength)/4

The intriguing Koide relation between lepton masses, , involving electron mass me, muon mass mμ, and tau mass mt, was first presented in 1982. The reason why Q1 ≈ 2/3 has long been unclear. However, describing Standard Model fermions as spheres with radius (Compton wavelength)/4, allows only three fermions in each charge state and avoids the infinite energy density of point particles. Then the Koide parameter Q1 ≈ 2/3 because the electron Compton wavelength is more than 200 times the muon and tau Compton wavelengths. A tau mass equivalent of 1776.98 MeV, within experimental error bars, would result in Q1 = 2/3. The analysis is discussed in the context of efforts to extend the Standard Model of particle physics.

TJ cm−3 high energy density plasma formation from intense laser-irradiated foam targets composed of disordered carbon nanowires

High energy density plasma formation from intense laser-irradiated foam targets composed of disordered carbon nanowires is investigated using three-dimensional particle-in-cell simulations. It is shown that due to the unprecedentedly high laser energy absorption rate of the foam target, approximately three times larger as compared with simple solid targets, the plasma energy density reaches an unexplored TJ cm−3 regime at 1023 W cm−2 laser irradiation. In addition, nanowire thermal expansion caused by prepulse heating is considered. We find that after expansion, the target becomes relativistically transparent to the main pulse. The average value of particle energy density decreases slightly and its distribution tends to resemble that of solid targets. Furthermore, energy density scaling with laser intensities is given. It suggests that an even more extreme plasma state is reachable using ultraintense lasers, as the energy loss to photons caused by quantum electrodynamics effects is rather negligible.

The Parsec-scale Jet of the Neutrino-emitting Blazar TXS 0506+056

Abstract Recently the IceCube Collaboration detected very high energy (VHE) neutrinos and associated them with the blazar TXS 0506+056, raising a possible association of VHE neutrinos with this and other individual blazars. Very long baseline interferometry (VLBI) is so far the only technique enabling the imaging of the innermost jet at milliarcsec resolution (parsec scale), where the high-energy emission possibly originates from. Here, we report on the radio properties of the parsec-scale jet in TXS 0506+056 derived from the analysis of multiepoch, multifrequency archive VLBI data. The half opening angle of the jet beam is about 3.°8, and the jet inclination angle is about 20°. The overall jet structure shows a helical trajectory with a precessing period of 5–6 yr, likely originating from instabilities operating at parsec scales. The calculated beaming parameters (Doppler boosting factor, bulk Lorentz factor) suggest a moderately relativistic jet. The parsec-scale magnetic field strength is estimated in the contexts of core shift and variability, and is in general agreement in the range of 0.2–0.7 G. And it is found to decrease from a relatively larger value during the quiescent period before the ongoing flare. This suggests a conversion of magnetic field energy density to particle energy density that helps accelerate injected particles at the jet base and results in variable shocked emission. The neutrino event could be associated with the onset of energetic particle injection into the jet. This scenario then supports the lepto-hadronic origin of the VHE neutrinos and γ-ray emission owing to a cospatial origin.

Apple pruning residues: Potential for burning in boiler systems and pellet production

Residues from management activities of fruit growing can be an important source of biomass for energy generation. The aim of this study was to determine the potential use of apple pruning residues for energy generation as process steam or power energy. To this end, branches from the pruning of commercial apple orchards have been evaluated in the Santa Catarina State, Brazil. To compare with the traditional biomass used for energetic purposes, particles of Pinus sp. from the industrial timber processing have also been analysed. Homogeneous pellets of the two types of biomass were produced, and three more mixes containing the two raw materials were made. Pellets have been evaluated according to their physical and energetic properties. The results have been compared to the ISO 17,225-2 Standard. Apple pruning residues have the potential for energy generation in boilers, that is, for the production of process steam and electric power. Their potential can vary from 12,649.54 MWh y−1 to 115,442.44 MWh y−1. The physical and energetic properties varied between the analysed residues, except the gross calorific value (19.69 MJ kg−1 for pine wood particles and 20.27 MJ kg−1 for apple pruning). Comparing with the pine wood (87 kg m−3), the apple pruning (141 kg m−3) has a higher amount of biomass per unit volume processed for energy and less residence time in the burning systems (17.54% fixed carbon for apple pruning and 18.91% fixed carbon for pine wood). However, it generates more wastes (ashes) after burning (3.25% for apple pruning and 0.46% for pine wood). The pellets’ energy density increased by 3.35 times the energy density of the apple pruning particles after pelletizing. The homogeneous apple pruning pellets can only be applied to industrial use (I3), mainly because of its high ash content (2.27%). The pine wood with apple pruning mix used for pellet production reduces the ash content and increases the bulk density and energy density, which improves the quality of the pellets.

Kinetic approach to the Schwinger effect during inflation

Using the kinetic approach, we study the impact of the charged particle dynamics due to the Schwinger effect on the electric field evolution during inflation. As a simple model of the electric field generation, we consider the kinetic coupling of the electromagnetic field to the inflaton via the term ${f}^{2}(\ensuremath{\phi}){F}_{\ensuremath{\mu}\ensuremath{\nu}}{F}^{\ensuremath{\mu}\ensuremath{\nu}}$ with the Ratra coupling function $f=\mathrm{exp}(\ensuremath{\beta}\ensuremath{\phi}/{M}_{p})$. The production of charged particles is taken into account in the Boltzmann kinetic equation through the Schwinger source term. Produced particles are thermalized due to collisions which we model by using the collision integral in the self-consistent relaxation time approximation. We found that the current of created particles exhibits a non-Markovian character and cannot be described by a simple Ohm's law relation $j\ensuremath{\propto}E$. On the contrary, the electric current as well as the electric field are oscillatory functions of time with decreasing amplitudes and a phase difference due to the ballistic motion of charged carriers. Our qualitative results are checked by using a hydrodynamic approach. Deriving a closed system of equations for the number, current, and energy densities of charged particles and determining its solution, we find a good agreement with the results obtained in the kinetic approach.

Dynamics of anisotropic cosmic models with different matter sources in extended scalar-tensor theory

In this work, we develop some interesting models of cosmos exhibiting anisotropic properties in the extended scalar-tensor theory. In the first place, we consider the LRS Bianchi type I (BI) geometry filled with matter contents as magnetized bulk viscous cloud of strings. We developed analytic solutions and explore the cosmological significance of some interesting physical measures like cosmic volume, directional Hubble parameter, deceleration parameter, viscosity factor, particle energy density, shear and expansion scalars, and string tension density. Moreover, modified holographic Ricci dark energy is introduced in anisotropic scenario to discuss the dynamics of anisotropic comic models. In order to construct the exact cosmic solutions, we take hybrid law of scale factor as well as some viable ansatz for scalar field and its scalar potential. The physical viability of model parameters is discussed through graphical analysis. Physical analysis of both models show that our results are in agreement with the current observations and hence are cosmologically viable and promising.

A New Concept in Mechanics Based on the Notions of Space, Time, and Energy

A new concept in mechanics is proposed based on the notions of space, time, and energy. The energy is represented by the sum of thirteen terms expressed as products of invariants of the Lagrangian equations of motion and scalar factors corresponding to the physical properties of materials. Differential equations of motion and equilibrium are derived from the frame indifference condition for energy, in which the Eulerian variables are the sought functions and the Lagrangian variables are the arguments. Assumptions are made under which these equations can be transformed into the Poisson and Laplace equations. The law of conservation of energy is used to obtain dependences between the Lagrangian stresses and strains in the reversible deformation region; they are compared with the expressions used in the theory of elasticity. It is discussed whether the point of reference for the mean stresses may be chosen with regard to the volume energy density of particles in their initial state, as well as whether elastic deformation can be described using a single constant. As an example, the energy model and the equations of motion in the Lagrangian form are applied to describe the transition from reversible to irreversible deformation. The developed model differs from the classical one by using two independent infinitesimal operators for the time and space. It is shown that Newton’s law of inertia can be regarded as a variant for the determination of the generalized forces characterizing the kinetic energy change in a body with increments in the distance between the origin of the observer coordinate system and the center of mass of the body. The application of the Lagrangian variables and the superposition principle for describing any spatial motions (including for absolutely rigid bodies), which can be used in the dynamic analysis of linkages and other mechanisms, is validated. The multiple choice of generalized forces for absolutely rigid bodies, including when passive forces arise, is considered. The method of dynamic analysis of mechanisms developed on the basis of the energy model allows the law of conservation of energy to be satisfied for any part of the studied system in an arbitrary time interval.

Understanding gravitational particle production in quintessential inflation

The diagonalization method, introduced by a group of Russian scientists at the beginning of seventies, is used to compute the energy density of superheavy massive particles produced due to a sudden phase transition from inflation to kination in quintessential inflation models, the models unifying inflation with quintessence originally proposed by Peebles-Vilenkin. These superheavy particles must decay in lighter ones to form a relativistic plasma, whose energy density will eventually dominate the one of the inflaton field, in order to have a hot universe after inflation. In the present article we show that, in order that the overproduction of Gravitational Waves (GWs) during this phase transition does not disturb the Big Bang Nucleosynthesis (BBN) success, the decay has to be produced after the end of the kination regime, obtaining a maximum reheating temperature in the TeV regime.

Gravitational fermion creation during an anisotropic phase of cosmological expansion

The free Dirac equation is solved in a Bianchi Type I space-time, which represents a homogeneous but anisotropic universe, to show the creation of fermionic particles. It is found that unlike in the isotropic case, massless fermion production is possible. An estimate of the energy density of massless particles created during an early anisotropic phase of cosmological expansion is shown to cause substantial back-reaction on the gravitational field. The potential relevance to dark matter particle production, primordial magnetogenesis, and early universe cosmology is discussed briefly.

Production and backreaction of spin-2 particles of SU(2) gauge field during inflation

Primordial SU(2) gauge fields with an isotropic background lead to the production of spin-2 particles during inflation. We provide a unified formalism to compute this effect in all of the inflation models with isotropic SU(2) gauge fields such as Gauge-flation and Chromo-Natural inflation with and without spectator axion fields or the mass of the gauge field from the Higgs mechanism. First, we calculate the number and energy densities of the spin-2 particles. We then obtain exact analytical formulae for their backreaction on the background equations of motion of SU(2) and axion fields in (quasi) de Sitter expansion, which were calculated only numerically for one particular model in the literature. We show that the backreaction is directly related to the number density of the spin-2 field. Second, we relate the number density of the spin-2 particles to the power spectrum and the energy density of the gravitational waves sourced by them. Finally, we use the size of the backreaction to constrain the parameter space of the models. We find that the tensor-to-scalar ratio of the sourced gravitational waves can at most be on the order of that of the vacuum contribution to avoid a large backreaction on slow-roll dynamics of the gauge ssand axion fields in quasi-de Sitter expansion.

Analytical study of Whistler mode waves for relativistic plasma with AC electric field in inner magnetosphere of Saturn

The population of plasma present in the rotationally dominated inner magnetosphere of Saturn is identified by the observed plasma waves in the magnetosphere. Whistler mode emissions along with electrostatic cyclotron emissions often with harmonics are a common feature of Saturnian inner magnetosphere. We present the outcomes of a study of very large amplitude Whistler mode waves characteristics inside the magnetosphere of radial distance of less than 15 $$\hbox {R}_{\mathrm{s}}$$ . Whistler mode waves with temperature anisotropy in the magnetosphere of Saturn have been studied in the present work. Observations of Whistler mode emissions from Cassini Radio and Plasma Wave Science instruments have been obtained. Whistler mode waves were investigated using the method of characteristic solution by kinetic approach, in the presence of AC field. The observations made by space probes Voyager 1 and 2 and Cassini, launched by NASA, showed that charged particles are trapped in planet’s magnetic field lines. In 2004, the Cassini encounter with Saturn revealed that magnetosphere of Saturn exhibits Maxwellian distribution. So, the dispersion relation, real frequency and growth rate were evaluated using ring distribution function. Effect of AC frequency, temperature anisotropy, energy and number density of particles was found. Temperature anisotropies greater than one ( $$\hbox {T}_\bot {/}\hbox {T}_{\Vert } >1$$ ) and pancake-like distribution can generate Whistler mode emissions of the warmer plasma population. The study also extended to oblique propagation of Whistler mode waves in presence of AC electric field. However, when relativistic factor $${{\upbeta } }=\sqrt{\hbox {1}-\frac{\hbox {v}^{\mathrm {2}}}{\hbox {c}^{\mathrm {2}}}}$$ increases, growth rate decreases. Through comprehensive mathematical analysis, it was found that when Whistler mode waves propagate parallel to the intrinsic magnetic field of Saturn, its growth is enhanced more than in the case of oblique propagation. Results are also discussed while computing the rate with which the wave grows for a particular wavenumber.

Plasma chemical purification of flue gases using pulsed electron beams

The article presents the study of the pulsed electron beam propagation in oxygen and nitrogen. The researches were performed using the TEA-500 pulsed electron accelerator and drift tube. Parameters of the TEA-500 pulsed electron accelerator are as follows: the electron energy (varies) is 200-450 keV, the beam current is 10 kA, the half-amplitude current pulse duration is 60 ns, the pulse repetition rate is up to 10 Hz (in the pulse burst). The accelerator is equipped with the necessary means of diagnostics of the beam parameters: particle energy, current and current density, the total energy transferred by the beam. The drift tube includes a chamber consisting of two sections of reverse current shunts located along the entire length of the drift tube. The following precursors used N2 and O2. The specified types of gases were chosen as they are among the main components of the flue gases, whose treatment has been widely reported recently.

TeV γ-ray emission from Mrk 421 observed with TACTIC during December 2014–February 2015

We observed the TeV blazar Mrk421 in the very high energy (VHE) region with TACTIC from 21 December, 2014 to 21 February, 2015. The VHE γ-ray signal is detected from the source at a statistical significance of ∼ 9σ with 648 ± 74 γ-ray like events using a total observation time of 65.6 h of clean data. To denote the active period of the source, the entire observation has been divided into two spells: Spell I (21–30 December, 2014; MJD: 57012–57021) and Spell II (15 January-21 February, 2015; MJD: 57037–57074). The Spell I corresponds to relatively higher activity state wherein 337 ± 47 γ-rays are detected at a statistical significance of 7.39σ in 21.7 h. During Spell II, 311 ± 57 γ-ray events have been detected in ∼ 44c at a statistical significance of 5.6σ. The analysis of high energy (HE) γ-ray data from Fermi-LAT has been carried out for the period of TACTIC observations. In addition, near simultaneous multi-wavelength data from Swift-BAT and MAXI in the X-ray region, SPOL in optical V-band and OVRO at 15 GHz radio band have also been considered. The HE γ-ray and optical observations indicate variability during both the spells whereas hard X-ray observations are consistent with the average emission through out the TACTIC observations. The broad-band spectral energy distributions of the source are reproduced by single zone homogeneous synchrotron self Compton process for the two spells. The model parameters estimated for the two spells are similar except for the particle energy density which is obtained to be slightly higher during Spell I.

The 1.4 mm Core of Centaurus A: First VLBI Results with the South Pole Telescope

Abstract Centaurus A (Cen A) is a bright radio source associated with the nearby galaxy NGC 5128 where high-resolution radio observations can probe the jet at scales of less than a light day. The South Pole Telescope (SPT) and the Atacama Pathfinder Experiment performed a single-baseline very-long-baseline interferometry (VLBI) observation of Cen A in 2015 January as part of VLBI receiver deployment for the SPT. We measure the correlated flux density of Cen A at a wavelength of 1.4 mm on a ∼7000 km (5 Gλ) baseline. Ascribing this correlated flux density to the core, and with the use of a contemporaneous short-baseline flux density from a Submillimeter Array observation, we infer a core brightness temperature of 1.4 × 1011 K. This is close to the equipartition brightness temperature, where the magnetic and relativistic particle energy densities are equal. Under the assumption of a circular Gaussian core component, we derive an upper limit to the core size ϕ = 34.0 ± 1.8 μas, corresponding to 120 Schwarzschild radii for a black hole mass of 5.5 × 107 M ⊙.

Deriving uniform semiclassical approximations for one-dimensional fermionic systems.

A complete derivation is provided of the uniform semiclassical approximations to the particle and kinetic energy densities of N noninteracting bounded fermions in one dimension. The employed methodology allows the inclusion of non-perturbative quantum effects, including tunneling and quantum oscillations, via an infinite resummation of the Poisson summation formula. We explore the analytic behavior, physical meaning, and the relationship between the semiclassical uniform approximations for the fermionic kinetic energy and particle densities.

Broadband spectral fitting of blazars using XSPEC

The broadband spectral energy distribution (SED) of blazars is generally interpreted as radiation arising from synchrotron and inverse Compton mechanisms. Traditionally, the underlying source parameters responsible for these emission processes, like particle energy density, magnetic field, etc., are obtained through simple visual reproduction of the observed fluxes. However, this procedure is incapable of providing confidence ranges for the estimated parameters. In this work, we propose an efficient algorithm to perform a statistical fit of the observed broadband spectrum of blazars using different emission models. Moreover, we use the observable quantities as the fit parameters, rather than the direct source parameters which govern the resultant SED. This significantly improves the convergence time and eliminates the uncertainty regarding initial guess parameters. This approach also has an added advantage of identifying the degenerate parameters, which can be removed by including more observable information and/or additional constraints. A computer code developed based on this algorithm is implemented as a user-defined routine in the standard X-ray spectral fitting package, XSPEC. Further, we demonstrate the efficacy of the algorithm by fitting the well sampled SED of blazar 3C 279 during its gamma ray flare in 2014.

The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

The high brightness temperatures, $T_\mathrm{b}\gtrsim 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240,000 km we find two characteristic angular scales in the quasar core, about 100 $\mu$as and 10 $\mu$as. Some indications of scattering substructure are found. Very high brightness temperatures, $T_\mathrm{b}\geq 10^{13}$ K, are estimated at 4.8 GHz and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar.