4,083 research outputs found
Electromagnetic Zero Point Field as Active Energy Source in the Intergalactic Medium
For over twenty years the possibility that the electromagnetic zero point
field (ZPF) may actively accelerate electromagnetically interacting particles
in regions of extremely low particle density (as those extant in intergalactic
space (IGS) with n < 1 particle/m^3 has been studied and analyzed. This
energizing phenomenon has been one of the few contenders for acceleration of
cosmic rays (CR), particularly at ultrahigh energies. The recent finding by the
AGASA collaboration (Phys. Rev. Lett., 81, 1163, 1998) that the CR energy
spectrum does not display any signs of the Greisen-Zatsepin-Kuzmin cut-off
(that should be present if these CR particles were indeed generated in
localized ultrahigh energies CR sources, as e.g., quasars and other highly
active galactic nuclei), may indicate the need for an acceleration mechanism
that is distributed throughout IGS as is the case with the ZPF. Other
unexplained phenomena that receive an explanation from this mechanism are the
generation of X-ray and gamma-ray backgrounds and the existence of Cosmic
Voids. However recently, a statistical mechanics kind of challenge to the
classical (not the quantum) version of the zero-point acceleration mechanism
has been posed (de la Pena and Cetto, The Quantum Dice, 1996). Here we briefly
examine the consequences of this challenge and a prospective resolution.Comment: 7 pages, no figure
SGR 0418+5729, Swift J1822.3-1606, and 1E 2259+586 as massive fast rotating highly magnetized white dwarfs
Following Malheiro et al. (2012) we describe the so-called low magnetic field
magnetars, SGR 0418+5729, Swift J1822.3--1606, as well as the AXP prototype 1E
2259+586 as massive fast rotating highly magnetized white dwarfs. We give
bounds for the mass, radius, moment of inertia, and magnetic field for these
sources by requesting the stability of realistic general relativistic uniformly
rotating configurations. Based on these parameters, we improve the theoretical
prediction of the lower limit of the spindown rate of SGR 0418+5729; for a
white dwarf close to its maximum stable we obtain the very stringent interval
for the spindown rate of 4.1E-16< dP/dt < 6E-15, where the upper value is the
known observational limit. A lower limit has been also set for Swift
J1822.3-1606 for which a fully observationally accepted spin-down rate is still
lacking. The white dwarf model provides for this source dP/dt> 2.13E-15, if the
star is close to its maximum stable mass. We also present the theoretical
expectation of the infrared, optical and ultraviolet emission of these objects
and show their consistency with the current available observational data. We
give in addition the frequencies at which absorption features could be present
in the spectrum of these sources as the result of the scattering of photons
with the quantized electrons by the surface magnetic field.Comment: to appear in Astronomy & Astrophysic
Fundamental Frequencies in the Schwarzschild Spacetime
We consider the Keplerian, radial and vertical fundamental frequencies in the
Schwarzschild spacetime to study the so-called kilohertz quasi-periodic
oscillations from low-mass X-ray binary systems. We show that, within the
Relativistic Precession Model, the interpretation of observed kilohertz
quasi-periodic oscillations in terms of the fundamental frequencies of test
particles in the Schwarzschild spacetime, allows one to infer the total mass
of the central object, the internal and external radii of
accretion disks, and innermost stable circular orbits for test
particles in a low-mass X-ray binary system. By constructing the relation
between the upper and lower frequencies and exploiting the quasi-periodic
oscillation data of the Z and Atoll sources we perform the non-linear model fit
analysis and estimate the mass of the central object. Knowing the value of the
mass we calculate the internal and external radii of
accretion disks and show that they are larger than , what was
expected.Comment: 7 pages, 6 figures, 1 tabl
A white dwarf merger as progenitor of the anomalous X-ray pulsar 4U 0142+61?
It has been recently proposed that massive fast-rotating highly-magnetized
white dwarfs could describe the observational properties of some of Soft
Gamma-Ray Repeaters (SGRs) and Anomalous X-Ray Pulsars (AXPs). Moreover, it has
also been shown that high-field magnetic (HFMWDs) can be the outcome of white
dwarf binary mergers. The products of these mergers consist of a hot central
white dwarf surrounded by a rapidly rotating disk. Here we show that the merger
of a double degenerate system can explain the characteristics of the peculiar
AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We
also show that the observed properties of 4U 0142+6 are consistent with an
approximately 1.2 M_{\sun} white dwarf, remnant of the coalescence of an
original system made of two white dwarfs of masses 0.6\, M_{\sun} and 1.0\,
M_{\sun}. Finally, we infer a post-merging age kyr,
and a magnetic field G. Evidence for such a magnetic
field may come from the possible detection of the electron cyclotron absorption
feature observed between the and bands at Hz in the
spectrum of 4U 0142+61.Comment: to appear in ApJ Letter
Distributed Co-simulation for Smart Homes Energy Management in the Presence of Electrical Thermal Storage
Distributed generation and energy storage technologies have helped SmartGrid projects gain great momentum over the last decade. However, despite a large number of pilot and demonstration projects, low-level information is often unavailable. Therefore, tools for defining and building different operation scenarios are required. These tools can facilitate adopting novel approaches to multi-domain energy management. This paper proposes a distributed, flexible co-simulation framework to integrate simulators from separate domains and platforms. Particularly, the proposed scheme enables the development of hybrid thermal-electric systems for smart buildings. In this study, an object-oriented approach to modeling electrical thermal storage (ETS) units is also suggested. The evaluation process is carried out using real-world data. A case study is practiced by designing a residential agent that performs model predictive control (MPC) of residential heating load in the presence of ETS. The results show that proper integration of ETS into Home Energy Management Systems (HEMSs) can achieve economic savings of up to 45 %. The findings of this study demonstrate ETS's high potential for reducing customer bills while satisfying users' comfort. Furthermore, they recommend practical strategies for short-term planning of smart grids by increasing their flexibility based on ETS-integrated Demand Response (DR) programs. © 2022 IEEE
HST/FOS Time-resolved spectral mapping of IP Pegasi at the end of an outburst
We report an eclipse mapping analysis of time-resolved ultraviolet
spectroscopy covering three eclipses of the dwarf nova IP Pegasi on the late
decline of the 1993 May outburst. The eclipse maps of the first run show
evidence of one spiral arm, suggesting that spiral structures may still be
present in the accretion disc 9 days after the onset of the outburst. In the
spatially resolved spectra the most prominent lines appear in emission at any
radius, being stronger in the inner disc regions. The spectrum of the gas
stream is clearly distinct from the disc spectrum in the intermediate and outer
disc regions, suggesting the occurrence of gas stream overflow. The full width
half maximum of C IV is approximately constant with radius, in contrast to the
expected law for a gas in Keplerian orbits. This line
probably originates in a vertically extended region (chromosphere + disc wind).
The uneclipsed component contributes % of the flux in C IV in the
first run, and becomes negligible in the remaining runs. We fit stellar
atmosphere models to the spatially resolved spectra. The radial run of the disc
color temperature for the three runs is flatter than the expected
law for steady-state optically thick discs models, with
K in the inner regions and K in the outer disc
regions. The solid angles that result from the fits are smaller than expected
from the parameters of the system. The radial run of the solid angle suggests
that the disc is flared in outburst, and decreases in thickness toward the end
of the outburst.Comment: 14 pages, 14 figures, in press in Astronomy & Astrophysic
Compton Scattering of Fe K alpha Lines in Magnetic Cataclysmic Variables
Compton scattering of X-rays in the bulk flow of the accretion column in
magnetic cataclysmic variables (mCVs) can significantly shift photon energies.
We present Monte Carlo simulations based on a nonlinear algorithm demonstrating
the effects of Compton scattering on the H-like, He-like and neutral Fe K alpha
lines produced in the post-shock region of the accretion column. The peak line
emissivities of the photons in the post-shock flow are taken into consideration
and frequency shifts due to Doppler effects are also included. We find that
line profiles are most distorted by Compton scattering effects in strongly
magnetized mCVs with a low white dwarf mass and high mass accretion rate and
which are viewed at an oblique angle with respect to the accretion column. The
resulting line profiles are most sensitive to the inclination angle. We have
also explored the effects of modifying the accretion column width and using a
realistic emissivity profile. We find that these do not have a significant
overall effect on the resulting line profiles. A comparison of our simulated
line spectra with high resolution Chandra/HETGS observations of the mCV GK Per
indicates that a wing feature redward of the 6.4 keV line may result from
Compton recoil near the base of the accretion column.Comment: Accepted for publication in MNRAS, 10 pages with 8 figure
Advances in the proposed electromagnetic zero-point field theory of inertia
A NASA-funded research effort has been underway at the Lockheed Martin
Advanced Technology Center in Palo Alto and at California State University in
Long Beach to develop and test a recently published theory that Newton's
equation of motion can be derived from Maxwell's equations of electrodynamics
as applied to the zero-point field (ZPF) of the quantum vacuum. In this
ZPF-inertia theory, mass is postulated to be not an intrinsic property of
matter but rather a kind of electromagnetic drag force that proves to be
acceleration dependent by virtue of the spectral characteristics of the ZPF.
The theory proposes that interactions between the ZPF and matter take place at
the level of quarks and electrons, hence would account for the mass of a
composite neutral particle such as the neutron. An effort to generalize the
exploratory study of Haisch, Rueda and Puthoff (1994) into a proper
relativistic formulation has been successful. Moreover the principle of
equivalence implies that in this view gravitation would also be electromagnetic
in origin along the lines proposed by Sakharov (1968). With regard to exotic
propulsion we can definitively rule out one speculatively hypothesized
mechanism: matter possessing negative inertial mass, a concept originated by
Bondi (1957) is shown to be logically impossible. On the other hand, the linked
ZPF-inertia and ZPF-gravity concepts open the conceptual possibility of
manipulation of inertia and gravitation, since both are postulated to be
electromagnetic phenomena. It is hoped that this will someday translate into
actual technological potential. A key question is whether the proposed
ZPF-matter interactions generating the phenomenon of mass might involve one or
more resonances. This is presently under investigation.Comment: Revised version of invited presentation at 34th AIAA/ASME/SAE/ASEE
Joint Propulsion Conference, July 13-15, 1998, Cleveland, OH, 10 pages, no
figure
General Relativistic Radiant Shock Waves in the Post-Quasistatic Approximation
An evolution of radiant shock wave front is considered in the framework of a
recently presented method to study self-gravitating relativistic spheres, whose
rationale becomes intelligible and finds full justification within the context
of a suitable definition of the post-quasistatic approximation. The spherical
matter configuration is divided into two regions by the shock and each side of
the interface having a different equation of state and anisotropic phase. In
order to simulate dissipation effects due to the transfer of photons and/or
neutrinos within the matter configuration, we introduce the flux factor, the
variable Eddington factor and a closure relation between them. As we expected
the strength of the shock increases the speed of the fluid to relativistic
values and for some critical ones is larger than light speed. In addition, we
find that energy conditions are very sensible to the anisotropy, specially the
strong one. As a special feature of the model, we find that the contribution of
the matter and radiation to the radial pressure are the same order of magnitude
as in the mant as in the core, moreover, in the core radiation pressure is
larger than matter pressure.Comment: To appear in Journal of Physics:Conference Series:"XXIX Spanish
Relativity Meeting (ERE 2006): Einstein's Legacy: From the Theoretical
Paradise to Astrophysical Observations
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