11,089 research outputs found
Reflecting at the Speed of Light
A perfectly reflecting accelerating boundary produces thermal emission to an
observer at and a finite amount of energy to an observer at
by asymptotically traveling to the speed of light without an
acceleration horizon.Comment: 4 pages, 4 figures; In memory of Kerson Huan
Extreme Hawking Radiation
Modeling the collapse of an extreme Reissner-Nordstr\"om (ERN) black hole by
solving the corresponding moving mirror model for the trajectory that
asymptotically approaches uniform acceleration, we obtain the non-zero beta
coefficients for all times. Finite energy is emitted, the radiation spectra is
non-thermal (non-steady / not Planck), soft particles characterize the
evaporation, and particle production at ultra-late times is damped.
Entanglement entropy diverges with no Page curve turn-over, demonstrating
non-thermal information loss. The radiation obeys time-reversal symmetry.Comment: 11 pages, 12 figure
Slicing the Vacuum: New Accelerating Mirror Solutions of the Dynamical Casimir Effect
Radiation from accelerating mirrors in a Minkowski spacetime provides
insights into the nature of horizons, black holes, and entanglement entropy. We
introduce new, simple, symmetric and analytic moving mirror solutions and study
their particle, energy, and entropy production. This includes an asymptotically
static case with finite emission that is the black hole analog of complete
evaporation. The total energy, total entropy, total particles, and spectrum are
the same on both sides of the mirror. We also study its asymptotically
inertial, drifting analog (which gives a black hole remnant) to explore
differences in finite and infinite production.Comment: 8 pages, 10 figure
Signatures of Energy Flux in Particle Production: A Black Hole Birth Cry and Death Gasp
It is recently argued that if the Hawking radiation process is unitary, then
a black hole's mass cannot be monotonically decreasing. We examine the time
dependent particle count and negative energy flux in the non-trivial conformal
vacuum via the moving mirror approach. A new, exactly unitary solution is
presented which emits a characteristic above-thermal positive energy burst, a
thermal plateau, and negative energy flux. It is found that the characteristic
positive energy flare and thermal plateau is observed in the particle outflow.
However, the results of time dependent particle production show no overt
indication of negative energy flux. Therefore, a black hole's birth cry is
detectable by asymptotic observers via particle count, whereas its death gasp
is not.Comment: 12 pages, 6 figure
Eternal and Evanescent Black Holes: It's All Done With Mirrors
The analogy between black hole radiation and accelerating mirror radiation
(the dynamical Casimir effect) is particularly strong for mirror trajectories
giving rise to a constant thermal flux of particles. We present new ways to
achieve such thermal plateaus, and customize their finite, semi-infinite, and
eternal presence, corresponding to forming/collapsing,
complete-evaporation/remnants, and eternal black holes. We find simple
expressions for the energy flux in terms of the mirror rapidity as a function
of proper time and null time.Comment: 13 pages, 11 figure
Finite Energy but Infinite Entropy Production from Moving Mirrors
Accelerating mirrors provide a simple conceptual laboratory for studying
particle production and the relation between trajectory and particle, energy,
and entropy fluxes. We focus on the relation between energy and entropy,
studying some special cases with finite total energy but infinite integrated
entropy (though the entropy flux may be finite at any particular moment). We
present a new asymptotically static moving mirror trajectory with solvable beta
Bogolyubov coefficients, total energy and fully relativistic particle count.
The integrated entropy diverges despite finite global radiative particle and
energy emission. Another class of models includes exponentially accelerated
mirrors in proper time; one of its unexpected behaviors is finite energy
emission but divergent entropy. We compare mirrors exponentially accelerated in
other coordinates as well, showing their close relation and an interesting
duality property.Comment: 10 pages, 8 figures, 2 table
Atmospheric transition curves for geomagnetically-sensitive cosmic rays Final report
Atmospheric transition curves for geomagnetically sensitive cosmic ray
Interplanetary Coronal Mass Ejections observed by MESSENGER and Venus Express
Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER (MES)
and Venus Express (VEX) spacecraft have been catalogued and analysed. The ICMEs
were identified by a relatively smooth rotation of the magnetic field direction
consistent with a flux rope structure, coinciding with a relatively enhanced
magnetic field strength. A total of 35 ICMEs were found in the surveyed MES
data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed
VEX data (from May 2006 to December 2013). The ICME flux rope configurations
have been determined. Ropes with northward leading edges were about four times
more common than ropes with southward leading edges, in agreement with a
previously established solar cycle dependence. Ropes with low inclinations to
the solar equatorial plane were about four times more common than ropes with
high inclinations, possibly an observational effect. Left and right-handed
ropes were observed in almost equal numbers. In addition, data from MES, VEX,
STEREO-A, STEREO-B and ACE were examined for multipoint signatures of the
catalogued ICMEs. For spacecraft separations below 15{\deg} in heliocentric
longitude, the second spacecraft observed the ICME flux rope in 82% of cases;
this percentage dropped to 49% for separations between 15 and 30{\deg}, to 18%
for separations between 30 and 45{\deg}, and to 12% for separations between 45
and 60{\deg}. As spacecraft separation increased, it became increasingly likely
that only the sheath and not the flux rope of the ICME was observed, in
agreement with the notion that ICME flux ropes are smaller in longitudinal
extent than the shocks or discontinuities that they often drive. Furthermore,
this study has identified 23 ICMEs observed by pairs of spacecraft close to
radial alignment. A detailed analysis of these events could lead to a better
understanding of how ICMEs evolve during propagation.Comment: 28 pages, 7 figure
Time Dependence of Particle Creation from Accelerating Mirrors
Particle production due to a quantized, massless, minimally coupled scalar
field in two-dimensional flat spacetime with an accelerating mirror is
investigated, with a focus on the time dependence of the process. We analyze
first the classes of trajectories previously investigated by Carlitz and Willey
and by Walker and Davies. We then analyze four new classes of trajectories, all
of which can be expressed analytically and for which several ancillary
properties can be derived analytically. The time dependence is investigated
through the use of wave packets for the modes of the quantized field that are
in the out vacuum state. It is shown for most of the trajectories studied that
good time resolution of the particle production process can be obtained.Comment: 21 pages, 5 figure
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