4,476 research outputs found
Measuring the beaming angle of GRB 030329 by fitting the rebrightenings in its multiband afterglow
Multiple rebrightenings have been observed in the multiband afterglow of GRB
030329. Especially, a marked and quick rebrightening occurred at about t ~ 1.2
* 10^5 s. Energy injection from late and slow shells seems to be the best
interpretation for these rebrightenings. Usually it is assumed that the energy
is injected into the whole external shock. However, in the case of GRB 030329,
the rebrightenings are so quick that the usual consideration fails to give a
satisfactory fit to the observed light curves. Actually, since these late/slow
shells coast freely in the wake of the external shock, they should be cold and
may not expand laterally. The energy injection then should only occur at the
central region of the external shock. Considering this effect, we numerically
re-fit the quick rebrightenings observed in GRB 030329. By doing this, we were
able to derive the beaming angle of the energy injection process. Our result,
with a relative residual of only 5% - 10% during the major rebrightening, is
better than any previous modeling. The derived energy injection angle is about
0.035. We assume that these late shells are ejected by the central engine via
the same mechanism as those early shells that produce the prompt gamma-ray
burst. The main difference is that their velocities are much slower, so that
they catch up with the external shock very lately and manifest as the observed
quick rebrightenings. If this were true, then the derived energy injection
angle can give a good measure of the beaming angle of the prompt gamma-ray
emission. Our study may hopefully provide a novel method to measure the beaming
angle of gamma-ray bursts.Comment: 8 pages, 6 figures, Has been accepted by RAA (Research in Astronomy
and Astrophysics
Phase selection rule of high-entropy metallic glasses with different short-to-medium-range orders
Demonstration of Adiabatic Variational Quantum Computing with a Superconducting Quantum Coprocessor
Adiabatic quantum computing enables the preparation of many-body ground
states. This is key for applications in chemistry, materials science, and
beyond. Realisation poses major experimental challenges: Direct analog
implementation requires complex Hamiltonian engineering, while the digitised
version needs deep quantum gate circuits. To bypass these obstacles, we suggest
an adiabatic variational hybrid algorithm, which employs short quantum circuits
and provides a systematic quantum adiabatic optimisation of the circuit
parameters. The quantum adiabatic theorem promises not only the ground state
but also that the excited eigenstates can be found. We report the first
experimental demonstration that many-body eigenstates can be efficiently
prepared by an adiabatic variational algorithm assisted with a multi-qubit
superconducting coprocessor. We track the real-time evolution of the ground and
exited states of transverse-field Ising spins with a fidelity up that can reach
about 99%.Comment: 12 pages, 4 figure
Estudio de prefactibilidad para la instalación de una planta procesadora de snacks rellenos y fritos
El presente trabajo plantea la fabricación de snacks rellenos y fritos para ser comercializados en el actual mercado limeño a través de un proyecto de vida útil de seis años, desde 2017 hasta 2022. Como tal, se justifica técnicamente por la disponibilidad en el mercado de su materia prima, la masa tipo wantan, y sus principales insumos, jamonada y queso.. Económicamente, se justifica también, ya que estudios de productos similares presentan resultados favorables. Socialmente, contempla la importancia del trabajador, del consumidor final y del rol que, como empresa, cumple en la sociedad
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