425 research outputs found
The Art of War: Beyond Memory-one Strategies in Population Games
We define a new strategy for population games based on techniques from
machine learning and statistical inference that is essentially uninvadable and
can successfully invade (significantly more likely than a neutral mutant)
essentially all known memory-one strategies for the prisoner's dilemma and
other population games, including ALLC (always cooperate), ALLD (always
defect), tit-for-tat (TFT), win-stay-lose-shift (WSLS), and zero determinant
(ZD) strategies, including extortionate and generous strategies. We will refer
to a player using this strategy as an "information player" and the specific
implementation as . Such players use the history of play to identify
opponent's strategies and respond accordingly, and naturally learn to cooperate
with each other.Comment: 16 pages, 4 figure
Explosive Nucleosynthesis from GRB and Hypernova Progenitors: Direct Collapse versus Fallback
The collapsar engine behind long-duration gamma-ray bursts extracts the
energy released from the rapid accretion of a collapsing star onto a
stellar-massed black hole. In a collapsing star, this black hole can form in
two ways: the direct collapse of the stellar core into a black hole and the
delayed collapse of a black hole caused by fallback in a weak supernova
explosion. In the case of a delayed-collapse black hole, the strong
collapsar-driven explosion overtakes the weak supernova explosion before shock
breakout, and it is very difficult to distinguish this black hole formation
scenario from the direct collapse scenario. However, the delayed-collapse
mechanism, with its double explosion, produces explosive nucleosynthetic yields
that are very different from the direct collapse scenario. We present
1-dimensional studies of the nucleosynthetic yields from both black hole
formation scenarios, deriving differences and trends in their nucleosynthetic
yields.Comment: 47 pages, submitted to Ap
A Case Study of Small Scale Structure Formation in 3D Supernova Simulations
It is suggested in observations of supernova remnants that a number of large-
and small-scale structures form at various points in the explosion.
Multidimensional modeling of core-collapse supernovae has been undertaken since
SN1987A, and both simulations and observations suggest/show that
Rayleigh-Taylor instabilities during the explosion is a main driver for the
formation of structure in the remnants.
We present a case study of structure formation in 3D in a \msol{15} supernova
for different parameters. We investigate the effect of moderate asymmetries and
different resolutions of the formation and morphology of the RT unstable
region, and take first steps at determining typical physical quantities (size,
composition) of arising clumps. We find that in this progenitor the major RT
unstable region develops at the He/OC interface for all cases considered. The
RT instabilities result in clumps that are overdense by 1-2 orders of magnitude
with respect to the ambient gas, have size scales on the level of a few % of
the remnant diameter, and are not diffused after the first yrs of the
remnant evolution, in the absence of a surrounding medium.Comment: 59 pages, 34 figure
The Los Alamos Supernova Light Curve Project: Computational Methods
We have entered the era of explosive transient astronomy, in which upcoming
real-time surveys like the Large Synoptic Survey Telescope (LSST), the Palomar
Transient Factory (PTF) and Panoramic Survey Telescope and Rapid Response
System (Pan-STARRS) will detect supernovae in unprecedented numbers. Future
telescopes such as the James Webb Space Telescope may discover supernovae from
the earliest stars in the universe and reveal their masses. The observational
signatures of these astrophysical transients are the key to unveiling their
central engines, the environments in which they occur, and to what precision
they will pinpoint cosmic acceleration and the nature of dark energy. We
present a new method for modeling supernova light curves and spectra with the
radiation hydrodynamics code RAGE coupled with detailed monochromatic opacities
in the SPECTRUM code. We include a suite of tests that demonstrate how the
improved physics is indispensable to modeling shock breakout and light curves.Comment: 18 pages, 19 figures, published in ApJ Supplement
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