1,339 research outputs found
Photometry of SN 2002ic and Implications for the Progenitor Mass-Loss History
We present new pre-maximum and late-time optical photometry of the Type
Ia/IIn supernova 2002ic. These observations are combined with the published
V-band magnitudes of Hamuy et al. (2003) and the VLT spectrophotometry of Wang
et al. (2004) to construct the most extensive light curve to date of this
unusual supernova. The observed flux at late time is significantly higher
relative to the flux at maximum than that of any other observed Type Ia
supernova and continues to fade very slowly a year after explosion. Our
analysis of the light curve suggests that a non-Type Ia supernova component
becomes prominent days after explosion. Modeling of the non-Type Ia
supernova component as heating from the shock interaction of the supernova
ejecta with pre-existing circumstellar material suggests the presence of a
cm gap or trough between the progenitor system and the
surrounding circumstellar material. This gap could be due to significantly
lower mass-loss years prior to explosion or
evacuation of the circumstellar material by a low-density fast wind. The latter
is consistent with observed properties of proto-planetary nebulae and with
models of white-dwarf + asymptotic giant branch star progenitor systems with
the asymptotic giant branch star in the proto-planetary nebula phase.Comment: accepted for publication in Ap
Richard S. Vasey in a Senior Organ Recital of Original Compositions
This is the program for the senior organ recital of Richard S. Vasey, who performed original compositions. The performance was held on December 13, 1973, in Mitchell Hall. Sue Arnn assisted him, and he was accompanied by the Ouachita University Symphonic Band, which was directed by Marvin A. Lawson
Gamma-ray burst contributions to constraining the evolution of dark energy
We explore the gamma-ray bursts' (GRBs') contributions in constraining the
dark energy equation of state (EOS) at high () and at middle
redshifts () and estimate how many GRBs are needed to get
substantial constraints at high redshifts. We estimate the constraints with
mock GRBs and mock type Ia supernovae (SNe Ia) for comparisons. When
constraining the dark energy EOS in a certain redshift range, we allow the dark
energy EOS parameter to vary only in that redshift bin and fix EOS parameters
elsewhere to -1. We find that it is difficult to constrain the dark energy EOS
beyond the redshifts of SNe Ia with GRBs unless some new luminosity relations
for GRBs with smaller scatters are discovered. However, at middle redshifts,
GRBs have comparable contributions with SNe Ia in constraining the dark energy
EOS.Comment: 3 pages, 5 figures. Published in Astronomy and Astrophysics.
Corrected referenc
Dark Energy Accretion onto a Black Hole in an Expanding Universe
By using the solution describing a black hole embedded in the FLRW universe,
we obtain the evolving equation of the black hole mass expressed in terms of
the cosmological parameters. The evolving equation indicates that in the
phantom dark energy universe the black hole mass becomes zero before the Big
Rip is reached.Comment: 7 pages, no figures, errors is correcte
Type Ia Supernova Light Curve Inference: Hierarchical Bayesian Analysis in the Near Infrared
We present a comprehensive statistical analysis of the properties of Type Ia
SN light curves in the near infrared using recent data from PAIRITEL and the
literature. We construct a hierarchical Bayesian framework, incorporating
several uncertainties including photometric error, peculiar velocities, dust
extinction and intrinsic variations, for coherent statistical inference. SN Ia
light curve inferences are drawn from the global posterior probability of
parameters describing both individual supernovae and the population conditioned
on the entire SN Ia NIR dataset. The logical structure of the hierarchical
model is represented by a directed acyclic graph. Fully Bayesian analysis of
the model and data is enabled by an efficient MCMC algorithm exploiting the
conditional structure using Gibbs sampling. We apply this framework to the
JHK_s SN Ia light curve data. A new light curve model captures the observed
J-band light curve shape variations. The intrinsic variances in peak absolute
magnitudes are: sigma(M_J) = 0.17 +/- 0.03, sigma(M_H) = 0.11 +/- 0.03, and
sigma(M_Ks) = 0.19 +/- 0.04. We describe the first quantitative evidence for
correlations between the NIR absolute magnitudes and J-band light curve shapes,
and demonstrate their utility for distance estimation. The average residual in
the Hubble diagram for the training set SN at cz > 2000 km/s is 0.10 mag. The
new application of bootstrap cross-validation to SN Ia light curve inference
tests the sensitivity of the model fit to the finite sample and estimates the
prediction error at 0.15 mag. These results demonstrate that SN Ia NIR light
curves are as effective as optical light curves, and, because they are less
vulnerable to dust absorption, they have great potential as precise and
accurate cosmological distance indicators.Comment: 24 pages, 15 figures, 4 tables. Accepted for publication in ApJ.
Corrected typo, added references, minor edit
Interacting Cosmic Fluids in Brans-Dicke Cosmology
We provide a detailed description for power-law scaling FRW cosmological
models in Brans-Dicke theory dominated by two interacting fluid components
during the expansion of the universe.Comment: 13 pages, 8 figure
Lower bounds on photometric redshift errors from Type Ia supernovae templates
Cosmology with Type Ia supernovae heretofore has required extensive
spectroscopic follow-up to establish a redshift. Though tolerable at the
present discovery rate, the next generation of ground-based all-sky survey
instruments will render this approach unsustainable. Photometry-based redshift
determination is a viable alternative, but introduces non-negligible errors
that ultimately degrade the ability to discriminate between competing
cosmologies. We present a strictly template-based photometric redshift
estimator and compute redshift reconstruction errors in the presence of
photometry and statistical errors. With reasonable assumptions for a cadence
and supernovae distribution, these redshift errors are combined with systematic
errors and propagated using the Fisher matrix formalism to derive lower bounds
on the joint errors in and relevant to the next
generation of ground-based all-sky survey.Comment: 23 pages, 6 figure
Offspring Production among the Extended Relatives of Samoan Men and Fa'afafine
Androphilia refers to sexual attraction to adult males, whereas gynephilia refers to sexual attraction to adult females. Male androphilia is an evolutionary paradox. Its development is at least partially influenced by genetic factors, yet male androphiles exhibit lower reproductive output, thus raising the question of how genetic factors underlying its development persist. The sexual antagonism hypothesis posits that the fitness costs associated with genetic factors underlying male androphilia are offset because these same factors lead to elevated reproduction on the part of the female relatives of androphilic males. Western samples drawn from low fertility populations have yielded inconsistent results when testing this hypothesis. Some studies documented elevated reproduction among the matrilineal female kin of androphilic males, whereas others found such effects in the paternal line. Samoa is a high-fertility population in which individuals reproduce closer to their maximum capacities. This study compared the reproductive output of the paternal and maternal line grandmothers, aunts, and uncles of 86 Samoan androphilic males, known locally as fa'afafine, and 86 Samoan gynephilic males. Reproductive output was elevated in the paternal and maternal line grandmothers, but not aunts or uncles, of fa'afafine. These findings are consistent with the sexual antagonism hypothesis and suggest that male androphilia is associated with elevated reproduction among extended relatives in both the maternal and paternal line. Discussion focuses on how this study, in conjunction with the broader literature, informs various models for the evolution of male androphilia via elevated reproduction on the part of female kin
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