829 research outputs found
Soft Charges and Electric-Magnetic Duality
The main focus of this work is to study magnetic soft charges of the four
dimensional Maxwell theory. Imposing appropriate asymptotic falloff conditions,
we compute the electric and magnetic soft charges and their algebra both at
spatial and at null infinity. While the commutator of two electric or two
magnetic soft charges vanish, the electric and magnetic soft charges satisfy a
complex current algebra. This current algebra through Sugawara
construction yields two Kac-Moody algebras. We repeat the charge
analysis in the electric-magnetic duality-symmetric Maxwell theory and
construct the duality-symmetric phase space where the electric and magnetic
soft charges generate the respective boundary gauge transformations. We show
that the generator of the electric-magnetic duality and the electric and
magnetic soft charges form infinite copies of algebra. Moreover, we
study the algebra of charges associated with the global Poincar\'e symmetry of
the background Minkowski spacetime and the soft charges. We discuss physical
meaning and implication of our charges and their algebra.Comment: 41 pages, 4 figures; published version in JHE
Photometrically-Classified Superluminous Supernovae from the Pan-STARRS1 Medium Deep Survey: A Case Study for Science with Machine Learning-Based Classification
With the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time
(LSST), it is expected that only of all transients will be
classified spectroscopically. To conduct studies of rare transients, such as
Type I superluminous supernovae (SLSNe), we must instead rely on photometric
classification. In this vein, here we carry out a pilot study of SLSNe from the
Pan-STARRS1 Medium-Deep Survey (PS1-MDS) classified photometrically with our
SuperRAENN and Superphot algorithms. We first construct a sub-sample of the
photometric sample using a list of simple selection metrics designed to
minimize contamination and ensure sufficient data quality for modeling. We then
fit the multi-band light curves with a magnetar spin-down model using the
Modular Open-Source Fitter for Transients (MOSFiT). Comparing the magnetar
engine and ejecta parameter distributions of the photometric sample to those of
the PS1-MDS spectroscopic sample and a larger literature spectroscopic sample,
we find that these samples are overall consistent, but that the photometric
sample extends to slower spins and lower ejecta masses, which correspond to
lower luminosity events, as expected for photometric selection. While our
PS1-MDS photometric sample is still smaller than the overall SLSN spectroscopic
sample, our methodology paves the way to an orders-of-magnitude increase in the
SLSN sample in the LSST era through photometric selection and study.Comment: 13 pages, 6 figures, submitted to Ap
SN 2016iet: The Pulsational or Pair Instability Explosion of a Low Metallicity Massive CO Core Embedded in a Dense Hydrogen-Poor Circumstellar Medium
We present optical photometry and spectroscopy of SN 2016iet, an
unprecedented Type I supernova (SN) at with no obvious analog in the
existing literature. The peculiar light curve has two roughly equal brightness
peaks ( mag) separated by 100 days, and a subsequent slow decline
by 5 mag in 650 rest-frame days. The spectra are dominated by emission lines of
calcium and oxygen, with a width of only km s, superposed on a
strong blue continuum in the first year, and with a large ratio of at late times. There is no clear evidence
for hydrogen or helium associated with the SN at any phase. We model the light
curves with several potential energy sources: radioactive decay, central
engine, and circumstellar medium (CSM) interaction. Regardless of the model,
the inferred progenitor mass near the end of its life (i.e., CO core mass) is
M and up to M, placing the event in the
regime of pulsational pair instability supernovae (PPISNe) or pair instability
supernovae (PISNe). The models of CSM interaction provide the most consistent
explanation for the light curves and spectra, and require a CSM mass of
M ejected in the final decade before explosion. We further
find that SN 2016iet is located at an unusually large offset ( kpc) from
its low metallicity dwarf host galaxy ( Z, M), supporting the PPISN/PISN interpretation. In the final
spectrum, we detect narrow H emission at the SN location, likely due to
a dim underlying galaxy host or an H II region. Despite the overall consistency
of the SN and its unusual environment with PPISNe and PISNe, we find that the
inferred properties of SN\,2016iet challenge existing models of such events.Comment: 26 Pages, 17 Figures, Submitted to Ap
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