13,664 research outputs found
Generalized Hirota bilinear identity and integrable q-difference and lattice hierarchies.
Hirota bilinear identity for Cauchy-Baker-Akhieser (CBA) kernel is introduced
as a basic tool to construct integrable hierarchies containing lattice and
q-difference times. Determinant formula for the action of meromorphic function
on CBA kernel is derived. This formula gives opportunity to construct generic
solutions for integrable lattice equations.Comment: 6 pages, LaTeX, the text of the talk at NLS-94, Chernogolovka,
Russia, July 94
WDVV and DZM
We show how the WDVV equations and the DZM system can be characterized via a
background family of functions.Comment: Latex, 14 page
Non-Hamiltonian generalizations of the dispersionless 2DTL hierarchy
We consider two-component integrable generalizations of the dispersionless
2DTL hierarchy connected with non-Hamiltonian vector fields, similar to the
Manakov-Santini hierarchy generalizing the dKP hierarchy. They form a
one-parametric family connected by hodograph type transformations. Generating
equations and Lax-Sato equations are introduced, a dressing scheme based on the
vector nonlinear Riemann problem is formulated. The simplest two-component
generalization of the dispersionless 2DTL equation is derived, its differential
reduction analogous to the Dunajski interpolating system is presented. A
symmetric two-component generalization of the dispersionless elliptic 2DTL
equation is also constructed.Comment: 10 pages, the text of the talk at NEEDS 09. Notations clarified,
references adde
Modeling the X-rays from the Central Compact Object PSR J1852+0040 in Kesteven 79: Evidence for a Strongly Magnetized Neutron Star
I present modeling of the X-ray pulsations from the central compact object
(CCO) PSR J1852+0040 in the Galactic supernova remnant Kesteven 79. In the
context of thermal surface radiation from a rotating neutron star, a
conventional polar cap model can reproduce the broad, large-amplitude X-ray
pulse only with a "pencil plus fan" beam emission pattern, which is
characteristic of strongly magnetized (10^12 Gauss) neutron star
atmospheres, substantially stronger than the ~10^10 Gauss external dipole field
inferred from the pulsar spin-down rate. This discrepancy can be explained by
an axially displaced dipole. For other beaming patterns, it is necessary to
invoke high-aspect-ratio emitting regions that are greatly longitudinally
elongated, possibly due to an extremely offset dipole. For all assumed emission
models, the existence of strong internal magnetic fields (10^14}
Gauss) that preferentially channel internal heat to only a portion of the
exterior is required to account for the implied high-temperature contrast
across the stellar surface. This lends further observational evidence in
support of the "hidden" strong magnetic field scenario, in which CCOs possess
strong submerged magnetic fields that are substantially stronger than the
external dipole field, presumably due to burial by fallback of supernova
ejecta. I also conduct phase-resolved X-ray spectroscopy and find no evidence
for prominent spin-phase-dependent absorption features that could be produced
by cyclotron absorption/scattering.Comment: 12 pages, 7 figures; accepted for publication in the Astrophysical
Journa
Deep XMM-Newton Spectroscopic and Timing Observations of the Isolated Radio Millisecond Pulsar PSR J0030+0451
We present deep XMM-Newton EPIC spectroscopic and timing X-ray observations
of the nearby solitary radio millisecond pulsar, PSR J0030+0451. Its emission
spectrum in the 0.1-10 keV range is found to be remarkably similar to that of
the nearest and best studied millisecond pulsar, PSR J0437-4715, being well
described by a predominantly thermal two-temperature model plus a faint hard
tail evident above ~2 keV. The pulsed emission in the 0.3-2 keV band is
characterized by two broad pulses with pulsed fraction ~60-70%, consistent with
a mostly thermal origin of the X-rays only if the surface polar cap radiation
is from a light-element atmosphere. Modeling of the thermal pulses permits us
to place constraints on the neutron star radius of R>10.7 (95% confidence) and
R>10.4 km (at 99.9% confidence) for M=1.4 M_sun.Comment: 8 pages, 7 figures; accepted for publication in The Astrophysical
Journa
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