34,806 research outputs found
Long tails on thermonuclear X-ray bursts from neutron stars: a signature of inward heating?
We report the discovery of one-hour long tails on the few-minutes long X-ray
bursts from the `clocked burster' GS 1826-24. We propose that the tails are due
to enduring thermal radiation from the neutron star envelope. The enduring
emission can be explained by cooling of deeper NS layers which were heated up
through inward conduction of heat produced in the thermonuclear shell flash
responsible for the burst. Similar, though somewhat shorter, tails are seen in
bursts from EXO 0748-676 and 4U 1728-34. Only a small amount of cooling is
detected in all these tails. This is either due to compton up scattering of the
tail photons or, more likely, to a NS that is already fairly hot due to other,
stable, nuclear processes.Comment: Accepted for publication in Astronomy & Astrophysics, 12 pages, 14
figure
New Gauge Invariant Formulation of the Chern-Simons Gauge Theory: Classical and Quantal Analysis
Recently proposed new gauge invariant formulation of the Chern-Simons gauge
theory is considered in detail. This formulation is consistent with the gauge
fixed formulation. Furthermore it is found that the canonical (Noether)
Poincar\'e generators are not gauge invariant even on the constraints surface
and do not satisfy the Poincar\'e algebra contrast to usual case. It is the
improved generators, constructed from the symmetric energy-momentum tensor,
which are (manifestly) gauge invariant and obey the quantum as well as
classical Poincar\'e algebra. The physical states are constructed and it is
found in the Schr\"odinger picture that unusual gauge invariant longitudinal
mode of the gauge field is crucial for constructing the physical wavefunctional
which is genuine to (pure) Chern-Simons theory. In matching to the gauge fixed
formulation, we consider three typical gauges, Coulomb, axial and Weyl gauges
as explicit examples. Furthermore, recent several confusions about the effect
of Dirac's dressing function and the gauge fixings are clarified. The analysis
according to old gauge independent formulation a' la Dirac is summarized in an
appendix.Comment: No figures, 44 page
Our World as an Expanding Shell
In the model where the Universe is considered as a thin shell expanding in
5-dimensional hyper-space there is a possibility to have just one scale for a
particle theory corresponding to the Universe thickness. From a realistic model
the relation of this parameter to the Universe size was found.Comment: RevTeX, 4 pages, no figure
A lens-coupled scintillation counter in cryogenic environment
In this work we present an elegant solution for a scintillation counter to be
integrated into a cryogenic system. Its distinguishing feature is the absence
of a continuous light guide coupling the scintillation and the photodetector
parts, operating at cryogenic and room temperatures respectively. The prototype
detector consists of a plastic scintillator with glued-in wavelength-shifting
fiber located inside a cryostat, a Geiger-mode Avalanche Photodiode (G-APD)
outside the cryostat, and a lens system guiding the scintillation light
re-emitted by the fiber to the G-APD through optical windows in the cryostat
shields. With a 0.8mm diameter multiclad fiber and a 1mm active area G-APD the
coupling efficiency of the "lens light guide" is about 50%. A reliable
performance of the detector down to 3K is demonstrated.Comment: 14 pages, 11 figure
Indications for a slow rotator in the Rapid Burster from its thermonuclear bursting behaviour
We perform time-resolved spectroscopy of all the type I bursts from the Rapid
Burster (MXB 1730-335) detected with the Rossi X-ray Timing Explorer. Type I
bursts are detected at high accretion rates, up to \sim 45% of the Eddington
luminosity. We find evidence that bursts lacking the canonical cooling in their
time-resolved spectra are, none the less, thermonuclear in nature. The type I
bursting rate keeps increasing with the persistent luminosity, well above the
threshold at which it is known to abruptly drop in other bursting low-mass
X-ray binaries. The only other known source in which the bursting rate keeps
increasing over such a large range of mass accretion rates is the 11 Hz pulsar
IGR J174802446. This may indicate a similarly slow spin for the neutron star
in the Rapid Burster
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