18,559 research outputs found
Emission from Large-scale Jets in Quasars
We consider the emission processes in the large-scale jets of powerful
quasars based on the results obtained with the VLA, Spitzer, Hubble, and
Chandra. We show that two well-known jets, 3C 273 and PKS 1136-135, have two
distinct spectral components on large-scales: (1) the low-energy (LE)
synchrotron spectrum extending from radio to infrared, and (2) the high-energy
(HE) component arising from optical and extending to X-rays. The X-ray emission
in quasar jets is often attributed to inverse-Compton scattering of cosmic
microwave background (CMB) photons by radio-emitting electrons in a highly
relativistic jet. However, recent data prefer synchrotron radiation by a second
distinct population as the origin of the HE component. We anticipate that
optical polarimetry with Hubble will establish the synchrotron nature of the HE
component. Gamma-ray observations with GLAST (renamed as the Fermi Gamma-ray
Space Telescope), as well as future TeV observations, are expected to place
important constraints on the jet models.Comment: 4 pages, 4 figures, to appear in a special issue of the International
Journal of Modern Physics D, proceedings of "High Energy Phenomena in
Relativistic Outflows", held in Dublin Sept 200
Value Assignments to Observables Depending on a History of Context Change
The functional composition principle is generalized by taking into account of
history of context change. Analysis of Peres' example shows hysteresis of value
assignments. It is shown that value assignments which depend on the history of
context change are possible in the case that the Hilbert space of state vectors
is finite dimensional.Comment: 22 pages. Errors in the previous proof of Proposition 5 were
corrected. This is the full version of "On Hysteresis of Value Assignments to
Observables during Changes of Context" in Foundations of Probability and
Physics - 4, eds. A. Yu. Khrennikov et al., AIP Conf. Proc. 889, 2007, pp.
422-42
Two-Species Asymmetric Simple Exclusion Process with Open Boundaries
We study the steady state of the two-species Asymmetric Simple Exclusion
Process (ASEP) with open boundary conditions. The matrix product method works
for the determination of the stationary probability distribution. Several
physical quantities are calculated through an explicit representation for the
matrix products. By making full use of the relation with the continuous big
q-Hermite polynomials, we arrive at integral formulae for the partition
function and the n-point functions. We examine the thermodynamic limit and find
three phases: the low-density phase, the high-density phase and the maximal
current phase.Comment: 17 pages, 2 figure
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