3,828 research outputs found
The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs
Between 1996 July and 2002 April, one or more spacecraft of the
interplanetary network detected 787 cosmic gamma-ray bursts that were also
detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera
experiments aboard the BeppoSAX spacecraft. During this period, the network
consisted of up to six spacecraft, and using triangulation, the localizations
of 475 bursts were obtained. We present the localization data for these events.Comment: 89 pages, 3 figures. Submitted to the Astrophysical Journal
Supplement Serie
Unit organization of three topics in oral communication in junior high school.
Includes the three units: The unit on conversation; the unit on discussion techniques; and the unit for adventures in understanding.
Thesis (Ed.M.)--Boston Universit
A pertubative approach to the Kondo effect in magnetic atoms on nonmagnetic substrates
Recent experimental advances in scanning tunneling microscopy make the
measurement of the conductance spectra of isolated and magnetically coupled
atoms on nonmagnetic substrates possible. Notably these spectra are
characterized by a competition between the Kondo effect and spin-flip inelastic
electron tunneling. In particular they include Kondo resonances and a
logarithmic enhancement of the conductance at voltages corresponding to
magnetic excitations, two features that cannot be captured by second order
perturbation theory in the electron-spin coupling. We have now derived a third
order analytic expression for the electron-spin self-energy, which can be
readily used in combination with the non-equilibrium Green's function scheme
for electron transport at finite bias. We demonstrate that our method is
capable of quantitative description the competition between Kondo resonances
and spin-flip inelastic electron tunneling at a computational cost
significantly lower than that of other approaches. The examples of Co and Fe on
CuN are discussed in detail
The 1st INTEGRAL SPI-ACS Gamma-Ray Burst Catalogue
We present the sample of gamma-ray bursts detected with the anti-coincidence
shield ACS of the spectrometer SPI on-board INTEGRAL for the first 26.5 months
of mission operation (up to Jan 2005). SPI-ACS works as a nearly
omnidirectional gamma-ray burst detector above ~80 keV but lacks spatial and
spectral information. In this catalogue, the properties derived from the 50 ms
light curves (e.g., T90, Cmax, Cint, variability, V/Vmax) are given for each
candidate burst in the sample. A strong excess of very short events with
durations <0.25 s is found. This population is shown to be significantly
different from the short- and long-duration burst sample by means of the
intensity distribution and V/Vmax test and is certainly connected with cosmic
ray hits in the detector. A rate of 0.3 true gamma-ray bursts per day is
observed.Comment: 10 pages, 9 figures, A&A accepte
The random case of Conley's theorem
The well-known Conley's theorem states that the complement of chain recurrent
set equals the union of all connecting orbits of the flow on the compact
metric space , i.e. , where
denotes the chain recurrent set of , stands for
an attractor and is the basin determined by . In this paper we show
that by appropriately selecting the definition of random attractor, in fact we
define a random local attractor to be the -limit set of some random
pre-attractor surrounding it, and by considering appropriate measurability, in
fact we also consider the universal -algebra -measurability besides -measurability, we are able to obtain
the random case of Conley's theorem.Comment: 15 page
Canonical transformations in three-dimensional phase space
Canonical transformation in a three-dimensional phase space endowed with
Nambu bracket is discussed in a general framework. Definition of the canonical
transformations is constructed as based on canonoid transformations. It is
shown that generating functions, transformed Hamilton functions and the
transformation itself for given generating functions can be determined by
solving Pfaffian differential equations corresponding to that quantities. Types
of the generating functions are introduced and all of them is listed.
Infinitesimal canonical transformations are also discussed. Finally, we show
that decomposition of canonical transformations is also possible in
three-dimensional phase space as in the usual two-dimensional one.Comment: 19 pages, 1 table, no figures. Accepted for publication in Int. J.
Mod. Phys.
Exceptional flaring activity of the anomalous X-ray pulsar 1E 1547.0-5408
(Abridged) We studied an exceptional period of activity of the anomalous
X-ray pulsar 1E 1547.0-5408 in January 2009, during which about 200 bursts were
detected by INTEGRAL. The major activity episode happened when the source was
outside the field of view of all the INTEGRAL instruments. But we were still
able to study the properties of 84 bursts detected simultaneously by the
anti-coincidence shield of the spectrometer SPI and by the detector of the
imager ISGRI. We find that the luminosity of the 22 January 2009 bursts of 1E
1547.0-5408 was > 1e42 erg/s. This luminosity is comparable to that of the
bursts of soft gamma repeaters (SGR) and is at least two orders of magnitude
larger than the luminosity of the previously reported bursts from AXPs.
Similarly to the SGR bursts, the brightest bursts of 1E 1547.0-5408 consist of
a short spike of ~100 ms duration with a hard spectrum, followed by a softer
extended tail of 1-10 s duration, which occasionally exhibits pulsations with
the source spin period of ~2 s. The observation of AXP bursts with luminosities
comparable to the one of SGR bursts strengthens the conjecture that AXPs and
SGRs are different representatives of one and the same source type.Comment: 9 pages, 10 figures, accepted to Astronomy & Astrophysic
Magnetar-like Emission from the Young Pulsar in Kes 75
We report detection of magnetar-like X-ray bursts from the young pulsar PSR
J1846-0258, at the center of the supernova remnant Kes 75. This pulsar, long
thought to be rotation-powered, has an inferred surface dipolar magnetic field
of 4.9x10^13 G, higher than those of the vast majority of rotation-powered
pulsars, but lower than those of the ~12 previously identified magnetars. The
bursts were accompanied by a sudden flux increase and an unprecedented change
in timing behavior. These phenomena lower the magnetic and rotational
thresholds associated with magnetar-like behavior, and suggest that in neutron
stars there exists a continuum of magnetic activity that increases with
inferred magnetic field strength.Comment: 17 pages, 2 figures, accepted for publication in Science. Note: The
content of this paper is embargoed until February 21, 200
Furnishing the Galaxy with Pulsars
The majority of pulsar population synthesis studies performed to date have
focused on isolated pulsar evolution. Those that have incorporated pulsar
evolution within binary systems have tended to either treat binary evolution
poorly of evolve the pulsar population in an ad-hoc manner. Here we present the
first model of the Galactic field pulsar population that includes a
comprehensive treatment of both binary and pulsar evolution. Synthetic
observational surveys mimicking a variety of radio telescopes are then
performed on this population. As such, a complete and direct comparison of
model data with observations of the pulsar population within the Galactic disk
is now possible. The tool used for completing this work is a code comprised of
three components: stellar/binary evolution, Galactic kinematics and survey
selection effects. Here we give a brief overview of the method and assumptions
involved with each component. Some preliminary results are also presented as
well as plans for future applications of the code.Comment: 3 pages, 3 figures, Conference: "40 years of pulsars: Millisecond
pulsars, magnetars and more", McGill University, Montreal, Canada, ed.
A.Cumming et al., AI
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