387 research outputs found
The INTEGRAL Core Observing Programme
The Core Programme of the INTEGRAL mission is defined as the portion of the
scientific programme covering the guaranteed time observations for the INTEGRAL
Science Working Team. This paper describes the current status of the Core
Programme preparations and summarizes the key elements of the observing
programme.Comment: Contributed paper, 3rd INTEGRAL Workshop, Taormina/Sicily, Sep 1998,
to be published in Astrophys. Letters & Communications, 199
Photon acceleration in variable ultra-relativistic outflows and high-energy spectra of Gamma-Ray Bursts
MeV seed photons produced in shocks in a variable ultra-relativistic outflow
gain energy by the Fermi mechanism, because the photons Compton scatter off
relativistically colliding shells. The Fermi-modified high-energy photon
spectrum has a non-universal slope and a universal cutoff. A significant
increase in the total radiative efficiency is possible. In some gamma ray
bursts, most of the power might be emitted at the high-energy cutoff for this
mechanism, which would be close to 100 MeV for outflows with a mean bulk
Lorentz factor of 100.Comment: 8 pages, submitted to ApJ
Success Factors of International Education and Training Networks
In the last decade, several international education and training networks have been established in the nuclear field, striving to support – in general terms – the availability of qualified human resources in nuclear facilities (including research centers). Re-cently, several cooperation agreements have been signed between different net-works with the aim to further boost the impact and effectiveness of their work. The networks have become active in different geographical regions of the world, and their creation has been supported by different international organizations. Consequently, for stakeholders in the nuclear field it is increasingly difficult to receive an overview, and to differentiate substantially between the education and training impacts on their own human resource issues. In order to present an overview and a clearer view on existing education and training networks, and to assess the potential benefits of their work for concerned stakehold-ers, this paper presents 2 examples (European Nuclear Education Network / ENEN, European Fusion Education Network / FuseNet), comparing their history, their target groups and their members, their mission and objectives, their activities and working mechanisms, as well as their information and communication (web sites). The objective is to develop criteria and in particular success factors that may provide guidance for further development of international education and training networks
Measurements of Gamma-Ray Bursts (GRBs) with Glast
One of the scientific goals of the main instrument of GLAST is the study of
Gamma-Ray Bursts (GRBs) in the energy range from ~20 MeV to ~300 GeV. In order
to extend the energy measurement towards lower energies a secondary instrument,
the GLAST Burst Monitor (GBM), will measure GRBs from ~10 keV to ~25 MeV and
will therefore allow the investigation of the relation between the keV and the
MeV-GeV emission from GRBs over six energy decades. These unprecedented
measurements will permit the exploration of the unknown aspects of the
high-energy burst emission and the investigation of their connection with the
well-studied low-energy emission. They will also provide ne insights into the
physics of GRBs in general. In addition the excellent localization of GRBs by
the LAT will stimulate follow-up observations at other wavelengths which may
yield clues about the nature of the burst sources.Comment: 6 pages, 2 figures, to be published in Baltic Astronomy - Proceedings
of the minisymposium "Physics of Gamma-Ray Bursts", JENAM Conference, August
29-30, 2003, Budapes
COMPTEL Observations of AGN at MeV-Energies
The COMPTEL experiment aboard CGRO, exploring the previously unknown sky at
MeV-energies, has so far detected 10 Active Galactic Nuclei (AGN): 9 blazars
and the radio galaxy Centaurus A. No Seyfert galaxy has been found yet. With
these results COMPTEL has opened the field of extragalactic Gamma-ray astronomy
in the MeV-band.Comment: 4 pages, 2 figures including 1 color plot, to appear in the
Proceedings of the 3rd INTEGRAL Workshop "The Extreme Universe", held in
Taormina, Italy, 14-18 September 199
Multifrequency Observations of the Virgo Blazars 3C 273 and 3C 279 in CGRO Cycle 8
We report first observational results of multifrequency campaigns on the
prominent Virgo blazars 3C 273 and 3C 279 which were carried out in January and
February 1999. Both blazars are detected from radio to gamma-ray energies. We
present the measured X- to gamma-ray spectra of both sources, and for 3C 279 we
compare the 1999 broad-band (radio to gamma-ray) spectrum to measured previous
ones.Comment: 5 pages including 3 figures, latex2e, to appear in: 'Proc. of the 5th
Compton Symposium', AIP, in pres
SPI observations of positron annihilation radiation from the 4th galactic quadrant: sky distribution
During its first year in orbit the INTEGRAL observatory performed deep
exposures of the Galactic Center region and scanning observations of the
Galactic plane. We report on the status of our analysis of the positron
annihilation radiation from the 4th Galactic quadrant with the spectrometer
SPI, focusing on the sky distribution of the 511 keV line emission. The
analysis methods are described; current constraints and limits on the Galactic
bulge emission and the bulge-to-disk ratio are presented.Comment: 4 pages, 2 figures, accepted for publication in the proceedings of
the 5th INTEGRAL worksho
INTEGRAL and XMM-Newton observations of the weak GRB 030227
We present INTEGRAL and XMM-Newton observations of the prompt gamma-ray
emission and the X-ray afterglow of GRB030227, the first GRB for which the
quick localization obtained with the INTEGRAL Burst Alert System (IBAS) has led
to the discovery of X-ray and optical afterglows. GRB030227 had a duration of
about 20 s and a peak flux of 1.1 photons cm^-2 s^-1 in the 20-200 keV energy
range. The time averaged spectrum can be fit by a single power law with photon
index about 2 and we find some evidence for a hard to soft spectral evolution.
The X-ray afterglow has been detected starting only 8 hours after the prompt
emission, with a 0.2-10 keV flux decreasing as t^-1 from 1.3x10e-12 to 5x10e-13
erg cm^-2 s^-1. The afterglow spectrum is well described by a power law with
photon index 1.94+/-0.05 modified by a redshifted neutral absorber with column
density of several 10e22 cm^-2. A possible emission line at 1.67 keV could be
due to Fe for a redshift z=3, consistent with the value inferred from the
absorption.Comment: 16 pages, 5 figures, latex, Accepted for publication in The
Astrophysical Journal Letter
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