105,773 research outputs found
The Chinese-French SVOM mission for Gamma-Ray Burst studies
We present the Space-based multi-band astronomical Variable Objects Monitor
mission (SVOM) decided by the Chinese National Space Agency (CNSA) and the
French Space Agency (CNES). The mission which is designed to detect about 80
Gamma-Ray Bursts (GRBs) of all known types per year, will carry a very
innovative scientific payload combining a gamma-ray coded mask imagers
sensitive in the range 4 keV to 250 keV, a soft X-ray telescope operating
between 0.5 to 2 keV, a gamma-ray spectro-photometer sensitive in the range 50
keV to 5 MeV, and an optical telescope able to measure the GRB afterglow
emission down to a magnitude limit M with a 300 s exposure. A particular
attention will be also paid to the follow-up in making easy the observation of
the SVOM detected GRB by the largest ground based telescopes.
Scheduled for a launch in 2013, it will provide fast and reliable GRB
positions, will measure the broadband spectral energy distribution and temporal
properties of the prompt emission, and will quickly identify the optical
afterglows of detected GRBs, including those at very high redshift.Comment: Proceedings of the SF2A conference, Paris, 200
The Intermediate Line Region and the Baldwin Effect
Statistical investigations of samples of quasars have established that
clusters of properties are correlated. The strongest trends among the
ultraviolet emission-line properties are characterized by the object-to-object
variation of emission from low-velocity gas, the so-called ``intermediate-line
region'' or ILR. The strongest trends among the optical emission-line
properties are characterized by the object-to-object variation of the line
intensity ratio of [O III] 5007 to optical Fe II. Additionally, the strength of
ILR emission correlates with [O III]/Fe II, as well as with radio and X-ray
properties. The fundamental physical parameter driving these related
correlations is not yet identified. Because the variation in the ILR dominates
the variation in the equivalent widths of lines showing the Baldwin effect, it
is important to understand whether the physical parameter underlying this
variation also drives the Baldwin effect or is a primary source of scatter in
the Baldwin effect.Comment: 11 pages, to appear in the proceedings of the meeting on "Quasars as
Standard Candles for Cosmology" held on May 18-22, 1998, at La Serena, Chile.
To be published by ASP, editor G. Ferlan
Testing Inflation: A Bootstrap Approach
We note that the essential idea of inflation, that the universe underwent a
brief period of accelerated expansion followed by a long period of decelerated
expansion, can be encapsulated in a "closure condition" which relates the
amount of accelerated expansion during inflation to the amount of decelerated
expansion afterward. We present a protocol for systematically testing the
validity of this condition observationally.Comment: 4 pages, 2 figures, matches Phys. Rev. Lett. versio
- …