894 research outputs found
Do current WIMP direct measurements constrain light relic neutralinos?
New upper bounds on direct detection rates have recently been presented by a
number of experimental collaborations working on searches for WIMPs. In this
paper we analyze how the constraints on relic neutralinos which can be derived
from these results is affected by the uncertainties in the distribution
function of WIMPs in the halo. Various different categories of velocity
distribution functions are considered, and the ensuing implications for
supersymmetric configurations derived. We conservatively conclude that current
experimental data do not constrain neutralinos of small mass (below 50 GeV).Comment: 9 pages, 7 figures, typeset with ReVTeX4. The paper may also be found
at http://www.to.infn.it/~fornengo/papers/constraints05.ps.gz or through
http://www.astroparticle.to.infn.it/index.htm
Mechanisms of the Vertical Secular Heating of a Stellar Disk
We investigate the nonlinear growth stages of bending instability in stellar
disks with exponential radial density profiles.We found that the unstable modes
are global (the wavelengths are larger than the disk scale lengths) and that
the instability saturation level is much higher than that following from a
linear criterion. The instability saturation time scales are of the order of
one billion years or more. For this reason, the bending instability can play an
important role in the secular heating of a stellar disk in the direction.
In an extensive series of numerical -body simulations with a high spatial
resolution, we were able to scan in detail the space of key parameters (the
initial disk thickness , the Toomre parameter , and the ratio of dark
halo mass to disk mass ). We revealed three distinct
mechanisms of disk heating in the direction: bending instability of the
entire disk, bending instability of the bar, and heating on vertical
inhomogeneities in the distribution of stellar matter.Comment: 22 pages including 8 figures. To be published in Astronomy Letters
(v.29, 2003
8th Annual Seminar on Legal Issues for Financial Institutions
Outline of speakers\u27 presentations from the 8th Annual Seminar on Legal Issues for Financial Institutions held by UK/CLE on March 11-12, 1988
Dark matter and Colliders searches in the MSSM
We study the complementarity between dark matter experiments (direct
detection and indirect detections) and accelerator facilities (the CERN LHC and
a TeV Linear Collider) in the framework of the
constrained Minimal Supersymmetric Standard Model (MSSM). We show how
non--universality in the scalar and gaugino sectors can affect the experimental
prospects to discover the supersymmetric particles. The future experiments will
cover a large part of the parameter space of the MSSM favored by WMAP
constraint on the relic density, but there still exist some regions beyond
reach for some extreme (fine tuned) values of the supersymmetric parameters.
Whereas the Focus Point region characterized by heavy scalars will be easily
probed by experiments searching for dark matter, the regions with heavy
gauginos and light sfermions will be accessible more easily by collider
experiments. More informations on both supersymmetry and astrophysics
parameters can be thus obtained by correlating the different signals.Comment: 25 pages, 10 figures, corrected typos and reference adde
Toward Understanding the origin of the Fundamental Plane for Early-Type Galaxies
We present a panoramic review of several observational and theoretical
aspects of the modern astrophysical research about the origin of the
Fundamental Plane (FP) relation for Early-Type Galaxies (ETGs). The discussion
is focused on the problem of the tilt and the tightness of the FP, and on the
attempts to derive the luminosity evolution of ETGs with redshift. Finally, a
number of observed features in the FP are interpreted from the standpoint of a
new theoretical approach based on the two-component tensor virial theorem.Comment: 30 pages, 3 figure
Feeding habits of Chironomid larvae (Insecta: Diptera) from a stream in the Floresta da Tijuca, Rio de Janeiro, Brazil
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