Ref HAL: hal-00078988_v1
Ref Arxiv: astro-ph/0603725
DOI: 10.1086/527524
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
17 citations

Ref HAL: in2p3-00026029_v1
DOI: 10.1016/j.nima.2005.12.211
Exporter : BibTex | endNote
10 citations
Résumé:

The CsI calorimeter of the Gamma-Ray Large-Area Space Telescope (GLAST) will be calibrated in flight with cosmic-ray heavy ions. In order to determine the response of the calorimeter to relativistic heavy ions lighter than Fe, an experiment was carried out at the GSI heavy ion facility using the Fragment Separator (FRS). The measured response exhibits an unexpected feature for light ions, opposite to that observed at low incident energy: for a given deposited energy, the observed signal is greater for these ions than for protons (or more generally Z=1 minimum ionizing particles). Pulse shapes are found to be almost identical for carbon ions and Z=1 particles, with a significant slow scintillation component, which constitutes another departure from the low-energy behavior. Data on the energy resolution for the individual CsI crystals and on the loss of ions due to nuclear reactions in the calorimeter are also presented.

Commentaires: Publication commune GLAST et NEX

Ref HAL: in2p3-00109798_v1
Ref Arxiv: astro-ph/0601298
DOI: 10.1051/0004-6361:20054340
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
13 citations
Résumé:

If dark matter is made of neutralinos, annihilation of such Majorana particles should produce high energy cosmic rays, especially in galaxy halo high density regions like galaxy centres. M 31 (Andromeda) is our nearest neighbour spiral galaxy, and both its high mass and its low distance make it a source of interest for the indirect search for dark matter through $\gamma$-ray detection. The ground based atmospheric Cherenkov telescope CELESTE observed M 31 from 2001 to 2003, in the mostly unexplored energy range 50-500 GeV. These observations provide an upper limit on the flux above 50 GeV around $10^{-10}~\rm {cm}^{-2}\,\rm {s}^{-1}$ in the frame of supersymmetric dark matter, and more generally on any gamma emission from M 31.

Ref HAL: hal-00096030_v1
Ref Arxiv: astro-ph/0607258
DOI: 10.1051/0004-6361:20054078
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
14 citations
Résumé:

The TeV-emitting BL Lac object Mkn 421 was observed with very long baseline interferometry (VLBI) at three closely-spaced epochs one-month apart in March-April 1998. The source was also monitored at very-high gamma-ray energies (TeV measurements) during the same period in an attempt to search for correlations between TeV variability and the evolution of the radio morphology on parsec scales. While the VLBI maps show no temporal changes in the Mkn 421 VLBI jet, there is strong evidence of complex variability in both the total and polarized fluxes of the VLBI core of Mkn 421 and in its spectrum over the two-month span of our data. The high-energy measurements indicate that the overall TeV activity of the source was rising during this period, with a gamma-ray flare detected just three days prior to our second VLBI observing run. Although no firm correlation can be established, our data suggest that the two phenomena (TeV activity and VLBI core variability) are connected, with the VLBI core at 22 GHz being the self-absorbed radio counterpart of synchrotron self-Compton (SSC) emission at high energies. Based on the size of the VLBI core, we could derive an upper limit of 0.1 pc (3 x 10**17 cm) for the projected size of the SSC zone. This determination is the first model-free estimate of the size of the gamma-ray emitting region in a blazar.

Commentaires: 12 pages, 9 figures, accepted for publication in Astronomy & Astrophysics

DOI: 10.1007/10857580_45
Résumé:

Considering a NFW halo of M 31 made of neutralinos, predictions for the \x{03B3} fluxes are computed for different sets of SUSY parameters using the DarkSuspect MC simulation [1] [2]. Then they are compared with the efficiency of CELESTE Cerenkov telescope [3] which has a threshold energy of 30 GeV.

Commentaires: Astronomy, Cosmology and Fundamental Physics:

Ref HAL: in2p3-00087404_v1
Ref Arxiv: astro-ph/0212560
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

It is widely believed that dark matter exists within galaxies and clusters of galaxies. Under the assumption that this dark matter is composed of the lightest, stable supersymmetric particle, assumed to be the neutralino, the feasibility of its indirect detection via observations of a diffuse gamma-ray signal due to neutralino annihilation within M31 is examined.

Commentaires: Latex, 5 pages, 3 figures, to appear in the proceedings of the French Astrophysical Society, 2002 - GAM

DOI: 10.1007/10857580_49
1 citation
Résumé:

The distant globular cluster Palomar 13 has been found to have a very high mass-to-light ratio. Its profile can be well fitted either by using a King model with a tail, or by a NFW model [1]. This cluster may be the first case of the many clumps predicted by CDM simulations that would not be disrupted by the galactic halo potential. We assume that Pal 13 is made of neutralinos and we run the DarkSuspect code for five benchmark models. This code allows to estimate the gamma-ray flux produced in annihilations of neutralinos. These fluxes may be used as targets to be reached in proposals for future ground-based high altitude Cerenkov telescopes.

Commentaires: A 2-page poster.