Ref HAL: in2p3-00024345_v1
Ref Arxiv: astro-ph/0505380
DOI: 10.1051/0004-6361:200500130
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173 citations
Résumé:

We report the detection of TeV $\gamma$-rays from the shell-type supernova remnant RX J0852.0-4622 with data of 3.2 h of live time recorded with H.E.S.S. in February 2004. An excess of (700 $\pm$ 60) events from the whole remnant with a significance of 12 $\sigma$ was found. The observed emission region is clearly extended with a radius of the order of 1 degree and the spatial distribution of the signal correlates with X-ray observations. The spectrum in the energy range between 500 GeV and 15 TeV is well described by a power law with a photon index of $\Gamma=2.1 \pm 0.1_{stat} \pm 0.2_{syst}$ and a differential flux at 1 TeV of $\varphi$ 1TEV= (2.1 $\pm 0.2_{stat} \pm 0.6_{syst}) \times 10^{-11} cm^{-2} s^{-1} TeV^{-1}$. The integral flux above 1 TeV was measured to be $\Phi$ (E > 1 TeV) = (1.9 $\pm 0.3_{stat} \pm 0.6_{syst}) \times 10^{-11} cm^{-2} s^{-1}$, which is at the level of the flux of the Crab nebula at these energies. More data are needed to draw firm conclusions on the magnetic field in the remnant and the type of the particle population creating the TeV $\gamma$-rays.

Commentaires: SIMBAD objects in preparation

Ref HAL: in2p3-00024532_v1
Ref Arxiv: astro-ph/0508298
DOI: 10.1126/science.1113764
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255 citations
Résumé:

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and X-ray observations have led to the presumption that some X-ray binaries called microquasars behave as scaled down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission >100 GeV from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Commentaires: Originally published in Science Express on 7 July 2005

Ref HAL: in2p3-00024344_v1
Ref Arxiv: astro-ph/0505219
DOI: 10.1051/0004-6361:20053195
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67 citations
Résumé:

The serendipitous discovery of an unidentified extended TeV $\gamma$-ray source close to the galactic plane named HESS J1303-631 at a significance of 21 standard deviations is reported. The observations were performed between February and June 2004 with the H.E.S.S. stereoscopic system of Cherenkov telescopes in Namibia. HESS J1303-631 was discovered roughly 0.6 \degres north of the binary system PSR B1259-63/SS 2883, the target object of the initial observation campaign which was also detected at TeV energies in the same field of view. HESS J1303-631 is extended with a width of an assumed intrinsic Gaussian emission profile of $\sigma$ = (0.16 $\pm$ 0.02)\degres and the integral flux above 380 GeV is compatible with constant emission over the entire observational period of (17$\pm$ 3)% of the Crab Nebula flux. The measured energy spectrum can be described by a power-law dN/dE $\sim$ E$^{-\Gamma}$ with a photon index of $\Gamma$ = 2.44 $\pm 0.05$_{stat} \pm$ 0.2$_{syst}$. Up to now, no counterpart at other wavelengths is identified. Various possible TeV production scenarios are discussed.

Ref HAL: in2p3-00023291_v1
Ref Arxiv: astro-ph/0411533
DOI: 10.1038/nature02960
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402 citations
Résumé:

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy bold gamma-rays of TeV energies (1 TeV = 1012 eV). We present a TeV bold gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Ref HAL: in2p3-00025285_v1
Ref Arxiv: astro-ph/0406658
DOI: 10.1016/j.astropartphys.2004.06.006
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105 citations
Résumé:

H.E.S.S.—the high energy stereoscopic system—is a new system of large atmospheric Cherenkov telescopes for GeV/TeV astronomy. Each of the four telescopes of 107 m2 mirror area is equipped with a 960-pixel photomultiplier-tube camera. This paper describes the methods used to convert the photomultiplier signals into the quantities needed for Cherenkov image analysis. Two independent calibration techniques have been applied in parallel to provide an estimation of uncertainties. Results on the long-term stability of the H.E.S.S. cameras are also presented.

Ref HAL: in2p3-00022258_v1
Ref Arxiv: astro-ph/0408145
DOI: 10.1051/0004-6361:200400055
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342 citations
Résumé:

We report the detection of a point-like source of very high energy (VHE) gamma-rays coincident within 1' of Sgr A*, obtained with the H.E.S.S. array of Cherenkov telescopes. The gamma-rays exhibit a power-law energy spectrum with a spectral index of -2.2 +/- 0.09 +/- 0.15 and a flux above the 165 GeV threshold of (1.82 +/- 0.22) \times 10^{-7} m^{-2} s^{-1}. The measured flux and spectrum differ substantially from recent results reported in particular by the CANGAROO collaboration.