S. Hayashi

The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7-3946.

Protons with energies up to ∼1015u2009eV are the main component of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (π0), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in γ-rays with a particular spectral-energy distribution. Here we report the observation of cascade showers of optical photons resulting from γ-rays at energies of ∼1012u2009eV hitting Earths upper atmosphere, in the direction of the supernova remnant RX J1713.7–3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.

Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II

K. Tsuchiya, R. Enomoto, L. T. Ksenofontov, M. Mori, T. Naito, A. Asahara, G. V. Bicknell, R. W. Clay, Y. Doi, P. G. Edwards, S. Gunji, S. Hara, T. Hara, T. Hattori, Sei. Hayashi, C. Itoh, S. Kabuki, F. Kajino, H. Katagiri, A. Kawachi, T. Kifune, H. Kubo, T. Kurihara, R. Kurosaka, J. Kushida Y. Matsubara, Y. Miyashita, Y. Mizumoto, H. Moro, H. Muraishi, Y. Muraki, T. Nakase, D. Nishida, K. Nishijima, M. Ohishi, K. Okumura, J. R. Patterson, R. J. Protheroe, N. Sakamoto, K. Sakurazawa, D. L. Swaby, T. Tanimori, H. Tanimura, G. Thornton, F. Tokanai, T. Uchida, S. Watanabe, T. Yamaoka, S. Yanagita, T. Yoshida, and T. Yoshikoshi

Detection of gamma rays around 1 TeV from RX J0852.0-4622 by CANGAROO-II

We have detected gamma-ray emission at the 6 σ level at energies greater than 500 GeV from the supernova remnant RX J0852.0-4622 (G266.2-1.2) using the CANGAROO-II imaging atmospheric Cerenkov telescope. The flux was 0.12 times that of Crab at 1 TeV. The signal centroid is consistent with the peak of the X-ray emission in the northwest rim of the remnant.

Cangaroo III observations of the supernova remnant RX J0852.0-4622

Sub-TeV gamma-ray emission from the northwest rim of the supernova remnant RX J0852.0-4622 was detected with the CANGAROO II telescope and recently confirmed by the HESS group. In addition, the HESS data revealed a very wide (up to 2° in diameter), shell-like profile of the gamma-ray emission. We carried out CANGAROO III observations in 2005 January and February with three telescopes and show here the results of threefold coincidence data. We confirm the HESS results about the morphology and the energy spectrum and find that the energy spectrum in the NW rim is consistent with that of the whole remnant.

A Search for Sub-TeV Gamma Rays from the Vela Pulsar Region with CANGAROO-III

We made stereoscopic observations of the Vela pulsar region with two of the 10 m diameter CANGAROO-III imaging atmospheric Cerenkov telescopes in 2004 January and February in a search for sub-TeV gamma rays from the pulsar and surrounding regions. We describe the observations, provide a detailed account of the calibration methods, and introduce the improved and bias-free analysis techniques employed for CANGAROO-III data. No evidence of gamma-ray emission is found from either the pulsar position or the previously reported position offset by 013, and the resulting upper limits are a factor of 5 less than the previously reported flux from observations with the CANGAROO-I 3.8 m telescope. Following the recent report by the H.E.S.S. group of TeV gamma-ray emission from the pulsar wind nebula, which is ~05 south of the pulsar position, we examined this region and found supporting evidence for emission extended over ~06.We made stereoscopic observations of the Vela Pulsar region with two of the 10 m diameter CANGAROO-III imaging atmospheric Cherenkov telescopes in January and February, 2004, in a search for sub-TeV gamma-rays from the pulsar and surrounding regions. We describe the observations, provide a detailed account of the calibration methods, and introduce the improved and bias-free analysis techniques employed for CANGAROO-III data. No evidence of gamma-ray emission is found from either the pulsar position or the previously reported position offset by 0.13 degree, and the resulting upper limits are a factor of five less than the previously reported flux from observations with the CANGAROO-I 3.8 m telescope. Following the recent report by the H.E.S.S. group of TeV gamma-ray emission from the Pulsar Wind Nebula, which is

CANGAROO III Search for Gamma Rays from Centaurus A and the ω Centauri Region

sim

Development of an atmospheric Cherenkov imaging camera for the CANGAROO-III experiment

0.5 degree south of the pulsar position, we examined this region and found supporting evidence for emission extended over

CANGAROO-III OBSERVATIONS OF THE 2006 OUTBURST OF PKS 2155-304

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Observation of Gamma Rays Greater than 10 TeV from Markarian 421

0.6 degree.

CANGAROO-III Search for TeV Gamma-rays from Two Clusters of Galaxies

We have observed the giant radio galaxy Centaurus A and the globular cluster ω Centauri in the TeV energy region using the CANGAROO III stereoscopic system. The system has been in operation since 2004 with an array of four Imaging Atmospheric Cerenkov Telescopes (IACT) with ~100 m spacings. The observations were carried out in 2004 March and April. In total, approximately 10 hr of data were obtained for each target. No statistically significant gamma-ray signal has been found above 420 GeV over a wide angular region (a 1° radius from the pointing center), and we derive flux upper limits using the wholefield of view. Implications for the total energy of cosmic rays and the density of the cold dark matter are considered.