Chemistry and Physics publications

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Browsing Chemistry and Physics publications by Author "32nd International Cosmic Ray Conference (ICRC) (11 Aug 2011 - 18 Aug 2011 : Beijing, China)"

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    A multi-wavelength study of the unidentified TeV γ-ray source HESS J1626-490
    (Institute of High Energy Physics, 2011) Eger, P.; Rowell, G.; Kawamura, A.; Fukui, Y.; Rolland, L.; Stegmann, C.; 32nd International Cosmic Ray Conference (ICRC) (11 Aug 2011 - 18 Aug 2011 : Beijing, China)
    HESS J1626−490, so far only detected with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes, could not be unambiguously identified with any source seen at lower energies. Therefore, we analyzed data from an archival XMM-Newton observation, pointed towards HESS J1626−490, to classify detected point-like and extended X-ray sources according to their spectral properties. None of the detected X-ray point sources fulfills the energetic requirements to be considered as the synchrotron radiation (SR) counterpart to the VHE source assuming an Inverse Compton (IC) emission scenario. Furthermore, we did not detect any diffuse X-ray excess emission originating from the region around HESS J1626−490 above the Galactic Background. The derived upper limit for the total X-ray flux disfavors a purely leptonic emission scenario for HESS J1626−490. To characterize the Interstellar Medium surrounding HESS J1626−490 we analyzed 12CO(J=1-0) molecular line data from the NANTEN Galactic plane survey and H I data from the Southern Galactic Plane Survey (SGPS). We found a good morphological match between molecular and atomic gas in the −27 km/s to −18 km/s line-of-sight velocity range and HESS J1626−490. The cloud has a mass of 1.8×4M and is located at a mean kinematic distance of d = 1.8 kpc. Furthermore, we found a density depression in the H I gas at a similar distance which is spatially consistent with the SNR G335.2+00.1. Therefore, the most likely origin of the VHE γ-ray emission observed with H.E.S.S. is the hadronic interaction of cosmic rays with a moderately dense molecular cloud, which we detected with Nanten. The application of a detailed hadronic model for cosmic ray transport and interaction shows that the cosmic rays could originate from the nearby SNRG335.2+00.1.
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    R&D studies for very high energy gamma-ray astrophysics at energies greater than 10 TeV
    (Institute of High Energy Physics, 2011) Yoshikoshi, T.; Clay, R.W.; Dawson, B.R.; Matsubara, Y.; Mori, M.; Naito, T.; Nishijima, K.; Ohishi, M.; Rowell, G.P.; Toyama, T.; 32nd International Cosmic Ray Conference (ICRC) (11 Aug 2011 - 18 Aug 2011 : Beijing, China)
    In spite of more than 100 discoveries of TeV gamma-ray sources by the current imaging atmospheric Cherenkov telescope (IACT) arrays, Galactic cosmic ray accelerators up to the knee energies (∼ PeV) still remain unclear. PeV Explorer (or PeX) is a future project of a relatively small IACT array, optimized to detect gamma rays of energies greater than 10 TeV and aiming to explore Galactic accelerators up to PeV energies. We present the status of our hardware R & D studies for this project and some extension plans.