* Astronomy

Title: Discovery of high and very high-energy emission from the BL Lac object SHBL J001355.9-185406
Authors: H.E.S.S. Collaboration: A. Abramowski, F. Acero, F. Aharonian, A.G. Akhperjanian, E. Angüner, G. Anton, S. Balenderan, A. Balzer, A. Barnacka, Y. Becherini, J. Becker Tjus, K. Bernlöhr, E. Birsin, E. Bissaldi, J. Biteau, C. Boisson, J. Bolmont, P. Bordas, J. Brucker, F. Brun, P. Brun, T. Bulik, S. Carrigan, S. Casanova, M. Cerruti, P.M. Chadwick, R. Chalme-Calvet, R.C.G. Chaves, A. Cheesebrough, M. Chrétien, S. Colafrancesco, G. Cologna, J. Conrad, C. Couturier, M. Dalton, M.K. Daniel, I.D. Davids, B. Degrange, C. Deil, P. deWilt, H.J. Dickinson, A. Djannati-Ataï, W. Domainko, L.O'C. Drury, G. Dubus, K. Dutson, J. Dyks, M. Dyrda, T. Edwards, K. Egberts, P. Eger, P. Espigat, C. Farnier, S. Fegan, F. Feinstein, M.V. Fernandes, D. Fernandez, A. Fiasson, G. Fontaine, et al. (152 additional authors not shown)

The detection of the high-frequency peaked BL Lac object (HBL) SHBL J001355.9-185406 (z=0.095) at high (HE; 100 MeV<E100 GeV) with the Fermi Large Area Telescope (LAT) and the High Energy Stereoscopic System (H.E.S.S.) is reported. Dedicated observations have been performed with the H.E.S.S. telescopes, leading to a detection at the 5.5 sigma significance level. The measured flux above 310 GeV is (8.3 ± 1.7_stat ± 1.7_sys) x 10^{-13} photons cms (about 0.6% of that of the Crab Nebula), and the power law spectrum has a photon index of Gamma = 3.4±0.5stat ±0.2sys. Using 3.5 years of publicly available Fermi-LAT data, a faint counterpart has been detected in the LAT data at the 5.5 sigma significance level, with an integrated flux above 300 MeV of (9.3 ± 3.4_stat ± 0.8_sys) x 10^{-10} photons cms and a photon index of Gamma = 1.96 ± 0.20_stat ± 0.08_sys. X-ray observations with Swift-XRT allow the synchrotron peak energy in \nu F_\nu representation to be located at ~ 1.0 keV. The broadband spectral energy distribution is modelled with a one-zone synchrotron self-Compton (SSC) model and the optical data by a black-body emission describing the thermal emission of the host galaxy. The derived parameters are typical for HBLs detected at VHE, with a particle dominated jet.

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