Discovery of very high energy γ-ray emission from the BL Lacertae object H 2356-309 with the HESS Cherenkov telescopes

F. Aharonian, A. G. Akhperjanian, A. R. Bazer-Bachi, M. Beilicke, W. Benbow, D. Berge, K. Bernlöhr, C. Boisson, O. Bolz, V. Borrel, I. Braun, F. Breitling, A. M. Brown, R. Bühler, I. Büsching, S. Carrigan, P. M. Chadwick, L. M. Chounet, R. Cornils, L. CostamanteB. Degrange, H. J. Dickinson, A. Djannati-Ataï, L. O C Drury, G. Dubus, K. Egberts, D. Emmanoulopoulos, P. Espigat, F. Feinstein, E. Ferrero, G. Fontaine, S. Funk, S. Funk, Y. A. Gallant, B. Giebels, J. F. Glicenstein, P. Goret, C. Hadjichristidis, D. Hauser, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, W. Hofmann, M. Holleran, D. Horns, A. Jacholkowska, O. C. de Jager, B. Khélifi, N. Komin, A. Konopelko, I. J. Latham, R. le Gallou, A. Lemière, M. Lemoine-Goumard, T. Lohse, J. M. Martin, O. Martineau-Huynh, A. Marcowith, C. Masterson, T. J L McComb, M. de Naurois, D. Nedbal, S. J. Nolan, A. Noutsos, K. J. Orford, J. L. Osborne, M. Ouchrif, M. Panter, G. Pelletier, S. Pita, G. Pühlhofer, M. Punch, B. C. Raubenheimer, M. Raue, S. M. Rayner, A. Reimer, O. Reimer, J. Ripken, L. Rob, L. Rolland, G. Rowell, V. Sahakian, L. Saugé, S. Schlenker, R. Schlickeiser, U. Schwanke, H. Sol, D. Spangler, F. Spanier, R. Steenkamp, C. Stegmann, G. Superina, J. P. Tavernet, R. Terrier, C. G. Théoret, M. Tluczykont, C. van Eldik, G. Vasileiadis, C. Venter, P. Vincent, H. J. Völk, S. J. Wagner, M. Ward

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

The extreme synchrotron BL Lac object H 2356-309, located at a redshift of z = 0.165, was observed from June to December 2004 with a total exposure of ≈40 h live-time with the HESS (High Energy Stereoscopic System) array of atmospheric-Cherenkov telescopes (ACTs). Analysis of this data set yields, for the first time, a strong excess of 453 γ-rays (10 standard deviations above background) from H 2356-309, corresponding to an observed integral flux above 200 GeV of I(>200 GeV) = (4.1 ±0.5) × 10 -12 cm -2 s -1 (statistical error only). The differential energy spectrum of the source between 200 GeV and 1.3TeV is well-described by a power law with a normalisation (at 1 TeV) of N 0 = (3.00 ±0.80 stat ± 0.31 sys)× 10 -13 cm -2 s -1TeV -1 and a photon index of Γ = 3.09 ± 0.24 stat ± 0.10 sys. H 2356-309 is one of the most distant BL Lac objects detected at very-high-energy γ-rays so far. Results from simultaneous observations from ROTSE-III (optical), RXTE (X-rays) and NRT (radio) are also included and used together with the HESS data to constrain a single-zone homogeneous synchrotron self-Compton (SSC) model. This model provides an adequate fit to the HESS data when using a reasonable set of model parameters.

Original languageEnglish (US)
Pages (from-to)461-466
Number of pages6
JournalAstronomy and Astrophysics
Volume455
Issue number2
DOIs
StatePublished - Aug 2006

Keywords

  • Galaxies: BL Lacertae objects: individual: H 2356-309
  • Galaxies: active
  • Gamma rays; observations

Fingerprint

Dive into the research topics of 'Discovery of very high energy γ-ray emission from the BL Lacertae object H 2356-309 with the HESS Cherenkov telescopes'. Together they form a unique fingerprint.

Cite this