van Eldik C (2006)
Publication Status: Published
Publication Type: Journal article, Original article
Publication year: 2006
Publisher: EDP Sciences
Book Volume: 448
Pages Range: L19-L23
Journal Issue: 2
DOI: 10.1051/0004-6361:200600010
The high-frequency peaked BL Lac PG 1553+113 was observed in 2005 with the HESS stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. Using the HESS standard analysis, an excess was measured at the 4.0σ level in these observations (7.6 hours live time). Three alternative, lower-threshold analyses yield >5σ excesses. The observed integral flux above 200 GeV is (4.8 ± 1.3 ± 1.0) × 10 cm s, and shows no evidence for variability. The measured energy spectrum is characterized by a very soft power law (photon index of Γ = 4.0 ± 0.6). Although the redshift of PG 1553+113 is unknown, there are strong indications that it is greater than z = 0.25 and possibly larger than z = 0.78. The observed spectrum is interpreted in the context of VHE γ-ray absorption by the Extragalactic Background Light, and is used to place an upper limit on the redshift of z < 0.74. © ESO 2006.
APA:
van Eldik, C. (2006). Evidence for VHE γ-ray emission from the distant BL Lac PG 1553+113. Astronomy & Astrophysics, 448(2), L19-L23. https://doi.org/10.1051/0004-6361:200600010
MLA:
van Eldik, Christopher. "Evidence for VHE γ-ray emission from the distant BL Lac PG 1553+113." Astronomy & Astrophysics 448.2 (2006): L19-L23.
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