We report the discovery of TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's SNR. Observations performed in the period 2008-2010 with the VERITAS ground-based gamma-ray observatory reveal weak emission coming from the direction of the remnant, compatible with a point source located at 00h25m270, + 64°10′ 50″ (J2000). The TeV photon spectrum measured by VERITAS can be described with a power law dN/dE = C(E/3.42 TeV)-Γ with Γ = 1.95 ± 0.51stat 0.30sys and C = (1.55 ± 0.43 stat ± 0.47sys) × 10-14cm -2s-1TeV-1. The integral flux above 1TeV corresponds to 0.9% of the steady Crab Nebula emission above the same energy, making it one of the weakest sources yet detected in TeV gamma rays. We present both leptonic and hadronic models that can describe the data. The lowest magnetic field allowed in these models is 80 μG, which may be interpreted as evidence for magnetic field amplification.
Bibliographical noteFunding Information:
This research is supported by grants from the U.S. Department of Energy, the U.S. National Science Foundation and the Smithsonian Institution, by the Natural Sciences and Engineering Research Council (NSERC) in Canada, by Science Foundation Ireland (SFI 10/RFP/AST2748), and by the Science and Technology Facilities Council in the UK. The research presented in this Letter has used data from the Canadian Galactic Plane Survey, a Canadian project with international partners, supported by NSERC. D.B.S. acknowledges the NASA Delaware Space Grant Program for its support of this research. J.P.H. acknowledges support from NASA grant NNX08AZ86G to Rutgers University. Facility: VERITAS
- gamma rays: general