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Multiwavelength observations of the tev binary ls i +61° 303 with veritas,fermi-lat, andswift/xrt during a tev outburst
Aliu, E.; Archambault, S.; Behera, B.; Berger, K.; Beilicke, M.; Benbow, W.; Bird, R.; Bouvier, A.; Bugaev, V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dumm, J.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fortin, P.
We present the results of a multiwavelength observational campaign on the TeV binary system LS I +61 degrees 303 with the VERITAS telescope array (>200 GeV), Fermi-LAT (0.3-300 GeV), and Swift/XRT (2-10 keV). The data were taken from 2011 December through 2012 January and show a strong detection in all three wavebands. During this period VERITAS obtained 24.9 hr of quality selected livetime data in which LS I +61 degrees 303 was detected at a statistical significance of 11.9 sigma. These TeV observations show evidence for nightly variability in the TeV regime at a post-trial significance of 3.6 sigma. The combination of the simultaneously obtained TeV and X-ray fluxes do not demonstrate any evidence for a correlation between emission in the two bands. For the first time since the launch of the Fermi satellite in 2008, this TeV detection allows the construction of a detailed MeV-TeV spectral energy distribution from LS I +61 degrees 303. This spectrum shows a distinct cutoff in emission near 4 GeV, with emission seen by the VERITAS observations following a simple power-law above 200 GeV. This feature in the spectrum of LS I +61 degrees 303, obtained from overlapping observations with Fermi-LAT and VERITAS, may indicate that there are two distinct populations of accelerated particles producing the GeV and TeV emission.
Keyword(s): acceleration of particles; binaries general; gamma rays stars; relativistic processes; x-rays binaries; gamma-ray binary; x-ray; emission; +61-degrees-303; telescope; spectrum; star
Publication Date:
2018
Type: Journal article
Peer-Reviewed: Unknown
Institution: NUI Galway
Publisher(s): IOP Publishing
First Indexed: 2019-03-23 06:50:22 Last Updated: 2019-09-20 07:01:14