Abstract
We present the results of a multiwavelength observational campaign on the TeV binary system LS I +61°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°303 was detected at a statistical significance of 11.9σ. These TeV observations show evidence for nightly variability in the TeV regime at a post-trial significance of 3.6σ. 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°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°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.
| Original language | English |
|---|---|
| Article number | 88 |
| Journal | Astrophysical Journal |
| Volume | 779 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 10 Dec 2013 |
Keywords
- X-rays: binaries
- acceleration of particles
- binaries: general
- gamma rays: stars
- relativistic processes
Authors (Note for portal: view the doc link for the full list of authors)
- Authors
- 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, MP,Cui, W,Dumm, J,Falcone, A,Federici, S,Feng, Q,Finley, JP,Fortin, P,Fortson, L,Furniss, A,Galante, N,Gillanders, GH,Griffin, S,Griffiths, ST,Grube, J,Gyuk, G,Hanna, D,Holder, J,Hughes, G,Humensky, TB,Kaaret, P,Kertzman, M,Khassen, Y,Kieda, D,Krennrich, F,Lang, MJ,Maier, G,Majumdar, P,McArthur, S,McCann, A,Moriarty, P,Mukherjee, R,de Bhroithe, AO,Ong, RA,Otte, AN,Park, N,Perkins, JS,Pohl, M,Popkow, A,Prokoph, H,Quinn, J,Ragan, K,Rajotte, J,Ratliff, G,Reynolds, PT,Richards, GT,Roache, E,Sembroski, GH,Sheidaei, F,Skole, C,Smith, AW,Staszak, D,Telezhinsky, I,Tyler, J,Varlotta, A,Vincent, S,Wakely, SP,Weekes, TC,Weinstein, A,Welsing, R,Zajczyk, A,Zitzer, B
- Aliu, E. and Archambault, S. and Behera, B. and Berger, K. and Beilicke, M. and Benbow, W. and Bird, R. and Bouvier, A. and Bugaev, V. and Cerruti, M. and Chen, X. and Ciupik, L. and Connolly, M. P. and Cui, W. and Dumm, J. and Falcone, A. and Federici, S. and Feng, Q. and Finley, J. P. and Fortin, P. and Fortson, L. and Furniss, A. and Galante, N. and Gillanders, G. H. and Griffin, S. and Griffiths, S. T. and Grube, J. and Gyuk, G. and Hanna, D. and Holder, J. and Hughes, G. and Humensky, T. B. and Kaaret, P. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krennrich, F. and Lang, M. J. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and de Bhroithe, A. O'Faolain and Ong, R. A. and Otte, A. N. and Park, N. and Perkins, J. S. and Pohl, M.