@article{AbeysekaraBenbowBirdetal.2018,
  author    = {Abeysekara, A. U. and Benbow, Wystan and Bird, Ralph and Brill, A. and Brose, Robert and Buckley, J. H. and Chromey, A. J. and Daniel, M. K. and Falcone, A. and Finley, J. P. and Fortson, L. and Furniss, Amy and Gent, A. and Gillanders, Gerald H. and Hanna, David and Hassan, T. and Hervet, O. and Holder, J. and Hughes, G. and Humensky, T. B. and Kaaret, Philip and Kar, P. and Kertzman, M. and Kieda, David and Krause, Maria and Krennrich, F. and Kumar, S. and Lang, M. J. and Lin, T. T. Y. and Maier, Gernot and Moriarty, P. and Mukherjee, Reshmi and Ong, R. A. and Otte, Adam Nepomuk and Park, Nahee and Petrashyk, A. and Pohl, Martin and Pueschel, Elisa and Quinn, J. and Ragan, K. and Richards, Gregory T. and Roache, E. and Sadeh, I. and Santander, Marcos and Schlenstedt, S. and Sembroski, G. H. and Sushch, Iurii and Tyler, J. and Vassiliev, V. V. and Wakely, S. P. and Weinstein, A. and Wells, R. M. and Wilcox, P. and Wilhelm, Alina and Williams, David A. and Williamson, T. J. and Zitzer, B. and Acciari, V. A. and Ansoldi, S. and Antonelli, L. A. and Engels, A. Arbet and Baack, D. and Babic, A. and Banerjee, B. and de Almeida, U. Barres and Barrio, J. A. and Becerra Gonzalez, Josefa and Bednarek, Wlodek and Bernardini, Elisa and Berti, A. and Besenrieder, J. and Bhattacharyya, W. and Bigongiari, C. and Biland, A. and Blanch, O. and Bonnoli, G. and Busetto, G. and Carosi, R. and Ceribella, G. and Cikota, S. and Colak, S. M. and Colin, P. and Colombo, E. and Contreras, J. L. and Cortina, J. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Lotto, B. and Delfino, M. and Delgado, J. and Di Pierro, F. and Do Souto Espinera, E. and Dominguez, A. and Prester, D. Dominis and Dorner, D. and Doro, M. and Einecke, S. and Elsaesser, D. and Ramazani, V. Fallah and Fattorini, A. and Fernandez-Barral, A. and Ferrara, G. and Fidalgo, D. and Foffano, L. and Fonseca, M. V. and Font, L. and Fruck, C. and Galindo, D. and Gallozzi, S. and Lopez, R. J. Garcia and Garczarczyk, M. and Gasparyan, S. and Gaug, Markus and Giammaria, P. and Godinovic, N. and Guberman, D. and Hadasch, D. and Hahn, A. and Herrera, J. and Hoang, J. and Hrupec, D. and Inoue, S. and Ishio, K. and Iwamura, Y. and Kubo, H. and Kushida, J. and Kuvezdic, D. and Lamastra, A. and Lelas, D. and Leone, Francesco and Lindfors, E. and Lombardi, S. and Longo, Francesco and Lopez, M. and Lopez-Oramas, A. and Machado de Oliveira Fraga, B. and Maggio, C. and Majumdar, P. and Makariev, M. and Mallamaci, M. and Maneva, G. and Manganaro, M. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Martinez, M. and Masuda, S. and Mazin, D. and Minev, M. and Miranda, J. M. and Mirzoyan, R. and Molina, E. and Moralejo, A. and Moreno, V. and Moretti, E. and Munar-Adrover, Pere and Neustroev, V. and Niedzwiecki, Andrzej and Rosillo, Mireia Nievas and Nigro, C. and Nilsson, Kari and Ninci, D. and Nishijima, K. and Noda, K. and Nogues, L. and Noethe, M. and Paiano, Simona and Palacio, J. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Pedaletti, G. and Penil, P. and Peresano, M. and Persic, M. and Moroni, P. G. Prada and Prandini, E. and Puljak, I. and Garcia, J. R. and Rhode, W. and Ribo, Marc and Rico, J. and Righi, C. and Rugliancich, A. and Saha, Lab and Sahakyan, Narek and Saito, T. and Satalecka, K. and Schweizer, T. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Somero, A. and Stamerra, A. and Strzys, M. and Suric, T. and Tavecchio, Fabrizio and Temnikov, P. and Terzic, T. and Teshima, M. and Torres-Alba, N. and Tsujimoto, S. and van Scherpenberg, J. and Vanzo, G. and Vazquez Acosta, M. and Vovk, I. and Will, M. and Zaric, D.},
  title     = {Periastron Observations of TeV Gamma-Ray Emission from a Binary System with a 50-year Period},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters},
  volume    = {867},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  organization    = {VERITAS Collaboration MAGIC Collaboration},
  issn      = {2041-8205},
  doi       = {10.3847/2041-8213/aae70e},
  pages     = {8},
  year      = {2018},
  abstract  = {We report on observations of the pulsar/Be star binary system PSR J2032+4127/MT91 213 in the energy range between 100 GeV and 20 TeV with the Very Energetic Radiation Imaging Telescope Array and Major Atmospheric Gamma Imaging Cherenkov telescope arrays. The binary orbit has a period of approximately 50 years, with the most recent periastron occurring on 2017 November 13. Our observations span from 18 months prior to periastron to one month after. A new point-like gamma-ray source is detected, coincident with the location of PSR J2032+4127/MT91 213. The gamma-ray light curve and spectrum are well characterized over the periastron passage. The flux is variable over at least an order of magnitude, peaking at periastron, thus providing a firm association of the TeV source with the pulsar/Be star system. Observations prior to periastron show a cutoff in the spectrum at an energy around 0.5 TeV. This result adds a new member to the small population of known TeV binaries, and it identifies only the second source of this class in which the nature and properties of the compact object are firmly established. We compare the gamma-ray results with the light curve measured with the X-ray Telescope on board the Neil Gehrels Swift Observatory and with the predictions of recent theoretical models of the system. We conclude that significant revision of the models is required to explain the details of the emission that we have observed, and we discuss the relationship between the binary system and the overlapping steady extended source, TeV J2032+4130.},
  language  = {en}
}
@article{AcciariAliuArlenetal.2011,
  author    = {Acciari, V. A. and Aliu, E. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bradbury, S. M. and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cannon, A. and Cesarini, A. and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dickherber, R. and Duke, C. and Errando, M. and Falcone, A. and Finley, J. P. and Finnegan, G. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Gillanders, G. H. and Godambe, S. and Griffin, S. and Grube, J. and Guenette, R. and Gyuk, G. and Hanna, D. and Holder, J. and Hughes, G. and Hui, C. M. and Humensky, T. B. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and LeBohec, S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pohl, Martin and Prokoph, H. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rose, H. J. and Ruppel, J. and Saxon, D. B. and Schroedter, M. and Sembroski, G. H. and Senturk, G. D. and Smith, A. W. and Staszak, D. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Varlotta, A. and Vassiliev, V. V. and Vincent, S. and Vivier, M. and Wakely, S. P. and Ward, J. E. and Weekes, T. C. and Weinstein, A. and Weisgarber, T. and Williams, D. A. and Zitzer, B.},
  title     = {VERITAS OBSERVATIONS OF THE TeV BINARY LS I+61 degrees 303 DURING 2008-2010},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {738},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/738/1/3},
  pages     = {8},
  year      = {2011},
  abstract  = {We present the results of observations of the TeV binary LS I + 61 degrees 303 with the VERITAS telescope array between 2008 and 2010, at energies above 300 GeV. In the past, both ground-based gamma-ray telescopes VERITAS and MAGIC have reported detections of TeV emission near the apastron phases of the binary orbit. The observations presented here show no strong evidence for TeV emission during these orbital phases; however, during observations taken in late 2010, significant emission was detected from the source close to the phase of superior conjunction (much closer to periastron passage) at a 5.6 standard deviation (5.6 sigma) post-trials significance. In total, between 2008 October and 2010 December a total exposure of 64.5 hr was accumulated with VERITAS on LS I + 61 degrees 303, resulting in an excess at the 3.3 sigma significance level for constant emission over the entire integrated data set. The flux upper limits derived for emission during the previously reliably active TeV phases (i.e., close to apastron) are less than 5\% of the Crab Nebula flux in the same energy range. This result stands in apparent contrast to previous observations by both MAGIC and VERITAS which detected the source during these phases at 10\% of the Crab Nebula flux. During the two year span of observations, a large amount of X-ray data were also accrued on LS I + 61 degrees 303 by the Swift X-ray Telescope and the Rossi X-ray Timing Explorer Proportional Counter Array. We find no evidence for a correlation between emission in the X-ray and TeV regimes during 20 directly overlapping observations. We also comment on data obtained contemporaneously by the Fermi Large Area Telescope.},
  language  = {en}
}