@article{AleksicAnsoldiAntonellietal.2015,
  author    = {Aleksic, J. and Ansoldi, S. and Antonelli, L. A. and Antoranz, P. and Babic, A. and Bangale, P. and de Almeida, U. Barres and Barrio, J. A. and Gonzalez, J. Becerra and Bednarek, W. and Berger, K. and Bernardini, E. and Bilandli, A. and Bianch, O. and Bock, R. K. and Bonnefoy, S. and Bonnoli, G. and Borracci, F. and Bretz, T. and Carmona, E. and Carosi, A. and Fidalgo, D. Carreto 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 Caneva, G. and De Lotto, B. and Delgado Mendez, C. and Doert, M. and Dominguez, A. and Prester, Dijana Dominis and Dorner, D. and Doro, M. and Einecke, S. and Eisenacher, D. and Elsaesser, D. and Farina, E. and Ferenc, D. and Fonseca, M. V. and Font, L. and Frantzen, K. and Fruck, C. and Garcia Lopez, R. J. and Garczarczyki, M. and Garrido Terrats, D. and Gaug, M. and Giavitto, G. and Godinovic, N. and Gonzalez Munoz, A. and Gozzini, S. R. and Hadamek, A. and Hadasch, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Idec, W. and Kadenius, V. and Kellermann, H. and Knoetig, M. L. and Krause, J. and Kushida, J. and La Barbera, A. and Lelas, D. and Lewandowska, N. and Lindfors, E. and Longo, F. and Lombardi, S. and Lopez, M. and Lopez-Coto, R. and Lopez-Oramas, A. and Lorenz, E. and Lozano, I. and Makariev, M. and Mallot, K. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Marcote, B. and Mariotti, M. and Martinez, M. and Mazin, D. and Menzel, U. and Meucci, M. and Miranda, J. M. and Mirzoyan, R. and Moralejo, A. and Munar-Adrover, P. and Nakajima, D. and Niedzwiecki, A. and Nilsson, K. and Nowak, N. and Orito, R. and Overkemping, A. and Paiano, S. and Palatiello, M. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Paredes-Fortuny, X. and Partini, S. and Persic, M. and Prada, F. and Moroni, P. G. Prada and Prandini, E. and Preziuso, S. and Puljak, I. and Reinthal, R. and Rhode, W. and Ribo, M. and Rico, J. and Garcia, J. Rodriguez and Ruegamer, S. and Saggion, A. and Saito, K. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schuliz, C. and Schweizer, T. and Shore, S. N. and Sillanpaa, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Stamatescu, V. and Stamerra, A. and Steinbring, T. and Storz, J. and Sun, S. and Suric, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzic, T. and Tescaro, D. and Teshima, M. and Thaele, J. and Tibolla, O. and Torres, D. F. and Toyama, T. and Treves, A. and Uellenbeck, M. and Vogler, P. and Wagner, R. M. and Zandanel, F. and Zanin, R. and Archambault, S. and Behera, B. and Beilicke, M. and Benbow, W. and Bird, R. and Buckley, J. H. and Bugaev, V. and Cerruti, M. and Chen, X. and Ciupik, L. and Collins-Hughes, E. and Cui, W. and Dumm, J. and Eisch, J. D. and Falcone, A. and Federici, S. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortin, P. and Fortson, L. and Furniss, A. 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 Johnson, C. A. and Kaaret, P. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Ong, R. A. and Otte, A. N. and Park, N. and Pichel, A. and Pohl, M. and Popkow, A. and Prokoph, H. and Quinn, M. J. and Ragan, K. and Rajotte, J. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Theiling, M. and Tucci, J. V. and Tyler, J. and Varlotta, A. and Wakely, S. P. and Weekes, T. C. and Weinstein, A. and Welsing, R. and Wilhelm, Alina and Williams, D. A. and Zitzer, B. and Villata, M. and Raiteri, C. and Aller, H. D. and Aller, M. F. and Chen, W. P. and Jordan, B. and Koptelova, E. and Kurtanidze, O. M. and Lahteenmaki, A. and McBreen, B. and Larionov, V. M. and Lin, C. S. and Nikolashvili, M. G. and Angelakis, E. and Capalbi, M. and Carraminana, A. and Carrasco, L. and Cassaro, P. and Cesarini, A. and Fuhrmann, L. and Giroletti, M. and Hovatta, T. and Krichbaum, T. P. and Krimm, H. A. and Max-Moerbeck, W. and Moody, J. W. and Maccaferri, G. and Mori, Y. and Nestoras, I. and Orlati, A. and Pace, C. and Pearson, R. and Perri, M. and Readhead, A. C. S. and Richards, J. L. and Sadun, A. C. and Sakamoto, T. and Tammi, J. and Tornikoski, M. and Yatsu, Y. and Zook, A.},
  title     = {The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {576},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGIC Collaboration, VERITAS Collaboration, MAGIC Collaboration},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/201424216},
  pages     = {18},
  year      = {2015},
  abstract  = {Aims. We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z = 0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study. Methods. We performed a 4.5-month multi-instrument campaign on Mrk 421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. This extensive radio to very-high-energy (VHE; E > 100 GeV) gamma-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution. Results. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical /UV and X-rays extending over the duration of the campaign. Conclusions. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multiwavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk 421 during non-flaring activity. Such a temporally extended X-ray /VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies.},
  language  = {en}
}
@article{AleksicAnsoldiAntonellietal.2015,
  author    = {Aleksic, J. and Ansoldi, S. and Antonelli, L. A. and Antoranz, P. and Babic, A. and Bangale, P. and de Almeida, U. Barres and Barrio, J. A. and Gonzalez, J. Becerra and Bednarek, W. and Bernardini, E. and Biasuzzi, B. and Biland, A. and Blanch Bigas, O. and Boller, A. and Bonnefoy, S. and Bonnoli, G. and Borracci, F. and Bretz, T. and Carmona, E. and Carosi, A. 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 Caneva, G. and De Lotto, B. and Wilhelmi, E. de Ona and Mendez, C. Delgado and Prester, Dijana Dominis and Dorner, D. and Doro, M. and Einecke, S. and Eisenacher, D. and Elsaesser, D. and Fonseca, M. V. and Font, L. and Frantzen, K. and Fruck, C. and Galindo, D. and Lopez, R. J. Garcia and Garczarczyk, M. and Terrats, D. Garrido and Gaug, M. and Godinovic, N. and Munoz, A. Gonzalez and Gozzini, S. R. and Hadasch, D. and Hanabata, Y. and Hayashida, M. and Herrera, J. and Hildebrand, D. and Hose, J. and Hrupec, D. and Hughes, G. and Idec, W. and Kadenius, V. and Kellermann, H. and Knoetig, M. L. and Kodani, K. and Konno, Y. and Krause, J. and Kubo, H. and Kushida, J. and La Barbera, A. and Lelas, D. and Lewandowska, N. and Lindfors, E. and Lombardi, S. and Lopez, M. and Lopez-Coto, R. and Lopez-Oramas, A. and Lorenz, E. and Lozano, I. and Makariev, M. and Mallot, K. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Marcote, B. and Mariotti, M. and Martinez, M. and Mazin, D. and Menzel, U. and Miranda, J. M. and Mirzoyan, R. and Moralejo, A. and Munar-Adrover, P. and Nakajima, D. and Niedzwiecki, A. and Nilsson, K. and Nishijima, K. and Noda, K. and Orito, R. and Overkemping, A. and Paiano, S. and Palatiello, M. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Paredes-Fortuny, X. and Persic, M. and Moroni, P. G. Prada and Prandini, E. and Puljak, I. and Reinthal, R. and Rhode, W. and Ribo, M. and Rico, J. and Garcia, J. Rodriguez and Rugamer, S. and Saito, T. and Saito, K. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Sun, S. and Shore, S. N. and Sillanpaa, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Stamatescu, V. and Stamerra, A. and Steinbring, T. and Steinke, B. and Storz, J. and Strzys, M. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzic, T. and Tescaro, D. and Teshima, M. and Thaele, J. and Tibolla, O. and Torres, D. F. and Toyama, T. and Treves, A. and Uellenbeck, M. and Vogler, P. and Zanin, R. and Archambault, S. and Archer, A. and Beilicke, M. and Benbow, W. and Berger, K. and Bird, R. and Biteau, Jonathan and Buckley, J. H. and Bugaev, V. and Cerruti, M. and Chen, Xiaoming and Ciupik, L. and Collins-Hughes, E. and Cui, W. and Eisch, J. D. and Falcone, A. 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 Gyuk, G. and Hakansson, Nils and Holder, J. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kertzman, M. and Kieda, D. and Lang, M. J. and McArthur, S. and McCann, A. and Meagher, K. and Millis, J. and Moriarty, P. and Ong, R. A. and Otte, A. N. and Perkins, J. S. and Pichel, A. and Pohl, Manuela and Popkow, A. and Prokoph, H. and Pueschel, Elisa and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rovero, A. C. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Varlotta, A. and Wakely, S. P. and Welsing, R. and Wilhelm, Alina and Williams, D. A. and Buson, S. and Finke, J. and Villata, M. and Raiteri, C. and Aller, H. D. and Aller, M. F. and Cesarini, A. and Chen, W. P. and Gurwell, M. A. and Jorstad, S. G. and Kimeridze, G. N. and Koptelova, E. and Kurtanidze, O. M. and Kurtanidze, S. O. and Lahteenmaki, A. and Larionov, V. M. and Larionova, E. G. and Lin, H. C. and McBreen, B. and Moody, J. W. and Morozova, D. A. and Marscher, A. P. and Max-Moerbeck, W. and Nikolashvili, M. G. and Perri, M. and Readhead, A. C. S. and Richards, J. L. and Ros, J. A. and Sadun, A. C. and Sakamoto, T. and Sigua, L. A. and Smith, P. S. and Tornikoski, M. and Troitsky, I. S. and Wehrle, A. E. and Jordan, B.},
  title     = {Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {578},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGIC Collaboration, VERITAS Collaboration},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/201424811},
  pages     = {26},
  year      = {2015},
  abstract  = {Context. Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED). Aims. The goal is to better understand the mechanisms responsible for the broadband emission and the temporal evolution of Mrk 421. These mechanisms may also apply to more distant blazars that cannot be studied with the same level of detail. Methods. A flare occurring in March 2010 was observed for 13 consecutive days (from MJD 55 265 to MJD 55 277) with unprecedented wavelength coverage from radio to very high energy (VHE; E > 100 GeV) gamma-rays with MAGIC, VERITAS, Whipple, Fermi-LAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We modeled the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigated the physical parameters, and evaluated whether the observed broadband SED variability can be associated with variations in the relativistic particle population. Results. The activity of Mrk 421 initially was high and then slowly decreased during the 13-day period. The flux variability was remarkable at the X-ray and VHE bands, but it was minor or not significant at the other bands. The variability in optical polarization was also minor. These observations revealed an almost linear correlation between the X-ray flux at the 2-10 keV band and the VHE gamma-ray flux above 200 GeV, consistent with the gamma-rays being produced by inverse-Compton scattering in the Klein-Nishina regime in the framework of SSC models. The one-zone SSC model can describe the SED of each day for the 13 consecutive days reasonably well, which once more shows the success of this standard theoretical scenario to describe the SEDs of VHE BL Lacs such as Mrk 421. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission, while the other smaller zone, which is spatially separated from the first, contributes to the daily variable emission occurring at X-rays and VHE gamma-rays. The second blob is assumed to have a smaller volume and a narrow electron energy distribution with 3 x 10(4) < gamma < 6 x 10(5), where. is the Lorentz factor of the electrons. Such a two-zone scenario would naturally lead to the correlated variability at the X-ray and VHE bands without variability at the optical/UV band, as well as to shorter timescales for the variability at the X-ray and VHE bands with respect to the variability at the other bands. Conclusions. Both the one-zone and the two-zone SSC models can describe the daily SEDs via the variation of only four or five model parameters, under the hypothesis that the variability is associated mostly with the underlying particle population. This shows that the particle acceleration and cooling mechanism that produces the radiating particles might be the main mechanism responsible for the broadband SED variations during the flaring episodes in blazars. The two-zone SSC model provides a better agreement with the observed SED at the narrow peaks of the low-and high-energy bumps during the highest activity, although the reported one-zone SSC model could be further improved by varying the parameters related to the emitting region itself (delta, B and R), in addition to the parameters related to the particle population.},
  language  = {en}
}
@article{AleksicAnsoldiAntonellietal.2015,
  author    = {Aleksic, J. and Ansoldi, S. and Antonelli, L. A. and Antoranz, P. and Babic, A. and Bangale, P. and de Almeida, U. Barres and Barrio, J. A. and Becerra Gonzalez, J. and Bednarek, W. and Berger, K. and Bernardini, E. and Biland, A. and Blanch Bigas, O. and Bock, R. K. and Bonnefoy, S. and Bonnoli, G. and Borracci, F. and Bretz, T. and Carmona, E. and Carosi, A. and Fidalgo, D. Carreto 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 Caneva, G. and De Lotto, B. and Delgado Mendez, C. and Doert, M. and Dominguez, A. and Prester, Dijana Dominis and Dorner, D. and Doro, M. and Einecke, S. and Eisenacher, D. and Elsaesser, D. and Farina, E. and Ferenc, D. and Fonseca, M. V. and Font, L. and Frantzen, K. and Fruck, C. and Garcia Lopez, R. J. and Garczarczyk, M. and Garrido Terrats, D. and Gaug, M. and Giavitto, G. and Godinovic, N. and Gonzalez Munoz, A. and Gozzini, S. R. and Hadamek, A. and Hadasch, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Idec, W. and Kadenius, V. and Kellermann, H. and Knoetig, M. L. and Krause, J. and Kushida, J. and La Barbera, A. and Lelas, D. and Lewandowska, N. and Lindfors, E. and Lombardi, S. and Lopez, M. and Lopez-Coto, R. and Lopez-Oramas, A. and Lorenz, E. and Lozano, I. and Makariev, M. and Mallot, K. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Marcote, B. and Mariotti, M. and Martinez, M. and Mazin, D. and Menzel, U. and Meucci, M. and Miranda, J. M. and Mirzoyan, R. and Moralejo, A. and Munar-Adrover, P. and Nakajima, D. and Niedzwiecki, A. and Nilsson, K. and Nowak, N. and Orito, R. and Overkemping, A. and Paiano, S. and Palatiello, M. and Paneque, D. and Paoletti, R. and Paredes, J. M. and Paredes-Fortuny, X. and Partini, S. and Persic, M. and Prada, F. and Moroni, P. G. Prada and Prandini, E. and Preziuso, S. and Puljak, I. and Reinthal, R. and Rhode, W. and Ribo, M. and Rico, J. and Garcia, J. Rodriguez and Ruegamer, S. and Saggion, A. and Saito, T. and Saito, K. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shore, S. N. and Sillanpaa, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Stamatescu, V. and Stamerra, A. and Steinbring, T. and Storz, J. and Sun, S. and Suric, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzic, T. and Tescaro, D. and Teshima, M. and Thaele, J. and Tibolla, O. and Torres, D. F. and Toyama, T. and Treves, A. and Uellenbeck, M. and Vogler, P. and Wagner, R. M. and Zandanel, F. and Zanin, R. and Behera, B. and Beilicke, M. and Benbow, W. and Berger, K. and Bird, R. and Bouvier, A. and Bugaev, V. and Cerruti, M. and Chen, Xuhui and Ciupik, L. and Collins-Hughes, E. and Cui, W. and Duke, C. and Dumm, J. and Falcone, A. and Federici, Simone and Feng, Q. and Finley, J. 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 Johnson, C. A. and Kaaret, P. and Kertzman, M. and Kieda, D. and Krawczynski, H. and Lang, M. J. and Madhavan, A. S. and Maier, G. and Majumdar, P. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Pichel, A. and Pohl, Manula and Popkow, A. and Prokoph, H. and Quinn, J. and Rajotte, J. and Ratliff, G. and Reyes, L. C. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Sembroski, G. H. and Shahinyan, K. and Sheidaei, F. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Theiling, M. and Tyler, J. and Varlotta, A. and Vincent, S. and Wakely, S. P. and Weekes, T. C. and Welsing, R. and Williams, D. A. and Zajczyk, A. and Zitzer, B. and Villata, M. and Raiteri, C. M. and Ajello, M. and Perri, M. and Aller, H. D. and Aller, M. F. and Larionov, V. M. and Efimova, N. V. and Konstantinova, T. S. and Kopatskaya, E. N. and Chen, W. P. and Koptelova, E. and Hsiao, H. Y. and Kurtanidze, O. M. and Nikolashvili, M. G. and Kimeridze, G. N. and Jordan, B. and Leto, Paolo and Buemi, C. S. and Trigilio, C. and Umana, G. and Lahteenmaki, A. and Nieppola, E. and Tornikoski, M. and Sainio, J. and Kadenius, V. and Giroletti, M. and Cesarini, A. and Fuhrmann, L. and Kovalev, Yu. A. and Kovalev, Y. Y.},
  title     = {Multiwavelength observations of Mrk 501 in 2008},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {573},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGIC Collaboration, VERITAS Collaboration},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/201322906},
  pages     = {12},
  year      = {2015},
  abstract  = {Context. Blazars are variable sources on various timescales over a broad energy range spanning from radio to very high energy (>100 GeV, hereafter VHE). Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its first VHE detection in 1996. However, most of the gamma-ray studies performed on Mrk 501 during the past years relate to flaring activity, when the source detection and characterization with the available gamma-ray instrumentation was easier to perform. Aims. Our goal is to characterize the source gamma-ray emission in detail, together with the radio-to-X-ray emission, during the non-flaring (low) activity, which is less often studied than the occasional flaring (high) activity. Methods. We organized a multiwavelength (MW) campaign on Mrk 501 between March and May 2008. This multi-instrument effort included the most sensitive VHE gamma-ray instruments in the northern hemisphere, namely the imaging atmospheric Cherenkov telescopes MAGIC and VERITAS, as well as Swift, RXTE, the F-GAMMA, GASP-WEBT, and other collaborations and instruments. This provided extensive energy and temporal coverage of Mrk 501 throughout the entire campaign. Results. Mrk 501 was found to be in a low state of activity during the campaign, with a VHE flux in the range of 10\%-20\% of the Crab nebula flux. Nevertheless, significant flux variations were detected with various instruments, with a trend of increasing variability with energy and a tentative correlation between the X-ray and VHE fluxes. The broadband spectral energy distribution during the two different emission states of the campaign can be adequately described within the homogeneous one-zone synchrotron self-Compton model, with the (slightly) higher state described by an increase in the electron number density. Conclusions. The one-zone SSC model can adequately describe the broadband spectral energy distribution of the source during the two months covered by the MW campaign. This agrees with previous studies of the broadband emission of this source during flaring and non-flaring states. We report for the first time a tentative X-ray-to-VHE correlation during such a low VHE activity. Although marginally significant, this positive correlation between X-ray and VHE, which has been reported many times during flaring activity, suggests that the mechanisms that dominate the X-ray/VHE emission during non-flaring-activity are not substantially different from those that are responsible for the emission during flaring activity.},
  language  = {en}
}
@article{AliuArlenAuneetal.2012,
  author    = {Aliu, E. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bouvier, A. 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 Godambe, S. and Griffin, S. and Grube, J. and Guenette, R. and Gyuk, G. and Hanna, D. and Holder, J. and Huan, H. and Hughes, G. and Hui, C. M. and Humensky, T. B. and Imran, A. 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 Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nunez, P. D. and Ong, R. A. and Orr, M. and Otte, A. N. and Park, N. and Perkins, J. S. and Pichel, A. 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 Sentuerk, G. D. and Skole, C. and Staszak, D. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Tyler, J. 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 day-scale flaring of M 87 in 2010 April},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {746},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/746/2/141},
  pages     = {7},
  year      = {2012},
  abstract  = {VERITAS has been monitoring the very-high-energy (VHE; > 100 GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +/- 0.16) x 10(-11) cm(-2) s(-1) at energies above 350 GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 +/- 0.68) x 10(-11) cm(-2) s(-1) for E > 350 GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90(-0.15)(+0.22) days. The shortest detected exponential rise time is three times as long, at 2.87(+1.65)(-0.99) days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +/- 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region.},
  language  = {en}
}
@article{AliuArchambaultArlenetal.2012,
  author    = {Aliu, E. and Archambault, S. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bouvier, A. 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 Decerprit, G. and Dickherber, R. and Duke, C. and Dumm, J. and Dwarkadas, Vikram V. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Finnegan, G. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Godambe, S. and Griffin, S. and Grube, J. and Gyuk, G. and Hanna, D. and Holder, J. and Huan, H. and Hughes, G. and Humensky, T. B. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and Lee, K. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Millis, J. and Moriarty, P. and Mukherjee, R. and Nunez, P. D. and Ong, R. A. and Orr, M. and Otte, A. N. and Pandel, D. and Park, N. and Perkins, J. S. and Pohl, M. 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 Skole, C. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Tyler, J. and Varlotta, A. 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 Welsing, R. and Williams, D. A. and Zitzer, B.},
  title     = {Veritas observations of the nova in V407 CYGNI},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {754},
  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/754/1/77},
  pages     = {7},
  year      = {2012},
  abstract  = {We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 x 10(-12) erg cm(-2) s(-1) (at the 95\% confidence level). When considered jointly with data from Fermi-LAT, this result places limits on the acceleration of very high energy particles in the nova.},
  language  = {en}
}
@article{AcciariAliuArayaetal.2011,
  author    = {Acciari, V. A. and Aliu, E. and Araya, M. 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 Cui, W. and Dickherber, R. and Duke, C. and Falcone, A. and Finley, J. P. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Godambe, S. and Griffin, S. and Guenette, R. and Gyuk, G. and Hanna, D. and Holder, J. and Hughes, G. and Hui, C. M. and Humensky, T. B. and Imran, A. and Kaaret, P. and Kertzman, M. and Krawczynski, H. and Krennrich, F. and Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and Moriarty, P. and Ong, R. A. and Otte, A. N. and Pandel, D. 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 Saxon, D. B. and Sembroski, G. H. and Sentuerk, G. D. and Smith, A. W. and Tesic, G. and Theiling, M. and Thibadeau, S. and Varlotta, A. 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 Weng, S. and Williams, D. A. and Wood, M. and Zitzer, B.},
  title     = {Gamma-ray observations of the Be/Pulsar binary 1A 0535+262 during a Giant X-Ray outburst},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {733},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/733/2/96},
  pages     = {10},
  year      = {2011},
  abstract  = {Giant X-ray outbursts, with luminosities of about 10(37) erg s(-1), are observed roughly every five years from the nearby Be/pulsar binary 1A 0535+262. In this article, we present observations of the source with VERITAS at very high energies (VHEs; E > 100 GeV) triggered by the X-ray outburst in 2009 December. The observations started shortly after the onset of the outburst and provided comprehensive coverage of the episode, as well as the 111 day binary orbit. No VHE emission is evident at any time. We also examined data from the contemporaneous observations of 1A 0535+262 with the Fermi/Large Area Telescope at high-energy photons (E > 0.1 GeV) and failed to detect the source at GeV energies. The X-ray continua measured with the Swift/X-Ray Telescope and the RXTE/PCA can be well described by the combination of blackbody and Comptonized emission from thermal electrons. Therefore, the gamma-ray and X-ray observations suggest the absence of a significant population of non-thermal particles in the system. This distinguishes 1A 0535+262 from those Be X-ray binaries (such as PSR B1259-63 and LS I +61 degrees 303) that have been detected at GeV-TeV energies. We discuss the implications of the results on theoretical models.},
  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 Christiansen, J. L. and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. 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 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 Jackson, D. J. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and Madhavan, A. S. and Maier, G. and McArthur, S. and McCann, A. and Moriarty, P. and Newbold, M. D. 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 Sentuerk, G. D. and Smith, A. W. and Staszak, D. and Swordy, S. P. 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 Wood, M.},
  title     = {Veritas observations of gamma-ray bursts detected by swift},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {743},
  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/743/1/62},
  pages     = {10},
  year      = {2011},
  abstract  = {We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t(-1.5) time profile. This temporal model is characteristic of GRB afterglows with high-energy, long-lived emission that have been detected by the Large Area Telescope on board the Fermi satellite. No significant very high energy (VHE) gamma-ray emission was detected and upper limits above the VERITAS threshold energy are calculated. The VERITAS upper limits are corrected for gamma-ray extinction by the extragalactic background light and interpreted in the context of the keV emission detected by Swift. For some bursts the VHE emission must have less power than the keV emission, placing constraints on inverse Compton models of VHE emission.},
  language  = {en}
}
@article{tAliuArchambaultArlenetal.2013,
  author    = {tAliu, E. and Archambault, S. and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bird, R. and Bouvier, A. 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 Dumm, J. and Dwarkadas, Vikram V. and Errando, M. and Falcone, A. and Federici, Simone and Feng, Q. 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 Gotthelf, E. V. and Griffin, S. and Grube, J. and Gyuk, G. and Hanna, D. and Holder, J. and Huan, H. and Hughes, G. and Humensky, T. B. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and Lee, K. and Madhavan, A. S. and Maier, G. and Majumdar, P. and McArthur, S. and McCann, A. and Millis, J. and Moriarty, P. and Mukherjee, R. and Nelson, T. and de Bhroithe, A. O'Faolain and Ong, R. A. and Orr, M. and Otte, A. N. and Pandel, D. and Park, N. and Perkins, J. S. and Pohl, Martin and Popkow, A. 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, Jens and Saxon, D. B. and Schroedter, M. and Sembroski, G. H. and Sentuerk, G. D. and Skole, C. and Telezhinsky, Igor O. and Tesic, G. and Theiling, M. and Thibadeau, S. and Tsurusaki, K. and Tyler, J. and Varlotta, A. and Vassiliev, V. V. and Vincent, S. and Wakely, S. P. and Ward, J. E. and Weekes, T. C. and Weinstein, A. and Weisgarber, T. and Welsing, R. and Williams, D. A. and Zitzer, B.},
  title     = {Discovery of TeV Gamma-Ray emission toward supernova remnant SNR G78.2+2.1},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {770},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/770/2/93},
  pages     = {7},
  year      = {2013},
  abstract  = {We report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0 degrees.23 +/- 0 degrees.03(stat-0 degrees.02sys)(+0 degrees.04) and its spectrum is well-characterized by a differential power law (dN/dE = N-0 x (E/TeV)-Gamma) with a photon index of Gamma = 2.37 +/- 0.14(stat) +/- 0.20(sys) and a flux normalization of N-0 = 1.5 +/- 0.2(stat) +/- 0.4(sys) x 10(-12) photon TeV-1 cm(-2) s(-1). This yields an integral flux of 5.2 +/- 0.8(stat) +/- 1.4(sys) x 10(-12) photon cm(-2) s(-1) above 320 GeV, corresponding to 3.7\% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the SNR shock.},
  language  = {en}
}
@article{AliuArchambaultArcheretal.2016,
  author    = {Aliu, E. and Archambault, S. and Archer, A. and Arlen, T. and Aune, T. and Barnacka, Anna and Behera, B. and Beilicke, M. and Benbow, W. and Berger, K. and Bird, R. and B{\"o}ttcher, Markus and Bouvier, A. and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Cardenzana, J. V. and Cerruti, M. and Cesarini, A. and Chen, Xuhui and Ciupik, L. and Collins-Hughes, E. and Connolly, M. P. and Cui, W. and Dumm, J. and Eisch, J. D. and Falcone, A. and Federici, Simone and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortin, P. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Gillanders, G. H. and Griffin, S. and Griffiths, S. T. and Grube, J. and Gyuk, G. and H{\"u}tten, M. and Hakansson, Nils and Holder, J. and Hughes, G. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krause, M. and Krawczynski, H. and Krennrich, F. and Lang, M. J. and Madhavan, A. S. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Millis, J. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Orr, M. and Otte, A. N. and Pandel, D. and Park, N. and Pelassa, V. and Perkins, J. S. and Pichel, A. and Pohl, Martin and Popkow, A. and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rousselle, J. and Rovero, A. C. and Saxon, D. B. and Sembroski, G. H. and Shahinyan, K. and Sheidaei, F. and Skole, C. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Theiling, M. and Todd, N. W. and Tucci, J. V. and Tyler, J. and Varlotta, A. and Vassiliev, V. V. and Vincent, S. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Welsing, R. and Wilhelm, Alina and Williams, D. A. and Zitzer, B. and Baring, M. G. and Gonzalez, J. Becerra and Cillis, A. N. and Horan, D. and Paneque, D.},
  title     = {Very high energy outburst of Markarian 501 in May 2009},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {594},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {Veritas Collaboration},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201628744},
  pages     = {12},
  year      = {2016},
  abstract  = {The very high energy (VHE; E > 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54 938-54 956), 2009, as part of an extensive multiwavelength campaign from radio to VHE. Strong VHE yray activity was detected on May 1st with Whipple and VERITAS, when the flux (E > 400 GeV) increased to 10 times the preflare baseline flux (3.9 x 10(-11) ph cm(-2) s(-1)), reaching five times the flux of the Crab Nebula. This coincided with a decrease in the optical polarization and a rotation of the polarization angle by 15. This VHE flare showed a fast flux variation with an increase of a factor similar to 4 in 25 min, and a falling time of similar to 50 min. We present the observations of the quiescent state previous to the flare and of the high state after the flare, focusing on the flux and spectral variability from Whipple, VERITAS, Fermi-LAT, RXTE, and Swift combined with optical and radio data.},
  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 Cui, W. and Dickherber, R. and Duke, C. and Errando, M. 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, J. P. 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 Madhavan, A. 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 Pandel, D. and Park, N. H. and Perkins, J. S. and Pohl, Martin and Quinn, J. and Ragan, K. and Reyes, L. C. and Reynolds, P. T. and Roache, E. and Rose, H. J. and Saxon, D. B. and Schroedter, M. and Sembroski, G. H. and Senturk, G. Demet and Slane, P. and Smith, A. W. 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 Wood, M. and Zitzer, B.},
  title     = {Discovery of OF TeV Gamma-Ray emission from tycho's supernova remnant},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters},
  volume    = {730},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {2041-8205},
  doi       = {10.1088/2041-8205/730/2/L20},
  pages     = {6},
  year      = {2011},
  abstract  = {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 00(h)25(m)27(s).0, +64 degrees 10'50 '' (J2000). The TeV photon spectrum measured by VERITAS can be described with a power law dN/dE = C(E/3.42 TeV)(-Gamma) with Gamma = 1.95 +/- 0.51(stat) +/- 0.30(sys) and C = (1.55 +/- 0.43(stat) +/- 0.47(sys)) x 10(-14) cm(-2) s(-1) TeV-1. The integral flux above 1 TeV corresponds to similar 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 similar to 80 mu G, which may be interpreted as evidence for magnetic field amplification.},
  language  = {en}
}