A Search for Pulsations from Geminga Above 100 GeV with VERITAS

E. Aliu, S. Archambault, A. Archer, T. Aune, A. Barnacka, M. Beilicke, W. Benbow, R. Bird, J. H. Buckley, V. Bugaev, K. Byrum, J. V Cardenzana, M. Cerruti, X. Chen, L. Ciupik, M. P. Connolly, W. Cui, H. J. Dickinson, J. Dumm, J. D. Eisch, M. Errando, A. Falcone, Q. Feng, J. P. Finley, H. Fleischhack, P. Fortin, L. Fortson, A. Furniss, G. H. Gillanders, S. Griffin, S. T. Griffiths, J. Grube, G. Gyuk, N. Hakansson, D. Hanna, J. Holder, T. B. Humensky, C. A. Johnson, P. Kaaret, P. Kar, M. Kertzman, D. Kieda, F. Krennrich, S. Kumar, M. J. Lang, M. Lyutikov, A. S Madhavan, G. Maier, S. McArthur, A. McCann, K. Meagher, J. Millis, P. Moriarty, R. Mukherjee, D. Nieto, A. O'Faolain de Bhroithe, R. A. Ong, A. N. Otte, N. Park, M. Pohl, A. Popkow, H. Prokoph, E. Pueschel, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, G. T. Richards, E. Roache, M. Santander, G. H. Sembroski, K. Shahinyan, A. W. Smith, D. Staszak, I. Telezhinsky, J. V. Tucci, J. Tyler, A. Varlotta, S. Vincent, S. P. Wakely, A. Weinstein, D. A. Williams, A. Zajczyk, B. Zitzer

Published 2014-12-15Version 1

We present the results of 71.6 hours of observations of the Geminga pulsar (PSR J0633+1746) with the VERITAS very-high-energy gamma-ray telescope array. Data taken with VERITAS between November 2007 and February 2013 were phase-folded using a Geminga pulsar timing solution derived from data recorded by the XMM-\emph{Newton} and \emph{Fermi}-LAT space telescopes. No significant pulsed emission above 100 GeV is observed, and we report upper limits at the 95% confidence level on the integral flux above 135 GeV (spectral analysis threshold) of 4.0$\times10^{-13}$ s$^{-1}$ cm$^{-2}$ and 1.7$\times10^{-13}$ s$^{-1}$ cm$^{-2}$ for the two principal peaks in the emission profile. These upper limits, placed in context with phase-resolved spectral energy distributions determined from five years of data from the \emph{Fermi}-LAT, constrain possible hardening of the Geminga pulsar emission spectra above $\sim$50 GeV.