Multiwavelength Observations and Modeling of 1ES 1959+650 in a Low Flux State

E. Aliu, Barnard College
S. Archambault, McGill University
T. Arlen, University of California - Los Angeles
T. Aune, University of California - Los Angeles
M. Beilicke, Washington University in St Louis
W. Benbow, Harvard-Smithsonian Center for Astrophysics
R. Bird, University College Dublin
M. Bottcher, Ohio University - Main Campus
A. Bouvier, University of California - Santa Cruz
V. Bugaev, Washington University in St Louis
K. Byrum, Argonne National Laboratory
A. Cesarini, National University of Ireland, Galway
L. Ciupik, Adler Planetarium and Astronomy Museum
M.P. Connolly, National University of Ireland, Galway
E. Collins-Hughes, University College Dublin
W. Cui, Purdue University
R. Dickherber, Washington University in St Louis
C. Duke, Grinnell College
J. Dumm, University of Minnesota - Twin Cities
M. Errando, Barnard College
A. Falcone, Pennsylvania State University - Main Campus
S. Federici, University of Potsdam
Q. Feng, Purdue University
J.P. Finley, Purdue University
G. Finnegan, University of Utah
L. Fortson, University of Minnesota - Twin Cities
A. Furniss, University of California - Santa Cruz
N. Galante, Harvard-Smithsonian Center for Astrophysics
D. Gall, University of Iowa
G.H. Gillanders, National University of Ireland, Galway
S. Griffin, McGill University
J. Grube, Adler Planetarium and Astronomy Museum
G. Gyuk, Adler Planetarium and Astronomy Museum
D. Hanna, McGill University
J. Holder, University of Delaware
Gary Hughes, California Polytechnic State University - San Luis Obispo
T.B. Humensky, Columbia University
P. Kaaret, University of Iowa
M. Kertzman, DePaul University
Y. Khassen, University College Dublin
D. Kieda, University of Utah
H. Krawczynski, Washington University in St Louis
F. Krennrich, Iowa State University
M.J. Lang, National University of Ireland, Galway
A.S. Madhavan, Iowa State University
G. Maier, DESY, Zeuthen, Germany
P. Majumdar, Saha Institute of Nuclear Physics
S. McArthur, University of Chicago
A. McCann, University of Chicago
P. Moriarty, Galway Mayo Institute of Technology
R. Mukherjee, Barnard College
T. Nelson, University of Minnesota - Twin Cities
A. O'Faolain de Bhroithe, University College Dublin
R.A. Ong, University of California - Los Angeles
M. Orr, Iowa State University
A.N. Otte, Georgia Institute of Technology - Main Campus
N. Park, University of Chicago
J.S. Perkins, University of Maryland - Baltimore County
A. Pichel, Instituto de Astronomia y Fisica del Espacio
M. Pohl, University of Potsdam
A. Popkow, University of California - Los Angeles
H. Prokoph, DESY, Zuethen, Germany
J. Quinn, University College Dublin
K. Ragan, McGill University
Luis Reyes, California Polytechnic State University - San Luis Obispo
P.T. Reynolds, Cork Institute of Technology
E. Roache, Harvard-Smithsonian Center for Astrophysics
D.B. Saxon, University of Delaware
M. Schroedter, Harvars-Smithsonian Center for Astrophysics
G.H. Sembroski, Purdue University
C. Skole, DESY, Zeuthen, Germany
A.W. Smith, University of Utah
D. Staszak, McGill University
I. Telezhinsky, University of Posdam
M. Theiling, Purdue University
J. Tyler, McGill University
A. Varlotta, Purdue University
V.V. Vassiliev, University of California - Los Angeles
S.P. Wakely, University of Chicago
T.C. Weekes, Harvard-Smithsonian Center for Astrophysics
A. Weinstein, Iowa State University
R. Welsing, DESY, Zeuthen, Germany
D.A. Williams, University of California - Santa Cruz
B. Zitzer, Argonne National Laboratory

Abstract

We report on the VERITAS observations of the high-frequency peaked BL Lac object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV energies by VERITAS at 16.4 standard deviation (σ) significance in 7.6 hr of observation in a low flux state. A multiwavelength spectral energy distribution (SED) is constructed from contemporaneous data from VERITAS, Fermi-LAT, RXTE PCA, and Swift UVOT. Swift XRT data is not included in the SED due to a lack of simultaneous observations with VERITAS. In contrast to the orphan γ-ray flare exhibited by this source in 2002, the X-ray flux of the source is found to vary by an order of magnitude, while other energy regimes exhibit less variable emission. A quasi-equilibrium synchrotron self-Compton model with an additional external radiation field is used to describe three SEDs corresponding to the lowest, highest, and average X-ray states. The variation in the X-ray spectrum is modeled by changing the electron injection spectral index, with minor adjustments of the kinetic luminosity in electrons. This scenario produces small-scale flux variability of the order of 2 in the high energy (E > 1 MeV) and very high energy (E > 100 GeV) γ-ray regimes, which is corroborated by the Fermi-LAT, VERITAS, and Whipple 10 m telescope light curves.

 

URL: http://digitalcommons.calpoly.edu/stat_fac/37