Research Note

Discovery of very high energy gamma-ray emission from the blazar 1ES 1727+502 with the MAGIC Telescopes

¹ IFAE, Edifici Cn., Campus UAB, 08193 Bellaterra, Spain
² INAF, National Institute for Astrophysics, 00136 Rome, Italy
³ Università di Siena, and INFN Pisa, 53100 Siena, Italy
⁴ Universidad Complutense, 28040 Madrid, Spain
⁵ Technische Universität Dortmund, 44221 Dortmund, Germany
⁶ Max-Planck-Institut für Physik, 80805 München, Germany
⁷ Inst. de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
e-mail: berger.karsten@gmail.com
⁸ University of Łódź, 90236 Lodz, Poland
⁹ Depto. de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Spain
¹⁰ Deutsches Elektronen-Synchrotron (DESY), 15738 Zeuthen, Germany
e-mail: gessica.de.caneva@desy.de
¹¹ ETH Zurich, CH-8093 Zurich, Switzerland
¹² Universität Würzburg, 97074 Würzburg, Germany
¹³ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, 28040 Madrid, Spain
¹⁴ Università di Udine, and INFN Trieste, 33100 Udine, Italy
¹⁵ Inst. de Astrofísica de Andalucía (CSIC), 18080 Granada, Spain
¹⁶ Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, 10000 Zagreb, Croatia
¹⁷ Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
¹⁸ Università dell’Insubria, Como, 22100 Como, Italy
¹⁹ Institut de Ciències de l’Espai (IEEC-CSIC), 08193 Bellaterra, Spain
²⁰ Tuorla Observatory, University of Turku, 21500 Piikkiö, Finland
²¹ Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, 277-8582, Chiba, Kashiwa, Japan
²² Inst. for Nucl. Research and Nucl. Energy, 1784 Sofia, Bulgaria
²³ Universitat de Barcelona (ICC/IEEC), 08028 Barcelona, Spain
²⁴ Università di Padova and INFN, 35131 Padova, Italy
²⁵ INAF/Osservatorio Astronomico and INFN, 34143 Trieste, Italy
²⁶ Università di Pisa, and INFN Pisa, 56126 Pisa, Italy
²⁷ ICREA, 08010 Barcelona, Spain
²⁸ Now at École polytechnique fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
²⁹ Supported by INFN Padova 
³⁰ Now at: Department of Physics & Astronomy, UC Riverside, CA 92521, USA
³¹ Now at: DESY, 15738 Zeuthen, Germany
³² Now at: Finnish Centre for Astronomy with ESO (FINCA), University of Turku, 21500 Piikkiö, Finland
³³ Also at Instituto de Fisica Teorica, UAM/CSIC, 28049 Madrid, Spain

Received: 25 February 2013
Accepted: 4 October 2013

Abstract

Motivated by the prediction of a high TeV luminosity we investigated whether the blazar 1ES 1727+502 (z = 0.055) is emitting very high energy (VHE, E > 100 GeV) γ rays. We observed the BL Lac object 1ES 1727+502 in stereoscopic mode with the two MAGIC telescopes for 14 nights between May 6th and June 10th 2011, for a total effective observing time of 12.6 h. To study the multiwavelength spectral energy distribution (SED), we used simultaneous optical R-band data from the KVA telescope, archival UV/optical and X-ray observations from instruments UVOT and XRT on board of the Swift satellite, and high energy (HE, 0.1 GeV–100 GeV) γ-ray data from the Fermi-LAT instrument. We detected, for the first time, VHE γ-ray emission from 1ES 1727+502 at a statistical significance of 5.5σ. The integral flux above 150 GeV is estimated to be (2.1 ± 0.4)% of the Crab nebula flux and the de-absorbed VHE spectrum has a photon index of (2.7 ± 0.5). No significant short-term variability was found in any of the wavebands presented here. We model the SED using a one-zone synchrotron self-Compton model obtaining parameters typical for this class of sources.