Observations of Sagittarius A* during the pericenter passage of the G2 object with MAGIC

¹ ETH Zurich, 8093 Zurich, Switzerland
² Università di Udine, and INFN Trieste, 33100 Udine, Italy
³ INAF National Institute for Astrophysics, 00136 Rome, Italy
⁴ Università di Siena, and INFN Pisa, 53100 Siena, Italy
⁵ Università di Padova and INFN, 35131 Padova, Italy
⁶ Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka, University of Split and University of Zagreb, 51000 Rijeka, Croatia
⁷ Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Salt Lake, Sector-1, 700064 Kolkata, India
⁸ Max-Planck-Institut für Physik, 80805 München, Germany
⁹ Universidad Complutense, 28040 Madrid, Spain
¹⁰ Inst. de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
¹¹ University of Łódź, 90236 Lodz, Poland
¹² Deutsches Elektronen-Synchrotron (DESY), 15738 Zeuthen, Germany
¹³ Institut de Fisica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona), Spain
¹⁴ Universität Würzburg, 97074 Würzburg, Germany
¹⁵ Institute for Space Sciences (CSIC/IEEC), 08193 Barcelona, Spain
¹⁶ Technische Universität Dortmund, 44221 Dortmund, Germany
¹⁷ Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Astronomy Division, University of Oulu, 90014 Oulu, Finland
¹⁸ Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
¹⁹ Universitat de Barcelona, ICC, IEEC-UB, 08028 Barcelona, Spain
²⁰ Japanese MAGIC Consortium, ICRR, The University of Tokyo, Department of Physics and Hakubi Center, Kyoto University; Tokai University, The University of Tokushima, KEK, Japan
²¹ Inst. for Nucl. Research and Nucl. Energy, 1784 Sofia, Bulgaria
²² Università di Pisa, and INFN Pisa, 56126 Pisa, Italy
²³ ICREA and Institute for Space Sciences (CSIC/IEEC), 08193 Barcelona, Spain
²⁴ Now at Centro Brasileiro de Pesquisas Físicas (CBPF/MCTI), R. Dr. Xavier Sigaud, 150 – Urca, 22290-180 Rio de Janeiro – RJ, Brazil
²⁵ Now at NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
²⁶ Humboldt University of Berlin, Institut für Physik Newtonstr. 15, 12489 Berlin Germany
²⁷ Also at University of Trieste, Italy
²⁸ Now at École polytechnique fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
²⁹ Now at Max-Planck-Institut fur Kernphysik, PO Box 103980, 69029 Heidelberg, Germany
³⁰ Also at Japanese MAGIC Consortium, Kyoto, Japan
³¹ Now at Finnish Centre for Astronomy with ESO (FINCA), 20014 Turku, Finland
³² Also at INAF-Trieste and Dept. of Physics & Astronomy, University of Bologna, Italy
³³ Also at ISDC – Science Data Center for Astrophysics, 1290 Versoix (Geneva), Switzerland
³⁴ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
³⁵ Now at Department of Physics and Department of Astronomy, University of Maryland, College Park, MD 20742, USA

^⋆ Corresponding authors: Christian Fruck, e-mail: fruck@mpp.mpg.de; Ievgen Vovk, e-mail: ievgen.vovk@mpp.mpg.de; and John Ennis Ward, e-mail: jward@ifae.es

Received: 20 July 2016
Accepted: 18 November 2016

Abstract

Context. We present the results of a multi-year monitoring campaign of the Galactic center (GC) with the MAGIC telescopes. These observations were primarily motivated by reports that a putative gas cloud (G2) would be passing in close proximity to the super-massive black hole (SMBH), associated with Sagittarius A*, located at the center of our galaxy. This event was expected to give astronomers a unique chance to study the effect of in-falling matter on the broad-band emission of a SMBH.

Aims. We search for potential flaring emission of very-high-energy (VHE; ≥100 GeV) gamma rays from the direction of the SMBH at the GC due to the passage of the G2 object. Using these data we also study the morphology of this complex region.

Methods. We observed the GC region with the MAGIC Imaging Atmospheric Cherenkov Telescopes during the period 2012–2015, collecting 67 h of good-quality data. In addition to a search for variability in the flux and spectral shape of the GC gamma-ray source, we use a point-source subtraction technique to remove the known gamma-ray emitters located around the GC in order to reveal the TeV morphology of the extended emission inside that region.

Results. No effect of the G2 object on the VHE gamma-ray emission from the GC was detected during the 4 yr observation campaign. We confirm previous measurements of the VHE spectrum of Sagittarius A*, and do not detect any significant variability of the emission from the source. Furthermore, the known VHE gamma-ray emitter at the location of the supernova remnant G0.9+0.1 was detected, as well as the recently discovered VHE source close to the GG radio arc.