Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes

Journal
Date Issued
2015
Author(s)
Aleksić, J.
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Ansoldi, S.
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Antoranz, P.
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Babic, A.
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Bangale, P.
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Barrio, J. A.
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Becerra González, J.
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Bednarek, W.
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Bernardini, E.
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Biasuzzi, B.
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Paneque, D.
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Paoletti, R.
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Paredes, J. M.
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Paredes-Fortuny, X.
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Prada Moroni, P. G.
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•
Preziuso, S.
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Puljak, I.
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Reinthal, R.
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Biland, A.
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Rhode, W.
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Ribó, M.
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Rico, J.
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Rodriguez Garcia, J.
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Rügamer, S.
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Saggion, A.
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Saito, T.
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Saito, K.
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Satalecka, K.
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Scalzotto, V.
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Blanch, O.
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Scapin, V.
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Schultz, C.
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Schweizer, T.
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Shore, S. N.
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Sillanpää, A.
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Sitarek, J.
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Snidaric, I.
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Sobczynska, D.
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Spanier, F.
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Stamatescu, V.
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Bonnefoy, S.
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Steinbring, T.
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Storz, J.
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Strzys, M.
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Takalo, L.
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Takami, H.
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Temnikov, P.
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Terzić, T.
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Tescaro, D.
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Teshima, M.
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Thaele, J.
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Tibolla, O.
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Torres, D. F.
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Toyama, T.
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Treves, A.
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Uellenbeck, M.
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Vogler, P.
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Wagner, R. M.
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Zanin, R.
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Borracci, F.
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Horns, D.
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Martín, J.
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Meyer, M.
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Bretz, T.
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Carmona, E.
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Colin, P.
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Colombo, E.
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Contreras, J. L.
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Cortina, J.
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Da Vela, P.
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De Angelis, A.
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De Caneva, G.
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De Lotto, B.
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de Oña Wilhelmi, E.
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Delgado Mendez, C.
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Doert, M.
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Dominis Prester, D.
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Dorner, D.
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Doro, M.
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Einecke, S.
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Eisenacher, D.
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Elsaesser, D.
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Fonseca, M. V.
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Font, L.
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Frantzen, K.
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Fruck, C.
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Galindo, D.
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García López, R. J.
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Garczarczyk, M.
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Garrido Terrats, D.
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Gaug, M.
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Godinović, N.
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González Muñoz, A.
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Gozzini, S. R.
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Hadasch, D.
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Hanabata, Y.
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Hayashida, M.
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Herrera, J.
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Hildebrand, D.
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Hose, J.
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Hrupec, D.
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Idec, W.
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Kadenius, V.
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Kellermann, H.
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Kodani, K.
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Konno, Y.
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Krause, J.
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Kubo, H.
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Kushida, J.
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Lelas, D.
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Lewandowska, N.
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Lindfors, E.
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López, M.
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López-Coto, R.
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López-Oramas, A.
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Lorenz, E.
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Lozano, I.
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Makariev, M.
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Mallot, K.
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Maneva, G.
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Mankuzhiyil, N.
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Mannheim, K.
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Maraschi, L.
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Marcote, B.
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Mariotti, M.
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Martínez, M.
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Mazin, D.
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Menzel, U.
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Miranda, J. M.
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Mirzoyan, R.
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Moralejo, A.
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Munar-Adrover, P.
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Nakajima, D.
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Niedzwiecki, A.
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Nilsson, K.
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Nishijima, K.
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Noda, K.
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Nowak, N.
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Orito, R.
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Overkemping, A.
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Palatiello, M.
DOI
Description
Acknowledgements We would like to thank the Instituto de Astrofsica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG , the Italian INFN and INAF , the Swiss National Fund SNF, the ERDF under the Spanish MINECO , and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Centro de Excelencia Severo Ochoa SEV-2012-0234 , CPAN CSD2007-00042 , and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme , by grant 268740 of the Academy of Finland , by the Croatian Science Foundation (HrZZ) Project 09/176 and the University of Rijeka Project 13.12.1.3.02 , by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3 , and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0 .
Abstract
The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereoscopic software provided an unprecedented precision of spectral and night-by-night light curve determination at gamma rays. We derived a differential spectrum with a single instrument from 50 GeV up to almost 30 TeV with 5 bins per energy decade. At low energies, MAGIC results, combined with Fermi-LAT data, show a flat and broad Inverse Compton peak. The overall fit to the data between 1 GeV and 30 TeV is not well described by a log-parabola function. We find that a modified log-parabola function with an exponent of 2.5 instead of 2 provides a good description of the data (χred2 = 35 / 26). Using systematic uncertainties of the MAGIC and Fermi-LAT measurements we determine the position of the Inverse Compton peak to be at (53 ±3stat +31syst -13syst) GeV, which is the most precise estimation up to date and is dominated by the systematic effects. There is no hint of the integral flux variability on daily scales at energies above 300 GeV when systematic uncertainties are included in the flux measurement. We consider three state-of-the-art theoretical models to describe the overall spectral energy distribution of the Crab Nebula. The constant B-field model cannot satisfactorily reproduce the VHE spectral measurements presented in this work, having particular difficulty reproducing the broadness of the observed IC peak. Most probably this implies that the assumption of the homogeneity of the magnetic field inside the nebula is incorrect. On the other hand, the time-dependent 1D spectral model provides a good fit of the new VHE results when considering a 80 μG magnetic field. However, it fails to match the data when including the morphology of the nebula at lower wavelengths.

Volume
5
Start page
30
Uri
Url
Issn Identifier
2214-4048
Ads BibCode
2015JHEAp...5...30A
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open.access
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