A Caltech Library Service

Probing the very-high-energy γ-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes

Aleksić, J. and Hovatta, T. and Max-Moerbeck, W. (2015) Probing the very-high-energy γ-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes. Monthly Notices of the Royal Astronomical Society, 450 (4). pp. 4399-4410. ISSN 0035-8711.

[img] PDF - Published Version
See Usage Policy.

PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


PG 1553+113 is a very high energy (VHE, E > 100 GeV) γ-ray emitter classified as a BL Lac object. Its redshift is constrained by intergalactic absorption lines in the range 0.4 < z < 0.58. The MAGIC telescopes have monitored the source's activity since 2005. In early 2012, PG 1553+113 was found in a high state, and later, in April of the same year, the source reached its highest VHE flux state detected so far. Simultaneous observations carried out in X-rays during 2012 April show similar flaring behaviour. In contrast, the γ-ray flux at E < 100 GeV observed by Fermi-LAT is compatible with steady emission. In this paper, a detailed study of the flaring state is presented. The VHE spectrum shows clear curvature, being well fitted either by a power law with an exponential cut-off or by a log-parabola. A simple power-law fit hypothesis for the observed shape of the PG 1553+113 VHE γ-ray spectrum is rejected with a high significance (fit probability P = 2.6 × 10^(−6)). The observed curvature is compatible with the extragalactic background light (EBL) imprint predicted by current generation EBL models assuming a redshift z ∼ 0.4. New constraints on the redshift are derived from the VHE spectrum. These constraints are compatible with previous limits and suggest that the source is most likely located around the optical lower limit, z = 0.4, based on the detection of Lyα absorption. Finally, we find that the synchrotron self-Compton model gives a satisfactory description of the observed multiwavelength spectral energy distribution during the flare.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle Paper
Alternate Title:Probing the very-high-energy gamma-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes
Additional Information:© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 April 9. Received 2015 April 9. In original form 2014 August 8. First published online May 22, 2015. We would like to thank the Instituto de Astrofísica 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, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0. Part of this work has been possible with the support of the Cluster of Excellence: ‘Connecting Particles with the Cosmos’, part of the Landesexzellenzinitiative Hamburg, and the support of the Marie Heim-Vögtlin grant of the Swiss National Science Foundation. The authors thank J. Finke, J. Perkins and A. Neronov for their comments and contributions. JBG would like to thank M. Raue for useful discussions. The Fermi-LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. We thank the Swift team duty scientists and science planners for making these observations possible. The OVRO 40-m monitoring program is supported in part by NASA grants NNX08AW31G and NNX11A043G, and NSF grants AST-0808050 and AST-1109911. The Metsähovi team acknowledges support from the Academy of Finland to our observing projects (numbers 212656, 210338, 121148 and others).
Funding AgencyGrant Number
Bundesministerium für Bildung und Forschung (BMBF)UNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)UNSPECIFIED
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Swiss National Fund (SNF)UNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Centro de Excelencia Severo OchoaSEV-2012-0234
Centro Nacional de Física de Partículas, Astropartículas y Nuclear (CPAN)CSD2007-00042
Centro Nacional de Física de Partículas, Astropartículas y Nuclear (CPAN)CSD2009-00064
Academy of Finland268740
Croatian Science Foundation (HrZZ)09/176
University of Rijeka13.
Deutsche Forschungsgemeinschaft (DFG)SFB823/C4
Deutsche Forschungsgemeinschaft (DFG)SFB876/C3
Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSW)745/N-HESS-MAGIC/2010/0
Landesexzellenzinitiative HamburgUNSPECIFIED
Academy of Finland212656
Academy of Finland210338
Academy of Finland121148
Subject Keywords:galaxies: active – BL Lacertae objects: general –BL Lacertae objects: individual: PG1553+113 – cosmic background radiation – gamma-rays: galaxies – gamma-rays: general
Issue or Number:4
Record Number:CaltechAUTHORS:20141218-071638889
Persistent URL:
Official Citation:J. Aleksić, S. Ansoldi,L. A. Antonelli,P. Antoranz,A. Babic,P. Bangale,J. A. Barrio,J. Becerra González,W. Bednarek,E. Bernardini,B. Biasuzzi,A. Biland,O. Blanch,S. Bonnefoy,G. Bonnoli,F. Borracci,T. Bretz,E. Carmona,A. Carosi,P. Colin,E. Colombo,J. L. Contreras,J. Cortina,S. Covino,P. Da Vela,F. Dazzi,A. De Angelis,G. De Caneva,B. De Lotto,E. de Oña Wilhelmi,C. Delgado Mendez,D. Dominis Prester,D. Dorner,M. Doro,S. Einecke,D. Eisenacher,D. Elsaesser,D. Fidalgo,M. V. Fonseca,L. Font,K. Frantzen,C. Fruck,D. Galindo,R. J. García López,M. Garczarczyk,D. Garrido Terrats,M. Gaug,N. Godinović, A. González Muñoz,S. R. Gozzini,D. Hadasch,Y. Hanabata,M. Hayashida,J. Herrera,D. Hildebrand,J. Hose,D. Hrupec,W. Idec,V. Kadenius,H. Kellermann,M. L. Knoetig,K. Kodani,Y. Konno,J. Krause,H. Kubo,J. Kushida,A. La Barbera,D. Lelas,N. Lewandowska,E. Lindfors,S. Lombardi,F. Longo,M. López,R. López-Coto,A. López-Oramas,E. Lorenz,I. Lozano,M. Makariev,K. Mallot,G. Maneva,K. Mannheim,L. Maraschi,B. Marcote,M. Mariotti,M. Martínez,D. Mazin,U. Menzel,J. M. Miranda,R. Mirzoyan,A. Moralejo,P. Munar-Adrover,D. Nakajima,V. Neustroev,A. Niedzwiecki,K. Nilsson,K. Nishijima,K. Noda,R. Orito,A. Overkemping,S. Paiano,M. Palatiello,D. Paneque,R. Paoletti,J. M. Paredes,X. Paredes-Fortuny,M. Persic,J. Poutanen,P. G. Prada Moroni,E. Prandini,I. Puljak,R. Reinthal,W. Rhode,M. Ribó,J. Rico,J. Rodriguez Garcia,S. Rügamer,T. Saito,K. Saito,K. Satalecka,V. Scalzotto,V. Scapin,C. Schultz,T. Schweizer,A. Sillanpää,J. Sitarek,I. Snidaric,D. Sobczynska,F. Spanier,A. Stamerra,T. Steinbring,J. Storz,M. Strzys,L. Takalo,H. Takami,F. Tavecchio,P. Temnikov,T. Terzić, D. Tescaro,M. Teshima,J. Thaele,O. Tibolla,D. F. Torres,T. Toyama,A. Treves,P. Vogler,M. Will,R. Zanin,(The MAGIC Collaboration),F. D'Ammando,S. Buson,(for the Fermi -LAT Collaboration),A. Lähteenmäki,M. Tornikoski,T. Hovatta,A. C. S. Readhead,W. Max-Moerbeck,and J. L. Richards Probing the very high energy γ-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes MNRAS (July 11, 2015) Vol. 450 4399-4410 doi:10.1093/mnras/stv811 First published online May 22, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52996
Deposited By: Ruth Sustaita
Deposited On:18 Dec 2014 16:59
Last Modified:03 Oct 2019 07:46

Repository Staff Only: item control page