Detection of persistent VHE gamma-ray emission from PKS 1510-089 by the MAGIC telescopes during low states between 2012 and 2017

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • Tartu Observatory
  • University of La Laguna
  • University of Udine
  • National Institute for Nuclear Physics
  • INAF National Institute for Astrophysics
  • Swiss Federal Institute of Technology Zurich
  • University of Padova
  • INFN, Sezione di Padova
  • Technische Universität Dortmund
  • Croatian MAGIC Consortium
  • Saha Institute of Nuclear Physics
  • Max-Planck-Institut für Physik
  • Centro Brasileiro de Pesquisas Físicas (CBPF\MCTI)
  • Universidad Complutense
  • University of Lódz
  • Deutsches Elektronen-Synchrotron
  • Barcelona Institute of Science and Technology (BIST)
  • University of Siena
  • INFN Pisa
  • University of Pisa
  • University of Würzburg
  • Finnish MAGIC Consortium
  • Universitat Autonoma de Barcelona
  • Universitat de Barcelona
  • Japanese MAGIC Consortium
  • Bulgarian Academy of Sciences
  • Humboldt University of Berlin
  • University of Trieste
  • University of Bologna
  • INAF, Osservatorio Astrofisico di Torino
  • Università dell'Insubria
  • INAF—Osservatorio Astronomico di Brera
  • California Institute of Technology
  • University of Turku
  • Universidad de Chile
  • Instituto de Radioastronomía Milimétrica (IRAM)
  • Instituto de Astrofisica de Andalucia (Spain)
  • Max-Planck-Institut für Radioastronomie

Abstract

PKS 1510-089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. We search for low-state VHE gamma-ray emission from PKS 1510-089. We aim to characterize and model the source in a broad-band context, which would provide a baseline over which high states and flares could be better understood. We use daily binned Fermi-LAT flux measurements of PKS 1510-089 to characterize the GeV emission and select the observation periods of MAGIC during low state of activity. For the selected times we compute the average radio, IR, optical, UV, X-ray and gamma-ray emission to construct a low-state spectral energy distribution of the source. The broadband emission is modelled within an External Compton scenario with a stationary emission region through which plasma and magnetic field are flowing. We perform also the emission-model-independent calculations of the maximum absorption in the broad line region (BLR) using two different models. Results. The MAGIC telescopes collected 75 hrs of data during times when the Fermi-LAT flux measured above 1 GeV was below 3x10-8cm-2s-1, which is the threshold adopted for the definition of a low gamma-ray activity state. The data show a strongly significant (9.5{\sigma}) VHE gamma-ray emission at the level of (4.27+-0.61stat)x10-12cm-2s-1 above 150GeV, a factor 80 smaller than the highest flare observed so far from this object. Despite the lower flux, the spectral shape is consistent with earlier detections in the VHE band. The broad-band emission is compatible with the EC scenario assuming a large emission region located beyond the BLR. For the first time the gamma-ray data allow us to place a limit on the location of the emission region during a low gamma-ray state of a FSRQ. For the used model of the BLR, the 95% C.L. on the location of the emission region allows us to place it at the distance >74% of the outer radius of the BLR.

Details

Original languageEnglish
Article numberA159
Number of pages12
JournalAstronomy and Astrophysics
Volume619
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Galaxies: active, Galaxies: jets, Gamma rays: galaxies, Quasars: individual: PKS 1510-089

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