Radio follow-up of the γ-ray flaring gravitational lens JVAS B0218+357

Research output: Contribution to journalArticle


  • C. Spingola
  • D. Dallacasa
  • M. Orienti
  • M. Giroletti
  • J. P. McKean
  • C. C. Cheung
  • Talvikki Hovatta

  • S. Ciprini
  • F. D'Ammando
  • E. Falco
  • S. Larsson
  • W. Max-Moerbeck
  • R. Ojha
  • A. C S Readhead
  • J. L. Richards
  • J. Scargle

Research units

  • INAF Istituto di Radioastronomia
  • Netherlands Institute for Radio Astronomy (ASTRON)
  • Naval Research Laboratory
  • Agenzia Spaziale Italiana
  • INAF, Osservatorio Astronomico di Roma
  • Harvard-Smithsonian Center for Astrophysics
  • KTH Royal Institute of Technology
  • National Radio Astronomy Observatory Socorro
  • NASA Goddard Space Flight Center
  • University of Maryland, College Park
  • The Catholic University of America
  • California Institute of Technology
  • Purdue University
  • NASA Ames Research Center
  • University of Bologna
  • University of Groningen
  • Oskar Klein Centre


We present results on multifrequency Very Long Baseline Array (VLBA) monitoring observations of the double-image gravitationally lensed blazar JVAS B0218+357. Multi-epoch observations started less than one month after the γ -ray flare detected in 2012 by the Large Area Telescope on board Fermi, and spanned a 2-month interval. The radio light curves did not reveal any significant flux density variability, suggesting that no clear correlation between the high-energy and low-energy emission is present. This behaviour was confirmed also by the long-term Owens Valley Radio Observatory monitoring data at 15 GHz. The milliarcsecondscale resolution provided by the VLBA observations allowed us to resolve the two images of the lensed blazar, which have a core-jet structure. No significant morphological variation is found by the analysis of the multi-epoch data, suggesting that the region responsible for the γ -ray variability is located in the core of the active galactic nuclei, which is opaque up to the highest observing frequency of 22 GHz.


Original languageEnglish
Pages (from-to)2263-2271
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1 Apr 2016
MoE publication typeA1 Journal article-refereed

    Research areas

  • Gravitational lensing: strong, Quasars: individual: JVAS B0218+357

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