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

Abstract

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 gamma-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 milliarcsecond-scale 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 gamma-ray variability is located in the core of the AGN, which is opaque up to the highest observing frequency of 22 GHz.

arXiv comment9 pages, 6 figures, 3 tables. Accepted for publication in MNRAS

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Cited by in corpus (4)

• Detection of very high energy gamma-ray emission from the gravitationally-lensed blazar QSO B0218+357 with the MAGIC telescopes
• The Structure of the Strongly Lensed Gamma-ray Source B2 0218+35
• Gravitational Lenses as High-Resolution Telescopes
• Using gravitational lensed images to investigate the intrinsic AGN variability