Publication Date:
2016-02-12
Description:
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 -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 -ray variability is located in the core of the active galactic nuclei, which is opaque up to the highest observing frequency of 22 GHz.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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