Possible Detection of Apparent Superluminal inward motion in Markarian 421 after the Giant X-ray flare in February, 2010

Abstract

We report on the VLBI follow-up observations using the Japanese VLBI Network (JVN) array at 22 GHz for the largest X-ray flare of TeV blazar Mrk 421 that occurred in mid-February, 2010. The total of five epochs of observations were performed at intervals of about 20 days between March 7 and May 31, 2010. No new-born component associated with the flare was seen directly in the total intensity images obtained by our multi-epoch VLBI observations. However, one jet component located at ~1 mas north-west from the core was able to be identified, and its proper motion can be measured as -1.66+/-0.46 mas yr^-1, which corresponds to an apparent velocity of -3.48+/-0.97 c. Here, this negative velocity indicates that the jet component was apparently moving toward the core. As the most plausible explanation, we discuss that the apparent negative velocity was possibly caused by the ejection of a new component, which could not be resolved with our observations. In this case, the obtained Doppler factor of the new component is around 10 to 20, which is consistent with the ones typically estimated by model fittings of spectral energy distribution for this source.

9 pages, 6 figures, 3 tables, accepted for publication in ApJ

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Cited by in corpus (10)

• The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies
• The TeV blazar Markarian 421 at the highest spatial resolution
• Time dependent spectral modeling of Markarian 421 during a violent outburst in 2010
• Discovery of a wandering radio jet base after a large X-ray flare in the blazar Markarian 421
• TeV $\gamma$-ray fluxes from the long campaigns on Mrk421 as constraints on the emission of TeV-PeV Neutrinos and UHECRs
• Could a plasma in quasi-thermal equilibrium be associated to the "orphan" TeV flares ?
• Optical polarization properties of February 2010 outburst of the blazar Mrk 421
• Multifrequency VLBI Observations of the Broad Absorption Line Quasar J1020+4320: Recently Restarted Jet Activity?
• The Parsec-Scale Structure of the Newer TeV Blazars
• Multi-epoch, multi-frequency VLBI study of the parsec-scale jet in the blazar 3C 66A