Probing Precise Location of Radio Core in TeV Blazar Mrk 501 with VERA at 43 GHz

Abstract

We investigate the position of the radio core in a blazar by multi-epoch astrometric observations at 43 GHz. Using the VLBI Exploration of Radio Astrometry (VERA), we have conducted four adjacent observations in February 2011 and another four in October 2011, and succeeded in measuring the position of the radio core in the TeV blazar Mrk 501 relative to a distant compact quasar NRAO 512. During our observations, we find that (1) there is no positional change within ~0.2 mas or ~2.0 pc de-projected with $\pm 1\sigma$ error for the weighted-mean phase-referenced positions of Mrk 501 core relative to NRAO 512 over four adjacent days, and (2) there is an indication of position change for 3C 345 core relative to NRAO 512. By applying our results to the standard internal shock model for blazars, we constrain the bulk Lorenz factors of the ejecta.

arXiv comment23 pages, 4 figures, 5 tables, accepted for publication in PASJ

References in corpus (12)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279
• Insights Into the High-Energy Gamma-ray Emission of Markarian 501 from Extensive Multifrequency Observations in the Fermi Era
• Flaring Behavior of the Quasar 3C~454.3 across the Electromagnetic Spectrum
• Location of gamma-ray Flare Emission in the Jet of the BL Lacertae Object OJ287 more than 14pc from the Central Engine
• Astrometry of Galactic Star Forming Region Sharpless 269 with VERA : Parallax Measurements and Constraint on Outer Rotation Curve
• On the Location of the Gamma-ray Emission in the 2008 Outburst in the BL Lacertae Object AO 0235+164 through Observations across the Electromagnetic Spectrum
• The jet of Markarian 501 from millions of Schwarzschild radii down to a few hundreds
• First Fringe Detection with VERA's Dual-Beam System and its Phase Referencing Capability
• Long-term Monitoring on Mrk 501 for Its VHE gamma Emission and a Flare in October 2011
• Bigradient Phase Referencing
• GENJI Programme: Gamma-ray Emitting Notable AGN Monitoring by Japanese VLBI

Cited by in corpus (3)

• Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
• Discovery of off-axis jet structure of TeV blazar Mrk 501 with mm-VLBI
• OGLE-BLG504.12.201843: A possible extreme dwarf nova