Detecting the Elusive Blazar Counter-Jets

Abstract

Detection of blazar pc scale counter-jets is difficult, but it can provide invaluable insight into the relativistic effects, radiative processes and the complex mechanisms of jet production, collimation and accelation in blazars. We build on recent populations models (optimized using the MOJAVE apparent velocity and redshift distributions) in order to derive the distribution of jet-to-counter-jet ratios and the flux densities of the counter-jet at different frequencies, in an effort to set minimum sensitivity limits required for existing and future telescope arrays in order to detect these elusive counter-jets. We find that: for the BL Lacs $5\%$ of their counter-jets have a flux-density higher than 100mJy, $15\%$ are higher than 10 mJy, and $32\%$ have higher flux-density than 1 mJy, whereas for the FSRQs $8\%$ have a flux-density higher than 10mJy, $17\%$ are higher than 1 mJy, and $32\%$ are higher than 0.1 mJy (at 15 GHz). Future telescopes like the SKA and newly operating like e-MERLIN and JVLA may detect up to $99\%$ of the BL Lac and $77\%$ of the FSRQ counter-jets. Sources with both low apparent velocity and a low Doppler factor make prime candidates for counter-jet detection. Combining our findings with literature values we have identified five such counter-jet detection candidates. Finally, we discuss possible effects beyond relativistic deboosting that may complicate the detection of counter-jets and that need to be accounted for in the interpretation of detections.

13 pages, 15 figures, accepted for publication in MNRAS

References in corpus (17)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Doppler factors, Lorentz factors and viewing angles for quasars, BL Lacertae objects and radio galaxies
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. V. Multi-epoch VLBA Images
• A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279
• The Last of FIRST: The Final Catalog and Source Identifications
• The Inner Jet of the Radio Galaxy M87
• Detection of significant cm to sub-mm band radio and gamma-ray correlated variability in Fermi bright blazars
• Time-correlation between the radio and gamma-ray activity in blazars and the production site of the gamma-ray emission
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. XI. Spectral distributions
• RoboPol: The optical polarization of gamma-ray--loud and gamma-ray--quiet blazars
• The jet of Markarian 501 from millions of Schwarzschild radii down to a few hundreds
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. III. Deep VLA Images at 1.4 GHz
• RoboPol: Do optical polarization rotations occur in all blazars?
• Discovery of a new subparsec counterjet in NGC 1275: the inclination angle and the environment
• The Shapes of Molecular Cloud Cores in Orion
• Population statistics of beamed sources. I: A new model for blazars
• The jet of Markarian 501 from the sub-parsec to the kpc scale

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• VLBI-Gaia offsets favor parsec-scale jet direction in Active Galactic Nuclei
• Detecting intermediate mass black holes in midiquasars with current and future surveys
• Identifying changing jets through their radio variability