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.

arXiv comment13 pages, 15 figures, accepted for publication in MNRAS

References in corpus (45)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long Baseline Array
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VI. Kinematics Analysis of a Complete Sample of Blazar Jets
• MOJAVE. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in AGN
• 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
• Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects: Superluminal Motion of Gamma-Ray Bright Blazars
• Sub-milliarcsecond Imaging of Quasars and AGN
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments - I. First-Epoch 15 GHz Linear Polarization 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
• A simplified view of blazars: clearing the fog around long-standing selection effects
• The Cosmic Evolution of Fermi BL Lacertae Objects
• MOJAVE XIII. Parsec-Scale AGN Jet Kinematics Analysis Based on 19 years of VLBA Observations at 15 GHz
• Spectroscopy of Broad Line Blazars from 1LAC
• The Inner Jet of the Radio Galaxy M87
• Fermi Discovery of Gamma-Ray Emission from NGC 1275
• 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
• Parsec-Scale Blazar Monitoring: Proper Motions
• RoboPol: The optical polarization of gamma-ray--loud and gamma-ray--quiet blazars
• Gamma-Ray and Parsec-Scale Jet Properties of a Complete Sample of Blazars From the MOJAVE Program
• RoboPol: First season rotations of optical polarization plane in blazars
• The stratified two-sided jet of Cygnus A. Acceleration and collimation
• RoboPol: optical polarization-plane rotations and flaring activity in blazars
• A Highly Magnetized Twin-Jet Base Pinpoints a Supermassive Black Hole
• A Sample of Low Redshift BL Lacs. I. The Radio Data
• 4C +12.50: A Superluminal Precessing Jet in the Recent Merger System IRAS 13451+1232
• 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
• First 3 mm-VLBI imaging of the two-sided jet in Cygnus A. Zooming into the launching region
• RoboPol: Do optical polarization rotations occur in all blazars?
• Discovery of a new subparsec counterjet in NGC 1275: the inclination angle and the environment
• VLBA monitoring of Mrk 421 at 15 GHz and 24 GHz during 2011
• Statistical Assessment of Shapes and Magnetic Field Orientations in Molecular Clouds through Polarization Observations
• PKS 1510-089: A Head-On View of a Relativistic Jet
• F-GAMMA: On the phenomenological classification of continuum radio spectra variability patterns of Fermi blazars
• Population statistics of beamed sources. II: Evaluation of Doppler factor estimates
• The Shapes of Molecular Cloud Cores in Orion
• Determination of Central Engine Position and Accretion Disk Structure in NGC 4261 by Core Shift Measurements
• Population statistics of beamed sources. I: A new model for blazars
• Anatomy of a blazar in the (sub-)millimeter: ALMA Observations of PKS 0521-365
• A turbulent model for the surface brightness of extragalactic jets
• The jet of Markarian 501 from the sub-parsec to the kpc scale

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• Fermi LAT AGN classification using supervised machine learning
• Estimating the distribution of rest-frame timescales for blazar jets: a statistical approach
• Detecting intermediate mass black holes in midiquasars with current and future surveys
• Identifying changing jets through their radio variability