Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Relationship between the $γ-$ray variability and the pc-scale jet in the blazar 3C 454.3

Eva Palafox, Víctor Manuel Patiño-Álvarez, Vahram Chavushyan, Sergio A. Dzib, Andrei Lobanov, J. Anton Zensus

TL;DR

This study addresses the location and mechanisms of γ-ray production in the blazar 3C 454.3 by synchronizing twelve years of γ-ray data with high-resolution VLBA imaging at 15 and 43 GHz. Using adaptive time-bin Spearman correlations and rigorous validation, the authors identify strong γ-ray associations with the 43 GHz core ($$β_{app}$$ and moving knot interactions) and with the 15 GHz core, revealing a multi-zone scenario where SSC appears to dominate for regions beyond the central parsec. They locate several emission regions within the jet, including a moving knot with $$β_{app}=9.9 \, ext{±} \, 1.1$$ c and a quasi-stationary feature at ~4.6 pc from the core, and demonstrate that these regions collectively account for substantial portions of the observed γ-ray variability. The results support a leptonic, SSC-dominated framework in the outer jet while illustrating the dynamic, non-stationary nature of γ-ray–emitting regions and their spatial distribution along the blazar jet.

Abstract

3C 454.3 is a flat spectrum radio quasar (FSRQ) known for its high variability across the electromagnetic spectrum, showing structural and flux variability in its pc-scale jet, and correlated variability among frequency bands. This study aims to identify the structure, dynamics, and radiative processes common to the innermost regions of the blazar 3C 454.3. We investigate whether any jet component can be associated with $γ-$ray emission and variability. We analyze the relationship between the variable $γ-$ray emission and pc-scale jet properties in 3C 454.3 by combining $γ-$ray data spanning twelve years with contemporaneous VLBA multi-epoch images at 15 and 43 GHz. Spearman rank correlation tests are conducted to determine if the flux variability of any jet component is associated with $γ-$ray variability. Core emission at 43 and 15 GHz strongly correlates with $γ-$ray emission. The 43 GHz core (Q0) contributes around 37$\%$ of the observed $γ-$ray variability, while the 15 GHz core (K0) accounts for 30$\%$. A quasi-stationary component at 43 GHz, at a projected distance of 4.6 pc, correlates with the $γ-$ray flux, accounting for 20$\%$ of its emission between 2016 and 2021. We found a mobile component (Q3 between 2010.18 and 2011.16) at 43 GHz with a projected distance between 0.8 and 2.3 pc and apparent velocity of $β_{app} = 9.9 \pm 1.1$ c, accounting for approximately 28% of the $γ-$ray emission. The observed simultaneous variability in emission regions beyond the central parsec strongly suggests synchrotron self-Compton (SSC) as the primary mechanism for $γ-$ray production in these regions. Our findings demonstrate the existence of multiple $γ-$ray emission regions within the blazar jet but also suggest that some of these regions are non-stationary over time.

Relationship between the $γ-$ray variability and the pc-scale jet in the blazar 3C 454.3

TL;DR

This study addresses the location and mechanisms of γ-ray production in the blazar 3C 454.3 by synchronizing twelve years of γ-ray data with high-resolution VLBA imaging at 15 and 43 GHz. Using adaptive time-bin Spearman correlations and rigorous validation, the authors identify strong γ-ray associations with the 43 GHz core ( and moving knot interactions) and with the 15 GHz core, revealing a multi-zone scenario where SSC appears to dominate for regions beyond the central parsec. They locate several emission regions within the jet, including a moving knot with c and a quasi-stationary feature at ~4.6 pc from the core, and demonstrate that these regions collectively account for substantial portions of the observed γ-ray variability. The results support a leptonic, SSC-dominated framework in the outer jet while illustrating the dynamic, non-stationary nature of γ-ray–emitting regions and their spatial distribution along the blazar jet.

Abstract

3C 454.3 is a flat spectrum radio quasar (FSRQ) known for its high variability across the electromagnetic spectrum, showing structural and flux variability in its pc-scale jet, and correlated variability among frequency bands. This study aims to identify the structure, dynamics, and radiative processes common to the innermost regions of the blazar 3C 454.3. We investigate whether any jet component can be associated with ray emission and variability. We analyze the relationship between the variable ray emission and pc-scale jet properties in 3C 454.3 by combining ray data spanning twelve years with contemporaneous VLBA multi-epoch images at 15 and 43 GHz. Spearman rank correlation tests are conducted to determine if the flux variability of any jet component is associated with ray variability. Core emission at 43 and 15 GHz strongly correlates with ray emission. The 43 GHz core (Q0) contributes around 37 of the observed ray variability, while the 15 GHz core (K0) accounts for 30. A quasi-stationary component at 43 GHz, at a projected distance of 4.6 pc, correlates with the ray flux, accounting for 20 of its emission between 2016 and 2021. We found a mobile component (Q3 between 2010.18 and 2011.16) at 43 GHz with a projected distance between 0.8 and 2.3 pc and apparent velocity of c, accounting for approximately 28% of the ray emission. The observed simultaneous variability in emission regions beyond the central parsec strongly suggests synchrotron self-Compton (SSC) as the primary mechanism for ray production in these regions. Our findings demonstrate the existence of multiple ray emission regions within the blazar jet but also suggest that some of these regions are non-stationary over time.

Paper Structure

This paper contains 11 sections, 1 equation, 6 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Observational data and analysis
  3. Gamma rays
  4. VLBA observations at 43 and 15 GHz
  5. OVRO 15 GHz observations
  6. Sub-Millimeter Array 230 and 350 GHz
  7. Jet structure model fitting
  8. Results and discussion
  9. Jet structure and kinematics
  10. Correlation analysis
  11. Summary and conclusions

Figures (6)

  • Figure 1: Multi-wavelength light curves of 3C 454.3. Each panel shows the blazar emission at a different wavelength (indicated by the label and color). The data source is specified within each panel. The solid vertical lines mark $\gamma$-ray flare events that appear to coincide with the passage of jet components K09 and K10 through the VLBI core 2013ApJ...773..147J. The dashed vertical line indicates the ejection of a relativistic component from the radio core (K14; 2020ApJ...902...61L). The dotted vertical line represents the time at which a knot crossed the 43 GHz core (K16; 2019ApJ...875...15W).
  • Figure 2: Left panel: VLBA intensity map at 15 GHz showing the position of K6 on November 21, 2020, convolved with a beam of 1.1 $\times$ 0.5 mas$^2$ at PA = 1°. Middle panel: Fitting result of the observed emission. Right panel: Residual image. The gray lines correspond to contour levels of 0.5, 3, 5, 30, 60, 75, and 95$\%$ of the peak total intensity.
  • Figure 3: Sample sequence of the VLBA images at 43 GHz. Red ellipses across images show the position of the moving component Q3 at four different epochs.
  • Figure 4: Relative distance to the core versus time of all the identified jet components in 3C 454.3 at 43 GHz (upper panel) and 15 GHz (lower panel). The gray shadowed area represents the position of the quasi-stationary region reported by this and previous studies. The dashed horizontal line shows the typical angular resolution.
  • Figure 5: Light curves of all the identified jet components in 3C 454.3 at 43 and 15 GHz.
  • ...and 1 more figures