Curvature induced polarization and spectral index behavior for PKS 1502+106

Abstract

A comprehensive study of multifrequency correlations can shed light on the nature of variation for blazars. In this work, we collect the long-term radio, optical and $\gamma$-ray light curves of PKS 1502+106. After performing the localized cross-correlation function analysis, we find that correlations between radio and $\gamma$-ray or $V$ band are beyond the $3\sigma$ significance level. The lag of the $\gamma$-ray relative to 15 GHz is $-60_{-10}^{+5}$ days, translating to a distance $3.18_{-0.27}^{+0.50}$ parsec (pc) between them. Within uncertainties, the locations of the $\gamma$-ray and optical emitting regions are roughly the same, and are away from the jet base within $1.2$ pc. The derived magnetic field in optical and $\gamma$-ray emitting regions is about $0.36$ G. The logarithm of $\gamma$-ray flux is significantly linearly correlated with that of $V$ band fluxes, which can be explained by the synchrotron self-Compton (SSC) process, the external Compton (EC) processes, or the combination of them. We find a significant linear correlation in the plot of $\log \prod$ (polarization degree) versus $\log \nu F_{\nu }$ at $V$ band, and use the empirical relation $\Pi \sim {\sin }^n{\theta }^{\prime }$ (${\theta }^{\prime }$ is the observing angle in the comoving frame blob) to explain it. The behaviors of color index (generally redder when brighter at the active state) and $\gamma$-ray spectral index (softer when brighter) could be well explained by the twisted jet model. These findings suggest that the curvature effect (mainly due to the change of the viewing angle) is dominant in the variation phenomena of fluxes, spectral indices, and polarization degrees for PKS 1502+106.

arXiv comment13 pages, 8 figures

References in corpus (31)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-Dependent Continuum Lags in Active Galactic Nuclei
• Blazars in the Fermi Era: The OVRO 40-m Telescope Monitoring Program
• Doppler factors, Lorentz factors and viewing angles for quasars, BL Lacertae objects and radio galaxies
• The blazar sequence: a new perspective
• Generating artificial light curves: Revisited and updated
• Polarization and structure of relativistic parsec-scale AGN jets
• Jet opening angles and gamma-ray brightness of AGN
• Magnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jets
• On the Reliability of Cross Correlation Function Lag Determinations in Active Galactic Nuclei
• Blazar spectral variability as explained by a twisting inhomogeneous jet
• The unprecedented optical outburst of the quasar 3C 454.3. The WEBT campaign of 2004-2005
• 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
• A method for the estimation of the significance of cross-correlations in unevenly sampled red-noise time series
• Similarity of the Optical-IR and Gamma-Ray Time Variability of Fermi Blazars
• The awakening of BL Lacertae: observations by Fermi, Swift, and the GASP-WEBT
• PKS 1502+106: a new and distant gamma-ray blazar in outburst discovered by the Fermi Large Area Telescope
• Low power BL Lacertae objects and the blazar sequence: Clues on the particle acceleration process
• A model for periodic blazars
• Constraints on minimum electron Lorentz factor and matter content of jets for a sample of bright Fermi blazars
• Temporal Correlations Between Optical and Gamma-ray Activity in Blazars
• A new method for estimating frequency-dependent core shifts in active galactic nucleus jets
• The photometric system of the One-meter Telescope at Weihai Observatory of Shandong University
• PKS 1502+106: A high-redshift Fermi blazar at extreme angular resolution. Structural dynamics with VLBI imaging up to 86 GHz
• Multi-wavelength study of flaring activity in BL Lac object S5 0716+714 during 2015 outburst
• Multiband Photopolarimetric Monitoring of the Outburst of the Blazar 3C~454.3 in 2007
• What can the 2008/10 broadband flare of PKS 1502+106 tell us? Nuclear opacity, magnetic fields, and the location of gamma rays
• Peak of spectral energy distribution play an important role in intra-day variability of Blazars?
• Polarization swings from curved trajectories of the emitting regions
• Extreme Superluminal Motion in the Curved Jet of PKS 1502+106

Cited by in corpus (8)

• Multi-wavelength and neutrino emission from blazar PKS 1502+106
• A ring accelerator? Unusual jet dynamics in the IceCube candidate PKS 1502+106
• A comprehensive study on the variation phenomena of AO 0235+164
• Locations of optical and $\gamma$-ray emitting regions in the jet of PMN J2345-1555
• Interpreting the variation phenomena of B2 1633+382 via the two-component model
• Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations
• Multi-messenger emission from the parsec-scale jet of the flat-spectrum radio quasar PKS 1502+106 coincident with high-energy neutrino IceCube-190730A
• Peculiar Behavior of Optical Polarization in Blazar 1ES 1959+650: Role of Jet Magnetic Field and Geometry