Fourier Analysis of Blazar Variability

Abstract

Blazars display strong variability on multiple timescales and in multiple radiation bands. Their variability is often characterized by power spectral densities (PSDs) and time lags plotted as functions of the Fourier frequency. We develop a new theoretical model based on the analysis of the electron transport (continuity) equation, carried out in the Fourier domain. The continuity equation includes electron cooling and escape, and a derivation of the emission properties includes light travel time effects associated with a radiating blob in a relativistic jet. The model successfully reproduces the general shapes of the observed PSDs and predicts specific PSD and time lag behaviors associated with variability in the synchrotron, synchrotron self-Compton (SSC), and external Compton (EC) emission components, from sub-mm to gamma-rays. We discuss applications to BL Lacertae objects and to flat-spectrum radio quasars (FSRQs), where there are hints that some of the predicted features have already been observed. We also find that FSRQs should have steeper PSD power-law indices than BL Lac objects at Fourier frequencies < 10^{-4} Hz, in qualitative agreement with previously reported observations by the Fermi Large Area Telescope.

17 pages, 8 figures. Accepted by ApJ

References in corpus (7)

• Synchrotron Self-Compton Analysis of TeV X-ray Selected BL Lacertae Objects
• Implications of very rapid TeV variability in blazars
• Periodic Oscillations in the Intra-day Optical Light Curves of the Blazar S5 0716+714
• Stochastic Modeling of the Fermi/LAT Gamma-ray Blazar Variability
• Blazar synchrotron emission of instantaneously power-law injected electrons under linear synchrotron, non-linear SSC, and combined synchrotron-SSC cooling
• Modeling the Spectral Energy Distribution and Variability of 3C 66A during the WEBT campaign of 2003 -- 2004
• A Fourier Transformed Bremsstrahlung Flash Model for the Production of X-Ray Time Lags in Accreting Black Hole Sources

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• Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155-304
• The long-term centimeter variability of active galactic nuclei: A new relation between variability timescale and accretion rate
• Particle acceleration in radio galaxies with flickering jets: GeV electrons to ultrahigh energy cosmic rays
• Optical variability power spectrum analysis of blazar sources on intranight timescales
• Simulations of Stochastic Long-Term Variability in Leptonic Models for External-Compton and Synchrotron Self-Compton Dominated Blazars
• Probing the disc-jet coupling in S4 0954+65, PKS 0903-57, & 4C +01.02 with $\gamma$-rays
• Optical variability modeling of newly identified blazar candidates behind Magellanic Clouds
• Searching for signatures of chaos in gamma-ray light curves of selected Fermi-LAT blazars