Optical variability power spectrum analysis of blazar sources on intranight timescales

Abstract

We report the first results of a systematic investigation to characterize blazar variability power spectral densities (PSDs) at optical frequencies using densely sampled (5--15 minutes integration time), high photometric accuracy ($\lesssim$0.2--0.5\%) R-band intranight light curves, covering timescales ranging from several hours to $\sim$15\,minutes. Our sample consists of 14 optically bright blazars, including nine BL Lacertae objects (BL Lacs) and five flat-spectrum radio quasars (FSRQs) which have shown statistically significant variability during 29 monitoring sessions. We model the intranight PSDs as simple power--laws and derive the best-fit slope along with uncertainty using the `power spectral response' method. Our main results are the following: (1) on 19 out of 29 monitoring sessions, the intranight PSDs show an acceptable fit to simple power-laws at the rejection confidence $\le$ 90\%; (2) for these 19 instances, the PSD slopes show a large range from 1.4 to 4.0, consistent with statistical characters of red (slope$\sim$2) and black (slope$\ge$3) noise stochastic processes; (3) the average PSD slopes for the BL Lacs and FSRQs are indistinguishable from one another; (4) the normalization of intranight PSDs for individual blazar sources which were monitored on more than one occasion turns out to be consistent with one another with a few exceptions. The average PSD slope, 2.9$\pm$0.3 (1$\sigma$ uncertainty) is steeper than the red-noise type character of variability found on longer timescales (many decades to days), indicative of a cutoff in the variability spectrum on timescales around a few days at the synchrotron frequencies of the emission spectrum.

ApJ accepted

References in corpus (24)

• A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279
• Relativistic Jets Shine through Shocks or Magnetic Reconnection?
• The blazar sequence: a new perspective
• CGRaBS: An All-Sky Survey of Gamma-Ray Blazar Candidates
• Implications of very rapid TeV variability in blazars
• Correlated Multi-Waveband Variability in the Blazar 3C~279 from 1996 to 2007
• A method for the estimation of the significance of cross-correlations in unevenly sampled red-noise time series
• Stochastic Modeling of the Fermi/LAT Gamma-ray Blazar Variability
• A Large Sample of BL Lacs from SDSS and FIRST
• Fourier Analysis of Blazar Variability
• The dual nature of blazar fast variability. Space and ground observations of S5 0716+714
• Characterizing the gamma-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT
• MAXI investigation into the longterm X-ray variability from the very-high-energy gamma-ray blazar Mrk 421
• Multi-wavelength variability study of the classical BL Lac object PKS 0735+178 on timescales ranging from decades to minutes
• Spectroscopic monitoring of the BL Lac object AO 0235+164
• Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155-304
• Optical Variability of TeV Blazars on long time-scales
• The long-term centimeter variability of active galactic nuclei: A new relation between variability timescale and accretion rate
• Blazar Variability From Turbulence in Jets Launched by Magnetically Arrested Accretion Flows
• Extremely rapid x-ray flares of tev blazars in the rxte era
• Multiband optical flux density and polarization microvariability study of optically bright blazars
• Violent intra-night optical variability of the blazar S4 0954+65 during its unprecedented 2015 February outburst
• Short-term X-ray Variability during Different Activity Phases of Blazars S5 0716+714 and PKS 2155-304
• Suborbital Fermi/LAT Analysis of the Brightest Gamma-Ray Flare of Blazar 3C 454.3

Cited by in corpus (5)

• Multiwavelength variability power spectrum analysis of the blazars 3C 279 and PKS 1510-089 on multiple 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
• Analysis of the intra-night variability of BL Lacertae during its August 2020 flare
• Optical variability of eight FRII-type quasars with 13-yr photometric light curves