Research output: Contribution to journal › Article › peer-review
Radio-to-γ-ray, broadband variability study of the classical BL Lac object PKS 0735+178. / Goyal, Arti; Stawarz, Łukasz; Ostrowski, Michal; Larionov, Valeri.
In: Galaxies, Vol. 4, No. 4, 42, 01.12.2016.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Radio-to-γ-ray, broadband variability study of the classical BL Lac object PKS 0735+178
AU - Goyal, Arti
AU - Stawarz, Łukasz
AU - Ostrowski, Michal
AU - Larionov, Valeri
N1 - Publisher Copyright: © 2016 by the authors. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - The power-lawshape of the power spectral density (PSD) of blazar light curves-P(Vk) α Vk -β k, where Vk is the temporal frequency-indicates that blazar variability is, in general, of the colored-type noise (β ≃ 1-3). A precise characterisation of PSD slopes, normalizations, or characteristic timescales (if any) manifesting as distinct features in the power spectra of blazars is important for constraining the physics of the emission and energy dissipation processes in relativistic jets. Here we present the results of the PSD analysis for the BL Lac object PKS 0735+178 at GeV (Fermi-LAT), optical (R-band), and radio (GHz band from UMRAO and OVRO programmes) frequencies, covering a broad range in variability timescales. The novelty of our approach is that in the optical regime, by combining the long-term and densely sampled R-band intra-night light curves, we constructed the PSD for time periods ranging from 23 years down to minutes. Our analysis reveals that: (1) the nature of processes generating flux variability at optical and radio frequencies is different from those operating at GeV photon energies (β ~ 2 and 1, respectively); (2) the main driver behind the optical variability is the same on timescales of years, months, days, and hours (a single power-law with β ~ 2). We discuss our findings in the framework of a model where the overall blazar variability is generated by an underlying single stochastic process (radio and optical frequencies), or a linear superposition of such processes (γ -ray regime).
AB - The power-lawshape of the power spectral density (PSD) of blazar light curves-P(Vk) α Vk -β k, where Vk is the temporal frequency-indicates that blazar variability is, in general, of the colored-type noise (β ≃ 1-3). A precise characterisation of PSD slopes, normalizations, or characteristic timescales (if any) manifesting as distinct features in the power spectra of blazars is important for constraining the physics of the emission and energy dissipation processes in relativistic jets. Here we present the results of the PSD analysis for the BL Lac object PKS 0735+178 at GeV (Fermi-LAT), optical (R-band), and radio (GHz band from UMRAO and OVRO programmes) frequencies, covering a broad range in variability timescales. The novelty of our approach is that in the optical regime, by combining the long-term and densely sampled R-band intra-night light curves, we constructed the PSD for time periods ranging from 23 years down to minutes. Our analysis reveals that: (1) the nature of processes generating flux variability at optical and radio frequencies is different from those operating at GeV photon energies (β ~ 2 and 1, respectively); (2) the main driver behind the optical variability is the same on timescales of years, months, days, and hours (a single power-law with β ~ 2). We discuss our findings in the framework of a model where the overall blazar variability is generated by an underlying single stochastic process (radio and optical frequencies), or a linear superposition of such processes (γ -ray regime).
KW - BL Lacertae objects: individual (PKS 0735+178)
KW - Galaxies: active
KW - Variability
UR - http://www.scopus.com/inward/record.url?scp=85043358285&partnerID=8YFLogxK
U2 - 10.3390/galaxies4040042
DO - 10.3390/galaxies4040042
M3 - Article
VL - 4
JO - Galaxies
JF - Galaxies
SN - 2075-4434
IS - 4
M1 - 42
ER -
ID: 7601370