J/MNRAS/467/4565 Bimodal radio variability in OVRO blazars (Liodakis+, 2017)
Bimodal radio variability in OVRO-40m-monitored blazars.
Liodakis I., Pavlidou V., Hovatta T., Max-Moerbeck W., Pearson T.J.,
Richards J.L., Readhead A.C.S.
<Mon. Not. R. Astron. Soc. 467, 4565 (2017)>
=2017MNRAS.467.4565L 2017MNRAS.467.4565L (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; QSOs ; Gamma rays ; Radio sources
Keywords: methods: statistical - galaxies: active - galaxies: jets
Abstract:
Blazars are known to show periods of quiescence followed by outbursts
visible throughout the electromagnetic spectrum. We present a novel
maximum likelihood approach to capturing this bimodal behavior by
examining blazar radio variability in the flux-density domain. We
separate quiescent and flaring components of a source's light curve by
modeling its flux-density distribution as a series of "off" and "on"
states. Our modeling allows us to extract information regarding the
flaring ratio, duty cycle, and the modulation index in the
"off"-state, in the "on"-state, as well as throughout the monitoring
period of each blazar. We apply our method to a flux-density-limited
subsample from the Owens Valley Radio observatory's 15 GHz blazar
monitoring program, and explore differences in the variability
characteristics between BL Lacs and FSRQs as well as between
γ-ray detected and non-detected sources. We find that: (1) BL
Lacs are more variable and have relatively larger outbursts than the
FSRQs; (2) unclassified blazar candidates in our sample show similar
variability characteristics as the FSRQs; and (3) γ-ray detected
differ from the γ-ray non-detected sources in all their
variability properties, suggesting a link between the production of
γ-rays and the mechanism responsible for the radio variability.
Finally, we fit distributions for blazar flaring ratios, duty cycles,
and on- and off- modulation indices that can be used in population
studies of variability-dependent blazar properties.
Description:
Variability parameters (duty cycle, off-state flux-density, standard
deviation on the off-state flux-density, on-state flux-density,
standard deviation on the on-state flux-density) and uncertainties on
each parameters for the OVRO monitored blazars using data from
05/01/2008 to 14/02/2016. The uncertainties are derived using two
methods: (1) The fischer information matrix; (2) likelihood slice (see
paper for details).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table8.dat 149 1193 Variability parameters of OVRO monitored sources
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See also:
J/MNRAS/438/3058 : 15GHz variability of γ-ray blazars (Richards+, 2014)
Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name OVRO name (1)
14- 18 F5.3 --- ft Duty cycle
20- 25 F6.4 --- e_ft Error on ft from the information matrix (2)
27- 32 F6.4 --- eftu Upper error on ft from the likelihood slice
34- 39 F6.4 --- eftl Lower error on ft from the likelihood slice
41- 46 F6.3 Jy SOFF Off-state flux-density (2)
48- 53 F6.4 Jy e_SOFF Error on Off-state flux-density from the
information matrix
55- 60 F6.4 Jy eSOFFu Upper error on Off-state flux-density from
the likelihood slice
62- 67 F6.4 Jy eSOFFl Lower error on Off-state flux-density from
the likelihood slice
69- 73 F5.3 Jy sigmaOFF Standard deviation on off-state flux-density
75- 80 F6.4 Jy e_sigmaOFF Error on the standard deviation of the
off-state flux-density from the information
matrix (2)
82- 87 F6.4 Jy esigmaOFFu Upper error on the standard deviation of the
off-state flux-density
89- 94 F6.4 Jy esigmaOFFl Lower error on the standard deviation of the
off-state flux-density
96-101 F6.3 Jy SON On-state flux-density
103-108 F6.4 Jy e_SON Error on On-state flux-density from the
information matrix
110-115 F6.4 Jy eSONu Upper error on On-state flux-density from the
likelihood slice
117-122 F6.4 Jy eSONl Lower error on On-state flux-density from the
likelihood slice
124-128 F5.3 Jy sigmaON Standard deviation on on-state flux-density
130-135 F6.4 Jy e_sigmaON Error on the standard deviation of the
on-state flux-density from the information
matrix (2)
137-142 F6.4 Jy esigmaONu Upper error on the standard deviation of the
on-state flux-density from the likelihood slice
144-149 F6.4 Jy esigmaONl Lower error on the standard deviation of the
on-state flux-density from the likelihood slice
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Note (1): The OVRO name is taken from Richards et al. (2014MNRAS.438.3058R 2014MNRAS.438.3058R,
Cat. J/MNRAS/438/3058). CGRaBS name (JHHMM+DDMM) or 1FGL name (JHHMM.m+DDMM).
Note (2): The uncertainties are derived using the variance and covariance matrix
through the fischer information matrix. For uncertainty values in the table
equal to zero, the matrix failed to provide an error estimate. In this case,
use upper and lower 1-sigma uncertainties from the likelihood slice
(see paper for details).
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Acknowledgements:
Ioannis Liodakis, liodakis(at)physics.uoc.gr
References:
Richards et al., 2014MNRAS.438.3058R 2014MNRAS.438.3058R, J/MNRAS/438/3058
Connecting radio variability to the characteristics of gamma-ray blazars
(End) I. Liodakis [Univ. of Crete, Greece], P. Vannier [CDS] 29-Mar-2017