J/A+A/710/L33 Optical polarization variability of 15 blazars (Grigoriou+, 2026)
Optical polarization variability and its relation to gamma-ray activity in
blazars.
Grigoriou S., Glykopoulou A., Liodakis I.
<Astron. Astrophys. 710, L33 (2026)>
=2026A&A...710L..33G 2026A&A...710L..33G (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Photometry ; Polarization ; Optical
Keywords: polarization - relativistic processes - galaxies: active -
BL Lacertae objects: general - galaxies: jets
Abstract:
Optical polarization can be an important probe of particle
acceleration and high-energy emission processes in relativistic jets
from supermassive black holes. Here, we combine publicly available
observations from three past blazar monitoring programs to produce
densely sampled light curves for 15 blazars in order to explore the
relation of gamma-ray activity to the polarization variability as well
as discover new rotations of the polarization angle. We find that
polarization degree does not correlate with gamma-ray flux either for
individual sources or different sub-samples of blazars, potentially
indicating multiple emission mechanisms. In the combined dataset, we
identified a total of 64 rotations in 12 sources, 39 of which are
newly identified rotations. We confirm the trend of lower polarization
degree during periods of polarization angle rotations for the whole
sample found in previous works. However, looking at the individual
sources, we identified cases where the rotation and non-rotation
polarization degree distributions are indistinguishable, providing
further evidence for the multiple emission mechanism hypothesis.
Description:
phot.dat contains the combined optical multi-telescope photometry
data for the sample of 15 blazars. pol.dat contains the corresponding
multi-telescope linear polarization degree and polarization angle
tracking values for the same targets.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 50 15 List of studied sources
phot.dat 41 7006 Combined multi-telescope photometry data
pol.dat 55 8264 Combined multi-telescope polarimetry data
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Target name
14- 15 I2 h RAh Simbad right ascension (J2000)
17- 18 I2 min RAm Simbad right ascension (J2000)
20- 24 F5.2 s RAs Simbad right ascension (J2000)
26 A1 --- DE- Simbad declination sign (J2000)
27- 28 I2 deg DEd Simbad declination (J2000)
30- 31 I2 arcmin DEm Simbad declination (J2000)
33- 36 F4.1 arcsec DEs Simbad declination (J2000)
38- 50 A13 --- SName Simbad name
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Byte-by-byte Description of file: phot.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Target name
17- 29 F13.5 d JD Julian date of the observation
31- 35 F5.2 mag mag ?=99.99 Magnitude in the observed filter band
37- 41 F5.2 mag e_mag ?=-9.99 Uncertainty on magnitude (1)
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Note (1): A value of -9.99 indicates a missing or recalculable error
due to insufficient data.
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Byte-by-byte Description of file: pol.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Target name
17- 29 F13.5 d JD Julian date of the observation
31- 35 F5.2 % PD Linear polarization degree
37- 41 F5.2 % e_PD The 1-sigma uncertainty on PD
43- 48 F6.1 deg PA []?=-999.0 Polarization angle (1)
50- 55 F6.2 deg e_PA ?=-9.99 Uncertainty on PA (2)
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Note (1): A value of -999.0 indicates a missing polarization angle.
Note (2): A value of -9.99 indicates a missing error value for the position
angle.
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Acknowledgements:
From Styliana Grigoriou, stilianagregoriou(at)gmail.com
We thank the teams operating the RoboPol program, the Kanata telescope,
and the Steward Observatory monitoring program used to collect this
multi-telescope dataset.
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 05-Jun-2026