2023MNRAS.526.4502R

Query : 2023MNRAS.526.4502R

2023MNRAS.526.4502R - Mon. Not. R. Astron. Soc., 526, 4502-4513 (2023/December-2)

Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ-ray brightness levels.

RAITERI C.M., VILLATA M., CARNERERO M.I., SAVCHENKO S.S., KURTANIDZE S.O., VLASYUK V.V., MARCHINI A., MATSUMOTO K., LOREY C., JONER M.D., GAZEAS K., CAROSATI D., MIRZAQULOV D.O., ACOSTA PULIDO J.A., AGUDO I., BACHEV R., BENITEZ E., BORMAN G.A., CALCIDESE P., CHEN W.P., DAMLJANOVIC G., EHGAMBERDIEV S.A., ELSASSER D., FEIGE M., FRASCA A., GAUR H., GRISHINA T.S., GUPTA A.C., HIRIART D., HOLLAND M., HORST B., IBRYAMOV S., IVANIDZE R.Z., JENSEN J., JITHESH V., JOVANOVIC M.D., KIEHLMANN S., KIMERIDZE G.N., KISHORE S., KOPATSKAYA E.N., KURTANIDZE O.M., LARIONOVA E.G., LIN H.C., MANNHEIM K., MARINELLI C., MOREIRA REYES J., MOROZOVA D.A., NIKOLASHVILI M.G., REINHART D., ROMANOV F.D., SEMKOV E., SEUFERT J., SHISHKINA E.V., SIGUA L.A., SKALIDIS R., SPIRIDONOVA O.I., STOJANOVIC M., STRIGACHEV A., TROITSKAYA Y.V., TROITSKIY I.S., TSAI A., VASILYEV A.A., VINCE O., VRONTAKI K., WANI K., WATTS D. and ZHOVTAN A.V.

Abstract (from CDS):

In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and γ-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to γ-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and γ-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates.

Abstract Copyright: © 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.

Journal keyword(s): galaxies: active - BL Lacertae objects: general - BL Lacertae objects: individual: S4 0954+65 - galaxies: jets

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 6C 095456+654857 BLL 09 58 47.2451872176 +65 33 54.819354600     17.0 15.75   ~ 771 1
2 3C 279 Bla 12 56 11.16657958 -05 47 21.5251510   18.01 17.75 15.87   ~ 3205 2
3 Z 225-7 BLL 16 53 52.21668403 +39 45 36.6088754 14.09 14.15 13.29 8.26   ~ 2304 2
4 PKS J2158-3013 BLL 21 58 52.0652249880 -30 13 32.118447792   13.36 13.09 12.62   ~ 1829 1

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