2026A&A...705A..23G

Query : 2026A&A...705A..23G

2026A&A...705A..23G - Astronomy and Astrophysics, volume 705A23 (2026/1-1)

Spatially resolved polarization swings in the supermassive binary black hole candidate OJ 287 with first Event Horizon Telescope observations.

GOMEZ J.L., CHO I., TRAIANOU E., KRICHBAUM T.P., ZHAO G.-Y., LICO R., FUENTES A., FOSCHI M., DAHALE R., GEORGIEV B., MORIYAMA K., WIELGUS M., GOLD R., PESCE D.W., MULLER H., JORSTAD S., TOSCANO T., RODER J., MARTI J.M., PERUCHO M., KOVALEV Y.Y., KOMOSSA S., GOPAKUMAR A., VALTONEN M.J., BRUNI G., CHANDRA S., AKIYAMA K., ALBENTOSA-RUIZ E., ALBERDI A., ALEF W., ALGABA J.C., ANANTUA R., ASADA K., AZULAY R., BACH U., BACZKO A.-K., BALL D., BALOKOVIC M., BANDYOPADHYAY B., BARRETT J., BAUBOCK M., BENSON B.A., BINTLEY D., BLACKBURN L., BLUNDELL R., BOUMAN K.L., BOWER G.C., BREMER M., BRISSENDEN R., BRITZEN S., BRODERICK A.E., BROGUIERE D., BRONZWAER T., BUSTAMANTE S., CARLOS D.F., CARLSTROM J.E., CHAEL A., CHAN C.-K., CHANG D.O., CHATTERJEE K., CHATTERJEE S., CHEN M.-T., CHEN Y., CHENG X., CHRISTIAN P., CONROY N.S., CONWAY J.E., CRAWFORD T.M., CREW G.B., CRUZ-OSORIO A., CUI Y., CURD B., DAVELAAR J., DE LAURENTIS M., DEANE R., DEMPSEY J., DESVIGNES G., DEXTER J., DHRUV V., DIHINGIA I.K., DOELEMAN S.S., DZIB S.A., EATOUGH R.P., EMAMI R., FALCKE H., FARAH J., FISH V.L., FOMALONT E., FORD H.A., FRAGA-ENCINAS R., FREEMAN W.T., FRIBERG P., FROMM C.M., GALISON P., GAMMIE C.F., GARCIA R., GENTAZ O., GEERTSEMA G., GODDI C., GOMEZ-RUIZ A.I., GU M., GURWELL M., HADA K., HAGGARD D., HESPER R., HEUMANN D., HO L.C., HO P., HONMA M., HUANG C.-W.L., HUANG L., HUGHES D.H., IKEDA S., IMPELLIZZERI C.M.V., INOUE M., ISSAOUN S., JAMES D.J., JANNUZI B.T., JANSSEN M., JETER B., JIANG W., JIMENEZ-ROSALES A., JOHNSON M.D., JONES A.C., JOSHI A.V., JUNG T., KARUPPUSAMY R., KAWASHIMA T., KEATING G.K., KETTENIS M., KIM D.-J., KIM J.-Y., KIM J., KIM J., KINO M., KOAY J.Y., KOCHERLAKOTA P., KOFUJI Y., KOCH P.M., KOYAMA S., KRAMER C., KRAMER J.A., KRAMER M., KUO C.-Y., LA BELLA N., LEE S.-S., LEVIS A., LI Z., LINDAHL G., LINDQVIST M., LISAKOV M., LIU J., LIU K., LIUZZO E., LO W.-P., LOBANOV A.P., LOINARD L., LONSDALE C.J., LOWITZ A.E., LU R.-S., MacDONALD N.R., MAO J., MARCHILI N., MARKOFF S., MARRONE D.P., MARSCHER A.P., MARTI-VIDAL I., MATSUSHITA S., MATTHEWS L.D., MEDEIROS L., MENTEN K.M., MIZUNO I., MIZUNO Y., MONTGOMERY J., MORAN J.M., MOSCIBRODZKA M., MULAUDZI W., MULLER C., MUS A., MUSOKE G., MYSERLIS I., NAGAI H., NAGAR N.M., NAIR D.G., NAKAMURA M., NARAYANAN G., NATARAJAN I., NATHANAIL A., NAVARRO FUENTES S., NEILSEN J., NI C., NOWAK M.A., OH J., OKINO H., OLIVARES SANCHEZ H.R., OYAMA T., OZEL F., PALUMBO D.C.M., PARASCHOS G.F., PARK J., PARSONS H., PATEL N., PEN U.-L., PIETU V., POPSTEFANIJA A., PORTH O., PRATHER B., PRINCIPE G., PSALTIS D., PU H.-Y., RAMAKRISHNAN V., RAO R., RAWLINGS M.G., REZZOLLA L., RICARTE A., RIPPERDA B., ROELOFS F., ROMERO-CANIZALES C., ROS E., ROSHANINESHAT A., ROTTMANN H., ROY A.L., RUIZ I., RUSZCZYK C., RYGL K.L.J., SANCHEZ S., SANCHEZ-ARGUELLES D., SANCHEZ-PORTAL M., SASADA M., SATAPATHY K., SAURABH, SAVOLAINEN T., SCHLOERB F.P., SCHONFELD J., SCHUSTER K.-F., SHAO L., SHEN Z., SILPA S., SMALL D., WON SOHN B., SOOHOO J., SOSAPANTA SALAS L.D., SOUCCAR K., STANWAY J.S., SUN H., TAZAKI F., TETARENKO A.J., TIEDE P., TILANUS R.P.J., TITUS M., TOMA K., TORNE P., TRENT T., TRIPPE S., TURK M., VAN BEMMEL I., VAN LANGEVELDE H.J., VAN ROSSUM D.R., VOS J., WAGNER J., WARD-THOMPSON D., WARDLE J., WASHINGTON J.E., WEINTROUB J., WHARTON R., WIIK K., WITZEL G., WONDRAK M.F., WONG G.N., WU Q., YADLAPALLI N., YAMAGUCHI P., YFANTIS A., YOON D., YOUNG A., YOUNSI Z., YU W., YUAN F., YUAN Y.-F., ZENG A.-L., ZENSUS J.A., ZHANG S. and ZHAO S.-S.

Abstract (from CDS):

We present the first Event Horizon Telescope 1.3 mm observations of the supermassive binary black hole candidate OJ 287. The observations achieved an unprecedented angular resolution of 18 μas and reveal significant structural and polarization variability over just five days, marking the shortest timescale on which such changes have been directly imaged in this source. The inner jet exhibits a twisted ridgeline structure, with features displaying apparent superluminal motions up to about 22 c. The linear polarization maps reveal three main polarized features whose electric-vector position angles (EVPAs) change substantially over the time span of our observations, including a component with a radial polarization consistent with being produced by a recollimation shock. Most notably, we directly resolved two innermost jet components whose EVPAs rotate in opposite directions. The faster component, moving at 2.4 ± 0.9 μas/day (17.4 ± 6.5 c), exhibits counterclockwise EVPA swings of roughly 3.7° per day, while the slower component, with a proper motion of 1.4 ± 0.3 μas/day (10.2 ± 2.2 c), rotates clockwise at approximately 2.5° per day. Previous studies inferred helical magnetic fields in AGN jets from time-resolved or integrated polarization variability but lacked the angular resolution to directly image this effect. Our results provide spatially resolved evidence that a helical magnetic field threads the jet's collimation and acceleration zone, ruling out models based on the superposition of unresolved components. Our analysis suggests that propagating shocks interact with a Kelvin-Helmholtz plasma instability, illuminating different phases of the helical magnetic field and producing the observed polarization spatial and temporal variability. Moreover, our model naturally accounts for the more rapid polarization rotation observed in the faster moving component. Our model predicts even more rapid swings in polarization, which could be tested with future observations featuring a more densely sampled time coverage.

Abstract Copyright: © The Authors 2026

Journal keyword(s): black hole physics - instabilities - radiation mechanisms: non-thermal - techniques: interferometric - galaxies: active - galaxies: individual: OJ 287

Simbad objects: 6

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Number of rows : 6
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 4C 71.07 Bla 08 41 24.36528508 +70 53 42.1730435     17.30 16.8   ~ 818 1
2 PG 0851+202 BLL 08 54 48.8749846272 +20 06 30.639583620   15.649 15.146 15.446   ~ 2513 1
3 M 87 AGN 12 30 49.42338414 +12 23 28.0436859 10.16 9.59 8.63   7.49 ~ 7815 3
4 3C 279 Bla 12 56 11.16657958 -05 47 21.5251510   18.01 17.75 15.87   ~ 3205 2
5 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 4970 3
6 NAME BL Lac BLL 22 02 43.2913536816 +42 16 39.979416792   15.66 14.72     ~ 2397 1

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