Standard
High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet. / Agudo, Iván; Liodakis, Ioannis; Otero-Santos, Jorge; Middei, Riccardo; Marscher, Alan; Jorstad, Svetlana; Zhang, Haocheng; Li, Hui; Di Gesu, Laura; Romani, Roger W.; Kim, Dawoon E.; Fenu, Francesco; Marshall, Herman L.; Pacciani, Luigi; Pedrosa, Juan Escudero; Aceituno, Francisco José; Agís-González, Beatriz; Bonnoli, Giacomo; Casanova, Víctor; Morcuende, Daniel; Piirola, Vilppu; Sota, Alfredo; Kouch, Pouya M.; Lindfors, Elina; McCall, Callum; Jermak, Helen E.; Steele, Iain A.; Borman, George A.; Grishina, Tatiana S.; Hagen-Thorn, Vladimir A.; Kopatskaya, Evgenia N.; Larionova, Elena G.; Morozova, Daria A.; Savchenko, Sergey S.; Shishkina, Ekaterina V.; Troitskiy, Ivan S.; Troitskaya, Yulia V.; Vasilyev, Andrey A.; Zhovtan, Alexey V.; Myserlis, Ioannis; Gurwell, Mark; Keating, Garrett; Rao, Ramprasad; Kang, Sincheol; Lee, Sang-Sung; Kim, Sanghyun; Cheong, Whee Yeon; Jeong, Hyeon-Woo; Angelakis, Emmanouil; Kraus, Alexander; Blinov, Dmitry; Maharana, Siddharth; Bachev, Rumen; Jormanainen, Jenni; Nilsson, Kari; Fallah Ramazani, Vandad; Casadio, Carolina; Fuentes, Antonio; Traianou, Efthalia; Thum, Clemens; Gómez, José L.; Antonelli, Lucio Angelo; Bachetti, Matteo; Baldini, Luca; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bianchi, Stefano; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolò; Capitanio, Fiamma; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chien-Ting; Ciprini, Stefano; Costa, Enrico; De Rosa, Alessandra; Del Monte, Ettore; Di Lalla, Niccolò; Di Marco, Alessandro; Donnarumma, Immacolata; Doroshenko, Victor; Dovčiak, Michal; Ehlert, Steven R.; Enoto, Teruaki; Evangelista, Yuri; Fabiani, Sergio; Ferrazzoli, Riccardo; García, Javier A.; Gunji, Shuichi; Hayashida, Kiyoshi; Heyl, Jeremy; Iwakiri, Wataru; Kaaret, Philip; Karas, Vladimir; Kislat, Fabian; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; Krawczynski, Henric; La Monaca, Fabio; Latronico, Luca; Maldera, Simone; Manfreda, Alberto; Marin, Frédéric; Marinucci, Andrea; Massaro, Francesco; Matt, Giorgio; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; Muleri, Fabio; Negro, Michela; Ng, Chi-Yung; O’Dell, Stephen L.; Omodei, Nicola; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel L.; Perri, Matteo; Pesce-Rollins, Melissa; Petrucci, Pierre-Olivier; Pilia, Maura; Possenti, Andrea; Poutanen, Juri; Puccetti, Simonetta; Ramsey, Brian D.; Rankin, John; Ratheesh, Ajay; Roberts, Oliver J.; Sgrò, Carmelo; Slane, Patrick; Soffitta, Paolo; Spandre, Gloria; Swartz, Douglas A.; Tamagawa, Toru; Tavecchio, Fabrizio; Taverna, Roberto; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; Tombesi, Francesco; Trois, Alessio; Tsygankov, Sergey S.; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C.; Wu, Kinwah; Xie, Fei; Zane, Silvia.
In:
Astrophysical Journal Letters, Vol. 985, No. 1, L15, 16.05.2025.
Research output: Contribution to journal › Article › peer-review
Harvard
Agudo, I, Liodakis, I, Otero-Santos, J, Middei, R, Marscher, A
, Jorstad, S, Zhang, H, Li, H, Di Gesu, L, Romani, RW, Kim, DE, Fenu, F, Marshall, HL, Pacciani, L, Pedrosa, JE, Aceituno, FJ, Agís-González, B, Bonnoli, G, Casanova, V, Morcuende, D, Piirola, V, Sota, A, Kouch, PM, Lindfors, E, McCall, C, Jermak, HE, Steele, IA, Borman, GA
, Grishina, TS, Hagen-Thorn, VA, Kopatskaya, EN, Larionova, EG, Morozova, DA, Savchenko, SS, Shishkina, EV, Troitskiy, IS, Troitskaya, YV, Vasilyev, AA, Zhovtan, AV, Myserlis, I, Gurwell, M, Keating, G, Rao, R, Kang, S, Lee, S-S, Kim, S, Cheong, WY, Jeong, H-W, Angelakis, E, Kraus, A, Blinov, D, Maharana, S, Bachev, R, Jormanainen, J, Nilsson, K, Fallah Ramazani, V, Casadio, C, Fuentes, A, Traianou, E, Thum, C, Gómez, JL, Antonelli, LA, Bachetti, M, Baldini, L, Baumgartner, WH, Bellazzini, R, Bianchi, S, Bongiorno, SD, Bonino, R, Brez, A, Bucciantini, N, Capitanio, F, Castellano, S, Cavazzuti, E, Chen, C-T, Ciprini, S, Costa, E, De Rosa, A, Del Monte, E, Di Lalla, N, Di Marco, A, Donnarumma, I, Doroshenko, V, Dovčiak, M, Ehlert, SR, Enoto, T, Evangelista, Y, Fabiani, S, Ferrazzoli, R, García, JA, Gunji, S, Hayashida, K, Heyl, J, Iwakiri, W, Kaaret, P, Karas, V, Kislat, F, Kitaguchi, T, Kolodziejczak, JJ, Krawczynski, H, La Monaca, F, Latronico, L, Maldera, S, Manfreda, A, Marin, F, Marinucci, A, Massaro, F, Matt, G, Mitsuishi, I, Mizuno, T, Muleri, F, Negro, M, Ng, C-Y, O’Dell, SL, Omodei, N, Oppedisano, C, Papitto, A, Pavlov, GG, Peirson, AL, Perri, M, Pesce-Rollins, M, Petrucci, P-O, Pilia, M, Possenti, A, Poutanen, J, Puccetti, S, Ramsey, BD, Rankin, J, Ratheesh, A, Roberts, OJ, Sgrò, C, Slane, P, Soffitta, P, Spandre, G, Swartz, DA, Tamagawa, T, Tavecchio, F, Taverna, R, Tawara, Y, Tennant, AF, Thomas, NE, Tombesi, F, Trois, A, Tsygankov, SS, Turolla, R, Vink, J, Weisskopf, MC, Wu, K, Xie, F & Zane, S 2025, '
High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet',
Astrophysical Journal Letters, vol. 985, no. 1, L15.
https://doi.org/10.3847/2041-8213/adc572APA
Agudo, I., Liodakis, I., Otero-Santos, J., Middei, R., Marscher, A.
, Jorstad, S., Zhang, H., Li, H., Di Gesu, L., Romani, R. W., Kim, D. E., Fenu, F., Marshall, H. L., Pacciani, L., Pedrosa, J. E., Aceituno, F. J., Agís-González, B., Bonnoli, G., Casanova, V., ... Zane, S. (2025).
High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet.
Astrophysical Journal Letters,
985(1), [L15].
https://doi.org/10.3847/2041-8213/adc572Vancouver
Author
Agudo, Iván ; Liodakis, Ioannis ; Otero-Santos, Jorge ; Middei, Riccardo ; Marscher, Alan
; Jorstad, Svetlana ; Zhang, Haocheng ; Li, Hui ; Di Gesu, Laura ; Romani, Roger W. ; Kim, Dawoon E. ; Fenu, Francesco ; Marshall, Herman L. ; Pacciani, Luigi ; Pedrosa, Juan Escudero ; Aceituno, Francisco José ; Agís-González, Beatriz ; Bonnoli, Giacomo ; Casanova, Víctor ; Morcuende, Daniel ; Piirola, Vilppu ; Sota, Alfredo ; Kouch, Pouya M. ; Lindfors, Elina ; McCall, Callum ; Jermak, Helen E. ; Steele, Iain A. ; Borman, George A.
; Grishina, Tatiana S. ; Hagen-Thorn, Vladimir A. ; Kopatskaya, Evgenia N. ; Larionova, Elena G. ; Morozova, Daria A. ; Savchenko, Sergey S. ; Shishkina, Ekaterina V. ; Troitskiy, Ivan S. ; Troitskaya, Yulia V. ; Vasilyev, Andrey A. ; Zhovtan, Alexey V. ; Myserlis, Ioannis ; Gurwell, Mark ; Keating, Garrett ; Rao, Ramprasad ; Kang, Sincheol ; Lee, Sang-Sung ; Kim, Sanghyun ; Cheong, Whee Yeon ; Jeong, Hyeon-Woo ; Angelakis, Emmanouil ; Kraus, Alexander ; Blinov, Dmitry ; Maharana, Siddharth ; Bachev, Rumen ; Jormanainen, Jenni ; Nilsson, Kari ; Fallah Ramazani, Vandad ; Casadio, Carolina ; Fuentes, Antonio ; Traianou, Efthalia ; Thum, Clemens ; Gómez, José L. ; Antonelli, Lucio Angelo ; Bachetti, Matteo ; Baldini, Luca ; Baumgartner, Wayne H. ; Bellazzini, Ronaldo ; Bianchi, Stefano ; Bongiorno, Stephen D. ; Bonino, Raffaella ; Brez, Alessandro ; Bucciantini, Niccolò ; Capitanio, Fiamma ; Castellano, Simone ; Cavazzuti, Elisabetta ; Chen, Chien-Ting ; Ciprini, Stefano ; Costa, Enrico ; De Rosa, Alessandra ; Del Monte, Ettore ; Di Lalla, Niccolò ; Di Marco, Alessandro ; Donnarumma, Immacolata ; Doroshenko, Victor ; Dovčiak, Michal ; Ehlert, Steven R. ; Enoto, Teruaki ; Evangelista, Yuri ; Fabiani, Sergio ; Ferrazzoli, Riccardo ; García, Javier A. ; Gunji, Shuichi ; Hayashida, Kiyoshi ; Heyl, Jeremy ; Iwakiri, Wataru ; Kaaret, Philip ; Karas, Vladimir ; Kislat, Fabian ; Kitaguchi, Takao ; Kolodziejczak, Jeffery J. ; Krawczynski, Henric ; La Monaca, Fabio ; Latronico, Luca ; Maldera, Simone ; Manfreda, Alberto ; Marin, Frédéric ; Marinucci, Andrea ; Massaro, Francesco ; Matt, Giorgio ; Mitsuishi, Ikuyuki ; Mizuno, Tsunefumi ; Muleri, Fabio ; Negro, Michela ; Ng, Chi-Yung ; O’Dell, Stephen L. ; Omodei, Nicola ; Oppedisano, Chiara ; Papitto, Alessandro ; Pavlov, George G. ; Peirson, Abel L. ; Perri, Matteo ; Pesce-Rollins, Melissa ; Petrucci, Pierre-Olivier ; Pilia, Maura ; Possenti, Andrea ; Poutanen, Juri ; Puccetti, Simonetta ; Ramsey, Brian D. ; Rankin, John ; Ratheesh, Ajay ; Roberts, Oliver J. ; Sgrò, Carmelo ; Slane, Patrick ; Soffitta, Paolo ; Spandre, Gloria ; Swartz, Douglas A. ; Tamagawa, Toru ; Tavecchio, Fabrizio ; Taverna, Roberto ; Tawara, Yuzuru ; Tennant, Allyn F. ; Thomas, Nicholas E. ; Tombesi, Francesco ; Trois, Alessio ; Tsygankov, Sergey S. ; Turolla, Roberto ; Vink, Jacco ; Weisskopf, Martin C. ; Wu, Kinwah ; Xie, Fei ; Zane, Silvia. /
High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet. In:
Astrophysical Journal Letters. 2025 ; Vol. 985, No. 1.
BibTeX
@article{2f31cd43e691420b90b65de06db4c7b7,
title = "High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae{\textquoteright}s Jet",
abstract = "Blazars, supermassive black hole systems with highly relativistic jets aligned with the line of sight, are the most powerful long-lived emitters of electromagnetic emission in the Universe. We report here on a radio-to-gamma-ray multiwavelength campaign on the blazar BL Lacertae with unprecedented polarimetric coverage from radio to X-ray wavelengths. The observations caught an extraordinary event on 2023 November 10–18, when the degree of linear polarization of optical synchrotron radiation reached a record value of 47.5%. In stark contrast, the Imaging X-ray Polarimetry Explorer found that the X-ray (Compton scattering or hadron-induced) emission was polarized at less than 7.4% (3σ confidence level). We argue here that this observational result rules out a hadronic origin of the high-energy emission and strongly favors a leptonic (Compton scattering) origin, thereby breaking the degeneracy between hadronic and leptonic emission models for BL Lacertae and demonstrating the power of multiwavelength polarimetry to address this question. Furthermore, the multiwavelength flux and polarization variability, featuring an extremely prominent rise and decay of the optical polarization degree, is interpreted for the first time by the relaxation of a magnetic “spring” embedded in the newly injected plasma. This suggests that the plasma jet can maintain a predominant toroidal magnetic field component parsecs away from the central engine.",
author = "Iv{\'a}n Agudo and Ioannis Liodakis and Jorge Otero-Santos and Riccardo Middei and Alan Marscher and Svetlana Jorstad and Haocheng Zhang and Hui Li and {Di Gesu}, Laura and Romani, {Roger W.} and Kim, {Dawoon E.} and Francesco Fenu and Marshall, {Herman L.} and Luigi Pacciani and Pedrosa, {Juan Escudero} and Aceituno, {Francisco Jos{\'e}} and Beatriz Ag{\'i}s-Gonz{\'a}lez and Giacomo Bonnoli and V{\'i}ctor Casanova and Daniel Morcuende and Vilppu Piirola and Alfredo Sota and Kouch, {Pouya M.} and Elina Lindfors and Callum McCall and Jermak, {Helen E.} and Steele, {Iain A.} and Borman, {George A.} and Grishina, {Tatiana S.} and Hagen-Thorn, {Vladimir A.} and Kopatskaya, {Evgenia N.} and Larionova, {Elena G.} and Morozova, {Daria A.} and Savchenko, {Sergey S.} and Shishkina, {Ekaterina V.} and Troitskiy, {Ivan S.} and Troitskaya, {Yulia V.} and Vasilyev, {Andrey A.} and Zhovtan, {Alexey V.} and Ioannis Myserlis and Mark Gurwell and Garrett Keating and Ramprasad Rao and Sincheol Kang and Sang-Sung Lee and Sanghyun Kim and Cheong, {Whee Yeon} and Hyeon-Woo Jeong and Emmanouil Angelakis and Alexander Kraus and Dmitry Blinov and Siddharth Maharana and Rumen Bachev and Jenni Jormanainen and Kari Nilsson and {Fallah Ramazani}, Vandad and Carolina Casadio and Antonio Fuentes and Efthalia Traianou and Clemens Thum and G{\'o}mez, {Jos{\'e} L.} and Antonelli, {Lucio Angelo} and Matteo Bachetti and Luca Baldini and Baumgartner, {Wayne H.} and Ronaldo Bellazzini and Stefano Bianchi and Bongiorno, {Stephen D.} and Raffaella Bonino and Alessandro Brez and Niccol{\`o} Bucciantini and Fiamma Capitanio and Simone Castellano and Elisabetta Cavazzuti and Chien-Ting Chen and Stefano Ciprini and Enrico Costa and {De Rosa}, Alessandra and {Del Monte}, Ettore and {Di Lalla}, Niccol{\`o} and {Di Marco}, Alessandro and Immacolata Donnarumma and Victor Doroshenko and Michal Dov{\v c}iak and Ehlert, {Steven R.} and Teruaki Enoto and Yuri Evangelista and Sergio Fabiani and Riccardo Ferrazzoli and Garc{\'i}a, {Javier A.} and Shuichi Gunji and Kiyoshi Hayashida and Jeremy Heyl and Wataru Iwakiri and Philip Kaaret and Vladimir Karas and Fabian Kislat and Takao Kitaguchi and Kolodziejczak, {Jeffery J.} and Henric Krawczynski and {La Monaca}, Fabio and Luca Latronico and Simone Maldera and Alberto Manfreda and Fr{\'e}d{\'e}ric Marin and Andrea Marinucci and Francesco Massaro and Giorgio Matt and Ikuyuki Mitsuishi and Tsunefumi Mizuno and Fabio Muleri and Michela Negro and Chi-Yung Ng and O{\textquoteright}Dell, {Stephen L.} and Nicola Omodei and Chiara Oppedisano and Alessandro Papitto and Pavlov, {George G.} and Peirson, {Abel L.} and Matteo Perri and Melissa Pesce-Rollins and Pierre-Olivier Petrucci and Maura Pilia and Andrea Possenti and Juri Poutanen and Simonetta Puccetti and Ramsey, {Brian D.} and John Rankin and Ajay Ratheesh and Roberts, {Oliver J.} and Carmelo Sgr{\`o} and Patrick Slane and Paolo Soffitta and Gloria Spandre and Swartz, {Douglas A.} and Toru Tamagawa and Fabrizio Tavecchio and Roberto Taverna and Yuzuru Tawara and Tennant, {Allyn F.} and Thomas, {Nicholas E.} and Francesco Tombesi and Alessio Trois and Tsygankov, {Sergey S.} and Roberto Turolla and Jacco Vink and Weisskopf, {Martin C.} and Kinwah Wu and Fei Xie and Silvia Zane",
year = "2025",
month = may,
day = "16",
doi = "10.3847/2041-8213/adc572",
language = "English",
volume = "985",
journal = "Astrophysical Journal Letters",
issn = "2041-8205",
publisher = "IOP Publishing Ltd.",
number = "1",
}
RIS
TY - JOUR
T1 - High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet
AU - Agudo, Iván
AU - Liodakis, Ioannis
AU - Otero-Santos, Jorge
AU - Middei, Riccardo
AU - Marscher, Alan
AU - Jorstad, Svetlana
AU - Zhang, Haocheng
AU - Li, Hui
AU - Di Gesu, Laura
AU - Romani, Roger W.
AU - Kim, Dawoon E.
AU - Fenu, Francesco
AU - Marshall, Herman L.
AU - Pacciani, Luigi
AU - Pedrosa, Juan Escudero
AU - Aceituno, Francisco José
AU - Agís-González, Beatriz
AU - Bonnoli, Giacomo
AU - Casanova, Víctor
AU - Morcuende, Daniel
AU - Piirola, Vilppu
AU - Sota, Alfredo
AU - Kouch, Pouya M.
AU - Lindfors, Elina
AU - McCall, Callum
AU - Jermak, Helen E.
AU - Steele, Iain A.
AU - Borman, George A.
AU - Grishina, Tatiana S.
AU - Hagen-Thorn, Vladimir A.
AU - Kopatskaya, Evgenia N.
AU - Larionova, Elena G.
AU - Morozova, Daria A.
AU - Savchenko, Sergey S.
AU - Shishkina, Ekaterina V.
AU - Troitskiy, Ivan S.
AU - Troitskaya, Yulia V.
AU - Vasilyev, Andrey A.
AU - Zhovtan, Alexey V.
AU - Myserlis, Ioannis
AU - Gurwell, Mark
AU - Keating, Garrett
AU - Rao, Ramprasad
AU - Kang, Sincheol
AU - Lee, Sang-Sung
AU - Kim, Sanghyun
AU - Cheong, Whee Yeon
AU - Jeong, Hyeon-Woo
AU - Angelakis, Emmanouil
AU - Kraus, Alexander
AU - Blinov, Dmitry
AU - Maharana, Siddharth
AU - Bachev, Rumen
AU - Jormanainen, Jenni
AU - Nilsson, Kari
AU - Fallah Ramazani, Vandad
AU - Casadio, Carolina
AU - Fuentes, Antonio
AU - Traianou, Efthalia
AU - Thum, Clemens
AU - Gómez, José L.
AU - Antonelli, Lucio Angelo
AU - Bachetti, Matteo
AU - Baldini, Luca
AU - Baumgartner, Wayne H.
AU - Bellazzini, Ronaldo
AU - Bianchi, Stefano
AU - Bongiorno, Stephen D.
AU - Bonino, Raffaella
AU - Brez, Alessandro
AU - Bucciantini, Niccolò
AU - Capitanio, Fiamma
AU - Castellano, Simone
AU - Cavazzuti, Elisabetta
AU - Chen, Chien-Ting
AU - Ciprini, Stefano
AU - Costa, Enrico
AU - De Rosa, Alessandra
AU - Del Monte, Ettore
AU - Di Lalla, Niccolò
AU - Di Marco, Alessandro
AU - Donnarumma, Immacolata
AU - Doroshenko, Victor
AU - Dovčiak, Michal
AU - Ehlert, Steven R.
AU - Enoto, Teruaki
AU - Evangelista, Yuri
AU - Fabiani, Sergio
AU - Ferrazzoli, Riccardo
AU - García, Javier A.
AU - Gunji, Shuichi
AU - Hayashida, Kiyoshi
AU - Heyl, Jeremy
AU - Iwakiri, Wataru
AU - Kaaret, Philip
AU - Karas, Vladimir
AU - Kislat, Fabian
AU - Kitaguchi, Takao
AU - Kolodziejczak, Jeffery J.
AU - Krawczynski, Henric
AU - La Monaca, Fabio
AU - Latronico, Luca
AU - Maldera, Simone
AU - Manfreda, Alberto
AU - Marin, Frédéric
AU - Marinucci, Andrea
AU - Massaro, Francesco
AU - Matt, Giorgio
AU - Mitsuishi, Ikuyuki
AU - Mizuno, Tsunefumi
AU - Muleri, Fabio
AU - Negro, Michela
AU - Ng, Chi-Yung
AU - O’Dell, Stephen L.
AU - Omodei, Nicola
AU - Oppedisano, Chiara
AU - Papitto, Alessandro
AU - Pavlov, George G.
AU - Peirson, Abel L.
AU - Perri, Matteo
AU - Pesce-Rollins, Melissa
AU - Petrucci, Pierre-Olivier
AU - Pilia, Maura
AU - Possenti, Andrea
AU - Poutanen, Juri
AU - Puccetti, Simonetta
AU - Ramsey, Brian D.
AU - Rankin, John
AU - Ratheesh, Ajay
AU - Roberts, Oliver J.
AU - Sgrò, Carmelo
AU - Slane, Patrick
AU - Soffitta, Paolo
AU - Spandre, Gloria
AU - Swartz, Douglas A.
AU - Tamagawa, Toru
AU - Tavecchio, Fabrizio
AU - Taverna, Roberto
AU - Tawara, Yuzuru
AU - Tennant, Allyn F.
AU - Thomas, Nicholas E.
AU - Tombesi, Francesco
AU - Trois, Alessio
AU - Tsygankov, Sergey S.
AU - Turolla, Roberto
AU - Vink, Jacco
AU - Weisskopf, Martin C.
AU - Wu, Kinwah
AU - Xie, Fei
AU - Zane, Silvia
PY - 2025/5/16
Y1 - 2025/5/16
N2 - Blazars, supermassive black hole systems with highly relativistic jets aligned with the line of sight, are the most powerful long-lived emitters of electromagnetic emission in the Universe. We report here on a radio-to-gamma-ray multiwavelength campaign on the blazar BL Lacertae with unprecedented polarimetric coverage from radio to X-ray wavelengths. The observations caught an extraordinary event on 2023 November 10–18, when the degree of linear polarization of optical synchrotron radiation reached a record value of 47.5%. In stark contrast, the Imaging X-ray Polarimetry Explorer found that the X-ray (Compton scattering or hadron-induced) emission was polarized at less than 7.4% (3σ confidence level). We argue here that this observational result rules out a hadronic origin of the high-energy emission and strongly favors a leptonic (Compton scattering) origin, thereby breaking the degeneracy between hadronic and leptonic emission models for BL Lacertae and demonstrating the power of multiwavelength polarimetry to address this question. Furthermore, the multiwavelength flux and polarization variability, featuring an extremely prominent rise and decay of the optical polarization degree, is interpreted for the first time by the relaxation of a magnetic “spring” embedded in the newly injected plasma. This suggests that the plasma jet can maintain a predominant toroidal magnetic field component parsecs away from the central engine.
AB - Blazars, supermassive black hole systems with highly relativistic jets aligned with the line of sight, are the most powerful long-lived emitters of electromagnetic emission in the Universe. We report here on a radio-to-gamma-ray multiwavelength campaign on the blazar BL Lacertae with unprecedented polarimetric coverage from radio to X-ray wavelengths. The observations caught an extraordinary event on 2023 November 10–18, when the degree of linear polarization of optical synchrotron radiation reached a record value of 47.5%. In stark contrast, the Imaging X-ray Polarimetry Explorer found that the X-ray (Compton scattering or hadron-induced) emission was polarized at less than 7.4% (3σ confidence level). We argue here that this observational result rules out a hadronic origin of the high-energy emission and strongly favors a leptonic (Compton scattering) origin, thereby breaking the degeneracy between hadronic and leptonic emission models for BL Lacertae and demonstrating the power of multiwavelength polarimetry to address this question. Furthermore, the multiwavelength flux and polarization variability, featuring an extremely prominent rise and decay of the optical polarization degree, is interpreted for the first time by the relaxation of a magnetic “spring” embedded in the newly injected plasma. This suggests that the plasma jet can maintain a predominant toroidal magnetic field component parsecs away from the central engine.
UR - http://arxiv.org/abs/2505.01832
http://dx.doi.org/10.3847/2041-8213/adc572
UR - https://www.mendeley.com/catalogue/095808d9-9869-3bae-baee-fefb230c2071/
U2 - 10.3847/2041-8213/adc572
DO - 10.3847/2041-8213/adc572
M3 - Article
VL - 985
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L15
ER -
