Portal de Periódicos da CAPES

X-Ray Polarization of BL Lacertae in Outburst

2023; IOP Publishing; Volume: 948; Issue: 2 Linguagem: Inglês

10.3847/2041-8213/acd242

2041-8213

Abel L. Peirson, Michela Negro, Ioannis Liodakis, R. Middei, Dawoon E. Kim, Alan P. Marscher, Herman L. Marshall, L. Pacciani, Roger W. Romani, Kinwah Wu, Alessandro Di Marco, Niccolò Di Lalla, N. Omodei, Svetlana G. Jorstad, I. Agudo, Pouya M. Kouch, E. Lindfors, F. J. Aceituno, M. Bernardos, G. Bonnoli, V. Casanova, Maya García‐Comas, Beatriz Agı́s-González, C. Husillos, Alessandro Marchini, A. Sota, C. Casadio, Juan Escudero, I. Myserlis, A. Sievers, Mark Gurwell, Ramprasad Rao, Ryo Imazawa, Mahito Sasada, Y. Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Hiroshi Akitaya, Yeon Cheong, Hyeon‐Woo Jeong, Sincheol Kang, Sang-Hyun Kim, Sang-Sung Lee, E. Angelakis, A. Kraus, N. Cibrario, I. Donnarumma, Juri Poutanen, F. Tavecchio, L. A. Antonelli, Matteo Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, Stephen D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, Fiamma Capitanio, Simone Castellano, E. Cavazzuti, Chien‐Ting Chen, S. Ciprini, E. Costa, Alessandra De Rosa, E. Del Monte, Laura Di Gesu, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Y. Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, W. Iwakiri, P. Kaaret, V. Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, H. Krawczynski, Fabio La Monaca, L. Latronico, G. Madejski, S. Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, F. Massaro, G. Matt, Ikuyuki Mitsuishi, Fabio Muleri, C.‐Y. Ng, Stephen L. O’Dell, C. Oppedisano, Alessandro Papitto, George G. Pavlov, M. Perri, M. Pesce-Rollins, Pierre-Olivier Petrucci, M. Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, O. J. Roberts, C. Sgrò, Patrick Slane, P. Soffitta, G. Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, A. Trois, Sergey S. Tsygankov, R. Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, Silvia Zane,

Neutrino Physics Research

Abstract We report the first >99% confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/ γ -ray outburst, a 287 ks observation (2022 November 27–30) was taken using the Imaging X-ray Polarimetry Explorer (IXPE), together with contemporaneous multiwavelength observations from the Neil Gehrels Swift observatory and XMM-Newton in soft X-rays (0.3–10 keV), NuSTAR in hard X-rays (3–70 keV), and optical polarization from the Calar Alto and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the IXPE energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find >99% confidence X-ray polarization <?CDATA ${{\rm{\Pi }}}_{2\mbox{--}4\mathrm{keV}}={21.7}_{-7.9}^{+5.6} \% $?> Π 2 – 4 keV = 21.7 − 7.9 + 5.6 % and electric vector polarization angle ψ 2–4keV = −28.°7 ± 8.°7 in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous IXPE BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs.