IXPE observation of PKS 2155-304 reveals the most highly polarized blazar
Creators: name: Kouch, Pouya M.
name: Liodakis, Ioannis
name: Middei, Riccardo
name: Kim, Dawoon E.
name: Tavecchio, Fabrizio
name: Marscher, Alan P.
name: Marshall, Herman L.
name: Ehlert, Steven R.
name: Di Gesu, Laura
name: Jorstad, Svetlana G.
name: Agudo, Iván
name: Madejski, Grzegorz M.
name: Romani, Roger W.
name: Errando, Manel
name: Lindfors, Elina
name: Nilsson, Kari
name: Toppari, Ella
name: Potter, Stephen B.
name: Imazawa, Ryo
name: Sasada, Mahito
name: Fukazawa, Yasushi
name: Kawabata, Koji S.
name: Uemura, Makoto
name: Mizuno, Tsunefumi
name: Nakaoka, Tatsuya
name: Akitaya, Hiroshi
name: McCall, Callum
name: Jermak, Helen E.
name: Steele, Iain A.
name: Myserlis, Ioannis
name: Gurwell, Mark
name: Keating, Garrett K.
name: Rao, Ramprasad
name: Kang, Sincheol
name: Lee, Sang-Sung
name: Kim, Sang-Hyun
name: Cheong, Whee Yeon
name: Jeong, Hyeon-Woo
name: Angelakis, Emmanouil
name: Kraus, Alexander
name: Aceituno, Francisco José
name: Bonnoli, Giacomo
name: Casanova, Víctor
name: Escudero, Juan
name: Agís-González, Beatriz
name: Husillos, César
name: Morcuende, Daniel
name: Otero-Santos, Jorge
name: Sota, Alfredo
name: Bachev, Rumen
name: Antonelli, Lucio Angelo
name: Bachetti, Matteo
name: Baldini, Luca
name: Baumgartner, Wayne H.
name: Bellazzini, Ronaldo
name: Bianchi, Stefano
name: Bongiorno, Stephen D.
name: Bonino, Raffaella
name: Brez, Alessandro
name: Bucciantini, Niccolò
name: Capitanio, Fiamma
name: Castellano, Simone
name: Cavazzuti, Elisabetta
name: Chen, Chien-Ting
name: Ciprini, Stefano
name: Costa, Enrico
name: De Rosa, Alessandra
name: Del Monte, Ettore
name: Di Lalla, Niccolò
name: Di Marco, Alessandro
name: Donnarumma, Immacolata
name: Doroshenko, Victor
name: Dovčiak, Michal
name: Enoto, Teruaki
name: Evangelista, Yuri
name: Fabiani, Sergio
name: Ferrazzoli, Riccardo
name: Garcia, Javier A.
name: Gunji, Shuichi
name: Hayashida, Kiyoshi
name: Heyl, Jeremy
name: Iwakiri, Wataru
name: Kaaret, Philip
name: Karas, Vladimir
name: Kislat, Fabian
name: Kitaguchi, Takao
name: Kolodziejczak, Jeffery J.
name: Krawczynski, Henric
name: La Monaca, Fabio
name: Latronico, Luca
name: Maldera, Simone
name: Manfreda, Alberto
name: Marin, Frédéric
name: Marinucci, Andrea
name: Massaro, Francesco
name: Matt, Giorgio
name: Mitsuishi, Ikuyuki
name: Muleri, Fabio
name: Negro, Michela
name: Ng, C. -Y.
name: O'Dell, Stephen L.
name: Omodei, Nicola
name: Oppedisano, Chiara
name: Papitto, Alessandro
name: Pavlov, George G.
name: Peirson, Abel Lawrence
name: Perri, Matteo
name: Pesce-Rollins, Melissa
name: Petrucci, Pierre-Olivier
name: Pilia, Maura
name: Possenti, Andrea
name: Poutanen, Juri
name: Puccetti, Simonetta
name: Ramsey, Brian D.
name: Rankin, John
name: Ratheesh, Ajay
name: Roberts, Oliver J.
name: Sgrò, Carmelo
name: Slane, Patrick
name: Soffitta, Paolo
name: Spandre, Gloria
name: Swartz, Douglas A.
name: Tamagawa, Toru
name: Taverna, Roberto
name: Tawara, Yuzuru
name: Tennant, Allyn F.
name: Thomas, Nicholas E.
name: Tombesi, Francesco
name: Trois, Alessio
name: Tsygankov, Sergey S.
name: Turolla, Roberto
name: Vink, Jacco
name: Weisskopf, Martin C.
name: Wu, Kinwah
name: Xie, Fei
name: Zane, Silvia
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half ($T_1$) of the IXPE pointing, the source exhibited the highest X-ray polarization degree detected for an HSP blazar thus far, (30.7$\pm$2.0)%, which dropped to (15.3$\pm$2.1)% during the second half ($T_2$). The X-ray polarization angle remained stable during the IXPE pointing at 129.4$^\circ$$\pm$1.8$^\circ$ and 125.4$^\circ$$\pm$3.9$^\circ$ during $T_1$ and $T_2$, respectively. Meanwhile, the optical polarization degree remained stable during the IXPE pointing, with average host-galaxy-corrected values of (4.3$\pm$0.7)% and (3.8$\pm$0.9)% during the $T_1$ and $T_2$, respectively. During the IXPE pointing, the optical polarization angle changed achromatically from $\sim$140$^\circ$ to $\sim$90$^\circ$ and back to $\sim$130$^\circ$. Despite several attempts, we only detected (99.7% conf.) the radio polarization once (during $T_2$, at 225.5 GHz): with degree (1.7$\pm$0.4)% and angle 112.5$^\circ$$\pm$5.5$^\circ$. The direction of the broad pc-scale jet is rather ambiguous and has been found to point to the east and south at different epochs; however, on larger scales (&gt; 1.5 pc) the jet points toward the southeast ($\sim$135$^\circ$), similar to all of the MW polarization angles. Moreover, the X-ray to optical polarization degree ratios of $\sim$7 and $\sim$4 during $T_1$ and $T_2$, respectively, are similar to previous IXPE results for several HSP blazars. These findings, combined with the lack of correlation of temporal variability between the MW polarization properties, agree with an energy-stratified shock-acceleration scenario in HSP blazars.
description: 17 pages, 10 figures, 4 tables, Accepted for publication in A&amp;A