Peirson, Abel L.Abel L.PeirsonLiodakis, IoannisIoannisLiodakisMIDDEI, RiccardoRiccardoMIDDEIKim, Dawoon E.Dawoon E.KimMarscher, Alan P.Alan P.MarscherMarshall, Herman L.Herman L.MarshallPACCIANI, LUIGILUIGIPACCIANIRomani, Roger W.Roger W.RomaniWu, KinwahKinwahWuDI MARCO, AlessandroAlessandroDI MARCODi Lalla, NiccolóNiccolóDi LallaPAPITTO, ALESSANDROALESSANDROPAPITTOPavlov, George G.George G.PavlovPERRI, MatteoMatteoPERRIPesce-Rollins, MelissaMelissaPesce-RollinsPetrucci, Pierre-OlivierPierre-OlivierPetrucciPILIA, MauraMauraPILIAPOSSENTI, ANDREAANDREAPOSSENTIPuccetti, SimonettaSimonettaPuccettiRamsey, Brian D.Brian D.RamseyRANKIN, JohnJohnRANKINOmodei, NicolaNicolaOmodeiRATHEESH, AJAYAJAYRATHEESHRoberts, Oliver J.Oliver J.RobertsSgró, CarmeloCarmeloSgróSlane, PatrickPatrickSlaneSOFFITTA, PAOLOPAOLOSOFFITTASpandre, GloriaGloriaSpandreSwartz, Douglas A.Douglas A.SwartzTamagawa, ToruToruTamagawaTaverna, RobertoRobertoTavernaTawara, YuzuruYuzuruTawaraJorstad, Svetlana G.Svetlana G.JorstadTennant, Allyn F.Allyn F.TennantThomas, Nicholas E.Nicholas E.ThomasTOMBESI, FrancescoFrancescoTOMBESITROIS, ALESSIOALESSIOTROISTsygankov, SergeySergeyTsygankovTurolla, RobertoRobertoTurollaVink, JaccoJaccoVinkWeisskopf, Martin C.Martin C.WeisskopfXIE, FEIFEIXIEZane, SilviaSilviaZaneAgudo, IvánIvánAgudoKouch, Pouya M.Pouya M.KouchLindfors, ElinaElinaLindforsAceituno, Francisco JoséFrancisco JoséAceitunoBernardos, Maria I.Maria I.BernardosBONNOLI, GiacomoGiacomoBONNOLICasanova, VíctorVíctorCasanovaGarcía-Comas, MayaMayaGarcía-ComasAgís-González, BeatrizBeatrizAgís-GonzálezHusillos, CésarCésarHusillosMarchini, AlessandroAlessandroMarchiniSota, AlfredoAlfredoSotaCasadio, CarolinaCarolinaCasadioEscudero, JuanJuanEscuderoMyserlis, IoannisIoannisMyserlisSievers, AlbrechtAlbrechtSieversGurwell, MarkMarkGurwellRao, RamprasadRamprasadRaoImazawa, RyoRyoImazawaSasada, MahitoMahitoSasadaFukazawa, YasushiYasushiFukazawaKawabata, Koji S.Koji S.KawabataUemura, MakotoMakotoUemuraMizuno, TsunefumiTsunefumiMizunoNakaoka, TatsuyaTatsuyaNakaokaAkitaya, HiroshiHiroshiAkitayaCheong, YeonYeonCheongJeong, Hyeon-WooHyeon-WooJeongKang, SincheolSincheolKangKim, Sang-HyunSang-HyunKimLee, Sang-SungSang-SungLeeAngelakis, EmmanouilEmmanouilAngelakisKraus, AlexanderAlexanderKrausCibrario, NicolóNicolóCibrarioDonnarumma, ImmacolataImmacolataDonnarummaPoutanen, JuriJuriPoutanenTAVECCHIO, FabrizioFabrizioTAVECCHIOANTONELLI, Lucio AngeloLucio AngeloANTONELLIBACHETTI, MatteoMatteoBACHETTIBaldini, LucaLucaBaldiniBaumgartner, Wayne H.Wayne H.BaumgartnerBellazzini, RonaldoRonaldoBellazziniBianchi, StefanoStefanoBianchiBongiorno, Stephen D.Stephen D.BongiornoBonino, RaffaellaRaffaellaBoninoBrez, AlessandroAlessandroBrezBUCCIANTINI, Niccolo'Niccolo'BUCCIANTINICAPITANIO, FIAMMAFIAMMACAPITANIOCastellano, SimoneSimoneCastellanoCavazzuti, ElisabettaElisabettaCavazzutiChen, Chien-TingChien-TingChenCiprini, StefanoStefanoCipriniCOSTA, ENRICOENRICOCOSTADE ROSA, AlessandraAlessandraDE ROSADEL MONTE, EttoreEttoreDEL MONTEDi Gesu, LauraLauraDi GesuDoroshenko, VictorVictorDoroshenkoDovčiak, MichalMichalDovčiakEhlert, Steven R.Steven R.EhlertEnoto, TeruakiTeruakiEnotoEVANGELISTA, YURIYURIEVANGELISTAFABIANI, SergioSergioFABIANIFERRAZZOLI, RiccardoRiccardoFERRAZZOLIGarcia, Javier A.Javier A.GarciaGunji, ShuichiShuichiGunjiHayashida, KiyoshiKiyoshiHayashidaHeyl, JeremyJeremyHeylIwakiri, WataruWataruIwakiriKaaret, PhilipPhilipKaaretKaras, VladimirVladimirKarasKitaguchi, TakaoTakaoKitaguchiKolodziejczak, Jeffery J.Jeffery J.KolodziejczakKrawczynski, HenricHenricKrawczynskiLA MONACA, FabioFabioLA MONACALatronico, LucaLucaLatronicoMadejski, GrzegorzGrzegorzMadejskiMaldera, SimoneSimoneMalderaManfreda, AlbertoAlbertoManfredaMarin, FrédéricFrédéricMarinMarinucci, AndreaAndreaMarinucciMASSARO, FRANCESCOFRANCESCOMASSAROMatt, GiorgioGiorgioMattMitsuishi, IkuyukiIkuyukiMitsuishiMULERI, FABIOFABIOMULERINg, C. -Y.C. -Y.NgO'Dell, Stephen L.Stephen L.O'DellOppedisano, ChiaraChiaraOppedisano2024-12-092024-12-0920232041-8205http://hdl.handle.net/20.500.12386/35420We 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 ${{\rm{\Pi }}}_{2\mbox{--}4\mathrm{keV}}={21.7}_{-7.9}^{+5.6} \% $ and electric vector polarization angle ψ <SUB>2-4keV</SUB> = -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.STAMPAenArticle10.3847/2041-8213/acd2422-s2.0-85159697882https://iopscience.iop.org/article/10.3847/2041-8213/acd242https://api.elsevier.com/content/abstract/scopus_id/851596978822023ApJ...948L..25PFIS/05 - ASTRONOMIA E ASTROFISICA