Data di Pubblicazione:
2023
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 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.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
Peirson A.L.; Negro M.; Liodakis I.; Middei R.; Kim D.E.; Marscher A.P.; Marshall H.L.; Pacciani L.; Romani R.W.; Wu K.; Di Marco A.; Di Lalla N.; Omodei N.; Jorstad S.G.; Agudo I.; Kouch P.M.; Lindfors E.; Aceituno F.J.; Bernardos M.I.; Bonnoli G.; Casanova V.; Garcia-Comas M.; Agis-Gonzalez B.; Husillos C.; Marchini A.; Sota A.; Casadio C.; Escudero J.; Myserlis I.; Sievers A.; Gurwell M.; Rao R.; Imazawa R.; Sasada M.; Fukazawa Y.; Kawabata K.S.; Uemura M.; Mizuno T.; Nakaoka T.; Akitaya H.; Cheong Y.; Jeong H.-W.; Kang S.; Kim S.-H.; Lee S.-S.; Angelakis E.; Kraus A.; Cibrario N.; Donnarumma I.; Poutanen J.; Tavecchio F.; Antonelli L.A.; Bachetti M.; Baldini L.; Baumgartner W.H.; Bellazzini R.; Bianchi S.; Bongiorno S.D.; 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 Gesu L.; Doroshenko V.; Dovciak M.; Ehlert S.R.; Enoto T.; Evangelista Y.; Fabiani S.; Ferrazzoli R.; Garcia J.A.; Gunji S.; Hayashida K.; Heyl J.; Iwakiri W.; Kaaret P.; Karas V.; Kitaguchi T.; Kolodziejczak J.J.; Krawczynski H.; La Monaca F.; Latronico L.; Madejski G.; Maldera S.; Manfreda A.; Marin F.; Marinucci A.; Massaro F.; Matt G.; Mitsuishi I.; Muleri F.; Ng C.-Y.; O'Dell S.L.; Oppedisano C.; Papitto A.; Pavlov G.G.; Perri M.; Pesce-Rollins M.; Petrucci P.-O.; Pilia M.; Possenti A.; Puccetti S.; Ramsey B.D.; Rankin J.; Ratheesh A.; Roberts O.J.; Sgro C.; Slane P.; Soffitta P.; Spandre G.; Swartz D.A.; Tamagawa T.; Taverna R.; Tawara Y.; Tennant A.F.; Thomas N.E.; Tombesi F.; Trois A.; Tsygankov S.; Turolla R.; Vink J.; Weisskopf M.C.; Xie F.; Zane S.
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