Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1.
Henric KrawczynskiFabio MuleriMichal DovčiakAlexandra VeledinaNicole Rodriguez CaveroJiri SvobodaAdam IngramGiorgio MattJavier A GarciaVladislav LoktevMichela NegroJuri PoutanenTakao KitaguchiJakub PodgornýJohn RankinWenda ZhangAndrei V BerdyuginSvetlana V BerdyuginaStefano BianchiDmitry BlinovFiamma CapitanioNiccoló Di LallaPaul DraghisSergio FabianiMasato KagitaniVadim KravtsovSebastian KiehlmannLuca LatronicoAlexander A LutovinovNikos MandarakasFrédéric MarinAndrea MarinucciJon M MillerTsunefumi MizunoSergey V MolkovNicola OmodeiPierre-Olivier PetrucciAjay RatheeshTakeshi SakanoiAndrei N SemenaRaphael SkalidisPaolo SoffittaAllyn F TennantPhillipp ThalhammerFrancesco TombesiMartin C WeisskopfJoern WilmsSixuan ZhangIvan AgudoLucio A AntonelliMatteo BachettiLuca BaldiniWayne H BaumgartnerRonaldo BellazziniStephen D BongiornoRaffaella BoninoAlessandro BrezNiccolò BucciantiniSimone CastellanoElisabetta CavazzutiStefano CipriniEnrico CostaAlessandra De RosaEttore Del MonteLaura Di GesuAlessandro Di MarcoImmacolata DonnarummaVictor DoroshenkoSteven R EhlertTeruaki EnotoYuri EvangelistaRiccardo FerrazzoliShuichi GunjiKiyoshi HayashidaJeremy HeylWataru IwakiriSvetlana G JorstadVladimir KarasJeffery J KolodziejczakFabio La MonacaIoannis LiodakisSimone MalderaAlberto ManfredaAlan P MarscherHerman L MarshallIkuyuki MitsuishiStephen C-Y NgStephen L O'DellChiara OppedisanoAlessandro PapittoGeorge G PavlovAbel L PeirsonMatteo PerriMelissa Pesce-RollinsMaura PiliaAndrea PossentiSimonetta PuccettiBrian D RamseyRoger W RomaniCarmelo SgróPatrick SlaneGloria SpandreToru TamagawaFabrizio TavecchioRoberto TavernaYuzuru TawaraNicholas E ThomasAlessio TroisSergey S TsygankovRoberto TurollaJacco VinkKinwah WuFei XieSilvia ZanePublished in: Science (New York, N.Y.) (2022)
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating that the jet is launched from the inner x-ray-emitting region. The polarization degree is 4.01 ± 0.20% at 2 to 8 kiloelectronvolts, implying that the accretion disk is viewed closer to edge-on than the binary orbit. These observations reveal that hot x-ray-emitting plasma is spatially extended in a plane perpendicular to, not parallel to, the jet axis.