Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1

Copyright and License

Copyright © 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Acknowledgement

We thank J. Miller-Jones, J. Orosz, and A. Zdziarski for very helpful discussions of the optical constraints on the orbital inclination of Cyg X-1 and optical position angles. We are grateful to three anonymous referees, whose excellent comments contributed to strengthening the paper. We thank T. Maccarone for emphasizing that stellar wind absorption may modify the jet orientation measurement results. This work is based on observations made with the IXPE mission, a joint US and Italian mission. The US contribution to the IXPE mission is supported by NASA and led and managed by its Marshall Space Flight Center, with industry partner Ball Aerospace (contract NNM15AA18C). The Italian contribution to the IXPE mission is supported by the Italian Space Agency (ASI) through contract ASI-OHBI-2017-12-I.0, agreements ASI-INAF-2017-12-H0 and ASI-INFN-2017.13-H0, and its Space Science Data Center (SSDC) with agreements ASI-INAF-2022-14-HH.0 and ASI-INFN 2021-43-HH.0; and by INAF and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. This research used data and software products or online services provided by the IXPE Team (Marshall Space Flight Center, the SSDC of the Italian Space Agency, the INAF, and INFN), as well as the High-Energy Astrophysics Science Archive Research Center (HEASARC), at NASA Goddard Space Flight Center. We thank the NICER, NuSTAR, INTEGRAL, Swift, and SRG/ART-XC teams and Science Operation Centers for their support of this observation campaign. DIPol-2 is a joint effort between University of Turku (Finland) and Leibniz Institut für Sonnenphysik (Germany). We are grateful to the Institute for Astronomy, University of Hawaii, for allocating observing time for the DIPol-2 polarimeter, and to the Skinakas Observatory for performing the observations with the RoboPol polarimeter at their 1.3-m telescope.

Funding

H.K. acknowledges NASA support under grants 80NSSC18K0264, 80NSSC22K1291, 80NSSC21K1817, and NNX16AC42G. F.Mu., J.R., S.B., S.F., A.R., P.So., E.D.M., E.Co., A.D.M., G.M., Y.E., R.F., F.L.M., M.Pe., and A.T. were funded through contract ASI-INAF-2017-12-H0. L.B., R.Bo., R.Be., A.Br., L.L., S.Ca., S.M., A.Man., C.O., M.P.-R., C.S., and G.S. were funded by the ASI through contracts ASI-INFN-2017.13-H0 and ASI-INFN 2021-43-HH.0. M.Pi. was funded through contract ASI-INAF-2022-14-HH.0. I.A. acknowledges support from MICINN (Ministerio de Ciencia e Innovación) Severo Ochoa award for the IAA-CSIC (SEV-2017-0709) and through grants AYA2016-80889-P and PID2019-107847RB-C44. M.D., J.S., and V.Ka. acknowledge support from GACR (Grantová agentura České republiky) project 21-06825X and institutional support from the Astronomical Institute of the Czech Academy of Sciences (RVO:67985815). J.A.G. acknowledges support from NASA grant 80NSSC20K0540. J.Pod. acknowledges support from Charles University project GA UK No. 174121 and from the Barrande Fellowship Programme of the Czech and French governments. A.V., J.Pou., and S.S.T. acknowledge support from Russian Science Foundation grant 20-12-00364 and the Academy of Finland grants 333112, 347003, 349144, and 349906. M.N. acknowledges support from NASA under award number 80GSFC21M0002. T.K. is supported by JSPS KAKENHI Grant Number JP19K03902. P.-O.P. acknowledges support from the High Energy National Programme (PNHE) of Centre national de la recherche scientifique (CNRS) and from the French space agency (CNES) as well as from the Barrande Fellowship Programme of the Czech and French governments. D.B., S.K., N.M., and R.S. acknowledge support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement no. 771282. V.Kr. thanks Vilho, Yrjö and Kalle Väisälä Foundation. P.T. and J.W. acknowledge funding from Bundesministerium für Wirtschaft and Klimaschutz under Deutsches Zentrum für Luft- und Raumfahrt grant 50 OR 1909. A.I. acknowledges support from the Royal Society. J.H. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), funding reference number 5007110, and the Canadian Space Agency. S.G.J. and A.P.M. are supported in part by National Science Foundation grant AST-2108622, by NASA Fermi Guest Investigator grant 80NSSC21K1917, and by NASA Swift Guest Investigator grant 80NSSC22K0537. C.-Y.N. is supported by a General Research Fund of the Hong Kong Government under grant number HKU 17305419. P.Sl. acknowledges support from NASA Contract NAS8-03060.

Contributions

H.K., F.Mu., M.D., A.V., N.R.C., J.S., A.I., G.M., J.A.G., V.L., and J.Pou. participated in the planning of the observation campaign and the analysis and modeling of the data. M.N., T.K., J.Pod., J.R., and W.Z. contributed to the analysis or modeling of the data. A.V.B., V.Kr., S.V.B., M.K., T.S., D.B., S.K., N.M., and R.S. contributed to the optical polarimetric data. J.M.M. and P.D. contributed the Swift results; J.W. and P.T. the INTEGRAL results; and A.A.L., S.V.M., and A.N.S. the SRG/ART-XC results. S.B., F.C., N.D.L., L.L., A.Mar., T.M., N.O., A.R., P.-O.P, P.So., A.F.T., F.To., M.C.W., and S.Zh. contributed to the discussion of the results. F.Ma. and S.F. served as internal referees. All other authors contributed to the design and science case of the IXPE mission and to planning the observations used in this paper. All authors provided input and comments on the manuscript.

Data Availability

The May and June IXPE observations are available at https://heasarc.gsfc.nasa.gov/FTP/ixpe/data/obs/01/01002901/ and https://heasarc.gsfc.nasa.gov/FTP/ixpe/data/obs/01/01250101/, respectively. The NICER data are available at https://heasarc.gsfc.nasa.gov/docs/nicer/nicer_archive.html under ObsIDs 5100320101, 5100320102, 5100320103, 5100320104, 5100320105, 5100320106, and 5100320107. The NuSTAR data are available at https://heasarc.gsfc.nasa.gov/db-perl/W3Browse/w3table.pl?tablehead=name%3Dnumaster&Action=More+Options under ObsIDs 30702017002, 30702017004, and 30702017006. The SWIFT XRT data are available at https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/swift.pl under ObsIDs 00034310009, 00034310010, 00034310011, 00034310012, 00034310013, and 00034310014. The extracted INTEGRAL ISGRI data are archived at Zenodo (32). The SRG ART-XC data are available at ftp://hea.iki.rssi.ru/public/SRG/ART-XC/data/Cygnus_X-1/. The MAXI light curves are available at http://maxi.riken.jp/star_data/J1958+352/J1958+352.html. The raw DIPol-2 and RoboPol data are archived at Zenodo (33, 34). The kerrC code (13) is available at https://gitlab.com/krawcz/kerrc-x-ray-fitting-code.git. The MONK code (35) is available at https://projects.asu.cas.cz/zhang/monk. The ixpeobssim software is available at https://github.com/lucabaldini/ixpeobssim and documented at https://ixpeobssim.readthedocs.io. Our derived x-ray polarization measurements are listed in tables S1 and S2, and the optical polarization measurements are listed in table S4. The numerical results of our model fitting are listed in table S5. Our models of polarized emission in the truncated disk geometry are archived at Zenodo (36).

Supplemental Material

• Materials and Methods
• Figs. S1 to S12
• Tables S1 to S5
• References (37–79)