A MULTIWAVELENGTH STUDY OF CYGNUS X-1: THE FIRST MID-INFRARED SPECTROSCOPIC DETECTION OF COMPACT JETS

dc.contributor.authorRahoui, Farid
dc.contributor.authorLee, Julia C.
dc.contributor.authorHeinz, Sebastian
dc.contributor.authorHines, Dean C.
dc.contributor.authorPottschmidt, Katja
dc.contributor.authorWilms, Jörn
dc.contributor.authorGrinberg, Victoria
dc.date.accessioned2023-09-22T16:05:19Z
dc.date.available2023-09-22T16:05:19Z
dc.date.issued2011-07-06
dc.description.abstractWe report on a Spitzer/InfraRed Spectrograph (mid-infrared), RXTE/PCA+HEXTE (X-ray), and Ryle (radio) simultaneous multiwavelength study of the microquasar Cygnus X-1, which aimed at an investigation of the origin of its mid-infrared emission. Compact jets were present in two out of three observations, and we show that they strongly contribute to the mid-infrared continuum. During the first observation, we detect the spectral break—where the transition from the optically thick to the optically thin regime takes place—at about 2.9 × 10¹³ Hz. We then show that the jet's optically thin synchrotron emission accounts for Cygnus X-1's emission beyond 400 keV, although it cannot alone explain its 3–200 keV continuum. A compact jet was also present during the second observation, but we do not detect the break, since it has likely shifted to higher frequencies. In contrast, the compact jet was absent during the last observation, and we show that the 5–30 μm mid-infrared continuum of Cygnus X-1 stems from the blue supergiant companion star HD 226868. Indeed, the emission can then be understood as the combination of the photospheric Rayleigh–Jeans tail and the bremsstrahlung from the expanding stellar wind. Moreover, the stellar wind is found to be clumpy, with a filling factor f∞ ≈ 0.09–0.10. Its bremsstrahlung emission is likely anti-correlated to the soft X-ray emission, suggesting an anti-correlation between the mass-loss and mass-accretion rates. Nevertheless, we do not detect any mid-infrared spectroscopic evidence of interaction between the jets and Cygnus X-1's environment and/or the companion star's stellar wind.en_US
dc.description.sponsorshipWe thank the anonymous referee for his/her useful comments. F.R. thanks J. Rodriguez for providing the INTEGRAL/IBIS data. J.C.L. thanks the Harvard Faculty of Arts and Sciences and the Harvard College Observatory. S.H. acknowledges support from JPL-NASA contract no. 1292543. This work was partially funded by the Bundesministerium für Wirtschaft und Technologie through Deutsches Zentrum für Luft- und Raumfahrt grant 50 OR 1007 and by the European Commission through contract ITN 215212 "Black Hole Universe." This research has made use of NASA's Astrophysics Data System, of the SIMBAD, and VizieR databases operated at CDS, Strasbourg, France.en_US
dc.description.urihttps://iopscience.iop.org/article/10.1088/0004-637X/736/1/63en_US
dc.format.extent14 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2wcm7-etbr
dc.identifier.citationRahoui, Farid, Julia C. Lee, Sebastian Heinz, Dean C. Hines, Katja Pottschmidt, Jörn Wilms, and Victoria Grinberg. “A MULTIWAVELENGTH STUDY OF CYGNUS X-1: THE FIRST MID-INFRARED SPECTROSCOPIC DETECTION OF COMPACT JETS.” The Astrophysical Journal 736, no. 1 (July 2011): 63. https://doi.org/10.1088/0004-637X/736/1/63.en_US
dc.identifier.urihttps://doi.org/10.1088/0004-637X/736/1/63
dc.identifier.urihttp://hdl.handle.net/11603/29831
dc.language.isoen_USen_US
dc.publisherIOP Publishingen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Center for Space Sciences and Technology
dc.relation.ispartofUMBC Faculty Collection
dc.relation.ispartofUMBC Physics Department
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.en_US
dc.titleA MULTIWAVELENGTH STUDY OF CYGNUS X-1: THE FIRST MID-INFRARED SPECTROSCOPIC DETECTION OF COMPACT JETSen_US
dc.typeTexten_US
dcterms.creatorhttps://orcid.org/0000-0002-4656-6881en_US

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