High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component
Cygnus X-1, the well-known accreting black hole system, exhibits several observational features hinting at an intricate interplay between the accretion disk, its atmosphere known as the corona, and the putative relativistic jet. It has been extensively studied using all available observational metho...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/ad118d |
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| author | Tanmoy Chattopadhyay Abhay Kumar A. R. Rao Yash Bhargava Santosh V. Vadawale Ajay Ratheesh Gulab Dewangan Dipankar Bhattacharya N. P. S. Mithun Varun Bhalerao |
| author_facet | Tanmoy Chattopadhyay Abhay Kumar A. R. Rao Yash Bhargava Santosh V. Vadawale Ajay Ratheesh Gulab Dewangan Dipankar Bhattacharya N. P. S. Mithun Varun Bhalerao |
| author_sort | Tanmoy Chattopadhyay |
| collection | DOAJ |
| description | Cygnus X-1, the well-known accreting black hole system, exhibits several observational features hinting at an intricate interplay between the accretion disk, its atmosphere known as the corona, and the putative relativistic jet. It has been extensively studied using all available observational methods, including using the newly available technique of sensitive X-ray polarimetry. X-ray polarization characteristics are distinct for coronal and jet emissions. The low X-ray polarization measured below ∼100 keV is understood as arising from the corona. In contrast, the high polarization measurements reported above ∼400 keV required a separate jet-dominated spectral component, which spectroscopy does not demonstrate conclusively. Here we report precise polarization measurements in the 100–380 keV region made during three different subclasses of spectral states of the source using the CZTI instrument onboard AstroSat. A high polarization (23% ± 4%) is found mainly in the Intermediate Hard State of the source, and the energy-resolved measurements smoothly connect the coronal and the jet regimes. When high polarization is observed, the simultaneous spectral data hints at a separate power-law component above 100 keV. We examine the possible sources of this energy-dependent high polarization in Cygnus X-1. |
| first_indexed | 2024-03-08T18:40:13Z |
| format | Article |
| id | doaj.art-b4a8ba7ae09b41fcbe9a8319ed345fee |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-08T18:40:13Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-b4a8ba7ae09b41fcbe9a8319ed345fee2023-12-29T09:19:42ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019601L210.3847/2041-8213/ad118dHigh Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet ComponentTanmoy Chattopadhyay0https://orcid.org/0000-0001-9856-1866Abhay Kumar1A. R. Rao2Yash Bhargava3https://orcid.org/0000-0002-5967-8399Santosh V. Vadawale4https://orcid.org/0000-0002-2050-0913Ajay Ratheesh5https://orcid.org/0000-0003-0411-4243Gulab Dewangan6https://orcid.org/0000-0003-1589-2075Dipankar Bhattacharya7https://orcid.org/0000-0003-3352-3142N. P. S. Mithun8https://orcid.org/0000-0003-3431-6110Varun Bhalerao9https://orcid.org/0000-0002-6112-7609Kavli Institute of Particle Astrophysics and Cosmology, Stanford University 452 Lomita Mall, Stanford, CA 94305, USA ; tanmoyc@stanford.eduPhysical Research Laboratory Thaltej , Ahmedabad, Gujarat 380009, IndiaInter-University Center for Astronomy and Astrophysics Pune , Maharashtra-411007, IndiaInter-University Center for Astronomy and Astrophysics Pune , Maharashtra-411007, India; Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research , 1 Homi Bhabha Road, Colaba, 400005 Mumbai, IndiaPhysical Research Laboratory Thaltej , Ahmedabad, Gujarat 380009, IndiaINAF—IAPS , Via Fosso del Cavaliere 100, I-00133 Rome, ItalyInter-University Center for Astronomy and Astrophysics Pune , Maharashtra-411007, IndiaInter-University Center for Astronomy and Astrophysics Pune , Maharashtra-411007, India; Department of Physics, Ashoka University Rai , Sonipat, Haryana-131029, IndiaPhysical Research Laboratory Thaltej , Ahmedabad, Gujarat 380009, IndiaIndian Institute of Technology Bombay Powai , Mumbai, Maharashtra 400076, IndiaCygnus X-1, the well-known accreting black hole system, exhibits several observational features hinting at an intricate interplay between the accretion disk, its atmosphere known as the corona, and the putative relativistic jet. It has been extensively studied using all available observational methods, including using the newly available technique of sensitive X-ray polarimetry. X-ray polarization characteristics are distinct for coronal and jet emissions. The low X-ray polarization measured below ∼100 keV is understood as arising from the corona. In contrast, the high polarization measurements reported above ∼400 keV required a separate jet-dominated spectral component, which spectroscopy does not demonstrate conclusively. Here we report precise polarization measurements in the 100–380 keV region made during three different subclasses of spectral states of the source using the CZTI instrument onboard AstroSat. A high polarization (23% ± 4%) is found mainly in the Intermediate Hard State of the source, and the energy-resolved measurements smoothly connect the coronal and the jet regimes. When high polarization is observed, the simultaneous spectral data hints at a separate power-law component above 100 keV. We examine the possible sources of this energy-dependent high polarization in Cygnus X-1.https://doi.org/10.3847/2041-8213/ad118dHigh mass x-ray binary starsX-ray astronomyStellar mass black holesPolarimetrySpectroscopyRadio jets |
| spellingShingle | Tanmoy Chattopadhyay Abhay Kumar A. R. Rao Yash Bhargava Santosh V. Vadawale Ajay Ratheesh Gulab Dewangan Dipankar Bhattacharya N. P. S. Mithun Varun Bhalerao High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component The Astrophysical Journal Letters High mass x-ray binary stars X-ray astronomy Stellar mass black holes Polarimetry Spectroscopy Radio jets |
| title | High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component |
| title_full | High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component |
| title_fullStr | High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component |
| title_full_unstemmed | High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component |
| title_short | High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component |
| title_sort | high hard x ray polarization in cygnus x 1 confined to the intermediate hard state evidence for a variable jet component |
| topic | High mass x-ray binary stars X-ray astronomy Stellar mass black holes Polarimetry Spectroscopy Radio jets |
| url | https://doi.org/10.3847/2041-8213/ad118d |
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