Dramatic Drop in the X-Ray Polarization of Swift J1727.8$-$1613 in the Soft Spectral State
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| Format: | Preprint |
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2024
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| author | Svoboda, Jiří Dovčiak, Michal Steiner, James F. Kaaret, Philip Podgorný, Jakub Poutanen, Juri Veledina, Alexandra Muleri, Fabio Taverna, Roberto Krawczynski, Henric Brigitte, Maïmouna Datta, Sudeb Ranjan Bianchi, Stefano Segura, Noel Castro García, Javier A. Ingram, Adam Matt, Giorgio Muñoz-Darias, Teo Nathan, Edward Weisskopf, Martin C. Altamirano, Diego Baldini, Luca Bollemeijer, Niek Capitanio, Fiamma Egron, Elise Emami, Razieh Hu, Kun Marra, Lorenzo Mastroserio, Guglielmo Negro, Michela Petrucci, Pierre-Olivier Ratheesh, Ajay Cavero, Nicole Rodriguez Soffitta, Paolo Tombesi, Francesco Yang, Yi-Jung Zhang, Yuexin |
| author_facet | Svoboda, Jiří Dovčiak, Michal Steiner, James F. Kaaret, Philip Podgorný, Jakub Poutanen, Juri Veledina, Alexandra Muleri, Fabio Taverna, Roberto Krawczynski, Henric Brigitte, Maïmouna Datta, Sudeb Ranjan Bianchi, Stefano Segura, Noel Castro García, Javier A. Ingram, Adam Matt, Giorgio Muñoz-Darias, Teo Nathan, Edward Weisskopf, Martin C. Altamirano, Diego Baldini, Luca Bollemeijer, Niek Capitanio, Fiamma Egron, Elise Emami, Razieh Hu, Kun Marra, Lorenzo Mastroserio, Guglielmo Negro, Michela Petrucci, Pierre-Olivier Ratheesh, Ajay Cavero, Nicole Rodriguez Soffitta, Paolo Tombesi, Francesco Yang, Yi-Jung Zhang, Yuexin |
| contents | Black-hole X-ray binaries exhibit different spectral and timing properties in different accretion states. The X-ray outburst of a recently discovered and extraordinarily bright source, Swift$~$J1727.8$-$1613, has enabled the first investigation of how the X-ray polarization properties of a source evolve with spectral state. The 2$-$8 keV polarization degree was previously measured by the Imaging X-ray Polarimetry Explorer (IXPE) to be $\approx$ 4% in the hard and hard intermediate states. Here we present new IXPE results taken in the soft state, with the X-ray flux dominated by the thermal accretion-disk emission. We find that the polarization degree has dropped dramatically to $\lesssim$ 1%. This result indicates that the measured X-ray polarization is largely sensitive to the accretion state and the polarization fraction is significantly higher in the hard state when the X-ray emission is dominated by up-scattered radiation in the X-ray corona. The combined polarization measurements in the soft and hard states disfavor a very high or low inclination of the system. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_04689 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Dramatic Drop in the X-Ray Polarization of Swift J1727.8$-$1613 in the Soft Spectral State Svoboda, Jiří Dovčiak, Michal Steiner, James F. Kaaret, Philip Podgorný, Jakub Poutanen, Juri Veledina, Alexandra Muleri, Fabio Taverna, Roberto Krawczynski, Henric Brigitte, Maïmouna Datta, Sudeb Ranjan Bianchi, Stefano Segura, Noel Castro García, Javier A. Ingram, Adam Matt, Giorgio Muñoz-Darias, Teo Nathan, Edward Weisskopf, Martin C. Altamirano, Diego Baldini, Luca Bollemeijer, Niek Capitanio, Fiamma Egron, Elise Emami, Razieh Hu, Kun Marra, Lorenzo Mastroserio, Guglielmo Negro, Michela Petrucci, Pierre-Olivier Ratheesh, Ajay Cavero, Nicole Rodriguez Soffitta, Paolo Tombesi, Francesco Yang, Yi-Jung Zhang, Yuexin High Energy Astrophysical Phenomena Black-hole X-ray binaries exhibit different spectral and timing properties in different accretion states. The X-ray outburst of a recently discovered and extraordinarily bright source, Swift$~$J1727.8$-$1613, has enabled the first investigation of how the X-ray polarization properties of a source evolve with spectral state. The 2$-$8 keV polarization degree was previously measured by the Imaging X-ray Polarimetry Explorer (IXPE) to be $\approx$ 4% in the hard and hard intermediate states. Here we present new IXPE results taken in the soft state, with the X-ray flux dominated by the thermal accretion-disk emission. We find that the polarization degree has dropped dramatically to $\lesssim$ 1%. This result indicates that the measured X-ray polarization is largely sensitive to the accretion state and the polarization fraction is significantly higher in the hard state when the X-ray emission is dominated by up-scattered radiation in the X-ray corona. The combined polarization measurements in the soft and hard states disfavor a very high or low inclination of the system. |
| title | Dramatic Drop in the X-Ray Polarization of Swift J1727.8$-$1613 in the Soft Spectral State |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2403.04689 |