_version_ 1866910963847921664
author Ewing, Melissa
Parra, Maxime
Mastroserio, Guglielmo
Veledina, Alexandra
Ingram, Adam
Dovčiak, Michal
García, Javier A.
Russell, Thomas D.
Baglio, Maria C.
Poutanen, Juri
Adegoke, Oluwashina
Bianchi, Stefano
Capitanio, Fiamma
Connors, Riley
Del Santo, Melania
De Marco, Barbara
Trigo, María Díaz
Gandhi, Poshak
Gupta, Maitrayee
Kang, Chulsoo
Kammoun, Elias
Loktev, Vladislav
Marra, Lorenzo
Matt, Giorgio
Nathan, Edward
Petrucci, Pierre-Olivier
Shidatsu, Megumi
Steiner, James F.
Tombesi, Francesco
author_facet Ewing, Melissa
Parra, Maxime
Mastroserio, Guglielmo
Veledina, Alexandra
Ingram, Adam
Dovčiak, Michal
García, Javier A.
Russell, Thomas D.
Baglio, Maria C.
Poutanen, Juri
Adegoke, Oluwashina
Bianchi, Stefano
Capitanio, Fiamma
Connors, Riley
Del Santo, Melania
De Marco, Barbara
Trigo, María Díaz
Gandhi, Poshak
Gupta, Maitrayee
Kang, Chulsoo
Kammoun, Elias
Loktev, Vladislav
Marra, Lorenzo
Matt, Giorgio
Nathan, Edward
Petrucci, Pierre-Olivier
Shidatsu, Megumi
Steiner, James F.
Tombesi, Francesco
contents We report the first detection of the X-ray polarisation of the transient black hole X-ray binary IGRJ17091-3624 taken with the Imaging X-ray polarimetry Explorer (IXPE) in March 2025, and present the results of an X-ray spectro-polarimetric analysis. The polarisation was measured in the 2--8 keV band with 5.2$σ$ statistical confidence. We report a polarisation degree (PD) of $9.1\pm1.6$ per cent and a polarisation angle of $83^{\circ} \pm 5^{\circ}$ (errors are $1σ$ confidence). There is a hint of a positive correlation of PD with energy that is not statistically significant. We report that the source is in the corona-dominated hard state, which is confirmed by a hard power-law dominated spectrum with weak reflection features and the presence of a Type-C quasi-periodic oscillation at $\sim0.2$~Hz. The orientation of the emitted radio jet is not known, and so we are unable to compare it with the direction of X-ray polarization, but we predict the two to be parallel if the geometry is similar to that in Cygnus X-1 and Swift J1727.8-1613, the two hard state black hole binaries previously observed by IXPE. In the Comptonisation scenario, the high observed PD requires a very favourable geometry of the corona, a high inclination angle (supported by the presence of a dip in the light curve) and possibly a mildly relativistic outflow and/or scattering in an optically thick wind.
format Preprint
id arxiv_https___arxiv_org_abs_2503_22665
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The very high X-ray polarisation of accreting black hole IGRJ17091-3624 in the hard state
Ewing, Melissa
Parra, Maxime
Mastroserio, Guglielmo
Veledina, Alexandra
Ingram, Adam
Dovčiak, Michal
García, Javier A.
Russell, Thomas D.
Baglio, Maria C.
Poutanen, Juri
Adegoke, Oluwashina
Bianchi, Stefano
Capitanio, Fiamma
Connors, Riley
Del Santo, Melania
De Marco, Barbara
Trigo, María Díaz
Gandhi, Poshak
Gupta, Maitrayee
Kang, Chulsoo
Kammoun, Elias
Loktev, Vladislav
Marra, Lorenzo
Matt, Giorgio
Nathan, Edward
Petrucci, Pierre-Olivier
Shidatsu, Megumi
Steiner, James F.
Tombesi, Francesco
High Energy Astrophysical Phenomena
We report the first detection of the X-ray polarisation of the transient black hole X-ray binary IGRJ17091-3624 taken with the Imaging X-ray polarimetry Explorer (IXPE) in March 2025, and present the results of an X-ray spectro-polarimetric analysis. The polarisation was measured in the 2--8 keV band with 5.2$σ$ statistical confidence. We report a polarisation degree (PD) of $9.1\pm1.6$ per cent and a polarisation angle of $83^{\circ} \pm 5^{\circ}$ (errors are $1σ$ confidence). There is a hint of a positive correlation of PD with energy that is not statistically significant. We report that the source is in the corona-dominated hard state, which is confirmed by a hard power-law dominated spectrum with weak reflection features and the presence of a Type-C quasi-periodic oscillation at $\sim0.2$~Hz. The orientation of the emitted radio jet is not known, and so we are unable to compare it with the direction of X-ray polarization, but we predict the two to be parallel if the geometry is similar to that in Cygnus X-1 and Swift J1727.8-1613, the two hard state black hole binaries previously observed by IXPE. In the Comptonisation scenario, the high observed PD requires a very favourable geometry of the corona, a high inclination angle (supported by the presence of a dip in the light curve) and possibly a mildly relativistic outflow and/or scattering in an optically thick wind.
title The very high X-ray polarisation of accreting black hole IGRJ17091-3624 in the hard state
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2503.22665