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| Format: | Preprint |
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2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2309.06830 |
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| _version_ | 1866916231313883136 |
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| author | Garg, Akash Rawat, Divya Méndez, Mariano |
| author_facet | Garg, Akash Rawat, Divya Méndez, Mariano |
| contents | The incoming Imaging X-ray Polarimetry Explorer (IXPE) observations of X-ray binaries provide a new tool to investigate the underlying accretion geometry. Here we report the first measurements of X-ray polarization of the extra-galactic black-hole X-ray binary LMC X$-$3. We find a polarization fraction of $\sim 3%$ at a polarization angle of $\sim 135^\circ$ in the $2-8$ keV energy band with statistical significance at the 7$σ$ level. This polarization measurement significantly exceeds the minimum detectable polarization threshold of 1.2% for the source, ascertained at a 99% confidence level within the $2-8$ keV energy band. The simultaneous spectro-polarimetric fitting of NICER, Swift/XRT, and IXPE revealed the presence of a disc with a temperature of $\sim$1 keV and a Comptonized component with a power-law index of $\sim$ 2.4, confirming the soft nature of the source. The polarization degree increases with energy from $\sim$3% in the $2-5.7$ keV band to $\sim$9% in the $5.7-8$ keV band, while the polarization angle is energy independent. The observed energy dependence and the sudden jump of polarization fraction above 5 keV supports the idea of a static slab coronal geometry for the Comptonizing medium of LMC X$-$3. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2309_06830 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Unveiling the X-ray polarimetric properties of LMC X-3 with IXPE, NICER, and Swift/XRT Garg, Akash Rawat, Divya Méndez, Mariano High Energy Astrophysical Phenomena The incoming Imaging X-ray Polarimetry Explorer (IXPE) observations of X-ray binaries provide a new tool to investigate the underlying accretion geometry. Here we report the first measurements of X-ray polarization of the extra-galactic black-hole X-ray binary LMC X$-$3. We find a polarization fraction of $\sim 3%$ at a polarization angle of $\sim 135^\circ$ in the $2-8$ keV energy band with statistical significance at the 7$σ$ level. This polarization measurement significantly exceeds the minimum detectable polarization threshold of 1.2% for the source, ascertained at a 99% confidence level within the $2-8$ keV energy band. The simultaneous spectro-polarimetric fitting of NICER, Swift/XRT, and IXPE revealed the presence of a disc with a temperature of $\sim$1 keV and a Comptonized component with a power-law index of $\sim$ 2.4, confirming the soft nature of the source. The polarization degree increases with energy from $\sim$3% in the $2-5.7$ keV band to $\sim$9% in the $5.7-8$ keV band, while the polarization angle is energy independent. The observed energy dependence and the sudden jump of polarization fraction above 5 keV supports the idea of a static slab coronal geometry for the Comptonizing medium of LMC X$-$3. |
| title | Unveiling the X-ray polarimetric properties of LMC X-3 with IXPE, NICER, and Swift/XRT |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2309.06830 |