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arXiv 2404.09643astro-ph.HE
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新发现的银河系暂现源Swift\,J151857.0-572147的X射线偏振首次探测

The first detection of X-ray polarization in a newly discovered Galactic transient Swift\,J151857.0-572147

Santanu Mondal, S. Pujitha Suribhatla, Kaushik Chatterjee, Chandra B. Singh, Rwitika Chatterjee

AI总结:

本文利用IXPE和NuSTAR观测数据,首次探测到银河系黑洞X射线双星Swift J151857.0-572147的X射线偏振,通过联合光谱分析限制了中心黑洞质量、自旋和盘倾角,发现其处于软谱态且偏振度较低。

摘要:

我们利用2024年3月的IXPE和NuSTAR观测数据,联合研究了新发现的黑洞X射线双星Swift J151857.0-572147的光谱偏振特性。对IXPE数据的分析显示,采用不依赖模型的方法首次探测到X射线偏振,其偏振度(PD)为$1.34\pm0.27$,偏振角(PA)为$-13.69^\circ\pm5.85^\circ$;而依赖模型的分析给出PD为$1.18\pm0.23$,PA为$-14.01^\circ\pm5.80^\circ$。宽波段数据的联合光谱分析与单独的NuSTAR分析将中心黑洞的质量限制在$\sim 9.2\pm1.6-10.1\pm1.7 M_\odot$之间,自旋参数为中等的$\sim0.6\pm0.1-0.7\pm0.2$,盘倾角为$\sim 35^\circ\pm7^\circ-46^\circ\pm15^\circ$。幂律光子指数和截止能量分别为$2.19\pm0.03-2.47\pm0.06$和$\sim 36\pm4-78\pm10$ keV,表明该源正过渡到软谱态(SS)。此外,相对较小的冕区尺寸$6\pm1-9\pm2$ $r_S$、较低的物质外流率($<3$% $\dot M_{\rm Edd}$),以及拟合得到的晕吸积率低于盘吸积率,都进一步证实了这一状态。软谱态中探测到的低偏振度可能源于致密冕内部的反复散射以及盘辐射占主导,这与低自旋和低盘倾角的结果相符。拟合得到的氢柱密度相对较高,为$\sim 4-5\times 10^{22}$ cm$^{-2}$。

英文摘要:

We study the spectro-polarimetric properties of a newly discovered black hole X-ray binary Swift\,J151857.0-572147 jointly using {\it IXPE} and {\it NuSTAR} observations during March 2024. The analysis of {\it IXPE} data reports the first detection of X-ray polarization with degree (PD) $1.34\pm0.27$ and polarization angle (PA) $-13.69^\circ\pm5.85^\circ$ using model-independent approach, while the model-dependent analysis gives PD $1.18\pm0.23$ and PA $-14.01^\circ\pm5.80^\circ$. The joint spectral analysis of the broadband data and {\it NuSTAR} analysis in isolation constrain the mass of the central black hole between $\sim 9.2\pm1.6-10.1\pm1.7 M_\odot$ and a moderate spin parameter of $\sim0.6\pm0.1-0.7\pm0.2$ with disk inclination $\sim 35^\circ\pm7^\circ-46^\circ\pm15^\circ$. The power-law photon index and cutoff energy are $2.19\pm0.03-2.47\pm0.06$ and $\sim 36\pm4-78\pm10$ keV, suggesting a transition to the soft spectral state (SS). Additionally, a relatively lower corona size of $6\pm1-9\pm2$ $r_S$, a low mass outflow rate ($<3$\% $\dot M_{\rm Edd}$), and the best-fitted halo accretion is less compared to the disk accretion rate further confirms the same state. The low PD detected in the SS can be due to repeated scattering inside the dense corona and the dominant emission from the disk, agrees with the low spin and low disk inclination. The hydrogen column density obtained from the fit is relatively high $\sim 4-5\times 10^{22}$ cm$^{-2}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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