A variable ionized disk wind in the black hole candidate EXO 1846-031

Wang, Yanan and Ji, Long and García, Javier A. and Dauser, Thomas and Méndez, Mariano and Mao, Junjie and Tao, L. and Altamirano, Diego and Maggi, Pierre and Zhang, S. N. and Ge, M. Y. and Zhang, L. and Qu, J. L. and Zhang, S. N. and Ma, X. and Lu, F. J. and Li, T. P. and Huang, Y. and Zheng, S. J. and Chang, Z. and Tuo, Y. L. and Song, L. M. and Xu, Y. P. and Chen, Y. P. and Liu, C. Z. and Bu, Q. C. and Cai, C. and Cao, X. L. and Chen, L. and Chen, T. X. and Chen, Y. P. and Cui, W. W. and Du, Y. Y. and Gao, G. H. and Gu, Y. D. and Guan, J. and Guo, C. C. and Han, D. W. and Huo, J. and Jia, S. M. and Jiang, W. C. and Jin, J. and Kong, L. D. and Li, B. and Li, C. K. and Li, G. and Li, W. and Li, X. and Li, X. B. and Li, X. F. and Li, Z. W. and Liang, X. H. and Liao, J. Y. and Liu, H. W. and Liu, X. J. and Lu, X. F. and Luo, Q. and Luo, T. and Meng, B. and Nang, Y. and Nie, J. Y. and Ou, G. and Sai, N. and Shang, R. C. and Song, X. Y. and Sun, L. and Tan, Y. and Wang, W. S. and Wang, Y. D. and Wang, Y. S. and Wen, X. Y. and Wu, B. B. and Wu, B. Y. and Wu, M. and Xiao, G. C. and Xiao, S. and Xiong, S. L. and Yang, S. and Yang, Y. J. and Yi, Q. B. and Yin, Q. Q. and You, Y. and Zhang, F. and Zhang, H. M. and Zhang, J. and Zhang, W. C. and Zhang, W. and Zhang, Y. F. and Zhao, H. S. and Zhao, X. F. and Zhou, D. K. (2020) A variable ionized disk wind in the black hole candidate EXO 1846-031. Astrophysical Journal, 906. 11. ISSN 1538-4357 (https://doi.org/10.3847/1538-4357/abc55e)

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After 34 yr, the black hole candidate EXO 1846-031 went into outburst again in 2019. We investigate its spectral properties in the hard intermediate and the soft states with NuSTAR and Insight-HXMT. A reflection component has been detected in the two spectral states but possibly originating from different illumination spectra: in the intermediate state, the illuminating source is attributed to a hard coronal component, which has been commonly observed in other X-ray binaries, whereas in the soft state, the reflection is probably produced by disk self-irradiation. Both cases support EXO 1846-031 as a low-inclination system of ∼ 40. An absorption line is clearly detected at ∼7.2 keV in the hard intermediate state, corresponding to a highly ionized disk wind (log, ξ > 6.1) with a velocity of up to 0.06c. Meanwhile, quasi-simultaneous radio emissions have been detected before and after the X-rays, implying the coexistence of disk winds and jets in this system. If only the high-flux segment of the NuSTAR observation is considered, the observed wind appears to be magnetically driven. The absorption line disappeared in the soft state and a narrow emission line appeared at ∼6.7 keV on top of the reflection component, which may be evidence for disk winds, but data with higher spectral resolution are required to examine this.