Work

The First Detection of X-Ray Polarization in a Newly Discovered Galactic Transient Swift J151857.0-572147

Year: 2024

Type: article

Abstract: We study the spectropolarimetric properties of a newly discovered black hole (BH) X-ray binary Swift J151857.0-572147 jointly using Imaging X-ray Polarimetry Explorer (IXPE) and NuSTAR observations during 2024 March. The analysis of IXPE data reports the first detection of X-ray with a polarization degree (PD) of 1.34 ± 0.27 and a polarization angle (PA) of −13.°69 ± 5.°85 using a model-independent approach, while the model-dependent analysis gives a PD of 1.18 ± 0.23 and a PA of −14.°01 ± 5.°80. The joint spectral analysis of the broadband data and NuSTAR analysis in isolation constrain the mass of the central BH between ∼9.2 ± 1.6 and 10.1 ± 1.7M ⊙ and a moderate spin parameter of ∼0.6 ± 0.1–0.7 ± 0.2 with a disk inclination of ∼35° ± 7°–46° ± 15°. The power-law photon index and cutoff energy are 2.19 ± 0.03–2.47 ± 0.06 and ∼36 ± 4–78 ± 10 keV, suggesting a transition to the soft spectral state. Additionally, a relatively lower corona size of 6 ± 1–9 ± 2r S , a low mass outflow rate ( < 3 % M ̇ Edd ), and the best-fitted halo accretion is less compared to the disk accretion rate further confirm the same state. The low PD detected in the soft state 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 at ∼4–5 × 1022 cm−2.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/ad7d92

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

Institutions: Indian Institute of Astrophysics, Yunnan University, Indian Space Research Organisation, U. R. Rao Satellite Centre

Language: English

Topic: Astrophysical Phenomena and Observations

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499