Timing analysis of Swift J1658.2-4242's outburst in 2018 with Insight-HXMT, NICER and AstroSat

TL;DR

This paper presents a comprehensive timing analysis of the 2018 outburst of the black hole candidate Swift J1658.2-4242 using data from Insight-HXMT, NICER, and AstroSat, revealing QPOs and their properties.

Contribution

It provides the first detailed timing and spectral analysis of Swift J1658.2-4242 during its outburst, including QPO characteristics and their relation to source properties.

Findings

Detection of Type-C QPOs in 0.8-3.5Hz range.

QPO properties correlate with intensity and hardness.

Support for Lense-Thirring precession origin of QPOs.

Abstract

We present the observational results from a detailed timing analysis of the black hole candidate Swift J1658.2-4242 during its 2018 outburst with the observations of Hard X-ray Modulation Telescope (Insight-HXMT), Neutron Star Interior Composition Explorer (NICER) and AstroSat in 0.1-250keV. The evolution of intensity, hardness and integrated fractional root mean square (rms) observed by Insight-HXMT and NICER are presented in this paper. Type-C quasi-periodic oscillations (QPOs) observed by NICER (0.8-3.5Hz) and Insight-HXMT (1-1.6Hz) are also reported in this work. The features of the QPOs are analysed with an energy range of 0.5-50keV. The relations between QPO frequency and other characteristics such as intensity, hardness and QPO rms are carefully studied. The timing and spectral properties indicate that Swift J1658.2-4242 is a black hole binary system. Besides, the rms spectra of the source calculated from the simultaneous observation of Insight-HXMT, NICER and AstroSat support the Lense-Thirring origin of the QPOs. The relation between QPO phase lag and the centroid frequency of Swift J1658.2-4242 reveals a near zero constant when < 4Hz and a soft phase lag at 6.68 Hz. This independence follows the same trend as the high inclination galactic black hole binaries such as MAXI J1659-152.