Low-Frequency Quasi-Periodic Oscillations in the X-ray Nova MAXI J1535-571 at the Initial Stage of Its 2017 Outburst

TL;DR

This paper reports the discovery and analysis of low-frequency quasi-periodic oscillations in the X-ray nova MAXI J1535-571 during its 2017 outburst, examining their evolution and implications for theoretical models.

Contribution

It presents the first detection of low-frequency QPOs in MAXI J1535-571 and analyzes their evolution and correlation with spectral changes during the outburst.

Findings

QPO frequency increased during the initial outburst phase

QPO properties correlated with spectral hardness and flux

Constraints placed on QPO generation models

Abstract

We report the discovery of low-frequency quasi-periodic oscillations (QPOs) in the power spectrum of the X-ray nova MAXI J1535-571 at the initial stage of its outburst in September 2017. Based on data from the SWIFT and INTEGRAL instruments, we have traced the evolution of the QPO parameters (primarily their frequency) with time and their correlation with changes in the X-ray spectrum of the source (changes in the emission flux and hardness). We place constraints on the theoretical QPO generation models.