A NuSTAR study of quasi-periodic oscillations from the ultraluminous X-ray sources in M82

TL;DR

This paper analyzes NuSTAR observations of M82's ultraluminous X-ray sources, focusing on the evolution of quasi-periodic oscillations to understand accretion physics around compact objects.

Contribution

It provides detailed analysis of QPO evolution in M82 X-1, revealing similarities with low-frequency oscillations in other accreting systems.

Findings

QPO observed in 20--300 mHz range.

No additional timing features detected.

QPO behavior resembles other low-frequency oscillations.

Abstract

The study of quasi-periodic oscillations in X-ray binaries provides valuable insights into the physics of accretion around compact objects. The M82 galaxy hosts two ultraluminous X-ray sources (ULXs), one of which is suspected to harbor an intermediate-mass black hole. Using 39 NuSTAR observations acquired between 2014--2024, we investigate the aperiodic X-ray variability in M82. In particular, we study in detail the evolution of the QPO from M82 X-1 in the range 20--300 mHz. We do not find additional timing features in the data, besides a frequent broad noise component at lower frequencies. The QPO behaves similarly to other classes of low-frequency oscillations in accreting compact objects, both black holes and neutron stars.