The Origin of The Soft X-Ray Excess in the Seyfert 1.5 Galaxy ESO 362-G18

TL;DR

This study investigates the origin of the soft X-ray excess in Seyfert 1.5 galaxy ESO 362-G18 using simultaneous X-ray observations, comparing different models to identify the most plausible explanation for the observed spectra.

Contribution

It provides a comprehensive spectral analysis of ESO 362-G18, evaluating multiple models and demonstrating that the warm corona model best reproduces the spectral and timing features.

Findings

Both Warm Corona and Relativistic Reflection models fit the time-averaged spectra well.

Warm corona model successfully reproduces RMS and covariance spectra.

Inner compact corona and neutral distant reflection contribute differently at various frequencies.

Abstract

We review the Seyfert 1.5 Galaxy ESO 362-G18 for exploring the origin of the soft X-ray excess. The Warm Corona and Relativistic Reflection models are two main scenarios to interpret the soft X-ray excess in AGNs at present. We use the simultaneous X-ray observation data of XMM-Newton and NuSTAR on Sep. 24th, 2016 to perform spectral analysis in two steps. First, we analyze the time-average spectra by using Warm Corona and Relativistic Reflection models. Moreover, we also explore the Hybrid model, Double Reflection model and Double Warm Corona model. We find that both of Warm Corona and Relativistic Reflection models can interpret the time-average spectra well but cannot be distinguished easily based on the time-averaged spectra fit statistics. Second, we add the RMS and covariance spectra to perform the spectral analysis with time-average spectra. The result shows that the warm corona could reproduce all of these spectra well. The the hot, optical thin corona and neutral distant reflection will increase their contribution with the temporal frequency, meaning that the corona responsible for X-ray continuum comes from the inner compact X-ray region and the neutral distant reflection is made of some moderate scale neutral clumps.