# A Long Look At MCG-5-23-16 With NuSTAR: I- Relativistic Reflection And Coronal Properties

## TL;DR

This study analyzes NuSTAR observations of MCG-5-23-16, revealing stable relativistic reflection features, a correlation between cutoff energy and flux, and insights into the coronal plasma's composition and variability mechanisms.

## Contribution

It provides the first detailed spectral analysis of MCG-5-23-16 over multiple years, highlighting stable reflection features and the relationship between coronal properties and X-ray emission.

## Key findings

- Stable reflection spectrum over two years
- Positive correlation between cutoff energy and flux
- Coronal plasma contains mostly electrons, not pairs

## Abstract

MCG-5-23-16 was targeted in early 2015 with a half mega-seconds observing campaign using NuSTAR. Here we present the spectral analysis of these datasets along with an earlier observation and study the relativistic reflection and the primary coronal source. The data show strong reflection features in the form of both narrow and broad iron lines plus a Compton reflection hump. A cutoff energy is significantly detected in all exposures. The shape of the reflection spectrum does not change in the two years spanned by the observations, suggesting a stable geometry. A strong positive correlation is found between the cutoff energy and both the hard X-ray flux and spectral index. The measurements imply that the coronal plasma is not at the runaway electron-positron pair limit, and instead contains mostly electrons. The observed variability in the coronal properties is driven by a variable optical depth. A constant heating to cooling ratio is measured implying that there is a feedback mechanism in which a significant fraction of the photons cooling the corona are due to reprocessed hard X-rays.