Tracking the spectral properties across the different epochs in ESO 511-G030

TL;DR

This study investigates the spectral variability of the AGN ESO 511-G030 across different epochs, revealing significant flux decline, spectral changes, and a lack of soft-excess in low flux states linked to accretion rate variations.

Contribution

It provides a detailed analysis of the spectral properties and variability of ESO 511-G030, highlighting the connection between accretion rate changes and spectral features in a low flux state.

Findings

Flux decreased by a factor of 10 in 2019 compared to earlier observations.

Spectral energy distribution shows a superposition of a power-law continuum and reflection components.

The accretion rate dropped from 2% to 0.2% of Eddington, correlating with spectral changes.

Abstract

The Type I active galactic nucleus (AGN) ESO 511-G030, a formerly bright and soft-excess dominated source, has been observed in 2019 in the context of a multi-wavelength monitoring campaign. However, in these novel exposures, the source was found in a $\sim$10 times lower flux state, without any trace of the soft-excess. Interestingly, the X-ray weakening corresponds to a comparable fading of the UV suggesting a strong link between these components. The UV/X-ray spectral energy distribution (SED) of ESO 511-G030 shows remarkable variability. We tested both phenomenological and physically motivated models on the data finding that the overall emission spectrum of ESO 511-G030 in this extremely low flux state is the superposition of a power-law-like continuum ($\Gamma\sim$1.7) and two reflection components emerging from hot and cold matter. has Both the primary continuum and relativistic reflection are produced in the inner regions. The prominent variability of ESO 511-G030 and the lack of a soft-excess can be explained by the dramatic change in the observed accretion rate, which dropped from an L/L$_{\rm Edd}$ of 2\% in 2007 to 0.2\% in 2019. The X-ray photon index also became harder during the low flux 2019 observations, perhaps as a result of a photon starved X-ray corona.