The extreme properties of the nearby hyper-Eddington accreting Active Galactic Nucleus in IRAS 04416+1215

TL;DR

This study analyzes the extreme accretion properties of the hyper-Eddington AGN IRAS 04416+1215 using X-ray observations, revealing unique spectral features, multi-phase winds, and the lowest coronal temperature measured, advancing understanding of accretion physics.

Contribution

First detailed X-ray spectral analysis of a hyper-Eddington AGN, uncovering its unique coronal temperature and wind structure, providing new insights into extreme accretion regimes.

Findings

IRAS 04416+1215 has the highest Eddington ratio (~472) in the local universe.

It exhibits a multi-phase absorption structure with potential co-spatial winds.

The coronal temperature is the lowest ever measured by NuSTAR (3-22 keV).

Abstract

The physical properties of the accretion flow and of the X-ray emitting plasma, in supermassive black holes accreting at extreme Eddington rates, are still very unclear. Here we present the analysis of simultaneous XMM-Newton and NuSTAR observations of the hyper-Eddington Seyfert 1 galaxy IRAS 04416+1215, carried out in 2020. The main goal of these observations is to investigate the properties of the X-ray corona, as well as the structure of the accretion flow and of the circumnuclear environment, in this regime of extreme accretion. IRAS 04416+1215 has one of the highest Eddington ratio ($\lambda_{\rm Edd}\simeq 472$) in the local Universe. It shows an interesting spectral shape, very similar to the standard Narrow Line Seyfert 1 galaxy's spectra, with the presence of multi-phase absorption structure composed of three phases, whose estimate of the minimum and maximum distances suggests two different interpretations, one consistent with the three X-ray winds being co-spatial, and possibly driven by magnetohydrodynamical processes, the other consistent with the multi-phase winds being also multi-scale. The X-ray spectrum of IRAS 04416+1215 also has a prominent soft excess component and a hard X-ray emission dominated by a reflection component. Moreover, our detailed spectral analysis shows that IRAS 04416+1215 has the lowest coronal temperature measured so far by NuSTAR ($kT_e=3-22$ keV, depending on the model). This is consistent with a hybrid coronal plasma, in which the primary continuum emission is driven by pair production due to high-energy tail of the energy distribution of non-thermal electrons.