Modeling reflection spectra of super-Eddington X-ray sources

TL;DR

This paper introduces reflux, a new X-ray reflection model tailored for super-Eddington sources, incorporating a slim-disk and wind framework to better understand accretion physics and spectral features.

Contribution

It develops two novel relativistic reflection models for super-Eddington accretion, accounting for disk thickening and outflow geometries, and applies them to observational data.

Findings

The slim-disk model alters the Fe K emission profile, reducing the blue horn brightness.

The wind model predicts a blue-shifted iron line due to high-velocity outflows.

Application to Swift J1644+57 constrains funnel opening angle and wind speed.

Abstract

Relativistic reflection is a common feature in the X-ray observations of accreting compact objects. We present reflux, a new X-ray reflection model for spectral analysis of super-Eddington sources. We develop two relativistic reflection frameworks for super-Eddington accretion: a slim-disk model that self-consistently accounts for disk thickening and self-shadowing, and an optically thick wind model that treats reflection off a funnel-shaped outflow. The slim-disk model offers a geometry where the inner disk thickness is proportional to radius, becoming thicker as the mass accretion rate increases. The wind model measures the opening angle of the funnel, the wind speed, and wind acceleration radius. The slim-disk profile reduces the brightness of the blue horn in the Fe K emission line for a fixed emissivity and significantly changes the intensity profile for a lamppost geometry. The wind model shows a blue-shifted iron line due to high velocity outflows. Both models assume a spherically symmetric spacetime. We apply the wind model to the XMM-Newton spectrum of the tidal disruption event Swift J1644+57, where the Fe K profile is expected to be shaped by scattering in an outflowing funnel. We constrain the opening angle of the funnel and find a high velocity of the wind.