Detection of a possible multiphase ultra-fast outflow in IRAS 13349+2438 with NuSTAR and XMM-Newton

TL;DR

This paper reports the detection of a complex, multi-layered ultra-fast outflow in the quasar IRAS 13349+2438, characterized by relativistic absorption features indicating stratified wind structures near the black hole.

Contribution

First detection of a multi-phase ultra-fast outflow in IRAS 13349+2438 using combined NuSTAR and XMM-Newton data, revealing stratified wind velocities and ionization states.

Findings

Identification of two relativistic iron absorption lines at 8 and 9 keV.

Evidence for stratified outflow with different velocities and ionization levels.

Detection of Lyα absorption lines consistent with the outflow's velocity structure.

Abstract

We present joint NuSTAR and XMM-Newton observations of the bright, variable quasar IRAS 13349+2438. This combined dataset shows two clear iron absorption lines at 8 and 9 keV, which are most likely associated with two layers of mildly relativistic blueshifted absorption, with velocities of 0.14c and 0.27c. We also find strong evidence for a series of Ly$\alpha$ absorption lines at intermediate energies in a stacked XMM-Newton EPIC-pn spectrum, at the same blueshift as the lower velocity iron feature. This is consistent with a scenario where an outflowing wind is radially stratified, so faster, higher ionization material is observed closer to the black hole, and cooler, slower material is seen from streamlines at larger radii.