Kinematic Stratification in Extremely Red Quasars Revealed by JWST

TL;DR

This study uses JWST spectra to analyze the complex, stratified kinematic structures of emission lines in extremely red quasars, revealing insights into their dust-obscured nuclei and gas dynamics.

Contribution

We present a detailed kinematic analysis of ERQ emission lines, deblending components and combining JWST data with archival SEDs to understand their dust obscuration and gas structures.

Findings

Kinematic components imply velocity- and density-stratified gas structures.

ERQs have dust-obscured nuclei with scattered UV/optical flux.

Optical emission-line ratios suggest a mix of scattered and obscured emission.

Abstract

We analyze the spectra of the central nuclei of extremely red quasars (ERQs) observed as part of the JWST ERS Q3D program. We focus on the complex kinematic structures of the prominent rest-frame optical emission lines. Our modeling allows us to deblend the lines and separate the emission into distinct kinematic components that imply velocity- and density-stratified gas structures on a range of physical scales within the ERQs. Supplementing the JWST data with archival data, we analyze the spectral energy distributions (SEDs) of the ERQs and find they are consistent with a significantly dust-obscured central source with a small amount of relatively-unobscured UV/optical flux that is scattered into our line-of-sight. While the kinematics of the UV and optical emission lines largely agree, the UV lines are dominated by scattered light. In contrast, the optical emission-line ratios indicate a combination of scattered and obscured emission. Our analysis focuses on one ERQ, J0834, because its distinct spectroscopic features allow the emission to be easily decomposed into separate kinematic components.