Slit and integral-field optical spectroscopy of the enigmatic quasar HE0450-2958

TL;DR

This study uses advanced spectroscopy techniques to analyze the gaseous and stellar environment of quasar HE0450-2958, revealing a complex, perturbed system with no detectable host galaxy despite detailed observations.

Contribution

It introduces new methods for separating quasar and diffuse components in spectra and provides detailed analysis of the quasar's environment using integral field spectroscopy.

Findings

Gas is mostly ionized by the QSO radiation and shocks.

The system is strongly perturbed with unrelated gas and star dynamics.

The host galaxy remains undetected despite extensive observations.

Abstract

Interest in the quasar HE0450-2958 arose following the publication of the non-detection of its expected massive host, leading to various interpretations. This article investigates the gaseous and stellar contents of the system through additional VLT/FORS slit spectra and integral field spectroscopy from VLT/VIMOS. We apply our MCS deconvolution algorithm on slit spectra for the separation of the QSO and diffuse components, and develop a new method to remove the point sources in Integral Field Spectra, allowing extraction of velocity maps, narrow-line images, spatially resolved spectra or ionization diagrams of the surroundings of HE0450-2958. The whole system is embedded in gas, mostly ionized by the QSO radiation field and shocks associated with radio jets. The observed gas and star dynamics are unrelated, revealing a strongly perturbed system. Despite longer spectroscopic observations, the host galaxy remains undetected.