Absorption features in the quasar HS 1603+3820 II. Distance to the absorber from photoionisation modelling

TL;DR

This study uses photoionisation modeling with multi-wavelength data to determine the proximity of an intrinsic absorber in quasar HS 1603+3820, finding it very close to the nucleus at about 0.1 parsecs.

Contribution

It provides the first detailed photoionisation analysis of the absorber in HS 1603+3820, estimating its distance from the quasar nucleus using spectral data and modeling.

Findings

Absorber located at approximately 0.1 parsecs from the nucleus.

High CIV to HI ratio constrains ionisation conditions.

Absorber is closer than the Broad Line Region in this quasar.

Abstract

We present photoionisation modelling of the intrinsic absorber in the bright quasar HS 1603+3820. We construct spectral energy distribution using optical/UV/X-ray observations as an input to photoionisation calculations. Spectra from Keck telescope show extremely high ratio of CIV to HI, for the first absorber in system A, named A1. This value, together with high column density of CIV ion, puts strong constraints on photoionisation model. We use photoionisation modeling to derive hydrogen number density at the cloud illuminated surface. Estimating bolometric luminosity of HS 1603+3820, from typical formula for quasars, we calculate the distance to A1. The derived location is as close as 0.1 pc, and situates an absorber even closer to the nucleus than the possible location of the Broad Line Region in this object