# Leaked Lya emission: an indicator of the size of quasar absorption outflows

## TL;DR

This paper introduces a new method to estimate the size of quasar absorption outflows using leaked Lya emission, revealing outflow sizes larger than theoretical predictions but smaller than previous estimates, with implications for galaxy feedback.

## Contribution

The study proposes a novel approach to measure BAL outflow sizes via leaked Lya emission, overcoming limitations of traditional absorption trough methods.

## Key findings

- Outflow sizes are 3-26 parsecs, larger than disc wind models predict.
- Lower limits of kinetic luminosity are 0.02%-0.07% of Eddington luminosity.
- Identified three quasars with leaked Lya emission in SDSS data.

## Abstract

The galactocentric distance of quasar absorption outflows are conventionally determined using absorption troughs from excited states, a method hindered by severely saturated or self-blended absorption troughs. We propose a novel method to estimate the size of a broad absorption line (BAL) region which partly obscures an emission line region by assuming virialized gas in the emission region surrounding a supermassive black hole with known mass. When a spiky Lya1216 line emission is present at the flat bottom of the deep Nv1240 absorption trough, the size of BAL region can be estimated. We have found 3 BAL quasars in the SDSS database showing such Lya lines. The scale of their BAL outflows are found to be 3-26 pc, moderately larger than the theoretical scale (0.01-0.1 pc) of trough forming regions for winds originating from accretion discs, but significantly smaller than most outflow sizes derived using the absorption troughs of the excited states of ions. For these three outflows, the lower limits of ratio of kinetic luminosity to Eddington luminosity are 0.02%-0.07%. These lower limits are substantially smaller than that is required to have significant feedback effect on their host galaxies.