# The properties of broad absorption line outflows based on a large sample of quasars

## TL;DR

This study statistically analyzes quasar outflows, revealing their typical distances, mass flow rates, and energy contributions, which are crucial for understanding galaxy evolution and black hole growth.

## Contribution

It provides the first large-sample statistical distribution of outflow distances and energetics based on broad absorption line variability in quasars.

## Key findings

- Average outflow distance is about 25 parsecs.
- Outflows have mass flow rates of tens to hundreds of solar masses per year.
- Kinetic luminosity ratios suggest outflows can significantly influence host galaxy evolution.

## Abstract

Quasar outflows carry mass, momentum and energy into the surrounding environment, and have long been considered a potential key factor in regulating the growth of supermassive black holes and the evolution of their host galaxies. A crucial parameter for understanding the origin of these outflows and measuring their influence on their host galaxies is the distance (R) between the outflow gas and the galaxy center. While R has been measured in a number of individual galaxies, its distribution remains unknown. Here we report the distributions of R and the kinetic luminosities of quasars outflows, using the statistical properties of broad absorption line variability in a sample of 915 quasars from the Sloan Digital Sky Surveys. The mean and standard deviation of the distribution of R are 10^{1.4+/-0.5} parsecs. The typical outflow distance in this sample is tens of parsec, which is beyond the theoretically predicted location (0.01 ~ 0.1 parsecs) where the accretion disc line-driven wind is launched, but is smaller than the scales of most outflows that are derived using the excited state absorption lines. The typical value of the mass-flow rate is of tens to a hundred solar masses per year, or several times the accretion rate. The typical kinetic-to-bolometric luminosity ratio is a few per cent, indicating that outflows are energetic enough to influence the evolution of their host galaxies.