Effect of nuclear stars gravity on quasar radiation feedback on the parsec-scale

TL;DR

This study investigates how nuclear star gravity influences quasar radiation-driven flows on parsec scales, revealing its significant role in outflow collimation and black hole accretion depending on X-ray photon contribution.

Contribution

It is the first to simulate the combined effects of nuclear star gravity and quasar radiation feedback on parsec-scale flows, highlighting the importance of X-ray photon fraction.

Findings

Nuclear star gravity helps collimate outflows driven by UV photons.

It weakens outflow power at the outer boundary.

It enhances the net accretion rate onto the black hole.

Abstract

It is often suggested that a super massive black hole is embedded in a nuclear bulge of size of a few $10^2$ $\text{ parsec}$ . The nuclear stars gravity is not negligible near $\sim 10 \text{ parsec}$. In order to study the effect of nuclear stars gravity on quasar radiation feedback on the parsec scale, we have simulated the parsec scale flows irradiated by a quasar by taking into account the gravitational potential of both the black hole and the nuclear star cluster. We find that the effect of nuclear stars gravity on the parsec-scale flows is related to the fraction of X-ray photons in quasar radiation. For the models in which the fraction of X-ray photons is not small (e.g. the X-ray photons contribute to $20\%$ of the quasar radiation), the nuclear stars gravity is very helpful to collimate the outflows driven by UV photons, significantly weakens the outflow power at the outer boundary and significantly enhances the net accretion rate onto the black hole. For the models in which X-ray photons are significantly decreased (e.g. the X-ray photons contribute to $5\%$ of the quasar radiation), the nuclear stars gravity can just slightly change properties of outflow and slightly enhance the net accretion rate onto the black hole.