# Vertical Advection Effects on Hyper-accretion Disks and Potential Link between Gamma-ray Bursts and Kilonovae

## TL;DR

This paper investigates how vertical advection in hyper-accretion disks influences their structure and radiation, suggesting a potential connection between gamma-ray bursts and kilonovae through gamma-ray photon escape.

## Contribution

It introduces a revised model of hyper-accretion disks incorporating vertical advection, highlighting its effects on temperature, neutrino, and gamma-ray luminosities, and proposes a link to gamma-ray bursts and kilonovae.

## Key findings

- Vertical advection lowers disk temperature compared to classic models.
- Neutrino luminosity from the disk is reduced due to strong cooling.
- Gamma-ray photons can escape in super-Eddington amounts, potentially powering gamma-ray bursts.

## Abstract

Recent simulations on super-Eddington accretion flows have shown that, apart from the diffusion process, the vertical advection based on magnetic buoyancy can be a more efficient process to release the trapped photons in the optically thick disk. As a consequence, the radiative luminosity from the accretion disk can be far beyond the Eddington value. Following this spirit, we revisit the structure and radiation of hyper-accretion disks with mass accretion rates in the range $10^{-3}\sim 10~M_{\sun}~{\rm s}^{-1}$. Our results show that, due to the strong cooling through the vertical advection, the disk temperature becomes lower than that in the classic model without the vertical advection process, and therefore the neutrino luminosity from the disk is lower. On the other hand, the gamma-ray photons released through the vertical advection can be extremely super-Eddington. We argue that the large amount of escaped gamma-ray photons may have more significant contribution to the primordial fireball than the neutrino annihilation, and may hint a link between gamma-ray bursts and kilonovae in the black hole hyper-accretion scenario.