Cooling waves in pair plasma

TL;DR

This paper investigates the cooling behavior of a pair plasma fireball, revealing a distinct cooling wave with specific temperature and density profiles, and characterizing its propagation velocity and emission properties.

Contribution

It introduces the concept of a cooling wave in pair plasma fireballs and details its structure, emission, and velocity characteristics at high temperatures.

Findings

Cooling occurs via a well-defined wave at T ≥ 0.5 m_e c^2

Surface temperature remains above 50 keV during cooling

Cooling wave velocity is much less than the speed of light and decreases with temperature

Abstract

We consider structure and emission properties of a pair plasma fireball that cools due to radiation. At temperatures $T \geq 0.5 m_e c^2$ the cooling takes a form of clearly defined cooling wave, whereby the temperature and pair density experience a sharp drop within a narrow region. The surface temperature, corresponding to the location where the optical depth to infinity reaches unity, never falls much below $0.1 m_e c^2 \approx 50$ keV. The propagation velocity of the cooling wave is much smaller than the speed of light and decreases with increasing bulk temperature.