Energy implications of temperature fluctuations in photoionized plasma

TL;DR

This paper investigates how temperature fluctuations in photoionized nebulae affect the energy radiated through emission lines, considering the impact of an unknown heating process and its correlation with metallicity.

Contribution

It quantifies the energy radiated due to temperature fluctuations in photoionized plasma and explores their dependence on metallicity and fluctuation amplitude.

Findings

Energy radiated scales with fluctuation amplitude t^2.

Fluctuations correlate with metallicity Z when Z > 0.7 solar.

Excess energy radiated is comparable to the energy absorbed, scaled by t^2.

Abstract

We quantify the energy radiated through all the collisionally excited lines in a photoionized nebula which is permeated by temperature fluctuations. We assume that these correspond to hot spots which are the results of an unknown heating process distinct from the photoelectric heating. We consider all the effects of using a higher mean temperature (as compared to the equilibrium temperature) due to the fluctuations not only on each emission line but also on the ionization state of the gas. If this yet unknown process was to radiate a fixed amount of energy, we find that the fluctuations should correlate with metallicity Z when it exceeds 0.7 solar. The excess energy radiated in the lines as a result of the fluctuations is found to scale proportionally to their amplitude t^2. When referred to the total energy absorbed through photoionization, the excess energy is comparable in magnitude to t^2.