Photometric entropy of stellar populations and related diagnostic tools

TL;DR

This paper introduces the concept of photometric entropy to analyze unresolved stellar populations, providing a statistical tool to interpret observational biases and improve diagnostics of clusters and distant galaxies.

Contribution

It presents a novel concept of photometric entropy as a diagnostic tool for unresolved stellar populations, enhancing interpretation of observational data.

Findings

Photometric entropy quantifies the effective number of stellar contributors.

It helps assess observational biases like crowding and surface brightness fluctuations.

The concept improves understanding of stellar population diagnostics.

Abstract

We discuss, from a statistical point of view, some leading issues that deal with the study of stellar populations in fully or partially unresolved aggregates, like globular clusters and distant galaxies. A confident assessment of the effective number and luminosity of stellar contributors can provide, in this regard, a very useful interpretative tool to properly assess the observational bias coming from crowding conditions or surface brightness fluctuations. These arguments have led us to introduce a new concept of "photometric entropy" of a stellar population, whose impact on different astrophysical aspects of cluster diagnostic has been reviewed here.