Astronomical Distance Determination in the Space Age. Secondary distance indicators

TL;DR

This paper reviews various methods for determining extragalactic distances, emphasizing recent developments and the prominent role of Supernovae Ia in measuring the universe's expansion.

Contribution

It provides a comprehensive overview of all distance determination methods, focusing on recent advancements and future prospects, beyond traditional primary and secondary classifications.

Findings

Supernovae Ia are the most successful distance indicators.

Recent methods are rapidly developing, improving distance measurements.

Traditional methods are also progressing alongside new techniques.

Abstract

The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations.