Published in Publications of the Astronomical Society of Australia, Volume 29, Issue 4, pp. 489-508, 2012.
https://arxiv.org/abs/1205.1498

For a PDF version of the article, click here.

DISTANCE MEASUREMENTS AND STELLAR POPULATION PROPERTIES VIA SURFACE BRIGHTNESS FLUCTUATIONS

Alexander Fritz A, B, C


A Gemini Observatory, 670 N. A’ohoku Place, Hilo, HI 96720, USA
B Istituto Nazionale di AstrofisicaIstituto di Astrofisica Spaziale e Fisica Cosmica Milano, Via E. Bassini 15, 20133 Milano, Italy
C VIPERS Fellow;


Abstract: Surface Brightness Fluctuations (SBFs) are one of the most powerful techniques to measure the distance and to constrain the unresolved stellar content of extragalactic systems. For a given bandpass, the absolute SBF magnitude bar{M} depends on the properties of the underlying stellar population. Multi-band SBFs allow scientists to probe different stages of the stellar evolution: UV and blue wavelength band SBFs are sensitive to the evolution of stars within the hot Horizontal Branch (HB) and post-Asymptotic Giant Branch (post-AGB) phase, whereas optical SBF magnitudes explore the stars within the Red Giant Branch (RGB) and HB regime. Near- and Far-infrared SBF luminosities probe the important stellar evolution stage within the AGB and Thermally-Pulsating Asymptotic Giant Branch (TP-AGB) phase. Since the first successful application by Tonry and Schneider, a multiplicity of works have used this method to expand the distance scale up to 150 Mpc and beyond. This article gives a historical background of distance measurements, reviews the basic concepts of the SBF technique, presents a broad sample of these investigations and discusses possible selection effects, biases, and limitations of the method. In particular, exciting new developments and improvements in the field of stellar population synthesis are discussed that are essential to understand the physics and properties of the populations in unresolved stellar systems. Further, promising future directions of the SBF technique are presented. With new upcoming space-based satellites such as Gaia, the SBF method will remain as one of the most important tools to derive distances to galaxies with unprecedented accuracy and to give detailed insights into the stellar content of globular clusters and galaxies.


Keywords: cosmology: distance scale — galaxies: distances and redshifts — galaxies: stellar content — galaxies: elliptical and lenticular, cD — galaxies: fundamental parameters — stars: statistics


Table of Contents

INTRODUCTION
Early Concepts
Important Steps Towards the Cosmological Distance Ladder
A Brief History of SBFs

THE METHOD
Types of Fluctuations
SBF Signal Measurement

OBSERVATIONS
Optical SBF
Near-Infrared SBF
SBF from HST
Optical
Near-Infrared
Stellar Population Gradients

SBF AS A STANDARD CANDLE
Caveats for Distance Determinations
Target Selection
PSF Modelling
Background Sources
The Good, the Bad, and the Ugly

THEORY MEETS OBSERVATION
Origin of SBFs
The Late Stages of Cool Giant Stars
Improved Stellar Population Models

A MEASURE OF DISTANCE-INDEPENDENT LUMINOSITIES

CONCLUSIONS

FUTURE DIRECTIONS

REFERENCES

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