The Intrinsic Properties of SDSS Galaxies

TL;DR

This paper analyzes how galaxy properties depend on inclination and derives corrections to recover their intrinsic, inclination-independent properties using SDSS and 2MASS data, revealing significant corrections influenced by galaxy structure.

Contribution

It provides a method to determine inclination corrections for galaxy properties based on luminosity and Sersic index, improving the accuracy of intrinsic galaxy measurements.

Findings

Inclination corrections can reach up to 1.2 mag in the g-band.

Corrections depend strongly on galaxy Sersic index.

The red-to-blue galaxy ratio changes when correcting for inclination.

Abstract

The observed properties of galaxies vary with inclination; for most applications we would rather have properties that are independent of inclination, intrinsic properties. One way to determine inclination corrections is to consider a large sample of galaxies, study how the observed properties of these galaxies depend on inclination and then remove this dependence to recover the intrinsic properties. We perform such an analysis for galaxies selected from the Sloan Digital Sky Survey which have been matched to galaxies from the Two-Micron All Sky Survey. We determine inclination corrections for these galaxies as a function of galaxy luminosity and Sersic index. In the g-band these corrections reach as as high as 1.2 mag and have a median value of 0.3 mag for all galaxies in our sample. We find that the corrections show little dependence on galaxy luminosity, except in the $u$ band, but are strongly dependent on galaxy Sersic index. We find that the ratio of red-to-blue galaxies changes from 1:1 to 1:2 when going from observed to intrinsic colors for galaxies in the range -22.75 < M_K < -17.75. We also discuss how survey completeness and photometric redshifts should be determined when taking into account that observed and intrinsic properties differ. Finally, we examine whether previous determinations of stellar mass give an intrinsic quantity or one that depends on galaxy inclination.