Galaxy structure from multiple tracers: I. A census of M87's globular cluster populations

TL;DR

This paper provides a comprehensive catalog of over 17,600 globular clusters around M87, analyzing their distributions and properties to understand galaxy formation processes.

Contribution

It introduces a new photometric catalog of M87's globular clusters and applies Bayesian analysis to characterize their populations and gradients.

Findings

GC populations are best described as two distinct groups.

Color gradients vary with radius in both GC populations.

Red GCs are more centrally concentrated, indicating different formation histories.

Abstract

We present a new photometric catalogue of the rich globular cluster (GC) system around M87, the brightest cluster galaxy in Virgo. Using archival Next Generation Virgo cluster Survey (NGVS) images in the ugriz bands, observed with CFHT/MegaPrime, we perform a careful subtraction of the galaxy's halo light in order to detect objects at small galactocentric radii as well as in the wider field, and find 17620 GC candidates over a radius range from 1.3 kpc to 445 kpc with g < 24 magnitudes. By inferring their colour, radial and magnitude distributions in a Bayesian way, we find that they are well described as a mixture of two GC populations and two distinct contaminant populations, but confirm earlier findings of radius-dependent colour gradients in both GC populations. This is consistent with a picture in which the more enriched GCs reside deeper in the galaxy's potential well, indicating a role for dissipative collapse in the formation of both the red and the blue GCs.