Low-Mass X-ray Binaries and Globular Clusters in Early-Type Galaxies. II. Globular Cluster Candidates and their Mass-Metallicity Relation
| dc.creator | Humphrey, Philip J | |
| dc.date | 2008-09-03 | |
| dc.date.accessioned | 2026-07-07T12:15:28Z | |
| dc.date.available | 2026-07-07T12:15:28Z | |
| dc.description | We present an astrometry and photometry catalogue of globular cluster (GC) candidates detected with HST WFPC2 in a sample of 19 early-type galaxies, appropriate for comparison to the low-mass X-ray binary (LMXB) populations observed with Chandra. In a companion paper, we present the Chandra data and investigate the relation between these populations. We demonstrate that, although there is little evidence of a colour-magnitude correlation for the GCs, after estimating mass and metallicity from the photometry, under the assumption of a single age simple stellar population, there is a significant positive correlation between mass and metallicity. We constrained [Z/H] = (-2.1+/-0.2)+(0.25+/-0.04)log M, with a 1-sigma intrinsic scatter of 0.62 dex in metallicity. If GCs are bimodal in metallicity this relation is consistent with recent suggestions of a mass-metallicity relation only for metal-poor clusters. Adopting a new technique to fit the GC luminosity function (GCLF) accounting for incompleteness and the Eddington bias, we compute the V-band local GC specific frequency (Sn) and specific luminosity (Sl) of each galaxy. We show that Sl is the more robust measure of the richness of a GC population where a significant fraction is undetected due to source detection incompleteness. We find that the absolute magnitude of the GCLF turnover exhibits intrinsic scatter from galaxy to galaxy of ~0.3mag (1-sigma), limiting its accuracy as a standard distance measure. | |
| dc.description | 15 pages, 7 figures. Accepted for publication in The Astrophysical Journal | |
| dc.identifier | https://arxiv.org/abs/0809.0698 | |
| dc.identifier | http://arxiv.org/abs/0809.0698 | |
| dc.identifier | Astrophys.J.690:512-525,2009 | |
| dc.identifier | doi:10.1088/0004-637X/690/1/512 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/211507 | |
| dc.subject | Astrophysics | |
| dc.title | Low-Mass X-ray Binaries and Globular Clusters in Early-Type Galaxies. II. Globular Cluster Candidates and their Mass-Metallicity Relation | |
| dc.type | text |