Globular clusters in the outer halo of M31: the survey

TL;DR

This paper reports the discovery of 40 new globular clusters in M31's halo, significantly extending the known extent of its GC system and updating the existing catalog with new positional and photometric data.

Contribution

It presents a large survey identifying new GCs in M31's outer halo, revealing a more extensive GC system than previously known, and updates the RBC catalog.

Findings

Discovered 40 new GCs in M31's halo.

Extended the known GC system to ~100 kpc.

Increased confirmed GCs by 10% and those beyond 14 kpc by 75%.

Abstract

We report the discovery of 40 new globular clusters (GCs) that have been found in surveys of the halo of M31 based on INT/WFC and CHFT/Megacam imagery. A subset of these these new GCs are of an extended, diffuse nature, and include those already found in Huxor et al. (2005). The search strategy is described and basic positional and V and I photometric data are presented for each cluster. For a subset of these clusters, K-band photometry is also given. The new clusters continue to be found to the limit of the survey area (~100 kpc), revealing that the GC system of M31 is much more extended than previously realised. The new clusters increase the total number of confirmed GCs in M31 by approximately 10% and the number of confirmed GCs beyond 1 degree (~14 kpc) by more than 75%. We have also used the survey imagery as well recent HST archival data to update the Revised Bologna Catalogue (RBC) of M31 globular clusters.