Searching for distant galaxy clusters in the XMM-XXL southern field using deep Z-band images from DECam

We present a high-redshift galaxy cluster candidate catalogue created using two galaxy based detection methods: z' and 3.6 μm red sequence method and the Stellar Bump Sequence method. This utilises new z' band observations from the dark energy camera on the 8 m Blanco telescope in CTIO, Chile, in addition to mid-infrared Spitzer observations from the SSDF survey. These observations have 5σ sensitivity limits of 24.4, 21.8 and 21.5 ABmagnitude in z', 3.6 μm and 4.5 μm bands respectively. We create an aperture corrected z' band catalogue which is cross-referenced with an existing aperture corrected Spitzer 3.6 μm and 4.5 μm catalogue, to produce a catalogue containing 2,137,515 unique objects in the XXL-S field. We then use custom redshifted BC03 stellar population models to simulate the galactic red sequence, that we use to match observed colours created from the three bands used. By assigning redshifts based on colours to objects in our catalogue, we are able to create a spatial density map which we then analyse to look for overdensities of galaxies. Finally, we present a catalogue that contains 802 candidate galaxy clusters in the redshiftrange 0:4 < z < 2:1, of which 721 are new detections. We also detect 32 spectroscopically confirmed X-ray selected galaxy clusters at redshifts up to z = 0:87.