Tutorial: Re-creating the ACT DR5 Cluster Catalog

Here we provide a guide to reproducing the ACT DR5 cluster catalog.

Note

The config files and scripts needed for this tutorial can be found in the examples/ACT-DR5-clusters directory of the Nemo source distribution.

Note

The released ACT DR5 cluster catalog v1.1 was produced with code that is closest (but not identical) to Nemo v0.5.0. Later versions of Nemo may produce slightly different output as the code is improved and bugs are fixed.

Downloading maps and other needed files

The first step is to download the ACT DR5 maps, described in Naess et al. (2020), from LAMBDA. In addition to this, we require some mask files, point source catalogs, and the beam profiles. These can all be downloaded and extracted by running a script:

sh FETCH_MAPS.sh

Each map is 5 Gb in size, so this may take a while. The archive named nemo-dr5-masking.tar.gz downloaded by this script contains the masks, point source catalogs, beam profiles, and a catalog of cluster redshifts (see Inferring cluster masses below).

Extracting the cluster candidate list

The DR5 maps are large, and so Nemo breaks these maps into tiles, which can be processed separately in parallel, before combining the output to make the final catalog and filtered maps. A script (DR5Clusters.slurm) is provided that will run nemo in this mode using the Slurm Workload Manager :

#!/bin/sh
#SBATCH --nodes=18
#SBATCH --ntasks-per-node=16
#SBATCH --mem=64000
#SBATCH --time=03:59:00
#SBATCH --output=DR5ClusterSearch.log
#SBATCH --error=DR5ClusterSearch.err

time mpiexec nemo DR5ClusterSearch.yml -M

Note the nemo -M switch is needed to enable parallel processing using MPI. The Nemo configuration for the ACT DR5 cluster search can be found in DR5ClusterSearch.yml.

After this job is completed, the cluster candidate list, filtered maps, and various other files will be found under the DR5ClusterSearch directory. For more information on what these are, see Output.

Inferring cluster masses

To infer cluster masses, a redshift catalog is needed. This is provided for the ACT DR5 clusters in the file redshifts_confirmed_v1.1.fits, which is included in the nemo-dr5-masking.tar.gz archive downloaded by the FETCH_MAPS.sh script.

The nemoMass tool can be used to estimate cluster masses:

mpiexec nemoMass DR5ClusterSearch.yml -M

This should take a few minutes to run, and will write a FITS-table format catalog to DR5ClusterSearch/DR5ClusterSearch_mass.fits.

The inferred masses depend on the assumed scaling relation parameters, which can be edited in the DR5ClusterSearch.yml config file.