This is the GitHub organisation for the LoVoCCS collaboration, where we hope to make our sample, analyses, and results easily available and version controlled. This is a part of our commitment to the principles of open-source science. We will also attempt to provide access to raw data, but that is most likely not feasible due to the size and number of files.

We are a collaboration studying a volume-limited set of 147 massive, local, galaxy clusters, selected from the Meta-Catalog of X-Ray Detected Clusters of Galaxies (MCXC) to be complete to $L^{0.1−2.4\rm{keV}}_{\rm{X}, 500} > 10^{44} \rm{erg} \rm{s}^{−1}$ (where $L_{\rm{X}}$ is the X-ray luminosity of the cluster). Our systems are being observed by the Dark Energy Camera (DECam) on the Victor M. Blanco telescope in Chile, and the Hyper Suprime Camera (HSC) on the Subaru telescope in Hawaii, with the goal of producing 2D weak-lensing mass maps.

The scale of this 2D weak-lensing study is unprecendented, both in terms of the number of weak-lensing maps being produced and the fact that we are studying local systems ($0.03 < z < 0.12$), for which it is much more difficult to measure the shears of background galaxies required for weak-lensing. We are also acting as a precursor survey to the Legacy Survey of Space and Time (LSST), which will be performed using the new Vera Rubin Observatory over the course of the next decade. We are helping to test the pipelines that will be used to analyse their data, and any analyses we develop for LoVoCCS will be applicable to LSST cluster studies.

While optical and near-infrared observations of clusters will lead us to the weak-lensing measurements that are the main goal of this project (and tell us something of the member galaxies in our clusters), they cannot fully describe our objects. For that we must turn to other wavelengths, which probe different components and processes of the galaxy clusters.

The X-LoVoCCS project is providing an extensive X-ray view of the LoVoCCS sample, making use of the large sets of archival data that have been collected by a variety of X-ray telescopes. This will help us to probe the intra-cluster medium, which can tell us a great deal about the astrophysics of clusters, their dynamical state, and whether their total and gas mass distributions are coincident, or separated (such as in the Bullet cluster). Combining X-ray and 2D weak-lensing mass maps for this large of a complete cluster sample will be very powerful, and allows us to construct scaling relations with a proper understanding of the scatter of properties with respect to each other.

The SZ-LoVoCCS project also provides a view into the intra-cluster medium of the LoVoCCS galaxy clusters, but this time using the Sunyaev Zel'dovich effect as observed by the Planck CMB observatory. The massive nature of our galaxy clusters all but ensures a detection by Planck, and provides another path (in addition to X-ray observations) to measuring ICM properties such as pressure. We also wish to make use of other CMB telescopes in the future.

• Determining the 2D total, and gas, mass distributions of the clusters.
• Leveraging the completeness of our sample to fully understand the scatter of various properties with respect to mass, in order to aid the use of clusters for cosmology.
• In doing so, we wish to create a comprehensive set of cluster scaling relations at $z = 0$
• Assess mass dependence of intrinsic property covariance
• Measure precisely how hot gas and stellar mass correlate at fixed halo mass
• Test simulation predictions within and across radial zones
• Providing a catalogue of quantitative cluster morphologies.
• And many more!

Read more about the collaboration, and our members, on the LoVoCCS website!

Please feel free to get in contact (decide on which email) if you are interested in our science and wish to contribute!