Lyndsay Old

ESA Research Fellow


Main Research Fields

Galaxy clusters trace the extreme peaks in the matter density field of the early Universe. Measuring their number density and clustering as a function of mass and cosmic time can not only tell us about the structures themselves, but also the physical laws that govern our Universe on the smallest and largest scales.

My research on galaxy clusters and their constituent galaxies is driven by open questions in cosmology and galaxy evolution such as: when did the largest gravitationally bound structures in the cosmic web, galaxy clusters, form and how have they evolved over cosmic time? What physical mechanisms drive the galaxies that reside in these giant structures to stop forming stars? I harness numerical simulations to support observational measurements. I then use observational measurements to inform and develop our theoretical understanding of these massive structures.​




  • Galaxy clusters
  • Galaxy Evolution
  • Large-scale Structure
  • Cosmology

Ongoing collaborations

The Galaxy Cluster Mass Reconstruction ProjectRadek Wojtak, Gary Mamon, Frazer Pearce, Ramin Skibba, Meghan Gray, Darren Croton, Alex Saro, Tiit Sepp, Cristobal Sifón, Elmo Tempel, Peter Behroozi, Reinaldo de Carvahlo, Eduardo Rozo, Eli Rykoff, Daniel Gifford, Anja von der Linden, Volker Müller & the GCMRP team.

GOGREEN surveyMichael Balogh,  Remco van der Burg, Adam Muzzin, Gregory Rudnick, Howard Yee, Irene Pintos-Castro, Michael C. Cooper, Chris Lidman, Andrea Biviano, Ricardo Demarco, Sean McGee, Julie Nantais, Allison Noble, Gillian Wilson, Pierluigi Cerulo, Jeffrey Chan, David Gilbank & Dennis Zaritsky.

Mocking AstrophysicsFrazer Pearce, Alexander Knebe, Gustavo Yepes, Chris Power, Romeel Dave, Pascal Elahi, Weiguang Cui, Darren Croton, Jake Arthur + Mocking Astrophysics team.

The evolution of the quenching of star formation in cluster galaxies from 0 < z < 1 in the SpARCS cluster fields: Irene Pintos-Castro, Howard Yee, Adam Muzzin, Remco van der Burg & Gillian Wilson.


A full list of my publications can be found via this ADS link.

Project/mission at ESA

I joined ESAC as an ESA Research Fellow in October 2018 as part of the Euclid team and the Galaxy Clusters and Cosmology group.

Link to my personal website