Characterizing Protoclusters and Protogroups at z $\sim$ 2.5 Using Ly$\alpha$ Tomography

Understand

Ly-$\alpha$ tomography surveys have begun to produce three-dimensional (3D) maps of the intergalactic medium (IGM) opacity at $z \sim 2.5$ with Mpc resolution.

• These surveys provide an exciting new way to discover and characterize high-redshift overdensities, including the progenitors of today's massive groups and clusters of galaxies, known as protogroups and protoclusters.
• We use the IllustrisTNG-$300$ hydrodynamical simulation to build mock maps that realistically mimic those observed in the Ly-$\alpha$ Tomographic IMACS Survey (LATIS).
• We introduce a novel method for delineating the boundaries of structures detected in 3D Ly-$\alpha$ flux maps by applying the watershed algorithm.