Prateek Gupta

The Universe at the present epoch is found to be a network of overdense and underdense regions of matter. The overdense regions are typically dominated by the dark matter (DM) filaments, where massive gravitationally bound structures such as groups and clusters of galaxies form. To date, this picture of the Universe is best revealed by cosmological DM simulations and large-scale galaxy redshift surveys. However, the crucial aspect is the appropriate identification of the structures. Such identification uses halo/group-finder methods, which are predominantly based on either the friends-of-friends (FoF) or spherical overdensity (SO) algorithms. The methods used so far either constrain the overdensity and impose the spherical geometry or capture the unstructured geometry. However both properties are significant simultaneously for the appropriate identification of large-scale structures. This talk will provide a concise overview of the aforementioned algorithms, followed by an introduction to my recently proposed approach to identifying bound structures. The new approach, known as MITRO algorithm, is capable of discerning both gravitationally bound and genuinely unstructured geometries with remarkable efficacy. Moreover, it is able to identify these structures within a predefined, physically motivated density threshold. The unique ability of the algorithm to identify structures will also be demonstrated, with examples drawn from both large-volume cosmological simulations and galaxy redshift surveys.