Mehmet Alpaslan

Welcome to my little slice of the internet, and make yourself at home! I'm an astronomer that likes to look at the largest known structures in the Universe.

My current research interests lie in the areas of galaxy evolutionlarge-scale structure, and astrostatistics.

We've known for several years that local environment has a big impact on galaxies - studies have shown that galaxies' morphology, for example, can vary greatly as a function of whether or not the galaxy is inside a dense group, or out in the field. Concurrently, we've been able to vastly increase the size and quality of data produced by galaxy surveys, allowing us to improve our understanding of some of the largest scale structures in the Universe. 

At the largest scales, the Universe is composed of large complexes of galaxies arranged into groups and clusters, which themselves are connected to other clusters via strands of matter dubbed 'filaments.' This filamentary structure surrounds vast, empty regions of space that contain only a few galaxies, called voids. Filaments, voids, and clusters are collectively referred to as the 'Cosmic Web.'

A simulation of the ‘Cosmic Web’ showing clusters of galaxies and a void in the middle of the image. Credit: Cui, Newton and Power (ICRAR), Cunnama (UWC).

My research brings together the Cosmic Web and studies of galaxy evolution. Notable results from some of my recent publications include:

  • Substructures of linear galaxies can indeed be observed in voids, and form discrete, linear mini-filaments, which we dubbed 'tendrils' (Alpaslan et al. 2014b).

  • The first ever derivation of the galaxy stellar mass function as a function of large-scale environment, showing that void galaxies occupy a uniquely low stellar mass parameter space (Alpaslan et al. 2015).

  • Spiral galaxies' star formation rates drop as they collapse into filaments; this effect is decoupled from any local group/pair interactions they experience (Alpaslan et al. 2016).

This final result has been driving my current interest and work in understanding how galaxies assemble their baryonic mass (and, in parallel, how their host halos accumulate their dark matter mass) throughout a variety of environments and across cosmic time. I am currently particularly interested in the role that a galaxy’s environment (most notably its host dark matter halo) plays in the processes that quench its star formation activity.