1:00–2:00 pm ERC 401
Gillian Beltz-Mohrmann (Vanderbilt University)"Developing an Accurate Probe of the Galaxy-Halo Connection"
The small-scale clustering of galaxies contains a wealth of information about galaxy formation and evolution, as well as large-scale structure formation and cosmology. Unlocking this information requires accurate and flexible models of small-scale galaxy clustering. As an alternative to running complex and computationally expensive hydrodynamic simulations, halo models provide a simple and computationally inexpensive way to investigate the connection between galaxies and their dark matter halos. In our recent work, we used the standard halo occupation distribution model to constrain the galaxy-halo connection in SDSS. By employing a fully numerical, mock-based modeling procedure, we were able to utilize a wide variety of galaxy clustering statistics beyond 2-point statistics. This allowed us to achieve tight constraints on our halo model parameters, which exhibited significant tension with the clustering of SDSS galaxies. This is consistent with results from our earlier work comparing halo models to hydrodynamic simulations, which suggested that the standard halo model struggles to accurately predict clustering when exotic effects are present. Motivated by these findings, we are currently working to expand this modeling procedure to include parameters for galaxy assembly bias in the halo model. Preliminary results of applying this model to the SDSS DR7 Mr <−19 sample indicate strong central galaxy assembly bias, but our best-fit model in this analysis still yields significant tension with the clustering of SDSS galaxies, suggesting that more freedom needs to be added to the model in future work. This work is the first example of using a fully numerical modeling procedure with a proper accounting of all systematic errors (including baryonic effects on the halo mass function) to constrain assembly bias in SDSS galaxies.
