Astrophysics Seminar | Image Simulation and Sample Characterization of DESI Large Red Galaxies

Wednesday, October 13, 2021 4:10pm

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Image Simulation and Sample Characterization of DESI Large Red Galaxies

The Astrophysical Institute is hosting a virtual talk by Hui Kong from The Ohio State University on Wednesday Oct 13 at 4:10 pm.

Abstract: The Dark Energy Spectroscopic Instrument (DESI) is about to measure the most accurate 3D map of the large scale structure of the universe. DESI targets are selected from imaging surveys, and this selection inevitably generates imaging systematics. Control and possibly mitigation of these systematic uncertainties is crucial for our understanding of large scale structure. Galaxy clustering is a very rich topic providing a wealth of information. On large scales, for example, it contains information of the very early universe such as the nature of the primordial density fluctuation during the period of inflation. These scales, however, are highly contaminated by aforementioned imaging systematics. 

In order to control these uncertainties, we developed a novel simulation tool that inserts simulating galaxies in the imaging survey data. Using the same pipeline that produces photometric catalogs, this method allows us to study the fluctuations in galaxy features at the pixel level. 

I will present the simulation tool we have developed for this purpose, demonstrate how it can be used to characterize the sample of large red galaxies used by DESI for cosmological analyses, and present an outlook of how a better control of the imaging systematics improves measurements of the f_nl parameter that describes primordial density fluctuations.

To attend, contact Dr. Joseph Shields at for dial-in information.

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Contact Dr. Joseph Shields at for more information.

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