BOSS spectral fitting

Ardingly students at MSSL: our week-long walk through the Universe

At the end of June, we had the opportunity to work at MSSL with Dr. Ignacio Ferreras for one week. As college (high school) students interested in pursuing careers in science and/or engineering, this was the perfect opportunity for us to not only get a taste of what research is like at the frontiers of science, but also to experience in first person the daily life of a scientist.

During our stay, we worked closely with Dr. Ferreras to build various synthetic spectra of galaxies with different star formation histories. For each case, we were able to identify the spectral changes associated with, for example, postponing the beginning of star formation, modifying the quenching time, simulating different decay types (e.g. linear versus exponential), adjusting the chemical composition (metallicity), etc. – basically changing all of the factors at play during the formation of galaxies.

Eventually, we compared our synthetic models with the exquisite data collected by the SDSS/BOSS survey. The data covered a wide range of velocity dispersions, allowing us to determine which models best predicted the observed spectra of the galaxies.

Unfortunately, we had only four days to work on this project. As Dr. Ferreras told us, a study of this extent requires more time to analyze and understand the results. However, thanks to Dr. Ferreras’ availability and passion, we were still able to gain a lot of insight on star formation and galaxy evolution and produce some interesting results. The figure in this blog post shows an example where the spectrum of a real galaxy is compared with the best-fit model (top panel). The middle panel shows the residual – the difference between model and data. The peak at 3727A is a characteristic emission line from oxygen! The bottom panel compares this residual with the observed error bars, showing potentially interesting features to explore.

BOSS spectral fitting


What was probably even more important for us in our four-day stay at MSSL was taking a close look at the world of scientific research. We met very passionate people at almost every corner of the building. One image in particular that we found striking was entering MSSL and just casually walking by the boxes containing material related to the instruments that will fly aboard ESA’s Euclid space telescope.

Throughout our stay, Dr. Ferreras was extremely kind to us; he was always available to help us with the code and look for ways to solve bugs, explain the astrophysical mechanisms behind star formation, or simply have a post-lunch chat over a cup of coffee about the latest developments and discoveries in Physics. Another thank you goes to Dr. De Pasquale for helping us with our analysis and for answering our questions on careers in astronomy research. We would also like to take this opportunity to thank our Physics teachers at Ardingly College, Dr. Andrew Spiers and Dr. Igor Zharkov, who offered us this wonderful opportunity. Following our stay at MSSL, we are now more sure than ever about pursuing a career in physics!

– Pietro Capuozzo and Leone Trascinelli, Ardingly College

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