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Colloquium with Gwendolyn Eadie and Suresh Sivanandam


Globular Cluster Systems and Their Relationship to Galaxy Stellar Mass – by Gwendolyn Eadie
Abstract: All galaxies with large stellar mass appear to have a globular cluster (GC) population, but the same cannot be said of all galaxies with small stellar mass. At the same time, the data from galaxies suggest that there is a range in stellar mass over which galaxies go from not having GCs to having them. What can this transition region tell us about globular cluster and galaxy evolution? To answer this question well, we first need a statistical model to estimate the extent of the transition region. In this talk, I will go over our investigation of the ability of three statistical models to describe the observed data: logistic regression, Poisson regression, and a lognormal Bayesian hurdle model. This will be an introductory talk to these methods, so no prior knowledge is needed!

Rethinking Spectroscopy with Astrophotonics – by Suresh SivanandamAbstract: Astrophotonics is an emerging field that can potentially supplant conventional astronomical instruments. I will provide a quick overview of the present state-of-the-art in astrophotonic instrumentation along with their associated pros and cons. I will discuss a new approach to traditional spectroscopy using photonic devices. Given that most spectroscopic problems in astronomy require some form of cross-correlation, e.g., measurement of kinematics or detection of atomic/molecular species, we have developed a new approach where the cross-correlation can be done entirely on-device. By creating photonic devices with a carefully designed transmission spectrum that can be modulated, the cross-correlation can be carried out optically, which vastly simplifies the instrument. These devices can be purpose-built to solve specific scientific problems. They are several orders of magnitude cheaper than echelle spectrographs, and can potentially be tiled on a focal plane to form an IFU. Lastly, I will present initial test results from devices we have recently fabricated.

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December 15, 2021
2:00 pm - 3:00 pm