12:00–1:00 pm ERC 501
Host: Austin Joyce
Madison Brady "Measuring Stellar Obliquity with the Rossiter-McLaughlin Effect"
The obliquities of exoplanet host stars, when studied as a population, can give us insight into the tides and dynamical histories of exoplanet systems. However, due to the minute nature of the signals involved, we don’t know much about what happens with rocky planets. In this talk, I will discuss what we know about stellar obliquities and some popular methods used to measure them, with a primary focus on the Rossiter-McLaughlin effect. I will then discuss recent observations of the TRAPPIST-1 system with MAROON-X as a demonstration of these concepts.
Giulia Giannini "Why are photometric redshifts so hard?"
Galaxy surveys rely heavily on an accurate redshift estimation to correctly probe the Large Scale Structure of the Universe. Ideally, having spectroscopic measurements for each galaxy would be the best approach, but despite numerous advancements (e.g. DESI) this is not feasible yet. Observing larger regions of the sky with few broad filters has the advantage of yielding much larger galaxy catalogs in a shorter period of time, which benefits the constraining power of the cosmological analysis. On the other hand, distinguish between different galaxies spectral features in the integrated flux of a broad band becomes prohibitive, generating a redshift-type degeneracy that needs to be addressed in order to correctly characterise the redshifts. To overcome these issues, over the years galaxy surveys have developed many calibration techniques, from fitting photometric measurements to a set of templates, to the more recent use of machine learning. We will explore the strengths and drawbacks of a range of these methodologies and finally, we will conclude with an outlook towards new techniques and the requirements related to photometric redshifts accuracy for future surveys.
