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Special Presentations

Shining light on the hidden pathways of galaxy transformation

Presented by: Katherine Alatalo (The Carnegie Observatories)
Category: Special Interest   Duration: 1 hour   Broadcast date: March 06, 2017
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The morphological and color bimodalities displayed by modern-day galaxies suggest that a galaxy must have rapidly transformed from one class to the other. In the modern universe, this transition is one-way, which makes it essential to gain a census of initial conditions capable of catalyzing this metamorphosis. Classical searches that capture transitioning galaxies via signatures of intermediate-aged stars and lack of nebular ionized gas emission exclude the very gas physics that are often fundamental to understanding the galaxy's transition. I will present the Shocked POststarburst Galaxy Survey (SPOGS), a novel method for finding previously-missed transitioning galaxies using their ionized gas line ratios. I will discuss early results suggesting my SPOGS criterion pinpoints objects at an earlier phase of transformation, when more signs of transition triggers still exist. Our exquisite case study, NGC1266, demonstrates the success of this method. These new observations shed light on the fundamental role gas plays in the ultimate quenching and transformation of a galaxy.