Talks & Events
Astro Tuesday Series
Astro Tuesday Series:
Past Astro Tuesday Series
Feedback from massive stars, integral field spectroscopy, and serendipitous discoveries
Feedback from massive stars plays a central role in shaping the evolution of entire galaxies. Despite a solid qualitative understanding of feedback, our quantitative knowledge remains poor. Currently, only a small number of HII regions have adequate observational information on both gas and stars needed for detailed feedback studies. However, the growing availability of integral field unit (IFU) instruments and the novel analysis techniques we've developed for them, now allow the study of stellar feedback in orders-of-magnitude more HII regions than previously possible, i.e. the numbers needed to fully quantify the effects of feedback over a large dynamic range of stellar and interstellar medium properties, and to connect the results to state-of-the-art star formation and galaxy evolution models.
I will discuss the first results of resolved stellar feedback studies from a MUSE IFU legacy dataset covering the nearby Sculptor galaxy NGC 300, as well as results from MUSE observations of HII regions in the Magellanic Clouds and the Milky Way. By merging the MUSE NGC 300 data with HST resolved stellar photometry, I demonstrate that ground-based IFU data of nearby galaxies is ideally suited to quantify feedback from massive stars all the way down to individual cloud scales. Moreover, I will discuss the MUSE observations in terms of a pathfinder to ongoing and next-generation IFU nearby galaxy surveys and instruments such as the Local Volume Mapper and JWST. Finally, I will highlight serendipitous discoveries only possible thanks to the 3D nature of IFU data.
Probing Inflation with Primordial Messengers
Some of our best ideas on early universe physics are about to be put to the test by an unprecedented array of cosmological probes. The data these will collect span a vast range of scales, from the CMB to large scale structure, from pulsar timing arrays all the way to laser interferometers. This combined wealth of new information holds the potential to transform not just our understanding of cosmology, but also particle physics. Probing the earliest accessible epoch, the accelerated expansion known as inflation, is absolutely crucial: inflation can provide a cosmological portal to otherwise unaccessible energy scales. This is the "cosmological collider" idea. The spectacular success of the inflationary paradigm in explaining the origin of cosmic structure demands that we tackle a number of compelling questions still in need of an answer: what is the energy scale of inflation? what fields were active during inflation?
Toward a More Complete Picture of Planet Formation
The studies of planet formation have long been dominated by theoretical work because observing planets in formation has been challenging. The situation is, however, gradually changing. Thanks to increasingly powerful observing facilities and techniques, we are now able to peer into the birthplaces of planets - protoplanetary disks, routinely finding signposts of ongoing planet formation. I will introduce state-of-the-art observations of protoplanetary disks, made available by the Atacama Large Millimeter/submillimeter Array and ground-based optical/IR telescopes equipped with adaptive optics. I will discuss how planet formation theories are being tested with and improved by observational data in conjunction with supercomputer simulations. I will conclude with a discussion of prospects for future directions, focusing on how we can connect studies of protoplanetary disks to those of solar and extrasolar planetary systems and develop a more complete picture of planet formation.
Is our Solar System Unique? A Holistic View of Exoplanet Demographics
The Kepler and K2 missions blessed the community with a plethora of planet transit detections which enabled studies of exoplanet size demographics. Much of the recent progress in this field is driven by improved characterization of the stellar hosts. Our group recently used precise radius measurements from the California-Kepler Survey (CKS) to detect a gap in the distribution of planet radii. The paucity of planets with sizes between 1.5 and 2.0 Earth radii supports the emerging picture that close-in planets smaller than Neptune are composed of small, rocky cores enveloped by varying amounts of low-density gas that determine their total sizes. This result demonstrated the value of precise and homogeneous stellar parameters. I will discuss implications of the radius distribution and our ongoing and complimentary work to measure the frequency of giant planets orbiting well beyond the snow line. The occurrence of close-in planets from Kepler combined with the latest results from long-baseline radial velocity surveys allow us to construct a comprehensive picture of planetary system architectures spanning three orders of magnitude in orbital separation and planet mass.
A new paradigm for particle cosmology
Modern cosmology has been remarkably successful in describing the Universefrom a second after the Big Bang until today. However, our currentunderstanding of the cosmos before that time is less precise. Moreover, cosmology profoundly involves particle theory beyond the Standard Model to explain its long-standing puzzles: the origin of the observed matter asymmetry, particle nature of dark matter, and cosmic inflation. In this colloquium, I will explain that relic axion-gauge fields in fractions of a second after the Big Bang can relate and explain these seemingly unrelated puzzles in early and late cosmology. As a smoking gun, such relics would provide a new window into the early Universe through primordial gravitational waves. Therefore, they are testable by future CMB missions.