Colloquia

Stephanie Wissel

Tuning into Cosmic Neutrinos at High Elevation 

Neutrinos are the ideal messenger for high-energy astrophysics. Weakly interacting and uncharged, they propagate undeterred and unabsorbed through the universe. In the last decade, the IceCube experiment has brought us the discovery of a flux of high-energy, TeV-scale neutrinos, and through a multi-messenger lens — the combined observations of neutrinos and other messengers like photons —  we are starting to see hints of energetic neutrino sources for the first time. At higher energies still, beyond the PeV scale, we can probe the most energetic sources of both neutrinos and cosmic rays, but current neutrino experiments become too small to observe a sizable flux. Radio experiments can achieve the large exposures necessary by taking advantage of the coherent broadband radio emission resulting from ultra-high-energy (E>10^17 eV) neutrino interactions as well as the large volumes visible from high elevations. In this talk, I will review results from current and future high-elevation radio experiments, both from balloon-borne instruments like PUEO and from mountaintop experiments like BEACON and HERON.

Stephanie Wissel

Tuning into Cosmic Neutrinos at High Elevation 

Neutrinos are the ideal messenger for high-energy astrophysics. Weakly interacting and uncharged, they propagate undeterred and unabsorbed through the universe. In the last decade, the IceCube experiment has brought us the discovery of a flux of high-energy, TeV-scale neutrinos, and through a multi-messenger lens — the combined observations of neutrinos and other messengers like photons —  we are starting to see hints of energetic neutrino sources for the first time. At higher energies still, beyond the PeV scale, we can probe the most energetic sources of both neutrinos and cosmic rays, but current neutrino experiments become too small to observe a sizable flux. Radio experiments can achieve the large exposures necessary by taking advantage of the coherent broadband radio emission resulting from ultra-high-energy (E>10^17 eV) neutrino interactions as well as the large volumes visible from high elevations. In this talk, I will review results from current and future high-elevation radio experiments, both from balloon-borne instruments like PUEO and from mountaintop experiments like BEACON and HERON.

Jeroen Audenaert

The NASA Transiting Exoplanet Survey Satellite (TESS): From Trillions of Data Points to Astrophysical Insights

The Transiting Exoplanet Survey Satellite (TESS) is an MIT-led NASA mission to discover transiting exoplanets, worlds beyond our solar system. Launched in 2018, TESS is now in its third extended mission, continuously observing millions of stars to search for subtle changes in brightness that can reveal everything from exoplanets and nearby asteroids to pulsating stars and supernovae.

The unprecedented volume of data from TESS opens new frontiers, but also poses a key challenge: how can we automatically and accurately analyze this vast, continuous stream of observations? In this colloquium, I will dive into the essential role machine learning and artificial intelligence play in this process, enabling everything from more accurate exoplanet detection models to building better instrument models, paving the way for an era of automated scientific discovery.

Jeroen Audenaert

The NASA Transiting Exoplanet Survey Satellite (TESS): From Trillions of Data Points to Astrophysical Insights

The Transiting Exoplanet Survey Satellite (TESS) is an MIT-led NASA mission to discover transiting exoplanets, worlds beyond our solar system. Launched in 2018, TESS is now in its third extended mission, continuously observing millions of stars to search for subtle changes in brightness that can reveal everything from exoplanets and nearby asteroids to pulsating stars and supernovae.

The unprecedented volume of data from TESS opens new frontiers, but also poses a key challenge: how can we automatically and accurately analyze this vast, continuous stream of observations? In this colloquium, I will dive into the essential role machine learning and artificial intelligence play in this process, enabling everything from more accurate exoplanet detection models to building better instrument models, paving the way for an era of automated scientific discovery.

Heather Lewandowski

Probing the Frontiers of Interstellar Chemistry Through Cold and Controlled Ion-Molecule Experiments

Ion-molecule reactions are fundamental to the chemistry that drives processes in the interstellar medium, but experimental measurements of these reactions are scarce due to significant technical challenges. We apply techniques from the field of cold atomic physics to examine ion-molecule reactions under well-controlled conditions that replicate the environment of space.

Our focus is on the reactions of small, carbon-based molecules. Benzene, an aromatic molecule, is widely considered a key precursor to larger polycyclic aromatic hydrocarbons (PAHs) in space. Despite benzene’s pivotal role in PAH formation, its formation mechanisms in the interstellar medium remain poorly understood. Scientists have suggested a pathway for interstellar benzene formation beginning with the protonation of acetylene, yet this reaction sequence has not been experimentally verified.

In our work, we present the first experimental study of sequential ion-molecule reactions initiated by acetylene protonation under single-collision conditions. Contrary to predictions, our results show that this reaction sequence does not produce benzene; instead, it terminates at the formation of C₆H₅⁺, a species unreactive to both acetylene and hydrogen. These results rule out a widely assumed pathway for interstellar benzene formation and place new constraints on the physical mechanisms underlying PAH growth in cold astrophysical environments.

Heather Lewandowski

Probing the Frontiers of Interstellar Chemistry Through Cold and Controlled Ion-Molecule Experiments

Ion-molecule reactions are fundamental to the chemistry that drives processes in the interstellar medium, but experimental measurements of these reactions are scarce due to significant technical challenges. We apply techniques from the field of cold atomic physics to examine ion-molecule reactions under well-controlled conditions that replicate the environment of space.

Our focus is on the reactions of small, carbon-based molecules. Benzene, an aromatic molecule, is widely considered a key precursor to larger polycyclic aromatic hydrocarbons (PAHs) in space. Despite benzene’s pivotal role in PAH formation, its formation mechanisms in the interstellar medium remain poorly understood. Scientists have suggested a pathway for interstellar benzene formation beginning with the protonation of acetylene, yet this reaction sequence has not been experimentally verified.

In our work, we present the first experimental study of sequential ion-molecule reactions initiated by acetylene protonation under single-collision conditions. Contrary to predictions, our results show that this reaction sequence does not produce benzene; instead, it terminates at the formation of C₆H₅⁺, a species unreactive to both acetylene and hydrogen. These results rule out a widely assumed pathway for interstellar benzene formation and place new constraints on the physical mechanisms underlying PAH growth in cold astrophysical environments.

Yamuna Phal

Mid-Infrared Technologies for Biosensing & Material Characterization

The mid-infrared (mid-IR) region of the electromagnetic spectrum, also known as the molecular fingerprint region, has long been a focus of scientific and technological research. Mid-IR microscopy is a non-destructive tool that can measure the molecular content of biological samples by probing fundamental vibrational modes, with potential applications in early disease detection and diagnosis. However, limitations such as long acquisition times, limited spatial detail, and a lack of understanding of light-matter interactions have impeded progress in this field. In this talk, I will present advanced mid-IR spectroscopic imaging platforms that address these challenges to improve perceived spatial resolution and enabling label-free classification of surgical tissue sections within minutes. Additionally, I will discuss the development of technology for imaging site-specific chirality of molecules, including the specific challenges and roadblocks to creating a viable and accurate system. The focus of this talk is on using theory and modeling to guide the development of measurement systems and open new opportunities for sensing biomolecules – in both terrestrial and space environments.

Yamuna Phal

Mid-Infrared Technologies for Biosensing & Material Characterization

The mid-infrared (mid-IR) region of the electromagnetic spectrum, also known as the molecular fingerprint region, has long been a focus of scientific and technological research. Mid-IR microscopy is a non-destructive tool that can measure the molecular content of biological samples by probing fundamental vibrational modes, with potential applications in early disease detection and diagnosis. However, limitations such as long acquisition times, limited spatial detail, and a lack of understanding of light-matter interactions have impeded progress in this field. In this talk, I will present advanced mid-IR spectroscopic imaging platforms that address these challenges to improve perceived spatial resolution and enabling label-free classification of surgical tissue sections within minutes. Additionally, I will discuss the development of technology for imaging site-specific chirality of molecules, including the specific challenges and roadblocks to creating a viable and accurate system. The focus of this talk is on using theory and modeling to guide the development of measurement systems and open new opportunities for sensing biomolecules – in both terrestrial and space environments.