Wednesday, April 30, 2025
02:00 PM - 03:30 PM
Engineering Colloquium
Applications and Hazards of Lithium-Ion Batteries
Jessica Gallo,Fire Protection Consultant at Fire & Risk Alliance (FRA)
Read more about this event Jessica Gallo,Fire Protection Consultant at Fire & Risk Alliance (FRA)
Thursday, May 01, 2025
12:00 PM - 01:00 PM
Special Seminar
Relativistically Broadened Line Emission Morphology: Encoding Black Hole & Accretion Disk Parameters
Delilah Gates (CfA Harvard, Black Hole Initiative)
Single-frequency emission from an accretion disk around a black hole is broadened into a line profile due to gravity and the motion of the disk relative to the observer. In this talk, I present unified analytical explanation for the line profile morphological features (i.e., its extent, kinks, and fall-off), and show how these features can be used to constrain black hole spin, observer inclination, and locations of the disk's inner and outer edges, working in the Standard disk model wherein particles in the disk travel on stable circular orbits. The line profile morphological features are model-dependent. Thus we also explore select models wherein disk particles deviate from stable circular orbits, demonstrating that our understanding of black hole and disk properties can be highly sensitive to the model assumptions made when interpreting measurements.
Read more about this event Delilah Gates (CfA Harvard, Black Hole Initiative)
Single-frequency emission from an accretion disk around a black hole is broadened into a line profile due to gravity and the motion of the disk relative to the observer. In this talk, I present unified analytical explanation for the line profile morphological features (i.e., its extent, kinks, and fall-off), and show how these features can be used to constrain black hole spin, observer inclination, and locations of the disk's inner and outer edges, working in the Standard disk model wherein particles in the disk travel on stable circular orbits. The line profile morphological features are model-dependent. Thus we also explore select models wherein disk particles deviate from stable circular orbits, demonstrating that our understanding of black hole and disk properties can be highly sensitive to the model assumptions made when interpreting measurements.
Tuesday, May 06, 2025
03:00 PM - 04:00 PM
SED Town Hall
The agenda will be shared with the Teams link as we get closer to the event. Actual start time is 3:10 p.m.
Read more about this event Tuesday, May 06, 2025
03:30 PM - 05:00 PM
ASD Colloquium Series
Local Dwarf Galaxies as Laboratories to Understand Massive Stars and the ISM in the Early Universe
Grace Telford (Princeton University)
Feedback from low-metallicity massive stars regulates the evolution of both dwarf and high-redshift galaxies. To understand those processes requires robust models of the metal-poor ISM in which stars form and of massive stars' winds and ionizing spectra. Yet, these models remain entirely theoretical and uncertain due to a lack of observational constraints in the extremely low-metallicity regime. In this talk, I will present a suite of JWST, HST, and Keck observations of the nearby 3% Solar metallicity galaxy Leo P. First, I will describe novel constraints on the wind properties and ionizing spectrum of the galaxy's only O-type star from modeling HST/COS and Keck/KCWI spectroscopy. This star is part of the Treasury of Extremely Metal-Poor O Stars (TEMPOS), a Large Treasury HST program that will extend this initial analysis to a much larger sample at ~5-10% Solar metallicity. I will then present new JWST/MIRI-MRS observations of Leo P, which enabled the first detection of cold molecular hydrogen at such low metallicity via rotationally excited emission from the photodissociation region illuminated by the O star. Our detailed understanding of that star's UV radiation from the HST data constrains the temperature and mass of the detected molecular hydrogen, providing a benchmark for models of the ISM at the very low metallicities typical at high redshift. Leo P showcases the potential of the metal-poor dwarf galaxies in our backyard to inform models of early galaxies.
Read more about this event Grace Telford (Princeton University)
Feedback from low-metallicity massive stars regulates the evolution of both dwarf and high-redshift galaxies. To understand those processes requires robust models of the metal-poor ISM in which stars form and of massive stars' winds and ionizing spectra. Yet, these models remain entirely theoretical and uncertain due to a lack of observational constraints in the extremely low-metallicity regime. In this talk, I will present a suite of JWST, HST, and Keck observations of the nearby 3% Solar metallicity galaxy Leo P. First, I will describe novel constraints on the wind properties and ionizing spectrum of the galaxy's only O-type star from modeling HST/COS and Keck/KCWI spectroscopy. This star is part of the Treasury of Extremely Metal-Poor O Stars (TEMPOS), a Large Treasury HST program that will extend this initial analysis to a much larger sample at ~5-10% Solar metallicity. I will then present new JWST/MIRI-MRS observations of Leo P, which enabled the first detection of cold molecular hydrogen at such low metallicity via rotationally excited emission from the photodissociation region illuminated by the O star. Our detailed understanding of that star's UV radiation from the HST data constrains the temperature and mass of the detected molecular hydrogen, providing a benchmark for models of the ISM at the very low metallicities typical at high redshift. Leo P showcases the potential of the metal-poor dwarf galaxies in our backyard to inform models of early galaxies.
Thursday, May 08, 2025
12:00 PM - 01:00 PM
SED Director’s Seminar
Please join us for the SED Director’s Seminar. Hosted by the Exoplanets and Stellar Astrophysics Laboratory, Code 667!
Read more about this event Tuesday, May 13, 2025
03:30 PM - 05:00 PM
ASD Colloquium Series
Local Dwarf Galaxies as Laboratories to Understand Massive Stars and the ISM in the Early Universe
Grace Telford (Princeton University)
Feedback from low-metallicity massive stars regulates the evolution of both dwarf and high-redshift galaxies. To understand those processes requires robust models of the metal-poor ISM in which stars form and of massive stars' winds and ionizing spectra. Yet, these models remain entirely theoretical and uncertain due to a lack of observational constraints in the extremely low-metallicity regime. In this talk, I will present a suite of JWST, HST, and Keck observations of the nearby 3% Solar metallicity galaxy Leo P. First, I will describe novel constraints on the wind properties and ionizing spectrum of the galaxy's only O-type star from modeling HST/COS and Keck/KCWI spectroscopy. This star is part of the Treasury of Extremely Metal-Poor O Stars (TEMPOS), a Large Treasury HST program that will extend this initial analysis to a much larger sample at ~5-10% Solar metallicity. I will then present new JWST/MIRI-MRS observations of Leo P, which enabled the first detection of cold molecular hydrogen at such low metallicity via rotationally excited emission from the photodissociation region illuminated by the O star. Our detailed understanding of that star's UV radiation from the HST data constrains the temperature and mass of the detected molecular hydrogen, providing a benchmark for models of the ISM at the very low metallicities typical at high redshift. Leo P showcases the potential of the metal-poor dwarf galaxies in our backyard to inform models of early galaxies.
Read more about this event Grace Telford (Princeton University)
Feedback from low-metallicity massive stars regulates the evolution of both dwarf and high-redshift galaxies. To understand those processes requires robust models of the metal-poor ISM in which stars form and of massive stars' winds and ionizing spectra. Yet, these models remain entirely theoretical and uncertain due to a lack of observational constraints in the extremely low-metallicity regime. In this talk, I will present a suite of JWST, HST, and Keck observations of the nearby 3% Solar metallicity galaxy Leo P. First, I will describe novel constraints on the wind properties and ionizing spectrum of the galaxy's only O-type star from modeling HST/COS and Keck/KCWI spectroscopy. This star is part of the Treasury of Extremely Metal-Poor O Stars (TEMPOS), a Large Treasury HST program that will extend this initial analysis to a much larger sample at ~5-10% Solar metallicity. I will then present new JWST/MIRI-MRS observations of Leo P, which enabled the first detection of cold molecular hydrogen at such low metallicity via rotationally excited emission from the photodissociation region illuminated by the O star. Our detailed understanding of that star's UV radiation from the HST data constrains the temperature and mass of the detected molecular hydrogen, providing a benchmark for models of the ISM at the very low metallicities typical at high redshift. Leo P showcases the potential of the metal-poor dwarf galaxies in our backyard to inform models of early galaxies.
