Wine and Cheese Fall 2023

This page records the schedule, titles and abstracts of the JHU/STScI CAS Astrophysics Wine & Cheese Series in Fall 2023.

Wine and Cheese sessions with one speaker will have a 50 minute talk with 10 minutes for questions. Sessions with two speakers will have two 25 minute talks, each with 5 minutes for questions. Sessions in the Graduate Student Series will have three 15 minute talks, each with 5 minutes for questions.

11 September

Ferah Munshi (George Mason)

Understanding Galaxy Evolution at the Lowest Masses
Low mass galaxies challenge our picture of galaxy formation and are an intriguing laboratory for the study of star formation, feedback and dark matter physics. I will present results from high resolution, cosmological simulations that contain many (isolated) dwarf galaxies [the MARVEL dwarfs] as well as satellite dwarf galaxies [the DC Justice League]. Together, they create the largest collection of high-resolution simulated dwarf galaxies to date and the first flagship suite to resolve ultra-faint dwarf galaxies in multiple environments. This sample spans a wide range of physical (stellar and halo mass), and evolutionary properties (merger history). I will present results and predictions constraining star formation, feedback and dark matter physics soon testable by telescopes like JWST, Rubin's LSST and the Roman Space Telescope. Finally, I will present results about satellite distributions around Milky Way analogs from both zoom-in simulations and from a large sample of analogs drawn from the Romulus 25-Mpc volume simulation. I will discuss the role of environment in addition to satellite quenching times and their mechanisms with an eye toward comparing with observations.

18 September

William Coulton (Flatiron Institute)

New Views of Galaxy Groups and Clusters with Precision CMB Secondary Measurements
High resolution cosmic microwave background (CMB) experiments provide a view of the Universe both at redshift ~1100, when the primary CMB was produced, and an integrated view of the Universe between then and now, through CMB secondary anisotropies. The CMB secondary anisotropies provide direct access to the integrated mass, electron density, electron pressure and electron temperature. In this talk, I will first present recent maps of CMB secondaries from the Atacama Cosmology Telescope collaboration. I will then show how upcoming experiments will be able to measure new observable signatures of galaxy groups, and how these can be used to inform our understanding of the thermodynamics of these objects.

25 September

Haowen Zhang (Arizona)

TRINITY: the Dark Matter Halo—Galaxy—Supermassive Black Hole (SMBH) Connection from z=0-10
Supermassive black holes (SMBHs) exist in many galaxies. Their growth is accompanied by strong energy output, which is capable of regulating host galaxy evolution. Understanding SMBH growth is thus critical for studying galaxy formation and evolution. However, it has been difficult to quantify SMBH growth in different galaxies and cosmic epochs. In this talk, I will present TRINITY, a new empirical technique to determine the typical SMBH mass and growth rate in different galaxies and dark matter halos from z=0-10. I will discuss how the galaxy—SMBH connection from TRINITY will help theoretical astronomers to create better simulations of galaxy evolution. In addition, I will show that the latest JWST-detected SMBHs match TRINITY’s predictions, in terms of their SMBH masses and growth rates.

Tony Chen (JHU)

The observed structure of the universe suggests that galaxy mergers and the co-evolution of their central supermassive black holes (SMBHs) are common throughout the cosmos. While the formation of binary SMBHs seems inevitable, direct observational evidence has been elusive. Active SMBHs, known as quasars, provide an excellent way to find and study distant dual SMBHs in electromagnetic waves. At kilo-parsec scales, large systematic searches of dual quasars at cosmic noon (z~2) are limited by the stringent angular resolution requirement in ground-based optical telescopes. I will introduce our recent efforts to find small-scale dual quasars. I will present a novel astrometric technique called Varstrometry, which enables the identification of unresolved dual quasars using all-sky surveys like Gaia. Using Varstrometry and observations from the Hubble Space Telescope, dozens of kpc dual quasar candidates were discovered. These kpc dual quasars are excellent samples to yield constraints on cosmological simulations and study the triggering of quasar activity due to galaxy mergers. In the end, I will summarize the talk with new exciting results and upcoming programs.

09 October

Alex Dittman (UMCP)

The Final Stages of Supermassive Black Hole Binary Mergers and their Multi-Messenger Signatures
Supermassive black hole binaries form in the aftermath of galaxy mergers, and the gas expected to abound in the centers of post-merger galaxies may both expedite the coalescence of these binaries and facilitate electromagnetic observations of these systems. I will illustrate how these systems evolve as gravitational waves begin to dominate their evolution, following their inspirals from hundreds of gravitational radii until merger. We find that binaries are likely to accrete throughout their time in the LISA band, but with unique signatures that may help localize these events, facilitating measurements of cosmological parameters and more precise constraints on binary constituent properties.

Jesse Bluem (GSFC)

Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way The Milky Way is surrounded by the circumgalactic medium (CGM), an extended reservoir of hot gas that has significant implications for the evolution of our Galaxy. The HaloSat all-sky survey was used to study the CGM's soft X-ray emission, finding evidence that at least two hot gas model components are required to produce the observed emission. The cooler component has a typical temperature of kT ~0.18 keV, while the hotter component has a typical temperature of kT ~0.7 keV. The emission measure in both components indicates that the CGM is clumpy.