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.

16 October

Lauren Weiss (Notre Dame)

Planets, Patterns, and the Origin of Life
Exoplanet science is an explosive new field catalyzed by the discovery of over 5000 extrasolar planets via the NASA Kepler and TESS missions. With precise transit photometry and high resolution spectroscopy (including radial velocities), we are learning about diverse types of planets, their interior and atmospheric compositions, their orbital properties, the systems in which they reside, and how the planets form and change over time. In this talk, I will discuss unanticipated patterns that emerge nearly ubiquitously in hundreds of exoplanet systems. These patterns have reshaped our understanding of planet formation, with implications for the origins of Earth-like planets and life. Continued characterization of these patterns with ground and space-based telescopes will reveal what kinds of planetary systems are common, perhaps at last establishing whether the solar system itself is common or rare.

23 October

Ruchi Pandey (Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad, India)

Shock-Induced Dust Formation in Novae: A Phenomenological Study
Novae are fascinating objects which have enabled the direct observation of the various aspects of circumstellar dust formation on a frequent basis. Since the timescale of dust formation in novae typically ranges from 30 to 100 days following an outburst, these environments can serve as test beds for studying the formation and evolution of astrophysical dust. However, dust formation in the hostile environment of novae ejecta has been an open question for many decades. Several attempts have been made to understand the physical and chemical conditions required for this phenomenon and its relationship with the observable parameters. Numerous hypotheses have been developed in order to explain the mechanisms that underlie the process of dust formation. An intriguing proposition is put forth, suggesting the possibility of shock-induced dust formation in novae. A recent study of Nova V2891 Cyg by a team of astronomers at Physical Research Laboratory, India has provided, most likely, the first observational evidence of such a method of dust formation in novae ejecta. In this seminar, I will commence with a concise introduction to the phenomenon of dust formation in novae, highlighting its significance and the current gaps in understanding the same. Subsequently, I will shed insights into the phenomenological modelling of Nova V2891 Cyg and bring out its relevance in illustrating the origin of some observational signatures of shock-induced dust formation.