Wine and Cheese Fall 2022

This page records the schedule, titles and abstracts of the JHU/STScI CAS Astrophysics Wine & Cheese Series in Fall 2022.

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.

12 September

Ann Hornschemeier Cardif (GSFC/JHU)

The Proposed STAR-X MIDEX Mission
STAR-X is a MIDEX proposed to NASA in December 2021, that was recently (August 2022) selected for competitive Phase A study. Comprising an X-ray Telescope (XRT) provided by GSFC and MIT, a UV Telescope (UVT) provided by the University of Colorado, and a spacecraft provided by Ball Aerospace, STAR-X is designed to conduct time-domain sruvesy and to respond rapidly to transient events discovered by other observatories such as LIGO, Rubin/LSST, Roman/WFIRST, and SKA. STAR-X is a timely response to Astro2020’s recommendation for a space-based, sustaining time-domain and multi-messenger program. This talk will cover the mission and science case.

19 September

Carrie Filion (JHU)

Galactic Archaeology with the Subaru Prime Focus Spectrograph
The Subaru Prime Focus Spectrograph (PFS) will soon embark on an ambitious, multi-year survey that will investigate the nature of dark matter and study the formation and evolution of structure on a range of astrophysical scales. In this talk, I will provide a brief overview of the planned observations of individual, faint stars in the Local Group. I will detail the science motivating these observations and discuss the insight that we hope to gain.

Justin Otter (JHU)

Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past
Post-starburst galaxies (PSBs) have recently and rapidly quenched their star-formation, thus they are an important way to understand how galaxies transition from star-forming late-types to quiescent early-types. The recent discovery of large cold gas reservoirs in PSBs calls into question the theory that galaxies must lose their gas to become quiescent. Optical Integral Field Spectroscopy (IFS) surveys have revealed two classes of PSBs: central PSBs with central quenching regions and ring PSBs with quenching in their outskirts. We analyze a sample of 13 nearby ($z < 0.1$) PSBs with spatially resolved optical IFS data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey and with matched resolution Atacama Large (sub-)Millimeter Array (ALMA) observations of $^{12}$CO(1-0). Disturbed stellar kinematics in 7/13 of our PSBs and centrally concentrated molecular gas is consistent with a recent merger for the majority of our sample. In galaxies without merger evidence, alternate processes may funnel gas inwards and suppress star-formation, including outflows, stellar bars, and minor mergers or interactions. The star-formation efficiencies of the post-starburst regions in nearly half our galaxies are suppressed while the gas fractions are consistent with star-forming galaxies. AGN feedback may drive this stabilization, and we observe AGN-consistent emission in the centers of 5/13 galaxies. Finally, our central and ring PSBs have similar properties except the ionized and molecular gas in central PSBs is more disturbed. Overall, the molecular gas in our PSBs tends to be compact and highly disturbed, resulting in concentrated gas reservoirs unable to form stars efficiently.

26 September

Thomas Essinger-Hileman (GSFC)

EXCLAIM: The EXperiment for Cryogenic Large-Aperture Intensity Mapping
The EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) will constrain star formation over cosmic time by carrying out a blind and complete census of redshifted carbon monoxide (CO) and ionized carbon ([CII]) emission in cross-correlation with galaxy survey data in redshift windows from the present to z=3.5 with a fully cryogenic, balloon-borne telescope. EXCLAIM will carry out extragalactic and Galactic surveys in a conventional balloon flight planned for 2023. EXCLAIM will be the first instrument to deploy µ-Spec silicon integrated spectrometers with a spectral resolving power R=512 covering 420-540 GHz. I will summarize the design, science goals, and status of EXCLAIM.

3 October

Namrata Roy (JHU)

Star Formation Suppression and Feedback in Nearby "Red Geyser" Galaxies
A key question in galaxy evolution is understanding how galaxies completely stop (or “quench”) their star formation towards the end of their lifetime. In spite of having the fuel necessary for forming stars, the lack of detected star formation in old massive galaxies indicates the presence of a feedback energy. Active galactic nuclei (AGN) driven feedback has been proposed to be the most efficient feedback mechanism capable of suppressing star formation - but direct evidence of such feedback in typical galaxies has been lacking. In this talk, I will present evidence from a series of papers that a new class of early-type galaxies, known as ‘red geysers’, may represent AGN feedback in action. I will show that these low redshift galaxies host low luminosity radio mode AGNs with signatures of large scale ionized gas outflows and suppressed star formation activities. These galaxies also frequently show signatures of inflowing cool neutral gas, possibly fueling the central AGN. I will present a multi-wavelength study of these red geyser population from a variety of observational datasets and discuss their role in the global quenching of star formation.

10 October

Yuan-Sen Ting (ANU)

Reconstructing Galaxy Merger History with Graph Neural Networks

17 October

Kalina Nedkova (STScI)

How Have Galaxies Grown Over the Last 10 Billion Years?
Signatures of the physical mechanisms that drive the formation pathways through which galaxies evolve are imprinted on their structure. In this talk, I will present how we have used a simultaneous multi-wavelength fitting approach to model the structure of HFF and CANDELS galaxies, which has allowed us to measure the sizes of faint, high redshift galaxies. Using these data, we have extended the stellar mass—size relation of galaxies over 0.2 ≤ z ≤ 2 to lower mass galaxies than previously studied at these redshifts. I will discuss key factors which may be responsible for driving the shape and evolution of the relations that we obtain. Finally, by modeling galaxies as a composition of bulges and disks, we can further investigate mass and size growth as a function of redshift not only of galaxies but individual galaxy components. I will conclude with some preliminary results showing the stellar mass—size relation of bulges and discs, and a brief discussion of the exciting prospects with JWST, Euclid, and the Nancy Grace Roman Telescope.

Samuel Grunblatt (JHU)

Planet Demographics from the Main Sequence to the Red Clump
Despite the recent discoveries of planets orbiting stars at all evolutionary stages, the evolution of planetary systems remains poorly understood. Studying planetary systems around subgiant and red giant stars is key to understanding how planetary systems change over time. The TESS 'Giants Transiting Giants' survey has yielded the detection of tens of planets and planet candidates orbiting subgiant and red giant stars. These planetary systems provide testbeds for understanding planet inflation and orbital decay, planet engulfment and potential chemical enhancement of host stars, and disruption of typical main sequence systems. Recent studies of the demographics of these systems have revealed that these systems display evidence for late-stage planet re-inflation (although the mechanism of this re-inflation is still up for debate), and a distribution of orbital eccentricities that may support evidence for planet-planet scattering and migration at late stages. Studying these systems as a function of stellar mass may resolve mysteries of giant planet formation as well. Extending the study of these systems to longer baselines will reveal the long-term stability of both hot Jupiters around rapidly evolving stars, as well as the longevity of Earthlike planets around Sunlike stars. Finally, studying these systems with the newest facilities can reveal new details of planetary system orbital and atmospheric evolution, as well as the occurrence of planets formed in other Galaxies.

24 October

Kevin Burdge (MIT)

Minute to Hour Timescale Periodic Optical Variability with the Zwicky Transient Facility: A Rich Discovery Space Filled with Exotic Objects
Here, we give an update on ongoing efforts to explore periodic variability at minute to hour timescales using photometric data obtained with the Zwicky Transient Facility. This effort has uncovered a diverse range of exotic phenomena, including dozens of new ultracompact binaries, black widow pulsars, black widow pulsar "imposters", AR Sco look-alikes, cataclysmic variables transitioning from hydrogen to helium accretion, and rapidly rotating white dwarf merger remnants. Notably, many of the sources being discovered in this search emit detectable gravitational radiation in the millhertz frequency regime, and will be detected by the Laser Space Interferometer Antenna (LISA).

31 Octobre

Brett McGuire (MIT)

The PAH Revolution: Cold, Dark Carbon at the Earliest Stages of Star Formation
Polycyclic Aromatic Hydrocarbons (PAHs) have been implicated as a large reservoir of reactive carbon in the interstellar medium since the 1980s. PAHs have been widely attributed as the carriers of the unidentified infrared bands where their aggregate vibrational emission spectra are extremely well matched to the observed line signals. Only in the last year have individual PAHs been detected in the ISM for the first time, however, allowing us to begin to investigate the detailed chemical pathways for the formation and destruction of these molecules. In this talk, I will discuss our detections of PAH molecules via their rotational transitions using Green Bank Telescope observations of TMC-1 from the GOTHAM collaboration. I will discuss the efforts to model the chemistry of these PAHs, the necessity of complementary laboratory kinetics work, our application of novel machine learning approaches to exploring the chemical inventory in TMC-1, and finally the benefits of unbiased reaction screening studies in the laboratory with Microwave Spectral Taxonomy.

7 November

Anne Jaskot (Williams)

Illuminating Cosmic Reionization with the Low-Redshift Lyman Continuum Survey
The reionization of the intergalactic medium (IGM) at z > 6 is one of the major transformations in the universe’s history, but we do not yet fully understand how it occurred. The most likely explanation is that Lyman continuum (LyC) radiation escaped into the IGM from early star-forming galaxies. Because IGM absorption prevents us from directly measuring LyC during the epoch of reionization itself, we must investigate LyC escape at lower redshift. To address this issue, we have undertaken the Low-Redshift Lyman Continuum Survey, the largest survey of LyC emission at low redshift to date. With HST UV observations of 66 galaxies, we have nearly tripled the number of low-redshift LyC detections, enabling us to systematically test proposed indirect diagnostics of LyC and establish the physical properties of LyC-emitting galaxies. I will share the initial results from the survey and their implications for our understanding of cosmic reionization.

14 Novembre

Emily Rauscher (UMich)

The Peril and Promise of Three-Dimensional Worlds
Much to the consternation of spherical cows everywhere, planets are three-dimensional objects. This is even true for exoplanets because, even though they are generally unresolvable in the glare from the stars around which they orbit, when we interpret atmospheric measurements of these worlds it may be inappropriate to pretend that all regions of the planet have the same temperature and composition. In fact, we may trick ourselves and retrieve biased values when we use 1-D models to interpret atmospheric characterization measurements. This is particularly true for the high signal-to-noise type of exoplanet known as “hot Jupiters” because of the intense stellar heating they receive on their permanent day sides. In this talk, I will discuss how we can turn this challenge into an opportunity, using 3-D models of exoplanet atmospheres to uncover the influence of complex physics in different types of observations and thereby empirically constrain the inherently 3-D structure of these planets. I will review how we measure exoplanet atmospheres and discuss my group's 3-D modeling work, highlighting connections to observations. The necessity of a 3-D approach to exoplanet atmospheric characterization is becoming more compelling as we move into the era of JWST and Extremely Large Telescopes, with their upcoming exquisitely detailed measurements.

28 Novembre

Blakesley Burkhart (Rutgers/Flatiron)

Turbulent Beginnings: A Predictive Theory of Star Formation in the Interstellar Medium
Our current view of the interstellar medium (ISM) is as a multiphase environment where magnetohydrodynamic (MHD) turbulence affects many key processes: star formation, cosmic ray acceleration, and the evolution of structure in the diffuse ISM. In part 1 of this talk, I shall review the fundamentals of galactic turbulence and discuss progress in the development of new techniques for comparing observational data with numerical MHD turbulence simulations. In part 2, I will focus on how turbulence affects the long-standing problem of star formation. From scales of giant molecular clouds (GMCs), I will demonstrate how the star formation efficiency can be analytically calculated from our understanding of how turbulence, gravity, and stellar feedback induce density fluctuations in the ISM via a probability distribution function analysis. This analytic calculation predicts star formation rates from pc size scales (GMCs) to kpc size scales in galaxies.

05 December

Sarah Marie Bruno (JHU)

Preserving Dark Skies for Astronomy
The anticipated ubiquity of privately owned and operated satellite spacecraft in low-Earth orbits will revolutionize the space domain. Space is becoming increasingly commercialized with satellite technology promising technological advancements such as low-cost global internet access. While satellite constellations will likely boost the global economy and increase internet accessibility worldwide, they will also introduce foreground contamination which may greatly impede astronomical observations from the ground. I will discuss the projected impact of the growing space industry on the field of astronomy. Optical, infrared, radio and microwave astronomy will be affected by commercial satellite constellations. While the prognosis for ground-based astronomy may be bleak, the expected upcoming prevalence of low-cost satellite technology may open new doors for astronomers within the next decade and beyond.