Major technological advances have enabled the discovery of a small number of directly imaged exoplanets. These imaged worlds can be studied in far greater detail than exoplanets detected by indirect methods such as transit and radial velocity techniques. Next-generation telescopes such as the recently launched James Webb Space Telescope and the upcoming 30-m telescopes (e.g. ELT, TMT, GMT) will enable direct exoplanet characterization. Based on the handful of exoplanets studied to date, it is clear that interpretation of future observational data hinges on a thorough understanding of their atmospheric processes. In this talk I will discuss our past, current and future efforts to investigate the atmospheres of extrasolar worlds. In particular, I will discuss how a combination of observational and computational techniques will reveal three critical atmospheric processes: clouds, winds and aurorae. Each of these processes are well-studied in our own Solar System and we can now begin to study them on worlds beyond our own. The speaker will be available for one-on-one meetings throughout their 2-day visit: they will be at UMass on Thursday and Amherst College on Friday. If you’re interested in meeting with them, please reserve a slot on the spreadsheet here: https://docs.google.com/document/d/1e0IgfjA4IOtTSroK_KEqm8GMVnyQhq5P7j6fUccu740/edit?usp=sharing.

This talk presents brand new data from our JWST program "Halfway to the Peak" which investigates the relationship between star forming galaxies and their central black holes at z~0.6, halfway back to the peak epoch of galaxy evolution. This program leverages the rich diagnostic power of mid-IR spectroscopy to separate the AGN and star formation energetics in galaxies, and only now with MIRI/MRS are we able to detect the rich mid-IR atomic lines to quantify the black hole accretion rates ([NeV], [NeVI]) and spatially resolve the star formation (Br-alpha) outside the local Universe. In order to fully realize the potential of these JWST data we developed several novel reduction methods which overcome unforeseen issues with this new instrument. This talk will provide a first look at these data and our future plans for full scientific exploration. Zoom: https://umass-amherst.zoom.us/j/91015254428?pwd=dUlwZ1RadXVMcW1Jd3BiQW1KRFhIdz09

The detections of gravitational waves from compact binary mergers and the followup observations of electromagnetic emissions together provide a powerful and independent tool to explore the Universe. With successive upgrades to the LIGO and Virgo sensitivities, and hence a growing number of detections, we are prepared to address a number of major questions in astrophysics. In this talk, I will discuss two topics in which I expect critical progress will be made in the next few years: (i) How do we make precise and accurate Hubble constant measurements with gravitational-wave events? (ii) What can we learn about neutron star nuclear physics from gravitational-wave observations? I will close with my outlook on the immense scientific opportunities that the next-generation gravitational-wave detectors will provide. Zoom: https://umass-amherst.zoom.us/j/91015254428?pwd=dUlwZ1RadXVMcW1Jd3BiQW1KRFhIdz09 The speaker will be available for one-on-one meetings throughout their visit. If you’re interested in meeting with them, please reserve a slot on the spreadsheet here: https://docs.google.com/document/d/1tvpckaJweKhE7683e1UK1p09Mg3wE_n1y7DuvNZCwi4/edit?usp=sharing All graduate students and postdocs are welcome and encouraged to join the speaker for an informal lunch discussion from 12:30-1:30 in LGRT 533, which can be attended remotely via https://umass-amherst.zoom.us/j/97165107867.

Dust within galaxies obscures light at UV, optical, and near infrared wavelengths. A description of this dust attenuation and how it evolves with time is a critical ingredient of future precision studies of distant galaxies. To date, there has been little work on establishing the extent to which attenuation curves vary within galaxies. This will be of critical importance to maximize returns from current and imminent facilities capable of high resolution imaging and spectroscopy (e.g., JWST, GMT, ELT). I will discuss my current and future work to address this issue using three state-of-the-art integral field spectroscopic surveys that together span 80% of cosmic time: (1) TYPHOON – a survey of 44 nearby (z~0), large-angular size (>few arcmin) galaxies, (2) MAGPI – a VLT/MUSE large program (340hr) of hundreds of resolved galaxies at z~0.3 across a range of environments (isolation, group, cluster), (3) PASSAGE – a JWST/NIRISS pure-parallel program (591hr) of thousands of galaxies at 1<z<2. By combining these surveys with ancillary data spanning rest-frame ultraviolet to infrared wavelengths, I will obtain a revolutionary view of how galaxies are affected by dust attenuation and how it evolves. As a developer of data products for these surveys, I will also highlight products that will be made publicly available in the future. These data will provide a unique opportunity for legacy science to study spatially-resolved properties of galaxies over cosmic time. Andrew will be available for one-on-one meetings on Thursday. If you’re interested in meeting with them, please reserve a slot on the spreadsheet here: https://docs.google.com/document/d/1Go4ch-RnyhPuOPEW7pctrBxbETtQ_xWbw68-QGb-9V4/edit?usp=sharing

In recent years, a major focus of research in galaxy formation and evolution has been on the ability of feedback to limit star formation. This happens at the scale of individual giant molecular clouds (GMCs), which are destroyed largely as the result of the radiation input from massive stars, and at the scale of whole galaxies, in which star formation can be quenched by the ejection of baryons in multiphase galactic superwinds. To understand this “face” of feedback in quantitative detail, high-resolution numerical radiation magnetohydrodynamic (RMHD) simulations with very high spatial resolution and accurate algorithmic implementations for key physical processes are required. I will report on recent results from our group based on simulations of this kind, which (1) allow us to distinguish the relative importance of photo-evaporation and radiation pressure on cloud destruction as a function of GMC properties, and produce observed GMC lifetimes and star formation efficiencies consistent with observations; and (2) provide predictions for the mass, energy, and metal loading scaling relations of galactic winds as a function of the large scale star formation rate. The second “face” of star formation feedback is its role — via radiation and supernovae -- in providing the heating and input of kinetic energy that offsets cooling and dissipation, in order to maintain the observed thermal, turbulent, and magnetic pressure in the three-phase ISM. Our numerical RMHD simulations and associated theory have also advanced understanding of this aspect of feedback, demonstrating that star formation and the ISM reach a co-regulated equilibrium state for a wide range of conditions in disk galaxies. I will argue that it is this equilibrium that underlies observed star formation scaling relations in disk galaxies, and that simple feedback “yield” parameters that encapsulate the complexities of heating/cooling and driving/dissipation processes can be used to predict star formation rates based on the large-scale gas and stellar contents of galaxies, in good agreement with observations. All graduate students and postdocs are welcome and encouraged to join the speaker for an informal lunch discussion from 12:30-1:30 in LGRT 533, which can be attended remotely via https://umass-amherst.zoom.us/j/97165107867. Please let John Weaver know if you are interested in attending dinner with the speaker on Thursday evening, the location of which is TBD.

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.

The Milky Way’s Galactic Center black hole Sagittarius A* is the closest to us supermassive black hole. It is an ideal candidate to explore near horizon effects, to test alternative theories of gravity, and to learn the mechanics of black hole feeding, accretion, and feedback -- forces shaping galaxies and the Universe as a whole. Despite its proximity, the accretion flow onto it is not well understood. At large scales (10^5 R_sch and beyond), the primary source of information about accretion flow comes from observations of hot X-ray emitting gas. At near horizon scales, the density of the flow is constrained by polarization measurements. At intermediate scales, there are too few model-independent probes to reliably determine physical properties of the gas. In 2019, using ALMA observations I discovered a disk of cool gas at intermediate distances (10^4 R_sch) from the black hole, which provides new clues to the physics of the inner accretion flow of the Sagittarius A*. In this talk, I will review what is known about the structure of the accretion flow around the black hole. I will discuss the properties of the cool disk and what we can learn from it about the structure of the accretion flow. I will show our new realistic simulations of the inner two parsecs of the Galactic Center which, for the first time, captures Sagittarius A*’s multiphase accretion physics.