Colloquia Archives

Taylor Hutchison, NASA
Thursday, November 30, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Eliot Vrijimoet, UMass Astronomy Department
Thursday, November 16, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Kyoungsoo Lee, Purdue University
Thursday, November 9, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Sarah Jeffreson, Harvard University
Thursday, November 2, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Anna Wright, John Hopkins University
Thursday, October 26, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
John Weaver, UMass Astronomy Department
Thursday, October 19, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Alex Gagliano, Massachuetts Institute of Technology
Thursday, October 12, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Shreyas Vissapragada, Harvard University
Thursday, October 5, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Paul Goldsmith, NASA Jet Propulsion Laboratory/Robotic Space
Thursday, September 28, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Jamboree
Thursday, September 21, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
Jamboree
Thursday, September 14, 2023
3:45 p.m.
LGRT 1033
Title:
TBD
TBA
Thursday, August 10, 2023
12:00 noon
ILCN 101
Title:
FCAD Undergraduate Research Symposium
Abstract:
The 2023 FCAD Undergraduate Research Symposium will be on Thursday, August 10th from 12:00 PM - 2:30 PM at the Integrated Learning Center N101. Please join us to hear about the great research that the students have done over the summer. Please arrive a few minutes early to get a seat as talks will start promptly at noon. This year there will be 11 presentations, each presentation will consist of 6 min talk + 3 min Q&A. Antonio's Pizza and soda will be provided for lunch and will be served from 1:00 PM - 1:40 PM
Ranita Jana - Tel Aviv University
Monday, July 31, 2023
12:00 noon
LGRT 533
Title:
X-ray signatures of galactic outflows in the circumgalactic medium
Abstract:
Extraplanar X-ray emission around galaxies reveals the nature of the circumgalactic medium (CGM) and how it interacts with feedback from the galaxy. Using idealized hydrodynamical simulations, we study how galactic outflows modify the X-ray signature of the hot CGM. We consider different initial CGM profiles and different energy injection mechanisms to account for model uncertainties. We find that outflows from the center shock-heat the inner CGM and remove gas from the center. The shock heating increases the brightness and also creates flatter X-ray (0.5 − 2 keV) surface brightness profiles within the inner 10’s of kpc, consistent with recent eROSITA observations. We also find that the effects of such outflows, including X-ray surface brightness can be modeled using a spherical shock propagation model in the CGM. Our models also produce X-ray luminosities that are consistent with Chandra observations of star-forming galaxies. Our models, therefore, provide a way to understand observed surface brightness profiles in terms of the energy from galactic outflows.
Joe Burchett, NMSU
Thursday, May 11, 2023
3:45 p.m.
LGRT 1033
Title:
A UV Spectroscopist's Apology: Slime Mold, Cosmic Ecosystems, and Why We Need an X-ray Imaging Microcalorimeter Probe
Abstract:
As galaxies bathe in their gaseous environments, whether it be their local circumgalactic medium (CGM) or the larger-scale intergalactic medium (IGM), it is clear that the symbiosis between them must drive galaxy evolution. I will present evidence from both observational and theoretical perspectives on the connection between galaxy evolution and the CGM/IGM. With a little help from slime mold, my team has developed a new framework to reconstruct the latent cosmic web structure within spectroscopic galaxy surveys. Given that our methodology enables us to infer cosmological overdensity far from galaxy positions, we can use traditional absorption line techniques as well as fast radio bursts to probe the gas physical conditions within the IGM permeating the large-scale structure. Using the TNG100 cosmological simulation, we have examined the relationship between galaxy star formation (SF) and large-scale environment over cosmic time. We have found a pronounced onset of the SF-environmental relationship, providing a critical test for galaxy formation theory in the era of surveys such as DESI, Roman, PFS, and LSST. Lastly, I will contend that the path forward to truly elucidating the connections among galaxies, feedback processes, and their gas reservoirs on both local and large scales must happen in the X-ray regime, particularly through imaging microcalorimetry in the next NASA probe mission. Hopefully, together, we can help this UV spectroscopist come to grips with that.
Chris Hayward, Research Scientist, Flatiron Institute
Thursday, May 4, 2023
3:45 p.m.
LGRT 1033
Title:
What can high-redshift, infrared-luminous galaxies tell us about galaxy formation physics and cosmology?
Abstract:
Interstellar dust is pervasive throughout the Universe, and most light from young, massive stars is absorbed by dust and reradiated as thermal emission in the infrared. Submillimeter galaxies (SMGs), a class of very infrared-luminous distant galaxies, are some of the most extreme star-forming galaxies known, forming stars at rates hundreds or even thousands of times greater than our own Milky Way. I will review our understanding of this enigmatic population, which has challenged galaxy formation theories since their discovery in the late 1990s. I will highlight how the population provides novel constraints on galaxy formation physics, cosmology, and possibly even the nature of dark matter. I will also show how they serve as beacons of galaxy clusters in the process of formation.
Erin Kara, MIT
Thursday, April 27, 2023
3:45 p.m.
LGRT 1033
Title:
Probing the causal connection between inflow and outflow in accreting black holes
Abstract:
Most of the power from an Active Galactic Nucleus is released close to the black hole, and thus studying the inner accretion flow, at the intersection of inflow and outflow, is essential for understanding how black holes grow and affect galaxy evolution. In the past decade, we have had a breakthrough in how we probe the inner accretion flow, through the discovery of X-ray Reverberation Mapping, where X-rays produced close to the black hole reverberate off inflowing gas. By measuring reverberation time delays, we can quantify the effects of strongly curved space time and the black hole spin, which is key for understanding how efficiently energy can be tapped from the accretion process. In this talk, I will give an overview of this field, and will show how extending these spectral-timing techniques to transient accretion events like Tidal Disruption Events and black hole X-ray binaries is helping us probe the formation of X-ray coronae, jets and other relativistic outflows.
Laurent Pueyo, STSci Astronomer
Thursday, April 20, 2023
3:45 p.m.
LGRT 1033
Title:
Resolved images of giant exoplanet in the era of JWST
Abstract:
In this presentation I will discuss how the one-year-old James Webb Space Telescope will revolutionize our understanding of giant planet formation and evolution. I will start by describing our current observational knowledge about giant planets, tying together solar system bodies, known exoplanets and their massive Brown Dwarf cousins. I will then briefly review highlights of JWST commissioning and its unique capabilities when it comes to giant exoplanets. Most of the talk will focus on three key observational diagnostics: giant planets as the low mass extension of the Brown Dwarf Initial Mass Function, atmospheric composition of giant planets at long and short orbital periods, and imaging giant planets at solar system scales. For each diagnostic I will review results obtained by our team using a combination of Hubble and ground-based telescopes and present very recent JWST observations that demonstrate the promises of this new observatory. I will conclude by discussing future NASA missions aimed at imaging habitable exoplanets, in particular drawing from the lessons we have learned through this first year of giant planet science with JWST.
Grant Wilson / University of Massachusetts Amherst
Thursday, April 13, 2023
3:45 p.m.
LGRT 1033
Title:
Swinging for the Fences - An Update on the TolTEC Project
Abstract:
The TolTEC Imaging Polarimeter is a new, 7000 pixel, millimeter wavelength camera. The camera is now installed and making commissioning observations at the Large Millimeter Telescope, after which it will both start a series of Legacy Surveys and be available for PI-led LMT projects. In this talk I will endeavor to bring everyone up to date on the instrument's status and prospects for new data. I will describe key aspects of the technologies that underlie the camera, review the key science questions that motivated its construction, describe its capabilities on the LMT, and focus in on our plans for the initial set of our TolTEC Legacy Surveys. I'll conclude the talk by returning to my laptop to continue working on the commissioning data.
Rachel Bezanson, University of Pittsburgh
Thursday, April 6, 2023
3:45 p.m.
LGRT 1033
Title:
How it started . . . How it’s going: tracing the formation and evolution of massive galaxies through cosmic time
Abstract:
Galaxies are extraordinarily complex collections of stars, gas, and dark matter. The largest galaxies, though relatively rare in number, host most of the stars in the Universe and deep in their cores harbor the most extreme supermassive black holes. Today massive galaxies are red and dead ellipticals with little ongoing star formation or organized rotation; naturally they were expected to be relics of a much earlier formation epoch. In this talk I will briefly review the paradigm that has emerged over the last decade, discussing the structural and kinematic evolution of massive galaxies during and after they stopped forming stars (“quenched”) and eventually transformed from rotationally supported disks into kinematically hot ellipticals. I will describe my team’s observational efforts to characterize the histories of galaxies like our Milky Way and larger at several critical moments in the 14 billion year history of the Universe, each corresponding to a large spectroscopic program. Spectroscopic studies of distant galaxies reveal the chemical compositions, detailed star formation histories, and internal motions of stars and gas and are necessary to answer open questions about the details of that cosmic formation and shutdown. This work includes studying galaxy metamorphosis at ~half the age of the Universe, highlighting results from the ultra-deep LEGA-C spectroscopic survey of ~3500 massive galaxies and the focused multi-wavelength SQUIGGLE survey of post-starburst galaxies caught immediately following their cosmic shutdown. I will discuss our JWST UNCOVER treasury program that will extend deep spectroscopic studies of galaxies to the earliest moments in cosmic history. Finally, my team will connect-the-dots through the peak of cosmic star formation (~10 billion years ago) using the next-generation massively multiplexed Prime Focus Spectrograph on the Subaru Telescope.
J.J. Hermes, Assistant Professor Boston University
Thursday, March 30, 2023
3:45 p.m.
LGRT 1033
Title:
Searching for signposts of failed white dwarf supernovae
Abstract:
Type Ia supernovae involve the thermonuclear detonation of white dwarf stars, and are an essential tool allowing us to study the Universe on vast scales. However, Type Ia supernovae are not the only byproducts of the mergers at the endpoints of binaries. I will discuss the growing number of observational signposts that can distinguish populations of white dwarf stars that descend from failed Type Ia supernovae. I will also discuss how space-based missions like Gaia, Kepler, and TESS have allowed us to better select merger byproducts among the population of typical stellar remnants, allowing us to better characterize the fossils in our nearby stellar graveyard.
Distinguished Faculty Lecture - Dr. Peter Schloerb
Thursday, March 23, 2023
4:00 p.m.
LGRT 1033
Title:
UMass and the Large Millimeter Telescope
Abstract:
In 2019, the first image ever made of a black hole triggered international excitement. The stunning image brought enormous attention to the University of Massachusetts, which played a key part in the global collaboration that captured the image. The image of the black hole was made possible by UMass Amherst’s leadership in the construction and operation of the 50-meter-diameter Large Millimeter Telescope (LMT), located atop a mountain in Mexico. One of the university’s most ambitious scientific projects, the LMT was built jointly by the country of Mexico and UMass Amherst. Professor Schloerb, an award-winning radio astronomer and planetary scientist who, has been a leader in the LMT project for over 30 years. In this lecture, he will tell the story of the university’s role in the conception, design, and construction of the world-leading telescope. He will discuss its most notable scientific achievement—the black hole image—and the LMT’s prospects for future exciting discoveries. The honoree will be introduced by Dean Nate Whitaker, and will be presented with the Chancellor’s Medal, the highest recognition bestowed upon faculty by the campus. Synopsis: In 2019, the first image ever made of a black hole triggered international excitement. The stunning image brought enormous attention to the University of Massachusetts, which played a key part in the global collaboration that captured the image. The image of the black hole was made possible by UMass Amherst’s leadership in the construction and operation of the 50-meter-diameter Large Millimeter Telescope (LMT), located atop a mountain in Mexico. One of the university’s most ambitious scientific projects, the LMT was built jointly by the country of Mexico and UMass Amherst. More information can be found here:
No Colloquium-Spring Recess
Thursday, March 16, 2023
3:45 p.m.
LGRT 1033
To Be Determined
Thursday, March 9, 2023
3:45 p.m.
LGRT 1033
Title:
To Be Determined:
Nicole Arulanantham, STSci
Thursday, March 2, 2023
3:45 p.m.
LGRT 1033
Title:
UV-driven Evolution and Chemistry of Protoplanetary Disks: Insights from HST’s ULLYSES Program
Abstract:
Beginning in December 2019, approximately 70 T Tauri stars were observed at UV wavelengths through the Hubble UV Legacy Library of Young Stars as Essential Standards Director's Discretionary program (ULLYSES). These publicly available spectra provide critical observational constraints on UV irradiation of protoplanetary disks, a key driver of the gas phase chemistry that sets the initial conditions for planet formation. We use the HST data and radiative transfer models to reproduce the LyA emission seen by surface layers of the gas disks, which typically makes up the largest component of the total integrated UV flux. The model LyA flux available to photodissociate molecules like H2O, HCN, and CH3CN within disks with dust cavities and gaps varies by two orders of magnitude, and we explore how the spread might translate to observable chemical differences. We also investigate whether ultraviolet emission lines from UV-fluorescent H2 can be used to break the degeneracy between disk flaring and UV irradiation of the gas in models of sub-mm CN emission. This work is critical for interpreting molecular features in T Tauri systems observed with ALMA and JWST, demonstrating how UV radiation propagates from the accretion shocks to the outer disks.
Johanna Vos, Postdoctoral Fellow, American Museum of Natural History
Thursday, February 23, 2023
3:45 p.m.
LGRT 1033
Title:
Exometeorology: Weather on Worlds Beyond our Own
Abstract:
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.
Thiago Goncalves
Thursday, February 16, 2023
3:45 p.m.
LGRT 1033
Title:
Lyman break analogues: local laboratories for galaxy formation and evolution under extreme conditions
Abstract:
The universe experienced the peak of star formation activity approximately 10 billion years ago, but objects at such epochs are difficult to observe in detail due to the large distances involved. In this talk, I will discuss the background and recent results of a series of works on a sample of local analogues of high-redshift star forming galaxies. These objects, selected based on their high UV luminosities and surface brightness, show characteristics more akin to galaxies at z ~ 1.5-2, while their proximity allows for detailed investigations of a wide variety of physical properties, including (among others) kinematics, gas masses, and environments. They also show signs of nuclear accretion onto central intermediate mass black holes, and as such could act as interesting laboratories for an important brief stage of black hole growth before the M-sigma relation is fully established.
Jason Young
Thursday, December 8, 2022
3:45 p.m.
LGRT 1033
Title:
Halfway to the Peak
Abstract:
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
Malena Rice, Yale University
Thursday, December 1, 2022
3:45 p.m.
LGRT 1033
Title:
Insights from the Orbital Architectures of Planetary Systems
Abstract:
The orbital configurations of planetary systems serve as fossilized signatures of their past dynamical evolution. These signatures provide a direct window into planetary systems’ formation histories at both the individual and population level, constraining the prevalence of mechanisms such as migration, secular evolution, and short-term scattering events. My research program investigates the dynamical relationship between stars, planets, and minor planets to demonstrate the key underlying processes that produce the observed diversity of planetary systems. I will draw from interconnected subfields of solar system and exoplanetary science to consider how the interface between subfields can be leveraged to develop a synthesized view of planetary system evolution.
No Colloquium
Thursday, November 24, 2022
3:45 p.m.
LGRT 1033
Title:
No Colloquium
Daniella Bardelez Gagliuffi, Amherst College
Thursday, November 17, 2022
3:45 p.m.
LGRT 1033
Title:
Reconstructing Planet Formation Using Dynamical and Chemical Fossils
Abstract:
The dynamical and chemical signatures of a planetary system are independent fossil records of its past. Orbital parameters are vestiges of its formation and dynamical evolution, while chemical compositions of planets and hosts are fingerprints of the stellar nursery and the protoplanetary disk where they formed. In this talk, I will explain the cutting-edge techniques I am using to measure orbital parameters and compositions and how to leverage them to reconstruct the history of planetary systems at a population scale. Obtaining these measurements in a volume-limited sample will enable robust statistics to develop a probabilistic model of formation mechanisms, observationally constraining their transition from stellar binary to planetary formation for the first time. This analysis will lead to the identification of spectroscopic signatures of formation with next generation observatories as we take our first steps towards a comprehensive theory of star and planet formation to uncover our cosmic origins. The link to sign up to meet with her is here: https://docs.google.com/document/d/1lCpmm1JUVt4zU59AZQ0SeQgzPjaIDxSMWBsLylp6q1A/edit?usp=sharing The Zoom link for the talk is here: https://umass-amherst.zoom.us/j/91015254428?pwd=dUlwZ1RadXVMcW1Jd3BiQW1KRFhIdz09

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