The passing of Dr. David Katzenstein, a friend and benefactor of the UConn Department of Physics
Dr. David Katzenstein, a friend, and benefactor of the UConn Department of Physics, passed away on January 25, 2021 due to Covid-19. David was the son of Henry Katzenstein, the first Physics Ph.D. from UConn and a major benefactor of our Department. Currently, both the annual Katzenstein Distinguished Lecture and the Katzenstein Prize for a […]
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A Signal from Beyond
UConn astrophysicist Chiara Mingarelli is part of a team of researchers who recently published data on a hint of a signal that sent ripples of excitement through the physics community. These monumental findings are the culmination of twelve and a half years of data gathered from NANOGrav — a network of pulsars across the galaxy — all in the hopes of detecting gravitational waves.
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UConn Physics alumnus Dr. Michael Wininger
UConn Physics alumnus Dr. Michael Wininger (BS, 2003) was recently featured in the professional journal O&P Almanac (Orthotics and Prosthetics). The article describes how his eclectic background, beginning with degrees from UConn, has enabled him to lead innovations in several areas of health research. Mike is currently an Assistant Clinical Professor in the Biostatistics Department […]
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UConn Researcher an Architect for Astronomical Survey Making Observations Toward a New Understanding of the Cosmos
November 2, 2020 – Elaina Hancock – UConn Communications The Sloan Digital Sky Survey’s fifth generation – a groundbreaking project to bolster our understanding of the formation and evolution of galaxies, including the Milky Way – collected its very first observations on the evening of October 23. Image: The Sloan Digital Sky Survey’s fifth generation […]
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The passing of UConn Physics Professor Emeritus, Arnold Russek
Arnold Russek, a theoretical atomic physicist, born July 13, 1926, in New York, passed away on October 13th, 2020, in Colorado. As a young man of 18, he served honorably as a radio engineer in the Pacific during WWII. He earned his Ph.D. at the Courant Institute at New York University in 1953, and taught […]
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AAS Author Interview with Gloria Fonseca Alvarez
UConn graduate student Gloria Fonseca Alvarez was featured with a video in the Author Interview series produced by the American Astronomical Society (AAS). In this video, Gloria talks about her work to understand the inner environments of black holes. The paper highlighted in the video shows that the orbits of emission-line gas around supermassive black holes are often smaller than expected from previous observations.
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Stretching Makes Superconductor
Most superconductors only work when they’re super cold. Chemists and metallurgists have experimented with different combinations of elements for years, trying to get superconductors that work at temperatures close to room temperature. Sochnikov and his students are thinking about it differently. What if mechanical changes such as squeezing or stretching could make a material a superconductor?
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Longtime Science Pioneer Passes Away
Throughout her long life, Cynthia Peterson educated and enriched her family, her students, and her community through science, discovery, and a lifelong enthusiasm for teaching prospective scientists. Through community outreach and during her many years as a professor, Cynthia taught many that wonderment can be found simply by looking up at the night sky.
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My Long-time Friend and Colleague, Prof. Cynthia W. Peterson
When I arrived in Storrs from New York City in 1969 to teach physics at the University of Connecticut, one of the first colleagues I met was Dr. Cynthia Peterson. She had an infectious enthusiasm that appealed to me and my wife Anne. It turned out that Anne and Cynthia had both been students at […]
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New Physics Faculty: Erin Scanlon
Erin Scanlon joins our Department in fall 2020 as Assistant Professor in Residence at the Avery Point Campus. Erin comes to UConn with an impressive track record of university teaching experience and scholarship in physics education research (PER). After earning a master’s degree in physics from Georgia Institute of Technology, Erin joined the faculty at […]
[Read More]2020-Newsletter Department Head Greeting
It’s been crazy. That holds for everybody over these past six months; UConn and the Physics Department as well. Events unfurled rapidly last March. Within a week the March Meeting of the APS was cancelled, our department had to postpone the 2020 Katzenstein Lecture with Donna Strickland, and then the University announced that students would […]
[Read More]Spring 2020: The Efforts of Many Made Distance Learning Possible
The transition to online learning that was necessitated due to the COVID-19 outbreak was not without its challenges. Faculty had roughly 10 days to adapt to a modality of instruction most were not used to. TAs had to simultaneously learn how to teach remotely while also adjusting to having the courses they were taking also […]
[Read More]Physics Alum Receives NSF CAREER Award
UConn Physic alum, Dr. Hyewon Pechkis, an Assistant Professor of Physics at the California State University Chico recently received the prestigious CAREER award from the National Science Foundation. This five-year grant titled “Making a Difference in First Year Underrepresented Students’ Education through Research: Quantum Coherence in a Bose Thermal Gas” will facilitate the involvement of […]
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New Physics Faculty: Chris Faesi
We are very excited to extend a warm welcome to a new UConn Physics Faculty member, Dr. Christopher Faesi. Chris is an astrophysicist, specializing in both observational work and modelling, primarily in the study of star formation. He got his PhD at Harvard University, followed by a postdoc at the Max Planck Institute for Astronomy […]
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Prof. Kyungseon Joo named Chair of CLAS Collaboration at Jefferson Lab
Kyungseon Joo, a professor of physics, has been named Chair of the CLAS Collaboration, one of the largest international collaborations in nuclear physics. CLAS involves 50 institutions from 9 countries and has about 250 collaborators. The collaboration recently completed the upgrade of the CEBAF Large Acceptance Spectrometer (CLAS12) for operation at 11 GeV beam energy […]
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Physics Department Joins APS-IDEA Network
The Physics Department’s Diversity & Multiculturalism Committee (DMC) was accepted into the APS Inclusion, Diversity and Equity Alliance (APS-IDEA). Despite years of efforts on local and national levels, the diversity in many physics departments is not reflective of the diversity nationwide. Our department is no exception in this regard. The new APS initiative was created […]
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Professor Luchang Jin receives prestigious DOE Early Career Award
Assistant Professor of Physics Luchang Jin has been chosen to receive a prestigious Early Career Award from the US Department of Energy’s Office of High Energy Physics (HEP) for 2020. The amount of the award is $750,000 to be used over five years. The DOE Early Career Award is extremely competitive: this year only 16 scientists in […]
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Jonathan Trump wins NSF Early Career Award
Jonathan Trump, Assistant Professor of Physics, will receive $738,090 over five years to compile a census of supermassive black holes in the universe. This will give insights into how supermassive black holes and galaxies evolve across cosmic time. Trump will also develop a bridge program for underrepresented undergraduate physics majors at UConn to increase their […]
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New result for part of muon anomaly
Professors Luchang Jin and Tom Blum, along with colleagues at BNL and Columbia, Nagoya and Regensburg universities have completed a first-ever calculation of the hadronic light-by-light scattering contribution to the muon’s anomalous magnetic moment with all errors controlled. The work is published in Physical Review Letters as an Editor’s Suggestion and also appeared in Physics […]
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Radiation Damage Spreads
A single x-ray can unravel an enormous molecule, physicists report in the March 17 issue of Physical Review Letters. Their findings could lead to safer medical imaging and a more nuanced understanding of the electronics of heavy metals. Medical imaging techniques such as MRIs use heavy metals from the bottom of the periodic table as …
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Professor Philip Mannheim University of Connecticut Physics Department Colloquium Series, Prof. Philip Mannheim (Physics Colloquium)3:30pm
3/5
Professor Philip Mannheim University of Connecticut Physics Department Colloquium Series, Prof. Philip Mannheim (Physics Colloquium)
Friday, March 5th, 2021
03:30 PM - 04:30 PM
Storrs Campus remote
Professor Philip Mannheim
University of Connecticut
Physics Department Colloquium Series
Title: Quantum mechanics off the beaten track
Abstract: We discuss some non-conventional options for quantum theory.
We show that not only do Hamiltonians not need
to be Hermitian to have real eigenvalues, they do not even need to be
diagonalizable or possess a complete spectrum of energy eigenstates. We
discuss how to formulate quantum mechanics in such cases.
We show that
it is not always possible to write the momentum operator as the familiar
derivative operator $-id/dx$ where x is real, and discuss what one should
then do. Following
work by Bender and Mannheim [Phys. Rev. Lett. 100, 110402 (2008)] we show
how these issues are relevant to the construction of a consistent theory
of quantum gravity in four spacetime dimensions. In this theory there is no observable graviton. -
Prof. Vernon Cormier, Department of Physics, University of Connecticut, "Earth's Core: formation, structure, and the geodynamo", Graduate Student Seminar12:15pm
3/5
Prof. Vernon Cormier, Department of Physics, University of Connecticut, "Earth's Core: formation, structure, and the geodynamo", Graduate Student Seminar
Friday, March 5th, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof. Vernon Cormier, Department of Physics, University of Connecticut
Earth's Core: formation, structure, and the geodynamo
Earth's magnetic field has been sustained for more than 3 b.y. by convection of a
liquid-iron alloy situated between a silicate outer mantle and a solid iron inner core in its center. Its magnetic field is characterized by a rich spectrum of secular and
spatial variations, having correlations with the elastic structures of the lowermost
mantle and an oscillating inner core, driven by lateral variations in convective and
conductive heat transport and Lorentz forces. In this talk, I will review current
research on the structure andevolution of Earth's core and its magnetic field -
Dr. Antonio Picón, Departamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid, "Mapping the real-time movies of chemical bonds", Atomic, Molecular, And Optical Physics Seminar4:00pm
3/3
Dr. Antonio Picón, Departamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid, "Mapping the real-time movies of chemical bonds", Atomic, Molecular, And Optical Physics Seminar
Wednesday, March 3rd, 2021
04:00 PM - 05:00 PM
Storrs Campus online
Dr. Antonio Picón, Departamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid
Mapping the real-time movies of chemical bonds
Valence electrons play a crucial role in the formation of chemical bonds within a molecular system and determine its charge and electron transfer properties. In the static regime, these properties are defined by the electron density distribution of the equilibrium geometry. However, when out of equilibrium, ultrafast electronic rearrangements within the order of a few femtoseconds together a significant alteration of the chemical bonds can occur. I will address in this talk our undergoing investigations for mapping these ultrafast changes through X-ray photoelectron spectroscopy that have been critical in retransforming the well-established concepts of chemical shifts. I will additionally illustrate our developments for the selective manipulation of chemical bonding through X-ray free electron laser pulses. -
Dr. Siddharth Mohite, UW-Milwaukee and CCA, Flatiron Institute, "Investigating Populations across the Gravitational-Wave Mass Spectrum: Statistical Tools and Implications for Astrophysics", Astronomy Seminar11:30am
3/3
Dr. Siddharth Mohite, UW-Milwaukee and CCA, Flatiron Institute, "Investigating Populations across the Gravitational-Wave Mass Spectrum: Statistical Tools and Implications for Astrophysics", Astronomy Seminar
Wednesday, March 3rd, 2021
11:30 AM - 12:00 PM
Storrs Campus online
Dr. Siddharth Mohite, UW-Milwaukee and CCA, Flatiron Institute
Investigating Populations across the Gravitational-Wave Mass Spectrum: Statistical Tools and Implications for Astrophysics
Merging compact object binaries comprising of pairs of black holes, neutron stars or a neutron star and a black hole are energetic sources of gravitational-wave (GW) and electromagnetic (EM) radiation. Current and future gravitational-wave observatories such as LIGO-Virgo-KAGRA, LISA and NANOGrav will help uncover a diverse population of these binaries across the mass spectrum. While the LIGO-Virgo-KAGRA observatories probe compact objects roughly from 1 to 100 times a solar mass, observatories such as LISA and NANOGrav are predicted to probe supermassive binaries in the million to billion solar mass regimes. On the other hand, telescopes around the world will aid in detecting binaries that contain neutron stars by observing an associated electromagnetic counterpart called a kilonova. Investigating the properties of these binary populations will shed light on some long-standing problems in astrophysics such as stellar and galaxy evolution and nuclear equation of state. In this talk, I will present an attempt to create a Bayesian framework that can simultaneously use information from GW and EM surveys to place constraints on the kilonova population. I will also briefly introduce a method to model the mass distribution of binaries detectable by LIGO-Virgo-KAGRA, using Gaussian processes. Finally, I will also present some investigations into modeling the effects of circum-binary gas and eccentricity on the expected gravitational-wave sources from merging supermassive black hole binaries detectable by observatories like NANOGrav. -
Joyce Caliendo, University of Connecticut , "Early Science with the Large Millimeter Telescope: Constraining the Gas Fraction of a Compact Quiescent Galaxy at z = 1.883 ", Astronomy Seminar11:00am
3/3
Joyce Caliendo, University of Connecticut , "Early Science with the Large Millimeter Telescope: Constraining the Gas Fraction of a Compact Quiescent Galaxy at z = 1.883 ", Astronomy Seminar
Wednesday, March 3rd, 2021
11:00 AM - 11:30 AM
Storrs Campus online
Joyce Caliendo, University of Connecticut
Early Science with the Large Millimeter Telescope: Constraining the Gas Fraction of a Compact Quiescent Galaxy at z = 1.883
We present constraints on the dust continuum flux and inferred gas content of a gravitationally lensed massive quiescent galaxy at z=1.883 +/- 0.001 using AzTEC 1.1mm imaging with the Large Millimeter Telescope. MRG-S0851 appears to be a prototypical massive compact quiescent galaxy but has evidence that it experienced a centrally concentrated rejuvenation event in the last 100 Myr. This galaxy is undetected in the AzTEC image but we calculate an upper limit on the millimeter flux and use this to estimate the H_2 mass limit via an empirically calibrated relation that assumes a constant molecular gas-to-dust ratio of 150.
We constrain the 3 sigma upper limit of the H_2 fraction from the dust continuum in MRG-S0851 to be M_(H_2)/M_* < 6.8%. MRG-S0851 has a low gas fraction limit with a moderately low sSFR owing to the recent rejuvenation episode, which together results in a relatively short depletion time of -
Dr. H. Larsson, California Institute of Technology, "Molecules in quantum motion --- Understanding electrons, nuclei, and their interactions", Atomic, Molecular, And Optical Physics Seminar4:00pm
3/1
Dr. H. Larsson, California Institute of Technology, "Molecules in quantum motion --- Understanding electrons, nuclei, and their interactions", Atomic, Molecular, And Optical Physics Seminar
Monday, March 1st, 2021
04:00 PM - 05:00 PM
Storrs Campus online
Dr. H. Larsson, California Institute of Technology
Molecules in quantum motion ---
Understanding electrons, nuclei, and their interactions
In order to fully understand the chemical physics of molecular systems, we need to simulate both the electronic and vibrational motion quantum mechanically. However, simulations of quantum many-body systems, such as molecules, scale exponentially with system size. I will explain how to tame this 'curse of dimensionality' by combining methods from the traditionally disjoint fields of electronic structure and nuclear dynamics. This combination has enabled the simulation of complex systems with unprecedented accuracy and speed. I will demonstrate how these methods make it possible to solve a diverse set of problems, ranging from characterizing hydrated protons on a molecular quantum level to the interaction of molecules with extremely short and intense light pulses on attosecond time scales. I will demonstrate how these simulations provide new insight into complex fundamental physical processes. -
Prof. Stella Offner, UT Austin, "Physics Department Colloquium", Professor Stella Offner (Physics Colloquium)3:30pm
2/26
Prof. Stella Offner, UT Austin, "Physics Department Colloquium", Professor Stella Offner (Physics Colloquium)
Friday, February 26th, 2021
03:30 PM - 04:30 PM
Storrs Campus remote
Prof. Stella Offner, UT Austin
Physics Department Colloquium
Title and abstract: TBD -
Graduate Student Yasaman Homayouni, Department of Physics, University of Connecticut, PhD Dissertation Defense1:00pm
2/26
Graduate Student Yasaman Homayouni, Department of Physics, University of Connecticut, PhD Dissertation Defense
Friday, February 26th, 2021
01:00 PM - 03:00 PM
Storrs Campus Video meeting
Graduate Student Yasaman Homayouni, Department of Physics,
University of Connecticut
Supermassive black holes are among the most exciting and unusual objects in our Universe, as literal rips in space and time. Reliable measurements of mass, the structure, and geometry of infalling material to supermassive black holes are critical to understanding the growth history of black holes and galaxy formation and evolution over cosmic time. Beyond the local Universe, the gold standard for black hole mass and accretion-disk structure is reverberation mapping. I will present a new generation of industrial-scale study of the structure, and geometry of infalling material and black hole mass studies from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project and Ultraviolet-monitoring using the Hubble Space Telescope. These new measurements have transformed our understanding of supermassive black holes by dramatically expanding the number of quasars with reliable mass and accretion structure in distant Universe. These measurements have also revealed a surprisingly large diversity in accretion structure and the broad-line region size of quasars at the peak of supermassive black hole assembly. My work lays the foundation by developing the framework to reliably measure mass and the structure of accretion using direct disk size measurements from future massive time-domain photometric monitoring studies from SDSS-V and Rubin/LSST.
Webex link: https://uconn-cmr.webex.com/join/jot16106 -
Prof. Nora Berrah, Department of Physics, University of Connecticut, "Probing Molecular Dynamics in Real Time with Fancy Lasers", Graduate Student Seminar12:15pm
2/26
Prof. Nora Berrah, Department of Physics, University of Connecticut, "Probing Molecular Dynamics in Real Time with Fancy Lasers", Graduate Student Seminar
Friday, February 26th, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof. Nora Berrah, Department of Physics, University of Connecticut
Probing Molecular Dynamics in Real Time with Fancy Lasers
The knowledge of the earliest time dynamics in molecular photophysics is critical because its role is to harness the energy from photons, initiating electronic and nuclear motion which is
fundamental in many areas of science. Our ultimate goal is to understand the coupled electronic and nuclear dynamics induced by the absorption of photons by molecules, which leads first to attosecond electron excitation within the molecules, followed by nuclear motion in the femtosecond range. This eventually results in the breaking and making of chemical bonds on the
picosecond timescale.
Our UConn lab uses ultrafast table-top lasers and a Cold Target Recoil-Ion Momentum
Spectroscopy (COLTRIMS) with IR and UV to determine processes such as double-H migration
in molecules as demonstrated by our recent work by McDonnel et al., "Ultrafast laser-induced
isomerization dynamics in Acetonitrile", J. Phys. Chem. Lett. 11, 6724−6729 (2020).
The past decade has seen the exciting birth of the first X-ray laser, the LCLS free electron laser (FEL) followed by other FELs around the world, leading to an explosion of new science, in the femtosecond and very recently in the attosecond regime. Our recent time-resolved experimental results using pump-probe technique with FELs to watch, in real time, the response of large
molecules to intense X-rays is included in Berrah et al., "X-ray multiphoton ionization of molecules: Femtosecond-resolved observation of delayed fragmentation and evaporation of neutral atoms", Nature
Physics 15, 1279 (2019).
We also investigate inner-shell molecular ionization and fragmentation dynamics of large
molecules using differential techniques such as double velocity map imaging (VMI) spectrometers to carry out electron-ion and ion-ion coincidence experiments at the ALS synchrotron at LBNL,
that allowed detail measurements such as our recent work by Obaid et al., "Intermolecular Coulombic decay in endohedral fullerene at the 4d→ 4f resonance", Phys. Rev Lett. 124 (11), 113002, (2020).
This work is funded by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic
Energy Sciences, Office of Science, US Department of Energy and the NSF. -
Dr. Jean Marcel Ngoko Djiokap, Department of Physics & Astronomy, University of Nebraska, Lincoln, "Control of Electron Motion on an Attosecond Timescale ", Atomic, Molecular, And Optical Physics Seminar4:00pm
2/24
Dr. Jean Marcel Ngoko Djiokap, Department of Physics & Astronomy, University of Nebraska, Lincoln, "Control of Electron Motion on an Attosecond Timescale ", Atomic, Molecular, And Optical Physics Seminar
Wednesday, February 24th, 2021
04:00 PM - 05:00 PM
Storrs Campus online
Dr. Jean Marcel Ngoko Djiokap, Department of Physics & Astronomy, University of Nebraska, Lincoln
Control of Electron Motion on an Attosecond Timescale
Technological advances 20 years ago in producing new extreme ultraviolet coherent light sources with attosecond duration have created a new research field, namely, attosecond physics. A main goal of attosecond physics is to control electron motion on its natural (attosecond) timescale, in order to probe bond formation and breaking in molecules during chemical reactions. A milestone toward achieving such goal is the experimental realization of isolated, few-cycle, attosecond pulses seeded by a free electron laser (FEL) or high harmonic generation (HHG) with stable and tunable carrier-envelope phase (CEP), and with full control of their polarizations. Unlike HHG, X-ray attosecond pulses from FEL have sufficient intensities that permit the realization of the holy grail (atto-pump/atto-probe experiments) of attosecond physics. Use of circularly or elliptically polarized attosecond light opens the possibility of presently investigating and manipulating linear and nonlinear effects that are not accessible with linearly-polarized pulses. In this talk, after briefly introducing the physical mechanisms at the basis of attosecond pulse generation, I will focus on our numerical and analytical methods for the investigation of ultrafast ionization processes in atoms and molecules of astrophysical interest, with emphasis on two-electron processes in which electron correlations play a key role. Enabled by the broad bandwidth of attosecond pulses, the first unusual effect we predicted in double photoionization of H2 by an intense few-cycle elliptically polarized attosecond pulse is the molecular symmetry-mixed dichroism (MSMD. The other effect is the novel electron phenomenon of electron vortices in attosecond photoionization of atoms and molecules, which provides a dramatic example of wave-particle duality. Our predictions of electron matter-wave vortices, which have now been observed experimentally, have already opened a new interdisciplinary area in physics. -
Dr. S. Feeney, UCL, "Clarifying the Hubble Constant Tension", Astronomy Seminar11:00am
2/24
Dr. S. Feeney, UCL, "Clarifying the Hubble Constant Tension", Astronomy Seminar
Wednesday, February 24th, 2021
11:00 AM - 12:00 PM
Storrs Campus online
Dr. S. Feeney, UCL
Clarifying the Hubble Constant Tension
Our best estimate of the Universe's current expansion rate (the Hubble constant) from the local Universe (via the Cepheid distance ladder) is in four-sigma tension with the value extrapolated from cosmic microwave background data assuming the standard cosmology. Whether this discrepancy represents physics beyond the Standard Model or deficiencies in our understanding of the data is the subject of intense debate. In this talk, I will review the community's attempts to explain and interpret the Hubble constant tension, clarifying the current picture using Bayesian probability theory, and consider the potential for independent gravitational wave observations to arbitrate the dispute. -
Prof. Chandrasekhar Roychoudhuri, Department of Physics, University of Connecticut, "Ubiquitous presence of "electric tension" & "magnetic resistance" all across physics theories", Graduate Student Seminar12:15pm
2/19
Prof. Chandrasekhar Roychoudhuri, Department of Physics, University of Connecticut, "Ubiquitous presence of "electric tension" & "magnetic resistance" all across physics theories", Graduate Student Seminar
Friday, February 19th, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof. Chandrasekhar Roychoudhuri, Department of Physics, University of Connecticut
Ubiquitous presence of
"electric tension" & "magnetic resistance" all across physics theories
I will use Huygens' process driven thinking introduced in the context of his
postulate of "Secondary Wavelets" along with his "Non-Interaction of Waves",
pronounced in his 1690 book, and his concept of a Cosmic Aether field. I also
accept the built-in causality in our math. Nature always harbors statistical
outcomes to assure sustainable diversity in the universe, but never non-causal in its
perpetual evolutionary transformations. I will try to show that Huygens' Cosmic
Aether, holding the operationally active parameters so far is the best
unifying platform for all branches of physics.
1. C. Roychoudhuri, "Causal Physics: Photon by Non-Interaction of Waves", Taylor &
Francis, 2014.
2. C. Roychoudhuri, "Next frontier in physics -- space as a complex tension field", J. Mod. Phys., Volume 3, Number 10 (October 2012). -
Dr. Anh-Thu Le, Missouri University of Science and Technology, "Toward Ultrafast Molecular Imaging with Intense Laser Pulses ", Atomic, Molecular, And Optical Physics Seminar4:00pm
2/17
Dr. Anh-Thu Le, Missouri University of Science and Technology, "Toward Ultrafast Molecular Imaging with Intense Laser Pulses ", Atomic, Molecular, And Optical Physics Seminar
Wednesday, February 17th, 2021
04:00 PM - 05:00 PM
Storrs Campus online
Dr. Anh-Thu Le, Missouri University of Science and Technology
Toward Ultrafast Molecular Imaging with Intense Laser Pulses
High harmonic generation (HHG), laser-induced electron diffraction, and other rescattering phenomena are at the heart of strong-field and attosecond physics. However, it is challenging to interpret experimental measurements as accurate ab initio calculations for molecules in intense laser fields are essentially prohibitive. Recently, we developed the quantitative rescattering theory to provide a simple solution to this problem. Our theory establishes direct links between these strongly nonlinear processes with the well-studied traditional scattering processes, thereby making realistic simulations possible. More importantly, our theory allows straightforward decoding of the imprints of the target structure from the experimental data. In this talk, I will present our recent contributions in interpreting different experiments and reconstructing molecular structure for targets that undergo ultrafast transformations. Furthermore, I will also discuss our progress in molecular imaging with ultrafast soft X-ray pulses from HHG or free-electron laser sources. Finally, I will discuss the challenges and our future directions in developing theoretical tools for practical realization of molecular "movies" with atomic resolution in space and time that can provide new insights into fundamental chemical reactions. -
Dr. Francois Mauger, Department of Physics & Astronomy, Louisiana State University, " Watching electrons move in molecules", Atomic, Molecular, And Optical Physics Seminar4:00pm
2/15
Dr. Francois Mauger, Department of Physics & Astronomy, Louisiana State University, " Watching electrons move in molecules", Atomic, Molecular, And Optical Physics Seminar
Monday, February 15th, 2021
04:00 PM - 05:00 PM
Storrs Campus online
Dr. Francois Mauger, Department of Physics & Astronomy,
Louisiana State University
Watching electrons move in molecules
Electrons are the glue that holds matter together: Their spatial arrangement defines chemical bonds, and their time evolution controls reactions. But electrons are light, and they move fast, reaching down to the femtosecond and attosecond regimes. So probing dynamics at the spatial and temporal scales of electron motions in molecules is a formidable challenge, one that holds the promise of going beyond the "what happened" of spectroscopy to the "how did that happen" that a movie provides. New ultrafast light sources, like X-ray lasers and table-top attosecond sources, together with state-of-the-art theoretical tools are opening this frontier. In this talk I will discuss recent developments and future perspectives for watching coherent electron motion in molecules. This research, at the frontier of ultrafast science, involves cross-disciplinary approaches intersecting atomic and molecular physics and chemistry, optics and lasers, applied mathematics and computer science. -
Professor Philip Mannheim University of Connecticut Physics Department Colloquium Series, CANCELED/POSTPONED: Prof. Philip Mannheim (Physics Department Colloquium)3:30pm
2/12
Professor Philip Mannheim University of Connecticut Physics Department Colloquium Series, CANCELED/POSTPONED: Prof. Philip Mannheim (Physics Department Colloquium)
Friday, February 12th, 2021
03:30 PM - 04:30 PM
Storrs Campus Remote
Professor Philip Mannheim
University of Connecticut
Physics Department Colloquium Series
Title: Quantum mechanics off the beaten track
Abstract: We discuss some non-conventional options for quantum theory.
We show that not only do Hamiltonians not need
to be Hermitian to have real eigenvalues, they do not even need to be
diagonalizable or possess a complete spectrum of energy eigenstates. We
discuss how to formulate quantum mechanics in such cases.
We show that
it is not always possible to write the momentum operator as the familiar
derivative operator $-id/dx$ where x is real, and discuss what one should
then do. Following
work by Bender and Mannheim [Phys. Rev. Lett. 100, 110402 (2008)] we show
how these issues are relevant to the construction of a consistent theory
of quantum gravity in four spacetime dimensions. In this theory there is no observable graviton. -
Prof M. Gai, Department of Physics, University of Connecticut, "Cold Fusion: What have we (and the white house) learned from this historical scientific blunder", Graduate Student Seminar12:15pm
2/12
Prof M. Gai, Department of Physics, University of Connecticut, "Cold Fusion: What have we (and the white house) learned from this historical scientific blunder", Graduate Student Seminar
Friday, February 12th, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof M. Gai,
Department of Physics,
University of Connecticut
Cold Fusion: What have we (and the white house) learned from this historical scientific blunder
Cold Fusion, a "discovery" announced in a press conference at the University of Utah, on March 23, 1989, is now recognized as the world most embarrassing scientific blunder. But at first it had seven weeks of glory (including Congress and the White House). Announcements of confirmations at Texas A&M, Georgia Tech, Los Alamos National Lab and other institutes worldwide, in Italy, Japan, USSR, etc. soon followed. The strong theoretical backing and indeed encouragement by Physics Nobel Laureate Julian Schwinger and his colleague at Harvard, Nobel Laureate Norman Ramsey, placed "Cold Fusion" on seemingly solid theoretical ground. The prospect of MIT applying for a patent on "Cold Fusion", as announced by MIT provost John Deutsch (later Head of the CIA), led a confused nation into celebrating a new future with endless cheap green energy contained in a jar of "Cold Fusion".
On May 2, 1989, in the historical meeting of the American Physical society in Baltimore, I reported the results of our Yale-Brookhaven collaboration, on the lack of the required neutrons and Nate Lewis of Caltech reported on lack of the much-touted excess heat. The two of us together (with others that followed) unambiguously demonstrated that "Cold Fusion", as claimed by many, does not exist.
I will review the so-called scientific claims and my personal story, as experienced by a young Assistant Professor at Yale. My mentor Professor D. Allan Bromely, the Science advisor to President H.W. Bush, Sr., reported to Congress and the White House the results of our Yale-Brookhaven measurement, and later, I led the only existing collaboration between a skeptic (myself) and a cold fusion advocate (Steve Jones of the Brigham Young University)-- the final nail that hit the jar. -
Dr. Kris Pardo, Jet Propulsion Laboratory , "Detecting Gravitational Waves and Dark Matter with the Roman Space Telescope's Exoplanet Microlensing Survey", Astronomy Seminar11:00am
2/10
Dr. Kris Pardo, Jet Propulsion Laboratory , "Detecting Gravitational Waves and Dark Matter with the Roman Space Telescope's Exoplanet Microlensing Survey", Astronomy Seminar
Wednesday, February 10th, 2021
11:00 AM - 12:00 PM
Storrs Campus online
Dr. Kris Pardo, Jet Propulsion Laboratory
Detecting Gravitational Waves and Dark Matter with the Roman Space Telescope's Exoplanet Microlensing Survey
The Roman Space Telescope's Exoplanet Microlensing Survey will take tens of thousands of exposures of 10 million stars over 5 years, pinpointing their positions with extreme accuracy. The nominal purpose of this mission is to detect over a thousand planets; however, its unique design and excellent astrometric precision also open other avenues of astrophysical study. Gravitational waves and dark matter halos can both cause apparent changes in stellar positions in a correlated manner. In this talk, I will explain these phenomena and how this survey will let us study supermassive black hole populations and dark matter properties.
WebEx meeting URL: https://uconn-cmr.webex.com/meet/cmf19005 -
Prof A. Balatsky, Department of Physics, University of Connecticut, "Dynamic Orders in Quantum matter ", Graduate Student Seminar12:15pm
2/5
Prof A. Balatsky, Department of Physics, University of Connecticut, "Dynamic Orders in Quantum matter ", Graduate Student Seminar
Friday, February 5th, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof A. Balatsky,
Department of Physics,
University of Connecticut
Dynamic Orders in Quantum matter
Quantum matter out of equilibrium emerge as an important platform to induce correlations and transient orders. Broad basic questions about orders that are inherently dynamic have been addressed in the context of driven cold atoms, spins, magnetic states and superconductors. I will discuss the example of emergent dynamic and entangled states in quantum paralelectrics where driven electric fluctuations induce magnetization, the *dynamic multiferroicity* phenomenon [1]. We see a rapidly growing list of unusual quantum states in time domain to be discovered. I will point to other examples of *dynamic orders* out of equilibrium, e.g. coherent states of magnons in Dirac materials [2]. In second part of the talk I will discuss the challenge of dark matter detection and quantum matter based sensors for Dark Matter.
[1] Dynamic multiferroicity of a ferroelectric quantum critical point, K Dunnett, JX Zhu, NA Spaldin, V Juričić, AV Balatsky, Physical review letters 122 (5), 057208 (2020); Dynamical multiferroicity, DM Juraschek, M Fechner, AV Balatsky, NA Spaldin, Physical Review Materials 1 (1), 014401(2017)
[2] Bose-Einstein condensate of Dirac magnons: pumping and collective modes, PO Sukhachov, S Banerjee, AV Balatsky, arXiv preprint arXiv:2008.01328 (2020) -
Dr. A. Stevens, NSF Postdoctoral Fellow, Michigan State University and University of Michigan, "Mapping Matter in Strong Gravity: Spectral-Timing of Black Holes and Neutron Stars ", Astronomy Seminar11:00am
2/3
Dr. A. Stevens, NSF Postdoctoral Fellow, Michigan State University and University of Michigan, "Mapping Matter in Strong Gravity: Spectral-Timing of Black Holes and Neutron Stars ", Astronomy Seminar
Wednesday, February 3rd, 2021
11:00 AM - 12:00 PM
Storrs Campus online
Dr. A. Stevens, NSF Postdoctoral Fellow, Michigan State University and University of Michigan
Mapping Matter in Strong Gravity: Spectral-Timing of Black Holes and Neutron Stars
One of the best laboratories to study strong-field gravity is the inner 100s of kilometers around black holes and neutron stars in binary systems with low-mass stars like our Sun. The X-ray light curves of these systems show variability on timescales from milliseconds to months -- the rapid variability can appear as quasi-periodic oscillations (QPOs), which may be produced by general relativistic effects. My research looks at QPOs from black holes and neutron stars by applying state-of-the-art "spectral-timing" techniques to constrain the physical origin of these signals. In this talk, I will discuss data from NICER, an X-ray telescope attached to the International Space Station. I will also highlight open-source astronomy research software and the importance of mental wellbeing in academia.
Webex link: https://uconn-cmr.webex.com/meet/jot16106 -
Prof. J. Haraldsen, University of North Florida , "Examining multi-band effects on the electronic compressibility of a 2D electron gas: Insights into the negative compressibility of LAO/STO", Condensed Matter Physics Seminar11:00am
2/3
Prof. J. Haraldsen, University of North Florida , "Examining multi-band effects on the electronic compressibility of a 2D electron gas: Insights into the negative compressibility of LAO/STO", Condensed Matter Physics Seminar
Wednesday, February 3rd, 2021
11:00 AM - 12:00 PM
Storrs Campus online
Prof. J. Haraldsen, University of North Florida
Examining multi-band effects on the electronic compressibility of a 2D electron gas: Insights into the negative compressibility of LAO/STO
In this study, we investigate the consequences of two electronic bands at the negative electronic compressibility (NEC) cross-over point for a two-dimensional electron gas (2DEG) using a simple homogeneous model with Coulombic interactions and first-order multi-band coupling. We examine the role of effective mass and relative permittivity in relation to the critical carrier density at the cross-over point through a comparison of one- and two-band models. In general, it is shown that the population of a second band, along with the presence of inter-band coupling, can dramatically change the cross-over carrier density. Given the difficulty in determining and confirming multi-band electronic systems, this model provides a potential method for identifying multi-band electronic systems using precise bulk electronic properties measurements. To help illustrate this method, we apply our results to the observed NEC in the 2D electron gas at the interface of LaAlO3/SrTiO3 (LAO/STO) and determine that, for the known parameters of LAO/STO, the system is likely a realization of a two-band 2D electron gas. Furthermore, we provide general limits on the inter-band coupling with respect to the electronic band population.
Zoom link: https://kth-se.zoom.us/j/62759109592 -
Prof. Stewart Prager, Princeton University, "Physicists Coalition for Nuclear Threat Reduction", Physics Colloquium (Professor Stewart Prager, Princeton University)3:30pm
1/29
Prof. Stewart Prager, Princeton University, "Physicists Coalition for Nuclear Threat Reduction", Physics Colloquium (Professor Stewart Prager, Princeton University)
Friday, January 29th, 2021
03:30 PM - 04:30 PM
Storrs Campus Online
Prof. Stewart Prager, Princeton University
Physicists Coalition for Nuclear Threat Reduction
The Increasing Peril from Nuclear Arms: and how physicists can help reduce the threat
With geopolitical and technological changes mostly driven by the nuclear weapons states, we are slipping towards a new arms race and deterioration of the multi-decade arms control regime. This talk will describe the current critical situation, feasible steps to reduce the nuclear threat, and a new project sponsored by the American Physical Society to engage physical scientists in advocacy for nuclear threat reduction.
Speaker Bio: Prof Stewart Prager is professor of astrophysical sciences at Princeton University, an affiliated faculty with the Program on Science and Global Security and former director of the Princeton Plasma Physics Laboratory, Previously, while professor of physics at the University of Wisconsin - Madison, he directed the Madison Symmetric Torus experiment and the Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas. His research has been in plasma physics and fusion energy, although his recent focus is on nuclear threat reduction.
Following the colloquium, there will be a discussion of opportunities to contribute to nuclear threat reduction efforts.
Webex meeting URL: https://uconn-cmr.webex.com/uconn-cmr/j.php?MTID=m9372216ae3469f40dad3befa84edcaec -
Prof C. Battersby, Department of Physics, University of Connecticut, "With the participation of Dr. Daniel Walker, and graduate student H Perry Hatchfield ", Graduate Student Seminar12:15pm
1/29
Prof C. Battersby, Department of Physics, University of Connecticut, "With the participation of Dr. Daniel Walker, and graduate student H Perry Hatchfield ", Graduate Student Seminar
Friday, January 29th, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof C. Battersby,
Department of Physics,
University of Connecticut
With the participation of Dr. Daniel Walker, and graduate student H Perry Hatchfield
The Milky Way Laboratory
Our own Milky Way Galaxy is a powerful and relatively nearby laboratory in which to study the physical processes that occur throughout the Universe. From the organization of gas on galactic scales to the life cycle of gas and stars under varied environmental conditions, studies of our Milky Way underpin many areas of modern astrophysics. I will present a brief tour of our Milky Way Laboratory, including 1) high-mass star formation from surveys of our Galaxy's disk, and 2) how observing and simulating our extreme, turbulent Galactic Center (the Central Molecular Zone) can help us learn more about how gas is converted into stars during the peak epoch of cosmic star formation. -
Prof. P. Mannheim, Department of Physics, University of Connecticut, "Is Dark Matter Fact or Fantasy -- Clues from the Data", Astronomy Seminar11:00am
1/27
Prof. P. Mannheim, Department of Physics, University of Connecticut, "Is Dark Matter Fact or Fantasy -- Clues from the Data", Astronomy Seminar
Wednesday, January 27th, 2021
11:00 AM - 12:00 PM
Storrs Campus online
Prof. P. Mannheim,
Department of Physics, University of Connecticut
Is Dark Matter Fact or Fantasy -- Clues from the Data
We discuss arguments both in favor of and against dark matter. With the repeated failure of experiment to date to detect dark matter we discuss what could be done instead, and to this end look for clues in the data themselves. We identify various regularities in galactic rotation curve data that correlate the total gravitational potential with luminous matter rather than dark matter. We identify a contribution to galactic rotation curves coming from the rest of the visible universe, and suggest that dark matter is just an attempt to describe this global effect in terms of standard local Newtonian gravity within galaxies. Thus the missing mass is not missing at all -- it has been hiding in plain sight all along as the rest of the visible mass in the universe.
Webex link: https://uconn-cmr.webex.com/meet/cab16109 -
Physics Colloquium, Prof. Chiara Mingarelli, UConn, Professor Chiara Mingarelli (Physics Colloquium)3:30pm
1/22
Physics Colloquium, Prof. Chiara Mingarelli, UConn, Professor Chiara Mingarelli (Physics Colloquium)
Friday, January 22nd, 2021
03:30 PM - 04:30 PM
Storrs Campus remote
Physics Colloquium
Prof. Chiara Mingarelli, UConn
Title:
Pulsar Timing Arrays: The Next Window to Open on the Gravitational-Wave Universe
Abstract:
Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz to microhertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from the NANOGrav Collaboration, hinting at the beginning of a new way to study the Universe. -
Prof C. Trallero, Department of Physics, University of Connecticut, "Quantum dynamics from solids to isolated atoms", Graduate Student Seminar12:15pm
1/22
Prof C. Trallero, Department of Physics, University of Connecticut, "Quantum dynamics from solids to isolated atoms", Graduate Student Seminar
Friday, January 22nd, 2021
12:15 PM - 01:15 PM
Storrs Campus online
Prof C. Trallero,
Department of Physics,
University of Connecticut
Quantum dynamics from solids to isolated atoms
We used coherent and intense laser pulses to image and study in dynamical systems such as electrons, molecules and solids. I will discuss the potential applications to quantum information and future studies. -
Dr. Caitlin Witt, Department of Physics and Astronomy, West Virginia University, Astronomy Seminar10:00am
1/20
Dr. Caitlin Witt, Department of Physics and Astronomy, West Virginia University, Astronomy Seminar
Wednesday, January 20th, 2021
10:00 AM - 11:00 AM
Storrs Campus online
Dr. Caitlin Witt, Department of Physics and Astronomy, West Virginia University
Multimessenger Astrophysics in the NANOGrav Pulsar Timing Array
Nearly all galaxies contain supermassive black holes, and when these galaxies merge, they can form supermassive black hole binaries. As they progress towards merger, these binaries emit strong nanohertz gravitational waves (GWs). In the next few years, pulsar timing arrays will reach the sensitivities required to detect GWs from both individual supermassive black hole binaries, as well as the stochastic GW background formed by the entire population of these binaries. However, GWs are not the only method used to search for supermassive binaries; by combining GW searches with electromagnetic searches, we enter the regime of multimessenger astrophysics. In this talk, I'll discuss multimessenger efforts within the NANOGrav pulsar timing array, including the recently published targeted multimessenger search for GWs that I led for the collaboration. We developed the first collaboration toolkit for analysis of multimessenger data, and applied it to the well-known binary candidate 3C 66B. We also demonstrated improvements to constraints that can be made by including electromagnetic data in this way. I'll also present some of my ongoing work on the electromagnetic searches for supermassive black hole binaries, where we are exploring the capabilities of binary detection methods on AGN with periodic variability, for both existing and future time-domain surveys.
Webex link: https://uconn-cmr.webex.com/meet/cmf19005 -
Graduate Student Phillip Price, Department of Physics, University of Connecticut, PhD Dissertation Defense1:00pm
12/9
Graduate Student Phillip Price, Department of Physics, University of Connecticut, PhD Dissertation Defense
Wednesday, December 9th, 2020
01:00 PM - 03:00 PM
Storrs Campus Video meeting
Graduate Student Phillip Price, Department of Physics,
University of Connecticut
We propose a model that combines magneto-association across a Feshbach resonance with STIRAP into a continuous and coherent process to form ultra- cold molecules. This can add to the toolbox of ultracold coherent chemistry and potentially enable the production of more ultracold molecules species. To that end, our proposed method should prove beneficial when the Feshbach molecule state has a very short lifetime, with the additional benefit of working within existing experimental setups. -
Anahita Alavi, University of California, Riverside, "Dwarf Galaxies Before Exciting Future Observations: The Importance of Extragalactic HST UV Imaging Surveys", Astronomy Seminar12:00pm
12/9
Anahita Alavi, University of California, Riverside, "Dwarf Galaxies Before Exciting Future Observations: The Importance of Extragalactic HST UV Imaging Surveys", Astronomy Seminar
Wednesday, December 9th, 2020
12:00 PM - 01:00 PM
Storrs Campus online
Anahita Alavi, University of California, Riverside
Dwarf Galaxies Before Exciting Future Observations: The Importance of Extragalactic HST UV Imaging Surveys
Dwarf galaxies (M*/M0 < 109) are the smallest and least luminous but most abundant galaxies in the universe. These galaxies are at the forefront of many important questions in galaxy formation theory, yet observationally we are only just beginning to constrain their physical properties, especially at high redshifts. Therefore, it is not surprising that JWST, Roman Telescope, and Euclid will be devoting some part of their time to study these galaxies via their stellar continuum and/or nebular emission lines at various redshifts.
In this talk, I will show how the combination of our deep UV imaging with WFC3/UVIS camera on HST and extensive spectroscopic observations with MOSFIRE spectrograph at the Keck observatory and grism data from WFC3 Infrared Spectroscopic Parallel Survey (WISP) allowed us to 1- observe dwarf galaxies at high redshifts (i.e., 1 (i.e., 1 < z < 3 ), which have always been below the detection limits of many surveys, and 2- better understand the formation and evolution of this population of galaxies via studying their number density evolution (i.e., luminosity function), star formation history (i.e., bursty SFH) and dust attenuation. In addition, I will introduce our new large UV imaging surveys with HST (UVCANDELS and UV Frontier Fields II), which will further explore the high-redshift dwarf galaxies. These UV surveys are vitally important because some of their primary science goals, such as studying the escaping ionizing radiation from galaxies, cannot fundamentally be studied by JWST. Relatedly, I will present our recent work of searching for escaping ionizing radiation from low-mass galaxies at high redshift. -
Condensed Matter Physics Seminar10:00am
12/8
Condensed Matter Physics Seminar
Tuesday, December 8th, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Peter Littlewood, University of Chicago
Dynamical phase transitions at many body exceptional point
Spontaneous synchronization is at the core of many natural phenomena. Your heartbeat is maintained because cells contract in a synchronous wave; some bird species synchronize their motion into flocks; quantum synchronization is responsible for laser action and superconductivity. The transition to synchrony, or between states of different patterns of synchrony, is a dynamical phase transition that has much in common with conventional phase transitions of state -- for example solid to liquid, or magnetism -- but the striking feature of driven dynamical systems is that the components are "active". Consequently quantum systems with dissipation and decay are described by non-Hermitian Hamiltonians, and active matter can abandon Newton's third law and have non-reciprocal interactions. This substantially changes the character of many-degree-of-freedom dynamical phase transitions and the critical phenomena in their vicinity, since the critical point is an "exceptional point" where eigenvalues become degenerate and eigenvectors coalesce. We will illustrate this in several different systems -- a Bose-Einstein condensate of polaritons, models of multicomponent active matter such as flocks of birds, generalised Kuramoto models, and others. We argue that there is a systematic theory, generalized phase diagram, and corresponding universality classes for these dynamical systems.
Fruchart et al., arXiv:2003.13176
Hanai et al., 10.1103/PhysRevLett.122.185301
Zoom Meeting: https://kth-se.zoom.us/j/67773156040 -
Prof P. Mannheim, Department of Physics, University of Connecticut, "The Ginzburg-Landau Theory of Phase Transitions", Graduate Student Seminar12:15pm
12/4
Prof P. Mannheim, Department of Physics, University of Connecticut, "The Ginzburg-Landau Theory of Phase Transitions", Graduate Student Seminar
Friday, December 4th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof P. Mannheim,
Department of Physics,
University of Connecticut
The Ginzburg-Landau Theory of Phase Transitions
We discuss the Ginzburg-Landau theory of phase transitions from both macroscopic and microscopic perspectives. We discuss applications to ferromagnetism, superconductivity, and the Higgs boson.
Reference: P. D. Mannheim, Prog. Part. Nucl. Phys. 94, 125 (2017). -
Prof. Steven Longmore, Liverpool John Moores University, "Ecosystems and Life", Astronomy Seminar10:00am
12/2
Prof. Steven Longmore, Liverpool John Moores University, "Ecosystems and Life", Astronomy Seminar
Wednesday, December 2nd, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Prof. Steven Longmore, Liverpool John Moores University
Ecosystems and Life
Abstract: I will cover two topics united under the theme of ecosystems shaping the potential for life. In the first half, I will present recent results showing that the architecture of planetary systems is shaped by their environmental ecosystems, in particular the degree of stellar clustering around their host star (Winter et al, 2020, Nature, 586, 528). We identify old, co-moving stellar groups around exoplanet host stars in the astrometric data from the Gaia satellite and demonstrate that the architecture of planetary systems exhibits a strong dependence on local stellar clustering in position-velocity phase space, implying a dependence on their formation or evolution environment. After controlling for host stellar age, mass, metallicity, and distance from the Sun, we obtain highly significant differences in planetary (system) properties between phase space overdensities and the field. The median semi-major axis and orbital period of planets in overdensities are 0.087 au and 9.6 days, respectively, compared to 0.81 au and 154 days for planets around field stars. 'Hot Jupiters' (massive, close-in planets) predominantly exist in stellar phase-space overdensities, strongly suggesting that their extreme orbits originate from environmental perturbations rather than internal migration or planet-planet scattering. Our findings suggest that stellar clustering is an important factor setting the architectures of planetary systems. In the second half of the talk, I will discuss how we are using astrophysics research techniques to help ecologists protect ecosystems, save critically endangered animal species, and stop peat forest fires that are a major contributor to climate change.
Webex link: https://uconn-cmr.webex.com/meet/cab16109 -
Prof. H.Haggard, Bard College, "Why do so many black holes measured in gravitational waves have zero spin?", Particle, Astrophysics, And Nuclear Physics Seminar2:00pm
11/30
Prof. H.Haggard, Bard College, "Why do so many black holes measured in gravitational waves have zero spin?", Particle, Astrophysics, And Nuclear Physics Seminar
Monday, November 30th, 2020
02:00 PM - 03:00 PM
Storrs Campus online
Prof. H.Haggard, Bard College
Why do so many black holes measured in gravitational waves have zero spin?
Black hole entropy is a robust prediction of quantum gravity with no established phenomenological consequences to date. We use the Bekenstein-Hawking entropy formula and general-relativistic statistical mechanics to determine the probability distribution of random geometries uniformly sampled in phase space. We show that this statistics (in the limit \( \hbar \to 0\) ) is relevant to large curvature perturbations, resulting in a population of primordial black holes with zero natal spin. In principle, the identification of such a population at LIGO, Virgo, and future gravitational wave observatories could provide the first observational evidence for the statistical nature of black hole entropy.