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Announcements

EVENTS 2024-10-14





GAPP Seminar

 * October 15th, 2024, 2 – 3pm 339 Davey

 * Guest speaker – Abigail Kopec

 * Title: Catching the Fog: Low-Energy Particle Interactions in Liquid
   Xenon-based Detectors

Astronomy Colloquium

 * October 23, 2024, 3:45 – 5pm 538 Davey Lab

 * Speaker - Jeff Valenti

 * Title: Brown Dwarf Science with the James Webb Space Telescope

Physics Colloquium

 * Thursday, October 17th, 2024, 3:45 – 4:45pm 119 Osmond Laboratory

 * Speaker – Alison Patteson

 * Title: Squishy Physics of Simple Tissues

PUG

 * 321 Whitmore, Friday, October 18th, 2024, 2 – 3pm



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INSTITUTE FOR GRAVITATION AND THE COSMOS



IGC recent news

ICDS CO-HIRE CONTRIBUTES TO GRAVITATIONAL WAVE RESEARCH

2024-10-10

A heavy use of computational tools can help to detect what has yet to be
discovered, according to Chad Hanna, professor of physics and of astronomy and
astrophysics at Penn State. Hanna, who started at the University in 2014 and is
a Penn State Institute for Computational and Data Sciences (ICDS) co-hire, works
in a large research group as part of the U.S. National Science Foundation’s
Laser Interferometer Gravitational-Wave Observatory (LIGO). Hanna’s research
team, which includes Research Innovations with Scientists and Engineers (RISE)
team member Ron Tapia, is working to discover astrophysical events — such as
gravitational waves, or ripples in spacetime predicted by Albert Einstein in
1916 — caused by the merger of two black holes or other celestial objects. “The
LIGO observatory measures tiny distortions in space that are caused by the
merging black holes,” Hanna said. “We are learning about the universe through
measuring these tiny distortions in space. It’s a big effort that requires a lot
of people for observations to run sustainably day and night.”

HOW DO SUPERMASSIVE BLACK HOLES GET SUPER MASSIVE?

2024-09-09

UNIVERSITY PARK, Pa. — By combining forefront X-ray observations with
state-of-the-art supercomputer simulations of the buildup of galaxies over
cosmic history, researchers have provided the best modeling to date of the
growth of the supermassive black holes found in the centers of galaxies. Using
this hybrid approach, a research team led by Penn State astronomers derived a
complete picture of black-hole growth over 12 billion years, from the Universe’s
infancy at around 1.8 billion years old to now at 13.8 billion years old.

INTERNATIONAL LZ EXPERIMENT SEES NEW RESULTS IN SEARCH FOR DARK MATTER

2024-08-26

Using the world’s most sensitive dark matter detector, an international
collaboration puts the best-ever limits on particles called WIMPs, a leading
candidate for what makes up the universe’s invisible mass. The nature of dark
matter, the invisible substance thought to make up most of the mass in our
universe, is one of the greatest mysteries in physics. Using new results from
the world’s most sensitive dark matter detector, LUX-ZEPLIN (LZ), an
international collaboration that includes Penn State researchers has narrowed
down the possible properties of one of the leading candidates for the particles
that compose dark matter: weakly interacting massive particles, or WIMPs.

FIRST FLIGHT OF HELIX

2024-07-10

The High Energy Light Isotope eXperiment is designed to measure various isotopes
of cosmic ray nuclei, which are sensitive to the history of propagation of these
energetic particles through our Milky Way galaxy, and which are linked to
energetic interactions in the interstellar medium (yielding antimatter as well
as rare nuclei). The instrument had its first stratospheric balloon flight on
May 28, 2024 from the Esrange rocket/balloon base in northern Sweden, landing on
Ellesmere Island in the Canadian high Arctic after more than 6 days. The Penn
State group includes IGC faculty Stephane Coutu and Isaac Mognet, and past and
present students Heather Allen, Carl Chen, Alex Pazoki and Monong Yu.

WHAT HAPPENS WHEN NEUTRON STARS COLLIDE?

2024-06-18

When stars collapse, they can leave behind incredibly dense but relatively small
and cold remnants called neutron stars. If two stars collapse in close
proximity, the leftover binary neutron stars spiral in and eventually collide,
and the interface where the two stars begin merging becomes incredibly hot. New
simulations of these events show hot neutrinos — tiny, essentially massless
particles that rarely interact with other matter — that are created during the
collision can be briefly trapped at these interfaces and remain out of
equilibrium with the cold cores of the merging stars for 2 to 3 milliseconds.
During this time, the simulations show that the neutrinos can weakly interact
with the matter of the stars, helping to drive the particles back toward
equilibrium — and lending new insight into the physics of these powerful events.

ASTRONOMERS FIND UNEXPECTED ACCELERATING QUASAR WINDS AROUND DISTANT BLACK HOLE

2024-06-11

A team of astronomers, including Penn State researchers, from the Sloan Digital
Sky Survey (SDSS) has used eight years of monitoring observations to discover
unexpected changes in the winds surrounding a distant black hole.

ASTRONOMERS FIND UNEXPECTED ACCELERATING QUASAR WINDS AROUND DISTANT BLACK HOLE

2024-06-11

A team of astronomers, including Penn State researchers, from the Sloan Digital
Sky Survey (SDSS) has used eight years of monitoring observations to discover
unexpected changes in the winds surrounding a distant black hole.

NASA’S CHANDRA IDENTIFIES A BLACK HOLE WHOSE BARK IS WORSE THAN ITS BITE

2024-03-21

Astronomers have revealed that a brilliant supermassive black hole is not living
up to expectations. Although it is responsible for high levels of radiation and
powerful jets, this giant black hole is not as influential on its surroundings
as many of its counterparts in other galaxies. A team including IGC faculty W.
Niel Brandt, the Eberly Family Chair Professor of Astronomy and Astrophysics and
professor of physics at Penn State, recently published this study in the Monthly
Notices of the Royal Astronomical Society.

ICECUBE IDENTIFIES SEVEN ASTROPHYSICAL TAU NEUTRINO CANDIDATES.

2024-03-12

The IceCube Neutrino Observatory, a cubic-kilometer-sized neutrino telescope at
the South Pole, has observed a new kind of astrophysical messenger. In a new
study recently accepted for publication as an Editors' Suggestion by the journal
Physical Review Letters and available online as a preprint, the IceCube
collaboration, including Penn State researchers, presented the discovery of
seven of the once-elusive astrophysical tau neutrinos.

Q&A WITH AAAS MASS MEDIA FELLOW UNNATI AKHOURI

2024-01-04

Unnati Akhour is a Mildred Dresselhaus Science Achievement Graduate Fellow in
Physics who was recently an American Association for the Advancement of Sciences
(AAAS) Mass Media Fellow at WITF, Inc.

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IGC Centers

CENTER FOR FUNDAMENTAL THEORY



CENTER FOR MULTIMESSENGER ASTROPHYSICS



CENTER FOR THEORETICAL AND OBSERVATIONAL COSMOLOGY


IGC topics of research

ASTROINFORMATICS



Astroinformatics applies data science and machine learning to astrophysics and
cosmology. IGC members working in astroinformatics are also affiliated with the
Institute for Computational and Data Sciences.

ASTROSTATISTICS



Astrostatistics is the study of how to use astronomical observations, with their
associated uncertainties, to constrain models of astrophysics and cosmology.
Measurements are made with imperfect instruments and the way in which many
objects are observed can be biased by something in their local environment, like
dust, that reduces or enhances the emitted signal. Accurately inferring the
model from the data requires a careful accounting for all those effects. Visit
Penn State's Center for Astrostatistics website to find out more about. [Image
Credit: NASA/Ames/JPL-Caltech]

BLACK HOLES



Black holes are regions of spacetime so dense that nothing can escape their
gravitational pull - not even light. Researchers at Penn State study black holes
theoretically in the context of general relativity and candidate theories for
quantum gravity as well as observationally through electromagnetic and
gravitational wave surveys.

COSMIC RAYS



Cosmic Rays are elementary particles and nuclei, detected on or near the Earth,
that originate in energetic processes in the universe. Physicists work to
characterize the cosmic ray spectrum: the abundance of different types of
particles and their energies. Observations of the primary particles are made in
space (e.g., the Alpha Magnetic Spectrometer, AMS, on the International Space
Station) and with high-altitude balloons (e.g., the High Energy Light Isotope
eXperiment, HELIX). When cosmic rays interact with the Earth's atmosphere, they
generate showers of other particles, called secondary cosmic rays, that are
detected by instruments on the ground (e.g., the Pierre Auger surface water
tanks and fluorescence detectors), and under the ground (e.g., the AMIGA, Auger
Muons and Infill for the Ground Array extension for Pierre Auger). Cosmic ray
data is used to constrain models for sources that can produce high-energy
particles, either extremely energetic astrophysical environments like those
around Active Galactic Nuclei (AGN) or extreme events like gamma ray bursts
(GRBs).

COSMIC SURVEYS



Cosmological surveys map out the distribution of matter in the universe. Some
surveys may target a particular type of object by looking for a very particular
spectral signal. For example, the HETDEX survey is designed to find a class of
galaxies, Lyman-$\alpha$ emitters, at a time when the universe was about 10-11
billion years younger than it is today. By precisely measuring how those
galaxies are receding from us, HETDEX will provide a new constraint on the
expansion rate of the universe and the role of dark energy in the past. Other
surveys collect light across a wider range of frequencies. For example, the
Rubin Observatory Legacy Survey of Space and Time (LSST) will take optical
images of a large fraction of the sky, nearly every night. LSST will detect
nearly 4 billion galaxies that can be measured so precisely that distortions in
galaxy shapes due to gravity can be used, statistically, to map out how both
dark and luminous matter are distributed in the Universe. Because LSST will
image the same part of the sky so often, it will also capture the variations of
light emitted by objects that are changing rapidly, allowing studies of the
dynamic universe.

DARK MATTER



Matter can be detected by its gravitational pull. Many different observations
together indicate that about 84% of the gravitating matter in the universe emits
no detectable photons. This is the dark matter, and the quest to understand what
it is drives the work of large communities in cosmology and particle physics.
Experiments like the Large Underground Xenon experiment, LUX, are designed to
search for possible interactions between dark matter particles and the particles
of the Standard Model. Surveys like the Rubin Observatory Legacy Survey of Space
and Time, LSST, will carefully map out the distribution of dark matter, probing
for signs that some particle physics interactions was at work along with gravity
and affected the evolution of structure. Gravitational wave observations may
also reveal something about the nature of dark matter if, for example, the
population of detected black holes is inconsistent with the expected
astrophysical population.

THE DYNAMIC UNIVERSE



Many dynamic phenomena in the universe occur over a period of seconds to years.
Events with quickly evolving signals include the explosions of Type 1a
supernovae, the destruction of stars passing too close to a black hole, and the
merger of neutron stars. Some transient phenomena, like Type Ia supernovae,
release light in such a reliable way that they can be used as standard reference
events to study the evolution of the universe. Other events provide information
about matter in extreme environments and at very high energies. These phenomena
may be observed not just through their electromagnetic emission, but also
through the generation of particles or gravitational waves. For example, a
merger of two neutron stars first detected as a gravitational wave event,
GW170817, was subsequently observed across the electromagnetic spectrum.
Fluctuations in the energetic matter streaming out from the vicinity of a black
hole in the center of a galaxy, the flaring blazar TXS 0506+056, produced both
neutrinos detected by IceCube and high-energy gamma rays. Several new
instruments promise to bring an explosion of data for the study of transient
phenomena in the universe. [Image Credit: Illustration: CXC/M. Weiss; X-ray:
NASA/CXC/UNH/D. Lin et al, Optical: CFHT. ]

GRAVITATIONAL WAVES



Gravitational waves are tiny ripples in space created by accelerating masses
such as the orbit of neutron stars and black holes. As a gravitational wave
passes through space it changes the distance between two points. Researchers at
Penn State study gravitational waves theoretically as well as observationally
through the LIGO and Virgo observatories.

LOOP QUANTUM GRAVITY



Loop Quantum Gravity is a theory of quantum gravity based on a geometric
formulation that predict discrete geometrical phenomena above some minimum
length scale (the Planck length).

MATHEMATICAL STRUCTURES



Physics often advances when crisp mathematical structures are uncovered in a
framework developed to describe observed phenomena. For example, in quantum
field theory there is a vast discrepancy between the current calculational
difficulty in making predictions for experiments and the simple, mathematical
form of the end result. The Amplitudes program seeks to explain and exploit this
surprising simplicity by reformulating the basic mathematical tools used to make
predictions.

MULTIMESSENGER ASTROPHYSICS



Many astrophysical phenomena release not just light (electromagnetic radiation),
but also gravitational waves and/or elementary particles including neutrinos and
cosmic rays. Each of those signals carries different information about the
physics of the source, so collecting more than one enables us to have a deeper
understanding of the event that produced them. However, it is an enormous
challenge for different types of instruments to coordinate simultaneous
observations, and to verify that signals have a common source. Projects like
AMON and SciMMA help alert the community to potential multi-messenger events so
that an observing program can be coordinated as quickly and efficiently as
possible.

NEUTRINOS



Neutrinos are light, electrically-neutral elementary particles that make up the
least-understood part of the Standard Model of particle physics. Facilities like
DUNE (the Deep Underground Neutrino Experiment) study neutrinos produced in the
Fermilab collider as well as neutrinos arriving from cosmic events. Project 8
will measure neutrino mass by looking at neutrinos emitted when tritium decays.
The CMB Stage 4 telescopes will use cosmological data to constrain the number of
neutrinos and their mass. Many other neutrino facilities focus on detecting
neutrinos produced in astrophysical processes, including ANITA, ARA, BEACON,
GRAND, IceCube, PUEO, and RNO-G. These cosmic neutrinos can carry key
information, along with electromagnetic radiation and gravitational waves, in
"multi-messenger" detections of dynamic events in the universe.

PHYSICAL MATHEMATICS



Physical mathematics is concerned with mathematics motivated by physics. Prime
example of physical mathematics is the pioneering work of Eugene Wigner on the
unitary representations of Poincare group which was motivated by his results
proving that symmetries of quantum systems must be realized unitarily on their
Hilbert spaces. His work opened up the huge field studying the unitary duals of
noncompact Lie groups which is still an unfinished chapter of mathematics. In a
similar vein, the discovery of supersymmetry by physicists led to the
development of the theory of unitary representations of Lie superalgebras.
Remarkably, though algebraically more complicated the theory of unitary
representations of noncompact Lie superalgebras turned out to be simpler than
those of noncompact Lie groups. Furthermore, some of the earliest results on
AdS/CFT dualities were obtained, in a true Wignerian sense, within the framework
of work on fitting the spectra of Kaluza-Klein supergravities into unitary
supermultiplets of their underlying supersymmetry algebras.

QUANTUM UNIVERSE



All physical systems obey the laws of quantum mechanics, but we have not yet
achieved a full understanding of the relationship between quantum mechanics,
general relativity, and cosmology. The primordial universe and black holes are
two arenas to study these questions in ways that are complementary to research
on laboratory quantum systems and quantum information.

QUASARS



Accreting supermassive black holes at the centers of galaxies

THE STRONG FORCE



The strong force out-competes the electromagnetic force on short distances to
hold protons together in atomic nuclei. Nuclear matter can be studied in
particle colliders and astrophysical objects like neutron stars. The quantum
effects of particles that feel the strong force are important for many
measurements in particle physics, including the recently measured anomalous
magnetic moment of the muon. Many theoretical predictions of the effects of the
strong force rely on the numerically-intensive work that requires
supercomputers.

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Penn State
University Park, PA 16802-6300
Phone: +1 814 863-9605
Fax: +1 814 863-9608




Copyright (c) 2024 Institute for Gravitation and the Cosmos - Penn State