Institute for Gravitation and the Cosmos

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.

IGC members who study Gravitational Waves

Name	Role	Affiliation	Email	Phone	Office Address	Affiliated Center(s)	Research Topics(s)
Shomik Adhicary	Graduate Student	Physics	sva5823@psu.edu	+1 814 865 7533	334 Whitmore Laboratory	IGC	Gravitational Waves, Dark Matter, Multimessenger Astrophysics, Black Holes
Kallan Berglund	Graduate Student	Physics	kmb670@psu.edu	--	322 Whitmore Laboratory	CFT	Black Holes, Loop Quantum Gravity, Gravitational Waves
Mukul Bhattacharya	Postdoc	Astronomy, Physics	mmb5946@psu.edu	--	320A Osmond Laboratory	CMA	Multimessenger Astrophysics, Gravitational Waves, Neutrinos, Cosmic Rays
Maitraya Bhattacharyya	Postdoc	Physics	mbb6217@psu.edu	+1 814 863 9605	314 Whitmore Laboratory	CMA	Multimessenger Astrophysics, Gravitational Waves, Black Holes
Allison Colarelli	Undergraduate Student	Math, Astronomy	atc5357@psu.edu	7175982124	N/A NONE	IGC, CFT	Gravitational Waves, Loop Quantum Gravity, Physical Mathematics, Black Holes
Aurora Colter	Undergraduate Student	Physics, Math	agc5654@psu.edu	-	- NONE	CFT, IGC	Physical Mathematics, Black Holes, Gravitational Waves, Loop Quantum Gravity, Quantum Universe
Viviana Cáceres	Graduate Student	Physics	vac5288@psu.edu	7872344444	114 Osmond Laboratory	CMA	Gravitational Waves
Arnab Dhani	Graduate Student	Physics	aud371@psu.edu	+1 814 865 7533	317 Whitmore Laboratory	IGC	Gravitational Waves, Black Holes
Pedro Espino	Postdoc	Physics	ple5069@psu.edu	--	320 Whitmore Laboratory	IGC	Neutrinos, Gravitational Waves, Multimessenger Astrophysics
Becca Ewing	Graduate Student	Physics	ree55@psu.edu	--	301 Whitmore Laboratory	CMA, IGC	Multimessenger Astrophysics, Gravitational Waves
Jacob Fields	Graduate Student	Physics	jmf6719@psu.edu	--	321E Whitmore Laboratory	CMA	Multimessenger Astrophysics, Gravitational Waves, Black Holes
Ish Gupta	Graduate Student	Physics	ishgupta@psu.edu	+1 814 865 7533	317 Whitmore Laboratory	IGC	Multimessenger Astrophysics, Gravitational Waves, Black Holes
James Gurian	Graduate Student	Astronomy	jhg5248@psu.edu	--	440 Davey Laboratory	IGC	Dark Matter, Black Holes, Gravitational Waves
Eduardo Gutiérrez	Postdoc	Physics	exg5366@psu.edu	+1 814 863 9605	301B Whitmore Laboratory	IGC	Black Holes, Multimessenger Astrophysics, Neutrinos, Gravitational Waves, Cosmic Rays
Peter Hammond	Postdoc	Physics	pph5189@psu.edu	+1 814 863 9605	307 Whitmore Laboratory	IGC	Neutrinos, Gravitational Waves, Multimessenger Astrophysics
Chad Hanna	Faculty	Physics, ICDS, Astronomy	crh184@psu.edu	+1 814 865 2924	303 Whitmore Laboratory	CMA	Gravitational Waves, Multimessenger Astrophysics, Dark Matter, Black Holes
Yun-Jing Huang	Graduate Student	Physics	yzh5436@psu.edu	--	334 Whitmore Laboratory	IGC	Gravitational Waves
Rachael Huxford	Graduate Student	Physics	reh255@psu.edu	--	317 Whitmore Laboratory	IGC	Gravitational Waves, Multimessenger Astrophysics
Donghui Jeong	Faculty	Astronomy	djeong@psu.edu	+1 814 865 1117	518 Davey Laboratory	CTOC	Gravitational Waves
Prathamesh Joshi	Graduate Student	ICDS, Physics	ppj5075@psu.edu	--	301D Whitmore Laboratory	IGC	Gravitational Waves, Multimessenger Astrophysics
James Kennington	Graduate Student	Physics	jwkennington@psu.edu	+1 814 865 7533	Box 66 Whitmore Laboratory	CFT	Gravitational Waves
Sanika Samir Khadkikar	Graduate Student	ICDS, Physics	sbk6031@psu.edu	--	321C Whitmore Laboratory	CMA	Multimessenger Astrophysics, Gravitational Waves
Samarth Khandelwal	Undergraduate Student	Physics, Math	smk6968@psu.edu	N/A	N/A Osmond Laboratory	IGC, CFT	Black Holes, Dynamic Universe, Gravitational Waves, Mathematical Structures
Gooderham McCormick	Graduate Student	Astronomy	gum66@psu.edu	+1 814 865 0419	537 Davey Laboratory	IGC	Gravitational Waves
Mainak Mukhopadhyay	Postdoc	Astronomy, Physics	mkm7190@psu.edu	--	320L Osmond Laboratory	CMA	Multimessenger Astrophysics, Gravitational Waves, Neutrinos
Eduardo Munguia Gonzalez	Graduate Student	ICDS, Astronomy	eem5633@psu.edu	814 863 5565	440 Davey Laboratory	IGC	Multimessenger Astrophysics, Gravitational Waves
Kohta Murase	Faculty	Physics, Astronomy	kum26@psu.edu	+1 814 863 9594	321B Osmond Laboratory	CMA	Cosmic Rays, Neutrinos, Multimessenger Astrophysics, Gravitational Waves, Dark Matter
Peter Mészáros	Faculty	Physics, Astronomy	nnp@psu.edu	814-863-4167	504 Davey Laboratory	CMA	Gravitational Waves, Neutrinos, Multimessenger Astrophysics
Victoria Niu	Graduate Student	Physics	wmn5062@psu.edu	+1 814 865 7533	334 Whitmore Laboratory	IGC	Multimessenger Astrophysics, Gravitational Waves, Dark Matter, Black Holes
Alexander Pace	Staff	Physics	aep14@psu.edu	+1 814 865 6995	334B Whitmore Laboratory	IGC	Multimessenger Astrophysics, Gravitational Waves
Surendra Padamata	Graduate Student	Physics	ssp5361@psu.edu	--	322 Osmond Laboratory	CMA	Multimessenger Astrophysics, Black Holes, Cosmic Rays, Gravitational Waves, Neutrinos
Shiksha Pandey	Graduate Student	Physics	spp5950@psu.edu	--	312 Whitmore Laboratory	IGC	Gravitational Waves, Dark Matter
Cort Posnansky	Graduate Student	Physics	clp5773@psu.edu	+1 814 863 9605	334 Whitmore Laboratory	CMA	Black Holes, Multimessenger Astrophysics, Gravitational Waves
Aviral Prakash	Graduate Student	ICDS, Astronomy, Physics	aup1075@psu.edu	--	317 Whitmore Laboratory	CMA	Neutrinos, Gravitational Waves, Multimessenger Astrophysics
Yi Qiu	Graduate Student	Physics	yiqiu@psu.edu	8142328268	114 Osmond Laboratory	IGC	Gravitational Waves
David Radice	Faculty	Astronomy, Physics	dur566@psu.edu	+1 814 865 7533	304 Whitmore Laboratory	CMA	Black Holes, Neutrinos, Multimessenger Astrophysics, Gravitational Waves
Samuele Ronchini	Postdoc	Astronomy	sjs8171@psu.edu	8148657705	- IV Building	CMA, IGC	Multimessenger Astrophysics, Gravitational Waves
Shio Sakon	Graduate Student	ICDS, Physics	sks6461@psu.edu	--	301D Whitmore Laboratory	IGC	Gravitational Waves, Black Holes, Multimessenger Astrophysics
B.S. Sathyaprakash	Faculty	Physics, Astronomy	bss25@psu.edu	--	312 Whitmore Laboratory	CMA, CTOC	Gravitational Waves, Dark Matter, Black Holes, Multimessenger Astrophysics
Sarah Shandera	Faculty	Physics	ses47@psu.edu	+1 814 863 9595	303A Whitmore Laboratory	CFT	Quantum Universe, Cosmic Surveys, Black Holes, Gravitational Waves, Dark Matter
Divya Singh	Graduate Student	Physics	dus960@psu.edu	--	301 Whitmore Laboratory	IGC	Dark Matter, Black Holes, Gravitational Waves
Mukesh Singh	Graduate Student	Astronomy	mks7196@psu.edu	8142808735	317 Whitmore Laboratory	IGC	Multimessenger Astrophysics, Gravitational Waves
Leo Tsukada	Faculty	Physics	lqt5311@psu.edu	+1 814 863 9605	301A Whitmore Laboratory	IGC	Gravitational Waves
V. Ashley Villar	Faculty	Astronomy, ICDS	vav5084@psu.edu	--	517 Davey Laboratory	CTOC	Multimessenger Astrophysics, Gravitational Waves

News about Gravitational Waves

Gravitational Wave Detector LIGO is Back Online after 3 Years of Upgrades

2023-05-30

After a three-year hiatus, scientists in the U.S. have just turned on detectors capable of measuring gravitational waves – tiny ripples in space itself that travel through the universe.

Unlike light waves, gravitational waves are nearly unimpeded by the galaxies, stars, gas and dust that fill the universe. This means that by measuring gravitational waves, astrophysicists like me can peek directly into the heart of some of these most spectacular phenomena in the universe.

Since 2020, the Laser Interferometric Gravitational-Wave Observatory – commonly known as LIGO – has been sitting dormant while it underwent some exciting upgrades. These improvements will significantly boost the sensitivity of LIGO and should allow the facility to observe more-distant objects that produce smaller ripples in spacetime.

By detecting more events that create gravitational waves, there will be more opportunities for astronomers to also observe the light produced by those same events. Seeing an event through multiple channels of information, an approach called multi-messenger astronomy, provides astronomers rare and coveted opportunities to learn about physics far beyond the realm of any laboratory testing.

According to Einstein’s theory of general relativity, mass and energy warp the shape of space and time. The bending of spacetime determines how objects move in relation to one another – what people experience as gravity.

Gravitational waves are created when massive objects like black holes or neutron stars merge with one another, producing sudden, large changes in space. The process of space warping and flexing sends ripples across the universe like a wave across a still pond. These waves travel out in all directions from a disturbance, minutely bending space as they do so and ever so slightly changing the distance between objects in their way.

Even though the astronomical events that produce gravitational waves involve some of the most massive objects in the universe, the stretching and contracting of space is infinitesimally small. A strong gravitational wave passing through the Milky Way may only change the diameter of the entire galaxy by three feet (one meter).

The first gravitational wave observations Though first predicted by Einstein in 1916, scientists of that era had little hope of measuring the tiny changes in distance postulated by the theory of gravitational waves.

Around the year 2000, scientists at Caltech, the Massachusetts Institute of Technology and other universities around the world finished constructing what is essentially the most precise ruler ever built – the LIGO observatory.

LIGO is comprised of two separate observatories, with one located in Hanford, Washington, and the other in Livingston, Louisiana. Each observatory is shaped like a giant L with two, 2.5-mile-long (four-kilometer-long) arms extending out from the center of the facility at 90 degrees to each other.

To measure gravitational waves, researchers shine a laser from the center of the facility to the base of the L. There, the laser is split so that a beam travels down each arm, reflects off a mirror and returns to the base. If a gravitational wave passes through the arms while the laser is shining, the two beams will return to the center at ever so slightly different times. By measuring this difference, physicists can discern that a gravitational wave passed through the facility.

LIGO began operating in the early 2000s, but it was not sensitive enough to detect gravitational waves. So, in 2010, the LIGO team temporarily shut down the facility to perform upgrades to boost sensitivity. The upgraded version of LIGO started collecting data in 2015 and almost immediately detected gravitational waves produced from the merger of two black holes.

Since 2015, LIGO has completed three observation runs. The first, run O1, lasted about four months; the second, O2, about nine months; and the third, O3, ran for 11 months before the COVID-19 pandemic forced the facilities to close. Starting with run O2, LIGO has been jointly observing with an Italian observatory called Virgo.

Between each run, scientists improved the physical components of the detectors and data analysis methods. By the end of run O3 in March 2020, researchers in the LIGO and Virgo collaboration had detected about 90 gravitational waves from the merging of black holes and neutron stars.

The observatories have still not yet achieved their maximum design sensitivity. So, in 2020, both observatories shut down for upgrades yet again.

Scientists have been working on many technological improvements.

One particularly promising upgrade involved adding a 1,000-foot (300-meter) optical cavity to improve a technique called squeezing. Squeezing allows scientists to reduce detector noise using the quantum properties of light. With this upgrade, the LIGO team should be able to detect much weaker gravitational waves than before.

My teammates and I are data scientists in the LIGO collaboration, and we have been working on a number of different upgrades to software used to process LIGO data and the algorithms that recognize signs of gravitational waves in that data. These algorithms function by searching for patterns that match theoretical models of millions of possible black hole and neutron star merger events. The improved algorithm should be able to more easily pick out the faint signs of gravitational waves from background noise in the data than the previous versions of the algorithms.

In early May 2023, LIGO began a short test run – called an engineering run – to make sure everything was working. On May 18, LIGO detected gravitational waves likely produced from a neutron star merging into a black hole.

LIGO’s 20-month observation run 04 will officially start on May 24, and it will later be joined by Virgo and a new Japanese observatory – the Kamioka Gravitational Wave Detector, or KAGRA.

While there are many scientific goals for this run, there is a particular focus on detecting and localizing gravitational waves in real time. If the team can identify a gravitational wave event, figure out where the waves came from and alert other astronomers to these discoveries quickly, it would enable astronomers to point other telescopes that collect visible light, radio waves or other types of data at the source of the gravitational wave. Collecting multiple channels of information on a single event – multi-messenger astrophysics – is like adding color and sound to a black-and-white silent film and can provide a much deeper understanding of astrophysical phenomena.

Astronomers have only observed a single event in both gravitational waves and visible light to date – the merger of two neutron stars seen in 2017. But from this single event, physicists were able to study the expansion of the universe and confirm the origin of some of the universe’s most energetic events known as gamma-ray bursts.

With run O4, astronomers will have access to the most sensitive gravitational wave observatories in history and hopefully will collect more data than ever before. My colleagues and I are hopeful that the coming months will result in one – or perhaps many – multi-messenger observations that will push the boundaries of modern astrophysics.

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IGC Alumn Cody Messick wins the Dissertation Award for LIGO Research

2023-04-25

Cody Messick, who earned a doctorate in physics from Penn State in 2019, was honored with the Northeastern Association of Graduate Schools’ 2023 Doctoral Dissertation Award. The annual award recognizes one outstanding dissertation that has been produced by a doctoral candidate at one of its member institutions.

“It’s exciting and incredibly validating to receive an award like this,” said Messick, now a postdoctoral researcher at the Massachusetts Institute of Technology. “I set out to write my dissertation from scratch instead of combining papers, because I wanted more control over the way I presented the story of my research. Receiving an award like this makes that effort feel seen, and, while I originally took the route, I did it for myself, and it’s an honor to receive recognition for it.”

Messick’s pioneering research focused on gravitational waves, which are ripples in space that were first hypothesized by Albert Einstein. Messick’s work led to the first-ever discovery in 2015 of gravitational waves using a highly sophisticated measurement device known as the Laser Interferometer Gravitational-Wave Observatory (LIGO), which uses lasers to measure miniscule changes in space occurring from distant astronomy events, such as a supernova. Today, LIGO and similar gravitational-wave detectors are used by an international research team, known as the LIGO-Virgo-KAGRA Collaboration, that is led, in part, by Penn State researchers.

For his doctoral dissertation, “Detecting Gravitational Waves for Multi-Messenger Astronomy,” Messick developed algorithms for sifting through large amounts of data produced by LIGO to identify subtle signals of a distant astronomical event. Messick’s innovations led to the identification of 11 separate gravitational wave signals, as well as the ability to detect signals in real time.

“The most exciting of these detections occurred on Aug. 17, 2017. I was the first person in the world to see that our analysis had identified a signal that went through our detectors within two seconds of an extremely energetic burst of electromagnetic radiation called a gamma-ray burst. We were able to confirm that these two events came from the same astrophysical source: two neutron stars colliding roughly 130 million light-years away,” said Messick. This work was recognized as Science’s Breakthrough of the Year in 2017.

Messick’s work helped to pave the way for LIGO’s data to be an integral part of multi-messenger astronomy, which leverages signals from different sources, such as neutrinos and electromagnetic waves, to create a deeper understanding of the universe.

“Gravitational wave astronomy is now a bona fide field of physics due, in no small measure, to the contributions of Cody Messick while he was a graduate student at Penn State, working on the Laser Interferometer Gravitational-Wave Observatory (LIGO),” said Doug Cowen, professor of physics and astronomy and astrophysics at Penn State. “His analysis techniques were central to the detection and subsequent localization of the first triply-detected gravitational wave, followed very shortly afterward by the first binary neutron star merger discovery, which led directly to the first coincident gravitational wave plus gamma-ray detection. Together, these momentous discoveries have elevated gravitational waves to a preeminent position in the nascent field of multi-messenger astronomy.”

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Upcoming International Seminar on Gravitational Waves!

2022-03-01

Interested in how scientists collaborate across borders? Or how STEM projects are operated on an international scale?

Then check out the upcoming “Crossing Borders to Map Our Universe” seminar this March 21.

Anyone can join through Zoom here: https://psu.zoom.us/j/92182953190?pwd=d1Z6QmlReWQ5SUdWanJvWllDbDZ4UT09

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Two probable black-hole mergers spotted in first weeks after gravitational-wave detector is updated

2019-06-16

Two new probable gravitational waves — ripples in the fabric of spacetime caused by cataclysmic cosmic events and first predicted by Albert Einstein over 100 years ago — have been detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo observatory in Italy in the first weeks after the detectors were updated. The IGC team of LIGO scientists, led by Chad Hanna, played a critical role.

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Black Holes, Dark Matter & Quantum Gravity, what’s new in Loop Quantum Gravity

2019-06-01

Are black holes related to dark matter? Do the observations of black holes by LIGO hint at a signature of quantum gravity ? Can we find evidence of black holes from a previous universe? In 2019 second place in the Buchalter Cosmology Prize was awarded to two of the speakers you will see in this film which explores some of the above themes. We filmed this at the Loop Quantum Gravity Conference in 2019 and plan to make a follow up film exploring the latest ideas in the field. Look out for the optical illusion around 8:12–8:25. YouTube Video prepared by Monica and Phil Halper. Filmed during Loops19 conference.

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