×
Available
Gravity Seminar
Monday, January 23, 2023
1:30 PM
Physics, Room TBA
Note special room.

 Add to your calendar

"Observational consequences of non-linear memory of gravitational waves"


Shubhanshu Tiwari , University of Zurich
[Host: Alexander Grant]
ABSTRACT:

Non-linear memory is one of the most intriguing predictions of general relativity which is generated by the passage of gravitational waves (GWs) leaving the spacetime permanently deformed. For example a GW signal from binary black hole (BBH) will have two parts the oscillatory part which is known as the “chirp” and a much fainter non-oscillatory (DC like) part which is non-linear memory. A non-linear memory is produced by all the sources of GWs and  has the peculiarity that even if the oscillatory part of the source lies at high frequency the non-linear memory will be available at low frequency. This property of non-linear memory makes it a valuable resource for GW astronomy. In this talk I will provide and introduction to how we can use gravitational waves memory as a resource for the current and future ground based detectors. To do this I will show examples of how one can creatively use the non-linear memory to probe seemingly inaccessible sources of GWs like ultra low mass compact binary mergers where the oscillatory part lies at outside the reach of any current detectors and only non-linear memory could be detected if these sources exist. Another example will be the matter effects from binary neutron stars and black hole neutron star binaries which are at high frequency but the non-linear memory is accessible. I will also discuss the post-merger neutron star memory and the prospects of its detection.

Gravity Seminar
Monday, January 30, 2023
1:30 PM
Physics, Room Zoom
Note special room.

Zoom link: https://virginia.zoom.us/j/96960494406?pwd=MFBMaDRvb1BQc1V3RVRpcm14eVdCQT09

Meeting ID: 969 6049 4406

Passcode: 287180


 Add to your calendar

Available
Gravity Seminar
Monday, February 6, 2023
1:30 PM
Physics, Room TBA
Note special room.

 Add to your calendar

"Next-Generation Black Hole and Neutron Star Collision Simulations"


Zachariah Etienne , University of Idaho
[Host: Alexander Grant]
ABSTRACT:

Perhaps the most significant astronomical discovery of our lifetimes, code-named GW170817, involved the collision of two neutron stars. The collision was detected both by gravitational wave observatories, and traditional electromagnetic telescopes. As neutron stars are made of the densest form of matter in our current Universe, this single "multimessenger" event was a watershed moment in our understanding as to how matter and gravity behave at their most extreme, far beyond what we can study in laboratories on Earth. For the most part, we compare observations against theoretical models to extract science from events like this. Unfortunately, these theoretical models are severely limited both in quality and quantity, leading to a critical need to improve them. Such improvements pose a key challenge to computational astrophysics, as our most detailed models require expensive supercomputer simulations that generate full, non-perturbative solutions of the general relativistic field equations (numerical relativity). After a gentle introduction to multimessenger astrophysics and the challenges associated with multimessenger source modeling, I will outline a new approach aimed at greatly reducing the cost of these simulations. With the reduced cost comes the potential to both perform colliding black hole simulations on the consumer-grade desktop computer, as well as add unprecedented levels of physical realism to colliding neutron star simulations on supercomputers.

Gravity Seminar
Monday, February 13, 2023
1:30 PM
Physics, Room Zoom
Note special room.

Zoom link: https://virginia.zoom.us/j/99508589926?pwd=TUFNMDJZMjZRUTJnaFd3TDgxNi9KZz09

Meeting ID: 995 0858 9926

Password: 441596


 Add to your calendar

Available
Gravity Seminar
Monday, February 20, 2023
1:30 PM
Physics, Room TBA
Note special room.

 Add to your calendar

"Gravitational waves from a particle physics perspective"


Jan Steinhoff , Max Planck Institute for Gravitational Physics
[Host: David Nichols]
ABSTRACT:

Continuing the success of gravitational wave observations demands considerable improvements of their theoretical predictions in the next decade, in order to keep their accuracy on par with upgrades of the detectors. This urges innovations on the methods by which gravitational waves from compact binaries are calculated. In this talk, we focus on approaches to analytic, perturbative predictions for relativistic binaries inspired by high-energy physics. In this area, effective field theories are highly useful and scattering amplitudes (the primary observable) can be calculated very efficiently using novel tools. These methods can indeed be applied the classical binaries and their gravitational waves. We give a basic introduction to the ideas of these approaches and recent progress.

Gravity Seminar
Monday, February 27, 2023
1:30 PM
Clark Hall - Virtual talk, Room 108
Note special room.

Join Zoom Meeting

https://virginia.zoom.us/j/97977658329?pwd=cDluSDJ0QlUzV3M0dWhHODVGc1FFQT09

 

Meeting ID: 979 7765 8329

Passcode: 357957


 Add to your calendar

"Gravitational Faraday rotation of gravitational waves by a Kerr black hole"


Zhao Li , University of Science and Technology of China
[Host: Kent Yagi]
ABSTRACT:

Gravitational Faraday Rotation (GFR) is a frame-dragging effect induced by rotating massive objects, which is one of the important characteristics of lensed gravitational waves (GWs). In my previous work, we calculate the GFR angle of GWs in the weak deflection limit, assuming it is lensed by a Kerr black hole (BH). We find that the GFR effect changes the initial polarization state of the lensed GW. Compared with the Einstein deflection angle, the dominant term of the rotation angle is a second-order correction to the polarization angle, which depends on the light-of-sight component of BH angular momentum. Such a rotation is tiny and degenerates with the initial polarization angle. In some critical cases, the GFR angle is close to the detection capability of the third-generation GW detector network, although the degeneracy has to be broken.

Gravity Seminar
Monday, March 6, 2023
1:30 PM
, Room Zoom
Note special room.

https://us02web.zoom.us/j/86544012000?pwd=ckJpMTY5L0dIbHc5WTZxNFMvM1lkdz09

Meeting ID: 865 4401 2000

Passcode: 033748


 Add to your calendar

"Hypermassive neutron stars and short gamma ray bursts"


Cecilia Chirenti , University of Maryland
[Host: Kent Yagi]
ABSTRACT:

Gamma ray bursts (GRBs) are the most luminous electromagnetic events in the universe. Short GRBs, typically lasting less than 2 seconds, have already been associated with binary neutron star (BNS) mergers, which are also sources of gravitational waves (GWs). The ultimate fate of a BNS, after coalescence, is usually expected to be a black hole (BH) with 2-3 solar masses. However, numerical relativity simulations indicate the possible formation of a short-lived hypermassive neutron star (HMNS), lasting for tens to hundreds of milliseconds after the BNS merger and before gravitational collapse forms a BH. The HMNS is expected to emit GWs with kHz frequencies that will be detectable by third generation ground-based GW detectors in the 2030s. I will present results from a recent analysis that revealed evidence for HMNSs by looking for kHz qusiperiodic oscillations in gamma-ray observations obtained in the 1990s with the Compton Gamma Ray Observatory. 

Gravity Seminar
Monday, March 13, 2023
1:30 PM
Physics, Room 313

 Add to your calendar

Available
Gravity Seminar
Monday, March 20, 2023
1:30 PM
Physics, Room Zoom
Note special room.

 Add to your calendar

"A study of gravitational wave memory effects in radiative geometries and wormholes "


Indranil Chakraborty , IIT Kharagpur
[Host: David Nichols]
ABSTRACT:

Gravitational memory effects are persistent deformations caused due to the passage of a gravitational wave pulse. It is a nonlinear effect in General Relativity that remains yet to be detected. In this talk, primarily from a theoretical perspective, we study memory effects in two different settings: i) Radiative geometries, ii) Lorentzian wormholes. In radiative geometries, we show how geodesic and geodesic deviation equations encode the gravitational wave memory. In the latter case, we perform a Bondi-Sachs analysis and try to show how the Bondi mass loss depends on the wormhole hair.

Gravity Seminar
Monday, March 20, 2023
1:30 PM
, Room Zoom
Note special room.

Join Zoom Meeting

https://virginia.zoom.us/j/97977658329?pwd=cDluSDJ0QlUzV3M0dWhHODVGc1FFQT09

 

Meeting ID: 979 7765 8329

Passcode: 357957


 Add to your calendar

"TBA"


Geraint Pratten , University of Birmingham
[Host: David Nichols]
ABSTRACT:

TBA

Gravity Seminar
Monday, March 27, 2023
1:30 PM
, Room Zoom
Note special room.

 Add to your calendar

Available
Gravity Seminar
Monday, April 3, 2023
1:30 PM
, Room Zoom
Note special room.

 Add to your calendar

"TBA"


Maya Fishbach , University of Toronto
[Host: Kent Yagi]
ABSTRACT:

TBA

Gravity Seminar
Monday, April 10, 2023
1:30 PM
TBA, Room TBA
Note special room.

 Add to your calendar

Available
Gravity Seminar
Monday, April 17, 2023
1:30 PM
Physics, Room TBA
Note special room.

 Add to your calendar

Available
Gravity Seminar
Monday, April 24, 2023
1:30 PM
Physics, Room TBA
Note special room.

 Add to your calendar

Available
Gravity Seminar
Monday, May 1, 2023
1:30 PM
Physics, Room TBA
Note special room.

 Add to your calendar

To add a speaker, send an email to dn2ep@Virginia.EDU Include the seminar type (e.g. Gravity Seminars), date, name of the speaker, title of talk, and an abstract (if available). [Please send a copy of the email to phys-speakers@Virginia.EDU.]