General Relativity & Quantum Cosmology

Displaying 1417 - 1428 of 1854

The effective field theory of general relativity, running couplings and Asymptotic Safety

John Donoghue University of Massachusetts Amherst
May 09, 2013

PIRSA:13050003
General Relativity & Quantum Cosmology
David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes

Paolo Pani Instituto Superior Tecnico - Departamento de Física
May 09, 2013

PIRSA:13050001
General Relativity & Quantum Cosmology
Propagation of entanglement in strongly coupled systems from gravity

Hong Liu Massachusetts Institute of Technology (MIT) - Department of Physics
May 08, 2013

PIRSA:13050035
General Relativity & Quantum Cosmology
Loop quantization of a weak-coupling limit of Euclidean gravity

Casey Tomlin Pennsylvania State University
April 25, 2013

PIRSA:13040104
General Relativity & Quantum Cosmology
Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Andrew Cumming McGill University
April 25, 2013

PIRSA:13040138
General Relativity & Quantum Cosmology
The imaginary part of the gravitational action and black hole entropy

Yasha Neiman Okinawa Institute of Science and Technology Graduate University
April 18, 2013

PIRSA:13040106
General Relativity & Quantum Cosmology
Quantum causal dynamics without absolute space or time
April 11, 2013

PIRSA:13040083
General Relativity & Quantum Cosmology
Spinning black-hole binaries as gravitational and cosmological probes

Enrico Barausse SISSA International School for Advanced Studies
April 11, 2013

PIRSA:13040082
General Relativity & Quantum Cosmology
Fundamental Physics with Optically Levitated Dielectric Objects

Asimina Arvanitaki Perimeter Institute
April 04, 2013

PIRSA:13040114
General Relativity & Quantum Cosmology
Shake, Rattle and Explode: Short GRBs and the Electromagnetic Counterparts of Gravitational Wave Sources

Edo Berger Harvard University
April 02, 2013

PIRSA:13040081
Astrophysics

General Relativity & Quantum Cosmology
Canonical gravity using unconstrained null initial data

Michael Reisenberger Universidad de la Republica Uruguay
March 28, 2013

PIRSA:13030092
General Relativity & Quantum Cosmology
Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

Lorenzo Sironi Columbia University
March 21, 2013

PIRSA:13030078
General Relativity & Quantum Cosmology

The effective field theory of general relativity, running couplings and Asymptotic Safety

John Donoghue University of Massachusetts Amherst
May 09, 2013

PIRSA:13050003
General Relativity & Quantum Cosmology
Effective field theory techniques allow reliable quantum calculations in general relativity at low energy. After a review of these techniques, I will discuss the attempts to define the gravitational corrections to running gauge couplings and to the couplings of gravity itself. I will also describe an attempt to understand the relation between the effective field theory and Asymptotic Safety in the region where they overlap.
David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes

Paolo Pani Instituto Superior Tecnico - Departamento de Física
May 09, 2013

PIRSA:13050001
General Relativity & Quantum Cosmology
In the last few years several interesting phenomena associated to the interaction between massive black holes and fundamental bosonic fields have been discovered. I present a selection of them, including superradiance instabilities of spin-0, spin-1 and spin-2 fields, floating orbits in extreme-mass ratio inspirals and black-hole spontaneous scalarization. The theoretical potential of these effects
as almost-model-independent smoking guns for exotic particles and modified gravity, as well as their limitations in realistic astrophysical scenarios, are discussed.
Propagation of entanglement in strongly coupled systems from gravity

Hong Liu Massachusetts Institute of Technology (MIT) - Department of Physics
May 08, 2013

PIRSA:13050035
General Relativity & Quantum Cosmology
Loop quantization of a weak-coupling limit of Euclidean gravity

Casey Tomlin Pennsylvania State University
April 25, 2013

PIRSA:13040104
General Relativity & Quantum Cosmology
I will describe recent work in collaboration with Adam Henderson, Alok Laddha, and Madhavan Varadarajan on the loop quantization of a certain $G_{\mathrm{N}}\rightarrow 0$ limit of Euclidean gravity, introduced by Smolin. The model allows one to test various quantization choices one is faced with in loop quantum gravity, but in a simplified setting. The main results are the construction of finite-triangulation Hamiltonian and diffeomorphism constraint operators whose continuum limits can be evaluated in a precise sense, such that the quantum Dirac algebra of constraints closes nontrivially and free of anomalies. The construction relies heavily on techniques of Thiemann's QSD treatment, and lessons learned applying such techniques to the loop quantization of parameterized scalar field theory and the diffeomorphism constraint in loop quantum gravity. I will also briefly discuss the status of the quantum constraint algebra in full LQG, and how some of the lessons learned from the present model may guide us in that setting.
Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Andrew Cumming McGill University
April 25, 2013

PIRSA:13040138
General Relativity & Quantum Cosmology
The last few years have seen new opportunities for constraining the physics of neutron star interiors. I will first discuss the current state of neutron star radius measurements and then go on to discuss thermal tomography as a probe of the nuclear, magnetic, and transport properties of neutron star crusts. In each case, I will emphasize the astrophysics that must be understood to make reliable inferences about the properties of dense matter from observations of neutron stars.
The imaginary part of the gravitational action and black hole entropy

Yasha Neiman Okinawa Institute of Science and Technology Graduate University
April 18, 2013

PIRSA:13040106
General Relativity & Quantum Cosmology
I present a candidate for a new derivation of black hole entropy. The key observation is that the action of General Relativity in bounded regions has an imaginary part, arising from the boundary term. The formula for this imaginary part is closely related to the Bekenstein-Hawking entropy formula, and coincides with it for certain classes of regions. This remains true in the presence of matter, and generalizes appropriately to Lovelock gravity. The imaginary part of the action is a versatile notion, requiring neither stationarity nor any knowledge about asymptotic infinity. Thus, it may provide a handle on quantum gravity in finite and dynamical regions. I derive the above results, make connections with standard approaches to black hole entropy, and speculate on the meaning of it all. Implications for loop quantum gravity are also discussed.
Quantum causal dynamics without absolute space or time
April 11, 2013

PIRSA:13040083
General Relativity & Quantum Cosmology
I will describe a discrete model of spacetime which is quantum-mechanical, causal, and background free. The kinematics is described by networks whose vertices are labelled with arrows. These networks can be evolved forwards (or backwards) in time by using unitary replacement rules. The arrow structure permits one to define dynamics without using an absolute time parameter. Based on arXiv:1201.2489.
Spinning black-hole binaries as gravitational and cosmological probes

Enrico Barausse SISSA International School for Advanced Studies
April 11, 2013

PIRSA:13040082
General Relativity & Quantum Cosmology
Fundamental Physics with Optically Levitated Dielectric Objects

Asimina Arvanitaki Perimeter Institute
April 04, 2013

PIRSA:13040114
General Relativity & Quantum Cosmology
In the past few years, optical cooling and manipulating of macroscopic objects, such as micro-mirrors and cantilevers has developed into an active field of research. In mechanical systems, the oscillator is attached to its suspension, a thermal contact that limits the motion isolation. On the other hand, when these small objects are levitated using the radiation pressure force of lasers, the excellent thermal isolation even at room temperatures helps produce very sensitive force detectors, and eventually quantum transducers for quantum computation purposes. These new techniques may have a variety of applications for fundamental physics such as short distance tests of gravity and gravitational wave detection at high frequencies. In addition, there are several proposals suggesting that optically levitated dielectrics can be cooled to the ground state of the center of mass motion, opening the exciting possibility of creating macroscopic matter-wave interferometers.
Shake, Rattle and Explode: Short GRBs and the Electromagnetic Counterparts of Gravitational Wave Sources

Edo Berger Harvard University
April 02, 2013

PIRSA:13040081
Astrophysics

General Relativity & Quantum Cosmology
The bimodality of gamma-ray burst (GRB) durations points to distinct progenitor classes for the long- and short-duration GRBs. While the progenitors of long-duration GRBs are now known to be massive stars, the progenitors of short-duration GRBs remain unidentified. In this talk I will discuss the discovery of short GRB afterglow and their host galaxies, detailed studies of their environments from parsec to galactic scales, and studies of their energetics and beaming. Taken together, these observations point to the coalescence of NS-NS/NS-BH binaries as the most likely progenitors. With the upcoming Advanced LIGO/VIRGO gravitational wave detectors it is therefore possible that short GRBs will be the first detected sources, and I will discuss various approaches to making this connection between gravitational wave and electromagnetic sources.
Canonical gravity using unconstrained null initial data

Michael Reisenberger Universidad de la Republica Uruguay
March 28, 2013

PIRSA:13030092
General Relativity & Quantum Cosmology
Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

Lorenzo Sironi Columbia University
March 21, 2013

PIRSA:13030078
General Relativity & Quantum Cosmology
The relativistic wind of pulsars consists of toroidal stripes of opposite magnetic field polarity, separated by current sheets of hot plasma. By means of 2D and 3D particle-in-cell simulations, we investigate particle acceleration and magnetic field dissipation at the termination shock of a striped pulsar wind. At the shock, the flow compresses and the alternating fields annihilate by driven magnetic reconnection. Irrespective of the stripe wavelength "lambda" or the wind magnetization "sigma" (in the regime sigma>>1 of magnetically-dominated flows), shock-driven reconnection transfers all the magnetic energy of the alternating fields to the particles. As the value of lambda/(r_L*sigma) increases (here, r_L is the relativistic Larmor radius in the wind), the post-shock spectrum passes from a thermal Maxwellian to a flat power-law tail with slope around -1.5, populated by particles accelerated by the reconnection electric field. The limit lambda/(r_L*sigma)>>1 is realized in relativistic jets, where kink instabilities may seed the conditions for magnetic reconnection. Here, we find that the particle spectrum in the current sheet approaches a flat power-law tail with slope between -1.5 and -2, regardless of the conditions in the jet. The spectrum extends to higher energies for larger magnetizations or colder plasma temperatures, everything else being fixed. Our results place important constraints on the emission models of Pulsar Wind Nebulae and magnetically-dominated astrophysical jets.

Title	Speaker(s)	Date	Talk Type	Info link
The effective field theory of general relativity, running couplings and Asymptotic Safety	John Donoghue	2013-05-09	Scientific Series	View details
David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes	Paolo Pani	2013-05-09	Scientific Series	View details
Propagation of entanglement in strongly coupled systems from gravity	Hong Liu	2013-05-08	Conference	View details
Loop quantization of a weak-coupling limit of Euclidean gravity	Casey Tomlin	2013-04-25	Scientific Series	View details
Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars	Andrew Cumming	2013-04-25	Scientific Series	View details
The imaginary part of the gravitational action and black hole entropy	Yasha Neiman	2013-04-18	Scientific Series	View details
Quantum causal dynamics without absolute space or time		2013-04-11	Scientific Series	View details
Spinning black-hole binaries as gravitational and cosmological probes	Enrico Barausse	2013-04-11	Scientific Series	View details
Fundamental Physics with Optically Levitated Dielectric Objects	Asimina Arvanitaki	2013-04-04	Scientific Series	View details
Shake, Rattle and Explode: Short GRBs and the Electromagnetic Counterparts of Gravitational Wave Sources	Edo Berger	2013-04-02	Scientific Series	View details
Canonical gravity using unconstrained null initial data	Michael Reisenberger	2013-03-28	Scientific Series	View details
Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets	Lorenzo Sironi	2013-03-21	Scientific Series	View details

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General Relativity & Quantum Cosmology

Format results

The effective field theory of general relativity, running couplings and Asymptotic Safety

David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes

Propagation of entanglement in strongly coupled systems from gravity

Loop quantization of a weak-coupling limit of Euclidean gravity

Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

The imaginary part of the gravitational action and black hole entropy

Quantum causal dynamics without absolute space or time

Spinning black-hole binaries as gravitational and cosmological probes

Fundamental Physics with Optically Levitated Dielectric Objects

Shake, Rattle and Explode: Short GRBs and the Electromagnetic Counterparts of Gravitational Wave Sources

Canonical gravity using unconstrained null initial data

Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

The effective field theory of general relativity, running couplings and Asymptotic Safety

David Defeats Goliath: How Ultralight Fields Affect The Dynamics of Massive Black Holes

Propagation of entanglement in strongly coupled systems from gravity

Loop quantization of a weak-coupling limit of Euclidean gravity

Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

The imaginary part of the gravitational action and black hole entropy

Quantum causal dynamics without absolute space or time

Spinning black-hole binaries as gravitational and cosmological probes

Fundamental Physics with Optically Levitated Dielectric Objects

Shake, Rattle and Explode: Short GRBs and the Electromagnetic Counterparts of Gravitational Wave Sources

Canonical gravity using unconstrained null initial data

Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets