Astrophysics

Displaying 1165 - 1176 of 2166

The Effective Field Theory of Large Scale Structures

Enrico Pajer Utrecht University
March 19, 2013

PIRSA:13030110
Astrophysics
Effective field theory approach to quasi-single field inflation

Masahide Yamaguchi Tokyo Institute of Technology
March 12, 2013

PIRSA:13030096
Astrophysics
12/13 PSI - Cosmology Review Lecture 14

Latham Boyle University of Edinburgh
March 08, 2013

PIRSA:13030045
Astrophysics
12/13 PSI - Cosmology Review Lecture 13

Latham Boyle University of Edinburgh
March 07, 2013

PIRSA:13030044
Astrophysics
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Astrophysics
12/13 PSI - Cosmology Review Lecture 12

Latham Boyle University of Edinburgh
March 06, 2013

PIRSA:13030043
Astrophysics
12/13 PSI - Cosmology Review Lecture 11

Latham Boyle University of Edinburgh
March 05, 2013

PIRSA:13030042
Astrophysics
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Astrophysics
12/13 PSI - Cosmology Review Lecture 10

Latham Boyle University of Edinburgh
March 04, 2013

PIRSA:13030041
Astrophysics
12/13 PSI - Cosmology Review Lecture 9

Latham Boyle University of Edinburgh
March 01, 2013

PIRSA:13030038
Astrophysics
12/13 PSI - Cosmology Review Lecture 8

Latham Boyle University of Edinburgh
February 28, 2013

PIRSA:13020108
Astrophysics
12/13 PSI - Cosmology Review Lecture 7

Latham Boyle University of Edinburgh
February 27, 2013

PIRSA:13020107
Astrophysics

The Effective Field Theory of Large Scale Structures

Enrico Pajer Utrecht University
March 19, 2013

PIRSA:13030110
Astrophysics
An analytical understanding of large-scale matter inhomogeneities is an important cornerstone of our cosmological model and helps us interpreting current and future data. The standard approach, namely Eulerian perturbation theory, is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small everywhere; it does not consistently account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV divergent, making predictions cutoff dependent and hence unphysical. I will present the systematic construction of an Effective Field Theory of Large Scale Structures and show that it successfully addresses all of the above issues. The idea is to smooth the density and velocity fields on a scale larger than the non-linear scale. The resulting smoothed fields are then small everywhere and provide a well-defined small parameter for perturbation theory. Smoothing amounts to integrating out the short scales, whose non-linear dynamics is hard to describe analytically. Their effects on the large scales are then determined by the symmetries of the problems. They introduce additional terms in the fluid equations such as an effective pressure, dissipation and stochastic noise. These terms have exactly the right scale dependence to cancel all divergences at one loop, and this should hold at all loops.
I will present a clean example of the renormalization of the theory in an Einstein de Sitter universe with self-similar initial conditions and discuss the relative importance of loop and effective corrections.
Effective field theory approach to quasi-single field inflation

Masahide Yamaguchi Tokyo Institute of Technology
March 12, 2013

PIRSA:13030096
Astrophysics
We apply the effective field theory approach to quasi-single field inflation, which contains an additional scalar field with Hubble scale mass other than inflaton. Based on the time-dependent spatial diffeomorphism, which is not broken by the time-dependent background evolution, the most generic action of quasi-single field inflation is constructed up to third order fluctuations. Using the obtained action, the effects of the additional massive scalar field on the primordial curvature perturbations are discussed. In particular, we calculate the power spectrum and discuss the momentum-dependence of three point functions in the squeezed limit for general settings of quasi-single field inflation. Our framework can be also applied to inflation models with heavy particles. We make a qualitative discussion on the effects of heavy particles during inflation and that of sharp turning trajectory in our framework.
12/13 PSI - Cosmology Review Lecture 14

Latham Boyle University of Edinburgh
March 08, 2013

PIRSA:13030045
Astrophysics
12/13 PSI - Cosmology Review Lecture 13

Latham Boyle University of Edinburgh
March 07, 2013

PIRSA:13030044
Astrophysics
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Astrophysics
This talk will begin by discussing one by one the various reasons why cosmologists today consider the big bang inflationary cosmology to be the leading, if not proven, theory of the universe and then explaining why each of these reasons is flawed. This leads naturally to the question: what is the alternative? Understanding the flaws helps point the way.
12/13 PSI - Cosmology Review Lecture 12

Latham Boyle University of Edinburgh
March 06, 2013

PIRSA:13030043
Astrophysics
12/13 PSI - Cosmology Review Lecture 11

Latham Boyle University of Edinburgh
March 05, 2013

PIRSA:13030042
Astrophysics
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Astrophysics
As black holes accrete surrounding gas, they often produce relativistic, collimated outflows, or jets. Jets are expected to form in the black hole vicinity making them powerful probes of strong-field gravity. However, how jet properties are connected to black hole and accretion flow properties has been unclear. Recent progress in computer simulations of black hole accretion enables studies of jet formation in unprecedented detail. For the first time, 3D general relativistic magnetohydrodynamic numerical simulations allow one to determine the maximum efficiency with which accretion onto black holes can power relativistic jets. I will present the dependence of this maximum efficiency on black hole spin and discuss how this dependence allows one to probe strong-field gravity. In realistic astrophysical systems, the angular momentum vector of the accretion flow can be tilted relative to the spin of the black hole. I will present the first simulations of jets from such tilted accretion systems and discuss their observational signatures.
12/13 PSI - Cosmology Review Lecture 10

Latham Boyle University of Edinburgh
March 04, 2013

PIRSA:13030041
Astrophysics
12/13 PSI - Cosmology Review Lecture 9

Latham Boyle University of Edinburgh
March 01, 2013

PIRSA:13030038
Astrophysics
12/13 PSI - Cosmology Review Lecture 8

Latham Boyle University of Edinburgh
February 28, 2013

PIRSA:13020108
Astrophysics
12/13 PSI - Cosmology Review Lecture 7

Latham Boyle University of Edinburgh
February 27, 2013

PIRSA:13020107
Astrophysics

Title	Speaker(s)	Date	Talk Type	Info link
The Effective Field Theory of Large Scale Structures	Enrico Pajer	2013-03-19	Scientific Series	View details
Effective field theory approach to quasi-single field inflation	Masahide Yamaguchi	2013-03-12	Scientific Series	View details
12/13 PSI - Cosmology Review Lecture 14	Latham Boyle	2013-03-08	Course	View details
12/13 PSI - Cosmology Review Lecture 13	Latham Boyle	2013-03-07	Course	View details
Rethinking Cosmology		2013-03-06	Scientific Series	View details
12/13 PSI - Cosmology Review Lecture 12	Latham Boyle	2013-03-06	Course	View details
12/13 PSI - Cosmology Review Lecture 11	Latham Boyle	2013-03-05	Course	View details
Getting the Most out of a Black Hole	Alexander Tchekhovskoy	2013-03-04	Scientific Series	View details
12/13 PSI - Cosmology Review Lecture 10	Latham Boyle	2013-03-04	Course	View details
12/13 PSI - Cosmology Review Lecture 9	Latham Boyle	2013-03-01	Course	View details
12/13 PSI - Cosmology Review Lecture 8	Latham Boyle	2013-02-28	Course	View details
12/13 PSI - Cosmology Review Lecture 7	Latham Boyle	2013-02-27	Course	View details

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Format results

The Effective Field Theory of Large Scale Structures

Effective field theory approach to quasi-single field inflation

12/13 PSI - Cosmology Review Lecture 14

12/13 PSI - Cosmology Review Lecture 13

Rethinking Cosmology

12/13 PSI - Cosmology Review Lecture 12

12/13 PSI - Cosmology Review Lecture 11

Getting the Most out of a Black Hole

12/13 PSI - Cosmology Review Lecture 10

12/13 PSI - Cosmology Review Lecture 9

12/13 PSI - Cosmology Review Lecture 8

12/13 PSI - Cosmology Review Lecture 7

The Effective Field Theory of Large Scale Structures

Effective field theory approach to quasi-single field inflation

12/13 PSI - Cosmology Review Lecture 14

12/13 PSI - Cosmology Review Lecture 13

Rethinking Cosmology

12/13 PSI - Cosmology Review Lecture 12

12/13 PSI - Cosmology Review Lecture 11

Getting the Most out of a Black Hole

12/13 PSI - Cosmology Review Lecture 10

12/13 PSI - Cosmology Review Lecture 9

12/13 PSI - Cosmology Review Lecture 8

12/13 PSI - Cosmology Review Lecture 7