Next meeting:
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Bill Wright,
Michael Kenna-Allison,
Sergi Sirera,
Molly Burkmar,
Sophie Hoyland,
Neel Shah,
Parth Bhargava|
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Votes: 2
9 years ago Author:
Pedro G. Ferreira, Christopher T. Hill, Graham G. Ross
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Votes: 2
9 years ago Author:
Mark P. Hertzberg
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9 years ago
Title: Norihiro Tanahashi "Causal structure and shock formation in the most general scalar-tensor theories"
Description: Wave propagation speed in scalar-tensor theories may vary depending on
environment, and it can cause many peculiar phenomena such as
superluminal propagation and wave form distortion. In this work, we
focus on Horndeski theory and its generalization to two scalar fields,
and examine causal structure and shock formation in those theories.
About the causal structure, we focus on a stationary black hole, and
check if scalar or gravitational wave could come out from black hole
interior to exterior by propagating superluminally. We find that the
scalar field must satisfy certain conditions to prohibit such a
propagation across the horizon. About the shock formation, we examine
conditions for that to occur in Horndeski theory. When the background
solution is symmetric enough, we find that the gravitational wave is
protected from the shock formation while the scalar field suffers from
it.
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9 years ago
Title: Jorgos Papadomanolakis "The Effective Field Theory of Dark Energy and Modified Gravity"
Description: In recent years the discovery of the late-time cosmic acceleration triggered the creation of a multitude of theories, which modify General Relativity, in order to give a satisfactory explanation to this phenomenon. Now, with the wealth of current and upcoming observational data, it becomes imperative to create efficient ways to put these theories to the test, both in a model dependent and independent way. This led to the creation of the Effective Field Theory of Dark Energy and Modified Gravity which provides a framework to accomplish this.
In this talk I will introduce the EFT of DE/MG and comment on how it can be used in a model dependent and independent way. Moreover I will exhibit its potential to constrain the landscape of theories by extensively studying the theoretical stability conditions (ghost, gradient and tachyonic/Jeans) of modified gravity theories in the presence of matter fluids.
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Votes: 1
9 years ago Author:
Xian O. Camanho, Gustavo Lucena Gomez, Rakibur Rahman
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Votes: 1
9 years ago Author:
A. Emir Gumrukcuoglu, Kazuya Koyama, Shinji Mukohyama
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Votes: 2
9 years ago Author:
Paolo Creminelli, David Pirtskhalava, Luca Santoni, Enrico Trincherini
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9 years ago
Title: "Effects of a toy-model of modified gravity on supernova cosmology results" by Bill
Description: Results from supernova cosmology data rely heavily on the ability of Type Ia supernovae to act as standard candles. How does modified gravity affect this 'standard-ness' and how would it affect the interpretation of the supernova cosmology data?.
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Votes: 2
9 years ago Author:
Louis Perenon, Christian Marinoni, Federico Piazza
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