Le contenu de cette page n’est pas disponible en français. Veuillez nous en excuser.

Cosmology & Gravitation

This series consists of talks in the areas of Cosmology, Gravitation and Particle Physics.

Seminar Series Events/Videos

TBA
mai 31 2016 - 11:00am
Room #: 400
Speaker(s):
Scientific Areas:
Speaker(s):
Scientific Areas:

 

Jeudi mai 12, 2016
Speaker(s): 

Spectral distortions of the CMB provide a powerful new probe of early Universe processes. Even if so far no average spectral distortion has been seen, LCDM does predict several signals that are within reach of current technology. In this talk, I will give a broad brush overview of our most recent understanding of the formation and evolution of distortions in the early Universe, highlighting guaranteed LCDM signals and what we hope to learn from them about the Universe we live in.

Collection/Series: 
Scientific Areas: 

 

Mardi mai 10, 2016
Speaker(s): 

Gravitational lensing by matter clumps can magnify various transient bursts in the sky, making them more detectable from the high redshift Universe. For one example, chirping gravitational waves from stellar-mass black hole binary mergers, as first detected by LIGO recently, can appear louder due to intervening galaxies. In the absence of electromagnetic counterpart, as I will discuss, lensing magnification can bias the determination of binary mass and redshift, which needs to be corrected for when testing source evolution and formation models through event statistics.

Collection/Series: 
Scientific Areas: 

 

Lundi mai 09, 2016
Speaker(s): 

In the last few years, we have made remarkable progress in understanding the properties of our observable Universe which appears to have evolved from a hot Big Bang 13.7 billion years ago. The fine-tuning of initial conditions required to reproduce our present day Universe suggests that our Universe may merely be a region within an eternally inflating super-region. Many other regions could exist beyond our observable Universe with each such region governed by a different set of physical parameters than the ones we have measured for our Universe.

Collection/Series: 
Scientific Areas: 

 

Mardi avr 26, 2016
Speaker(s): 

Planck's full-mission data, released in 2015, provides a high-resolution whole-sky polarization and temperature maps of the CMB and astrophysical components. I will talk about implications of Planck 2015 results for inflation, why cosmic dust is important, and what we are currently doing to study it. I will also highlight some tests of the statistical isotropy and Gaussianity of the cosmic microwave background (CMB) anisotropies we have done with observations made by the Planck satellite.

Collection/Series: 
Scientific Areas: 

 

Mardi avr 05, 2016
Speaker(s): 
Collection/Series: 
Scientific Areas: 

 

Mardi mar 29, 2016
Speaker(s): 
Since the Universe was filled with hydrogen atoms at early times, the

most promising method for observing the epoch of the first stars is to

measure the hyperfine line of hydrogen at a wavelength of 21 cm. Such

an observation of the "cosmic dawn" era was considered speculative

when I helped lay out the theoretical predictions a decade ago, but

there is now an enormous, promising observational effort (in which I

am involved within the Square Kilometre Array). There is also an

Collection/Series: 
Scientific Areas: 

 

Mardi mar 22, 2016
Speaker(s): 

I will discuss the cosmology of galileon models with a Minkowski limit and discuss whether they can account for the currently observed cosmological model. The full galileon model predicts the speed of gravitational waves to be different from that of photons. I will discuss this and compare with observations. I will then discuss a subdominant galileon model which is compatible. Finally I will discuss the shape dependence of screening in galileon models, showing that the fifth force is unscreened for planar objects.

Collection/Series: 
Scientific Areas: 

 

Mardi mar 15, 2016
Speaker(s): 

I will discuss phenomena associated with particle production and field excitation during inflation. In the first part of the talk I will present several

signatures that can originate from the coupling of an axion inflaton to gauge fields. In the second part I will test the robustness of the standard

implications associated with the detection of a gravity wave (GW) signal at CMB scales, by discussing what conditions can allow a visible

Collection/Series: 
Scientific Areas: 

 

Mardi mar 08, 2016
Speaker(s): 

Alternative theories of gravity are popular alternatives to the LCDM model because they can self-accelerate without a cosmological constant. On smaller scales, consistency with solar system tests of gravity is achieved by utilising screening mechanisms, which act to hide fifth-forces locally. This makes them difficult to distinguish from general relativity. In this talk I will describe recent work using astrophysical objects---stars, galaxies, and clusters---as new and novel probes of alternative gravity theories.

Collection/Series: 
Scientific Areas: 

 

Mardi fév 16, 2016

The kinetic Sunyaev-Zel'dovich effect is a direct probe of the distribution and velocity of electrons on cosmological scales. Recent progress in Cosmic Microwave Background observations allow statistical detections of this subtle effect originating from a number of different tracers populations. In my talk, I will review the observational status, highlight the consequences for astrophysics and cosmology and discuss future directions.

Collection/Series: 
Scientific Areas: 

Pages