Editing 2019 Fall Seminar List
== Spring 2019 LeCosPA Cosmology and Particle Astrophysics Seminars ==
Location : Room 7S1, LeCosPA center, NTU
if participants more than 20, we will change the lecture room from 7S1 to Room 7W3
Time : 11:00 am  12:00 am, Monday
Organizers : CheYu Chen
Date 
Name 
Title 
Affiliation 
File

Oct./07

Prof. Mariam BouhmadiLópez

Cosmological constraints of phantom dark energy models

On this talk, we will address three genuine phantom dark energy models where each of them induces the particular future events known as Big Rip, Little Rip and Little Sibling of the Big Rip. The background models are fully determined by a given dark energy equation of state. We first observationally constrain the corresponding model parameters that characterise each paradigm using the available data of supernova type Ia, Cosmic Microwave Background and Baryonic Acoustic Oscillations by using a Markov Chain Monte Carlo method. The obtained fits are used to solve numerically the first order cosmological perturbations. We compute the evolution of the density contrast of (dark) matter and DE, from the radiation dominated era till a totally DE dominated universe. Then, the obtained results are compared with respect to ΛCDM. We obtain the predicted current matter power spectrum and the evolution of fσ8 given by the models studied in this work. Finally, the models are tested by computing the reduced χ2 for the `Gold2017' fσ8 dataset. We will as well address some theoretical issues inherent to the phantom dark energy scenario on its largest scope.


University of Basque Country, Spain


ASIAALeCosPA seminar Oct./18 14:2015:20

Kazunori Kohri

AxionLike Particles and Recent Observations of the Cosmic Infrared Background Radiation and the GeVTeV Gammarays

The CIBER collaboration released their first observational data of the
Cosmic IR background (CIB) radiation, which has significant excesses
at around the wavelength ∼ 1 μm compared to theoreticallyinferred
values. The amount of the CIB radiation has a significant influence on
the opaqueness of the Universe for TeV gammarays emitted from distant
sources such as AGNs. With the value of CIB radiation reported by the
CIBER experiment, through the reaction of such TeV gammarays with the
CIB photons, the TeV gammarays should be significantly absorbed
during propagation, which would lead to energy spectra in disagreement
with current observations of TeV gamma ray sources. In this talk, I
discuss a possible resolution of this tension between the TeV
gammaray observations and the CIB data in terms of axion [or
AxionLike Particles (ALPs)] that can increase the transparency of the
Universe by the anomalyinduced photonaxion mixing. We find a region
in the parameter space of the axion mass, m_a ∼ 7.E−10 eV − 5.E−8 eV,
and the axionphoton coupling constant, 1.2E−11 GeV^−1 < g_aγγ <
8.8E−10 GeV^−1 that solves this problem.


KEK/Sokendai/Kavli IPMU

File:KazKohri20191018.pdf

Oct./21

Prof. YuTin Huang

Kerr black holes/ TaubNUT geometry from onshell Smatrix of higher spin particles/dyons

The nohair theorem states that black holes are completely characterized by its mass, charge and spin. The same set of quantum numbers also characterize elementary particles. In this talk, we give the precise statement of this correspondence in terms of onshell observables. In particular, we demonstrate that the classical potential, as well as the scattering angle of rotating blackholes is given by that of minimally coupled higher spin particles. Similarly the solution for TaubNut space time is mapped to dyons. This map also teaches us interesting properties of these classical solutions. In particular, the Kerr and TaubNut solution is simply a complex shift of Schwarzschild black holes.


Phy. Dept. , NTU

File:Yu Tin Huang.pdf

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