C-lab Seminar 2024 | Seminar | Nagoya University Cosmology Group (C-lab)

C-lab Seminar 2024

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Coming Seminars

Seminars in May

Speaker
Kiyotomo Ichiki

Date/Place
13:30-, 22(Wed), May @ES606

Title
Constraints on the optical depth of reionization from CMB low- and high-multipoles and Planck likelihoods

Abstract
The optical depth of cosmic reionization, as estimated from the CMB polarization by the WMAP satellite, was initially found to be larger than expected. However, detailed observations by the Planck satellite later revealed that the value was smaller than anticipated. This smaller value is mainly determined by Planck's large-angle E-mode power spectrum. According to a recent paper by William Giarè, Eleonora Di Valentino, and Alessandro Melchiorri (PRD, 2024), we discuss that the optical depth measurement independently of the E-mode can be done, resulting in slightly larger values of tau=0.07. We also discuss that this optical depth is useful in resolving the lensing and curvature anomalies in the CMB that were discussed a few years ago. On the other hand, these anomalies seem to be relaxed in likelihoods published after the Planck2018 results.

Speaker
Kotoyasu Matsumoto and Sachiko Ishida (Student Counseling Center, Nagoya university)

Date/Place
13:30-, 15(Wed), May @ES606

Title
Wellness Program

Abstract
This ‘Wellness Program’ is one of the tutorial courses to support your university life through think over your research environment (in terms of psychoeducation and organizational development). In this time, we mainly focus on ‘communication’ and ‘awareness’. Through this course, we aim to improve these abilities. Good relationships and communications are based on trust and empathy between you and others. Firstly, we do group work and discussion about the experiences related to these topics and then think again about your research environment and daily life. Finally, we discuss and consider how you can spend more fulfilling research life.

Speaker
Shuichiro Yokoyama

Date/Place
13:30-, 8(Wed), May @ES606

Title
Primordial non-Gaussianity in Large-Scale Structure

Abstract
Primordial non-Gaussianity has been extensively discussed as a probe of the physics of the early Universe. Planck CMB observations gave a tight constraint on such a primordial non-Gaussianity, but still we have a chance to test it by making use of ongoing/upcoming large-volume and precise measurements of the large-scale structure. In this seminar, I'd like to give a brief review of the characteristic impacts of primordial non-Gaussianity in large-scale structure, in particular,enhancement/reduction of halo mass function, scale-dependent bias, ... To evaluate these effects quantitatively to some extent, I would like to employ the so-called peak formalism and explain it by using the blackboard in the seminar. Through this seminar, I hope we can start new collaborations across the subgroups.

Speaker
Shohei Saga

Date/Place
13:30-, 1(Wed), May @ES606

Title
Dynamics of cold dark matters around collapse

Abstract
Cold dark matter (CDM) is microscopically modelled as a self-gravitating collisionless fluid obeying the Vlasov-Poisson equations. The cold nature suggests that the CDM phase-space structure is described as a three-dimensional sheet evolving in six-dimensional phase space. At the initial stage, the phase-space sheet represents a single-stream flow, but as a consequence of the non-linear evolution under self-gravity, the phase-space sheet self-interacts, and subsequently the phase-space sheet becomes a multi-stream flow. I will present how the multi-stream appears, and will discuss the importance of considering the effects of multi-stream regions in analysing the dynamics of CDM.

Seminars in April

Speaker
Kaito Yura

Date/Place
13:30-, 24(Wed), Apr. @ES606

Title
Self Introduction

Abstract
Self Introduction

Speaker
Sho Ukai

Date/Place
13:30-, 24(Wed), Apr. @ES606

Title
Self Introduction

Abstract
Self Introduction

Speaker
Shun Yoshioka

Date/Place
13:30-, 24(Wed), Apr. @ES606

Title
Self Introduction

Abstract
Self Introduction

Speaker
Kanta Ito

Date/Place
13:30-, 17(Wed), Apr. @ES606

Title
Self Introduction

Abstract
Self Introduction

Speaker
Kohei Onoda

Date/Place
13:30-, 17(Wed), Apr. @ES606

Title
Self Introduction

Abstract
Self Introduction

Speaker
Suchetha Cooray

Date/Place
13:30-, 10(Wed), Apr. @ES606

Title
Empirical Galaxy Formation Modeling

Abstract
I will introduce a class of models used for modeling the galaxy-halo connection. The motivation is that we need flexible models that can match all the observations self-consistently, which state-of-the-art cosmological hydrodynamical simulations have been unable to achieve. By extending this framework, we can try to extract the maximal information about galaxy formation and cosmology from observed images of telescopes (field-level inference). I will give an overview of the direction the field is heading towards as well as show some of my progress in the modeling side.

Speaker
Kiyotomo Ichiki

Date/Place
13:30-, 10(Wed), Apr. @ES606

Title
Policy speech

Abstract
Policy speech

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