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Colloquium のバックアップ(No.22)


理論コロキウム2017

理論コロキウムは原則として毎週水曜日の午後13:30から開催しています。
原則として英語で講演していただきますが、 講師・参加者が日本人だけの場合は日本語に切り替えてくださって結構です。
台内・台外また分野を問わず広く発表者(台外の方には旅費・謝金あり)を募集しています。
お問い合わせは以下のコロキウム係までお願いします(_AT_を@に変更してください)。

  • 滝脇知也 takiwaki.tomoya_AT_nao.ac.jp
  • 守屋 尭 takashi.moriya_AT_nao.ac.jp
  • Kenneth Wong ken.wong ATM nao.ac.jp
  • 高橋 博之 takahashi ATM cfca.jp
  • 平居 悠 yutaka.hirai ATM nao.ac.jp

Schedule & History

2010年度 2011年度 2012年度 2013年度 2014年度 2015年度 2016年度

DateSpeakerTitlePlace/Timeremarks
4/5all internal membersself-introductionConference room, Cosmos Lodge / 13:30
4/12Shing Chi Leung (Kavli IPMU)Nucleosynthesis of Type Ia supernovaeConference room, Cosmos Lodge / 13:30
4/17Toshihiko Kawano (LANL/Tokyo Tech)beta-delayed neutron emission and fission for r-process nucleosynthesisConference room, Cosmos Lodge / 13:30
4/19Masaki Yamaguchi (U. Tokyo)The number of black hole-star binaries discovered by the astrometric satellite, GaiaConference room, Cosmos Lodge / 13:30
4/26Tomohisa Kawashima (NAOJ DTA)TBAConference room, Cosmos Lodge / 13:30

Confirmed speakers

Abstract

4/12 Shing Chi Leung (Kavli IPMU) Nucleosynthesis of Type Ia supernovae
Type Ia supernovae (SNe Ia) are an important class of astrophysical objects. They are the standard candles of the universe and the major sources of iron-peak elements. It is known to be the explosion of a carbon-oxygen white dwarf by thermonuclear runaways. However, many theoretical uncertainties still persist, for example whether the progenitor of SNe Ia belongs to single degenerate or double degenerate scenario. Furthermore, the diversity in observations, such as the subclasses of Type Iax or super-luminous SNe Ia, suggests that the standard picture using the explosion of a Chandrasekhar mass white dwarf is insufficient to explain the variety of the observed SNe Ia. To resolve these, a systematic understanding in SNe Ia nucleosynthesis becomes necessary. In this present, I shall present hydrodynamics and nucleosynthesis results of multi-dimensional models for the explosion phase of SNe Ia. We explore the effects of model parameters on the explosion energetic and its chemical production. The influences of our SNe Ia models to galactic chemical evolution are discussed. I also present constraints on the progenitor properties of some recently observed SNe Ia and their remnants.
4/17 Toshihiko Kawano (LANL/Tokyo Tech) beta-delayed neutron emission and fission for r-process nucleosynthesis
We give a brief summary of our recent development of nuclear reaction theories with a particular focus on nuclear data production for the r-process nucleosynthesis. The topics include calculations of the beta-delayed process for neutron-rich nuclei, where several neutrons can be emitted, and eventually fission may take place as well. Our recent studies on fission itself are also given.
4/19 Masaki Yamaguchi (U. Tokyo) The number of black hole-star binaries discovered by the astrometric satellite, Gaia
Although it is believed that there are 10^8-9 stellar mass black holes (BH) in Milky Way, until now only ~60 BHs have been discovered. Moreover, masses of only a dozen BHs of them are constrained. By discovering more BHs and estimating their masses, we would obtain the mass distribution of BHs with a higher confidence level. This distribution is expected to constrain a theoretical model of the supernova explosion in which a BH is produced as a remnant. Gaia is now operated and have a capability to detect binaries with an unseen companion, such as a BH or a neutron star. Gaia performs a high-precision astrometry with the optical band (0.3-1.0um), and surveys a whole sky, where main observational targets are stars. If a target star has an unseen companion, it should show an elliptical motion on the celestial sphere. Gaia can confirm the companion by detecting such motion. Moreover, this elliptical motion leads to all orbital elements, which enables us to estimate the mass of companion. If this mass is larger than 3 solar masses, we can confirm the companion as a BH. In my talk, I will show how many BHs can be detected by such method with Gaia. Considering the binary evolution, we obtain the number of detectable BHs, ~600, for main sequence targets. This means that Gaia can discover the order of one thousand BHs whose masses can be found, although we know only a dozen such BHs now. We conclude that the astrometric observation for binaries is very powerful method for finding BHs.