October 1 Tue 10:30-11:30
太陽系小天体セミナー (Solar System Minor Body Seminar)
Zoom
October 2 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom
October 4 Fri 15:30-16:30
NAOJ Seminar
hybrid; Large Seminar Room in Subaru Building and Zoom
詳細は下記からご覧ください。
=============== October 1 Tue===============
キャンパス：三鷹
セミナー名：太陽系小天体セミナー (Solar System Minor Body Seminar)
定例・臨時の別：定例
日時： 10月 1日（火曜日）10時30分～11時30分 (いつもより30分遅れての開始となります)
場所：zoom
講演者：舘山平蔵、渡部翔也、空間翔太朗（産業医科大学医学部3年次）
タイトル: 中赤外からアプローチする彗星 Abstract: 彗星の結晶質・非結晶質シリケートの割合から原始太陽系円盤での 彗星の形成場所を探る。今回は、すばる望遠鏡のCOMICSを用いて、 4P/Faye、144P/Kushida、C/2013 US10、C/2014 S2の４彗星について 中赤外線の撮像及び分光観測データの解析を行った。C/2013 US10を 除く3つの彗星ではシリケート・フィーチャがみられた。本講演では そのフィーチャより算出した結晶質シリケートの比率を過去に研究 された他の彗星も含めて比較・検討する。
世話人の連絡先
-名前：渡部潤一
備考：zoomでの参加
===============October 2 Wed==============
Seminar: NAOJ Science Colloquium
Date and time: 2024 Oct. 02 (Wed.), 15:30-16:30 JST
Place: the large seminar room / Zoom (hybrid)
Speaker: TRAN Thi-Thai
Affiliation: Division of Science, NAOJ
Title: The contribution of the faint Lyman alpha galaxies to cosmic reionization as seen by MUSE/VLT
Abstract:
At the end of the Dark Ages, when the first structures of the Universe were formed,
radiation from these structures ionized the neutral hydrogen atom surrounding
its environment. This crucial phase is known as cosmic re-ionization. It is the last phase
transition undergone by the Universe, finishing around z~6. Today, various hypotheses
exist concerning the main contributors to this process, such as Active Galactic Nuclei (AGN),
star-forming galaxies, etc. I assess the contribution of the star-forming galaxies to cosmic
reionization by studying the evolution of the luminosity function with redshift, estimating
their star formation rate density as well as the escape fraction of Lyman alpha photon
at different redshift ranges through the use of VLT/MUSE as well as gravitational lensing.
For this purpose, the work assembles the largest sample of lensed Lyman-alpha emitters: faint
galaxies identified by the Lyman-α emission line (LAEs) to date (at redshifts between 2.9 and 6.7).
The best-fit results of the Schechter function at different redshift ranges allow us to determine
the luminosity density and convert it to the star formation rate density. These results, compared
with those of the critical value for the star formation density, suggest that galaxies selected by their
Lyα emission could be responsible for reionization assuming a Lyα photon escape fraction of 8%,
with a typical clumping factor of ∼ 3. On the other hand, when assessing the escape fraction of Lyman
alpha photons from star-forming galaxies we found that the LAE population could have provided
all the photons necessary for reionisation at z=6 using well-motivated assumptions about the ionising
photon efficiency and the escape of ionising photons from these galaxies.
Facilitator
-Name: Nanase Harada
Comment: English
===============October 4 Fri==============
Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：October 4, 2024 15:30-16:30
Place：Zoom/Large Seminar Room (hybrid)
Speaker：Prof. Agnieszka Janiuk
Affiliation：Physics Institute of PAN, Warsaw
Title：Accretion and outflows in the Gamma Ray Bursts central engines
Abstract:Gamma Ray Bursts (GRBs) are powered by transient jets launched by a central engine.
The plausible model of such engine is based on a black hole surrounded by the magnetized accretion disk.
This model explains various phenomenology of GRBs, such as its energetics, durations, and jet structure.
In addition, the neutrino-cooled winds from the central engine are found to be sites of r-process nucleosynthesis.
In this talk, I will present results of numerical simulations performed by our group at Center for Theoretical Physics in Warsaw. Our models address formation of the GRB engine through the compact binary mergers, as well as collapsar scenarios. I will dicuss the broad band emissions of GRBs jets and disk outflows. The prospects for multimessenger astrophysical phenomena will also be briefly presented.
Facilitator
-Name：Tai Oshima