4月25日（月）13：30～15：00 太陽系小天体セミナー 南棟２階会議室
Apr 25 mon Solar System Minor Body Seminar Conference Room, South Bldg.2F
4月25日（月）13：30～14:30 臨時理論コロキウム 中央棟（北）1F講義室
Apr 25 mon DTA special colloquium Lecture Room, Central Building (North)
4月27日（水）10:30～12:00 総研大コロキウム 中央棟（北）1F講義室
Apr 27 wed SOKENDAI colloquium Lecture Room
4月27日（水）13:30～14:30 理論コロキウム コスモス会館会議室
Apr 27 wed DTA colloquium Conference Room, Cosmos Lodge
詳細は以下をご覧下さい。
4月25日（月）
- キャンパス
- 三鷹
- セミナー名
- 太陽系小天体セミナー
- 定例・臨時の別
- 定例
- 日時
- 4月25日（月曜日）13時30分～15時00分
- 場所
- 南棟２階会議室
- 講演者
- 大坪貴文
- 連絡先
- 名前：渡部潤一
- 備考
- テレビ会議またはスカイプによる参加も可
4月25日（月）
- Campus
- Mitaka
- Seminar
- DTA special colloquium （臨時理論コロキウム）
- Regularly Scheduled/Sporadic
- Sporadic
- Date and time
- 25 April 2016, 13:30-14:30
- Place
- Lecture Room, Central Building (North)
- Speaker
- Kohei Inayoshi
- Affiliation
- Columbia University
- Title
- Hyper-Eddington accretion flows onto massive black holes
- Abstract
- How fast can black holes (BHs) grow? The existence of bright quasars at high-redshift provides a challenging puzzle about the origin of supermassive BHs. To form such massive objects within a billion year, rapid growth of seed BHs is required. We study very-high rate, spherically symmetric accretion flows onto massive BHs embedded in dense metal-poor clouds. We find solutions from outside the Bondi radius at hyper-Eddington rates, unimpeded by radiation feedback. Accretion rates in this regime are steady, and larger than 5000 L_Edd/c^2. At lower rates, the accretion is episodic due to radiative feedback and the average rate is below the Eddington rate. The hyper-Eddington accretion solution is maintained as long as the emergent luminosity is limited to < (10-30) L_Edd because of photon trapping due to electron scattering. We apply our result to the rapid formation of massive BHs in protogalaxies. Once a seed BH forms at the center of the galaxy, it can grow to a maximum ~ 10^5 Msun via gas accretion independent of the initial BH mass.
- Facilitator
- -Name：Tomoya Takiwaki
- Comment
- in English
4月27日（水）
- Campus
- Mitaka
Seminar Name : SOKENDAI colloquium
Regular / Irregular : Regular
Date：10:30-12:00,April 27,2016 - Place
- Lecture Room
Speaker 1：Kyoko Onishi
- Affiliation
- D3, SOKENDAI, Mitaka（supervisor : Satoru Iguchi）
- Title
- Molecular gas kinematics in the centres of galaxies
Speaker 2 : Koki Okutomi - Affiliation
- SOKENDAI, Mitaka（supervisor : ）
- Title
- TBD Organizer
Name : Kotomi Taniguchi
TV conference system is available connecting from Nobeyama, Hawaii,
Mizusawa, and Okayama.
4月27日（水）
- Campus
- Mitaka
- Seminar
- DTA colloquium
- Regularly Scheduled/Sporadic
- Regularly Scheduled Date and time：27 April 2016, 13:30-14:30
- Place
- Conference Room, Cosmos Lodge
- Speaker
- Tetsuo Taki
- Affiliation
- NAOJ CfCA
- Title
- Toward formation of rocky planetesimals: dust and gas density evolution at a local structure of protoplanetary disks
- Abstract
- The radial drift barrier is one of the most serious problem in the planetesimal formation process. We focus on a local disk structure called “radial pressure bump (Whipple, 1972; Haghighipour & Boss, 2003a, b)”. When a protoplanetary disk has the radial pressure bump, dust particles are trapped at a point where gas pressure is radially maximized. We investigate simultaneous evolution of dust and gas density profiles at a radial pressure bump. We find that the bump structure is flattened by a drag force from dust onto gas when the dust-to-gas mass ratio reaches ~1. Although the pressure bump is a favorable place for streaming instability (SI; Youdin & Goodman, 2005), the flattened bump structure inhibits SI from forming large particle clumps corresponding to 100-1000 km sized bodies, which has been previously proposed. If SI occurs there, the dust clumps formed would be 10-100 times smaller, that is, of about 1 – 100 km.
- Facilitator
- -Name：Tomoya Takiwaki
- Comment
- in English=
以上