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Abstract：We developed a numerical method to compute the gravitational field of an infinitely-thin axisymmetric disc with an arbitrary profile of the surface mass density. We evaluate the gravitational potential by a split quadrature using the double exponential rule and obtain the acceleration vector by numerically differentiating the potential by Ridder's algorithm. The new method is of around 12 digit accuracy and sufficiently fast because requiring only one-dimensional integration. By using the new method, we show the rotation curve of some non-trivial discs: (i) truncated power-law discs, (ii) discs with a non-negligible center hole, (iii) truncated Mestel discs with edge-softening, (iv) double power-law discs, (v) exponentially-damped power-law discs, and (vi) an exponential disc with a sinusoidal modulation of the density profile. Also, we present a couple of model fittings to the observed rotation curve of M33: (i) the standard deconvolution by assuming a spherical distribution of the dark matter and (ii) a direct fit of infinitely-thin disc mass with a double power-law distribution of the surface mass density. Although the number of free parameters is a little larger, the latter model provides a significantly better fit. The determined profile of the surface mass density of the disc is significantly larger than those of the observed stars and gas. This hints a disc-like distribution of the dark matter.
Abstract：Supermassive black holes, weighing between millions to billions times the mass of the Sun, are believed to power quasars and other energetic activity in the centers of galaxies. With the help of advanced telescopes from the ground and in space, operating across the electromagnetic spectrum, astronomers have now discovered that supermassive black holes not only exist, but that they are very common and play a critical role in the formation and evolution of galaxies in the Universe. A class of intermediate-mass black holes has also been found. These "seeds" help us understand the formation and growth of supermassive black holes and the origin of quasars in the early Universe. Mergers of seed black holes will provide an important source of gravitational wave radiation that can be detected with upcoming experiments. I describe these recent discoveries, which are among the most important developments in astronomy and astrophysics during the past 15 years.
東京大学・天文学教育研究センターでは2003年4月から, 院生コロキウムに引き続き, 談話会を開いています. 第一線で活躍されている研究者の方々を講師にお招きし, 最先端の研究成果をお話しいただきます. 講師の方には, 大学院生の参加者のことも考慮し, レビュー的な側面も含めた上で, ご自身の研究紹介をお願いしています.
| 13:30-14:30 | 院生コロキウム | 講義室 |
| 15:30-16:30 | 談話会 | 講義室 |
| 16:30- | お茶の時間 | 講義室横のお茶部屋~講師の方を交えて~ |
| # | Date | Speakers | Title |
| 278 | 2016/1/28 (Thu) 16:00 - 17:00 | Toshio FUKUSHIMA(NAOJ) | Rotation curve of M33 explained by dark matter disc |
| 279 | 2016/2/16 (Tue) 13:05 - 14:05 | Dave Sanders (Institute for Astronomy, Univ. of Hawaii) | The Role of Molecular Gas and Mergers in the Evolution of the Galaxy "Main Sequence" |
| 280 | 2016/2/17 (Wed) 11:00 - 12:00 | Luis Ho (Kavli Institute for Astronomy and Astrophysics, Peking University) | Supermassive Black Holes: Impact on Galaxy Formation and Evolution |
詳細はこちら: 平成27 (2015) 年度談話会
| # | 日付 | 講演者 (所属) | タイトル |
| 262 | 2015/4/09(Thu) | Linda Tacconi (MPE Garching) | The Evolution of Molecular Gas and Star Formation from the Peak Epoch of Galaxy Formation to the Present |
| 263 | 2015/4/16(Thu) | 齋藤正雄 (NRO, NAOJ) | Starformation Project: SOLA |
| 264 | 2015/5/14 (Thu) | 秋山和徳 (水沢VLBI観測所, NAOJ) | EHTによるM87のブラックホールの事象の地平面付近の探査 |
| 265 | 2015/5/21 (Thu) | Toshio FUKUSHIMA (NAOJ) | Precise and fast computation of generalized Fermi-Dirac integral by parameter polynomial approximation |
| 266 | 2015/6/11 (Thu) | 諸隈佳菜 (NAOJ) | 0<z<2における銀河の低温ガス量の進化: ガスを残しつつ星形成を止めるフィードバックの必要性 |
| 267 | 2015/7/2 (Thu) | 江草芙実 (NAOJ/チリ観測所) | Spiral structures of nearby galaxies from CO observations |
| 268 | 2015/7/9 (Thu) | John W Menzies (South African Astronomical Observatory) | The Southern African Large Telescope |
| 269 | 2015/7/23 (Thu) | 市川幸平 (NAOJ) | 赤外線観測によるAGNトーラスの研究 |
| 270 | 2015/9/24 (Thu) | 深川美里 (NAOJ/チリ観測所) | サブミリ波・近赤外撮像で探る惑星形成 |
| 271 | 2015/10/08 (Thu) | 川島朋尚 (NAOJ/CfCA) | 数値シミュレーションで探るブラックホール降着流・噴出流の観測的特徴 |
| 272 | 2015/10/15 (Thu) | 新納悠(国立天文台光赤外研究部) | ガンマ線バーストの起源を探る |
| 273 | 2015/10/29 (Thu) | 浜名崇(国立天文台理論研究部) | 重力レンズ銀河団計測による宇宙論パラメーター推定とHSC surveyによる重力レンズサイエンス |
| 274 | 2015/11/05 (Thu) | 利川潤(国立天文台光赤外研究部) | 広視野観測を用いた原始銀河団探査 |
| 275 | 2015/11/26 (Thu) | 志達めぐみ(理化学研究所) | ブラックホール X 線連星の降着流・噴出流の観測的研究 |
| 276 | 2015/12/17 (Thu) | 野沢貴也(国立天文台理論研究部) | 超新星とダスト |
| 277 | 2016/1/7(Thu) | 大宮正士(国立天文台太陽系外惑星探査プロジェクト室) | 近赤外高分散分光による太陽系外惑星探索 |
