- 追加された行はこの色です。
- 削除された行はこの色です。
#author("2020-10-08T11:59:53+00:00","default:wwwadm","wwwadm")
#contents
** No. 323: April 26 (Thu), 2018, 15:30 - 16:30 [#f0641eb7]
|BGCOLOR(cyan):#|BGCOLOR(cyan): Date|BGCOLOR(cyan):Speaker|BGCOLOR(cyan):Title|BGCOLOR(cyan):Chair|
|345|2019/04/01(Mon) 15:30 - 16:30 | J. Xavier Prochaska (UCO/Lick Observatory) | The Wolfe Disk: ALMA Discoveries of Distant, HI-selected Galaxies | KK |
|346|2019/06/27(Thu) 15:30 - 16:30 | Yuu NIINO (IoA/Univ. of Tokyo) | The origin of short and intense explosions in the universe | KK |
|347|2019/07/02(Tue) 16:00 - 17:00 | Wakiko ISHIBASHI (University of Zurich) | How AGN radiative feedback may shape black hole-galaxy co-evolution | KK |
|348|2019/07/04(Thu) 15:30 - 16:30 | Hidenobu YAJIMA (Univ. of Tsukuba) | Cosmological simulations of galaxy formation at the epoch of reionization | KK |
|349|2019/07/11(Thu) 15:30 - 16:30 | Fumihiko USUI (Kobe University) | 近赤外線分光観測による小惑星の含水鉱物探査 | RO |
|350|2019/08/26(Mon.) 15:30 - 16:30 | Glenn Orton (NASA/JPL) | The Exploration of Jupiter by the Juno Mission | RO |
|351|2019/10/2(Wed) 13:15 - 14:15 | 吉田健二 Kenji Yoshida (芝浦工業大学) | Correlations between Optical/Infrared and Gamma-ray Variability in Bright Well-Monitored Blazars 2008-2017 | YN|
|352|2019/10/24(Thu) 15:30 - 16:30 | 橋本哲也 Tetsuya Hashimoto (台湾国立清華大学) | Recent three discoveries from NTHU cosmology group | YN |
|353|2019/10/28(Mon) 13:00 - 14:-0 | Kevin Fogarty (Caltech) | Cooling and Condensation in Cool-Core Galaxy Clusters: the Case of MACS 1931.8-2635 | KK |
|354|2019/10/31(Thu) 15:30 - 16:30 | 徳田一起 Kazuki Tokuda (Osaka Prefecture University) | ALMAによる大小マゼラン雲とM33の巨大分子雲観測 ALMA observations of GMCs in the Large/Small Magellanic Clouds and M33 | KK |
|355|2019/11/07(Thu) 15:30 - 16:30 | 高倉理 Satoru Takakura (IPMU/U.Tokyo) | A measurement of the degree-scale CMB polarization with POLARBEAR | KK |
|356|2019/11/14(Thu) 14:30 - 15:30 | Ewine van Dishoeck (Leiden Univ.) | Molecules from clouds to disks and planets | KK |
|357|2019/12/05(Thu) 15:30 - 16:30 | 鮫島寛明 Hiroaki Sameshima (IoA/U.Tokyo) | Spectroscopic studies on quasars and stars | YN |
|358|2019/12/12(Thu) 15:30 - 16:30 | 坂野正明 Masaaki Sakano (Wise Babel) | 英語の『数』を考える — 冠詞、単数複数、非可算 | KK |
*** 講師: 福島登志夫（国立天文台） [#xb0c349e]
** No. 345: 1 April, 2019 (Mon.) 15:30 - 16:30 [#xb7a91df]
*** 題目: 自然科学における温故知新のすすめ [#k9157e01]
*** Speaker: Prof. J. Xavier Prochaska (UCO/Lick Observatory) [#m2d19922]
要旨: 「温故知新」は孔子の初学者に対する助言である。新しき学問や研究を
企てる際に重要なこの姿勢は自然科学においても有効な処方箋である
と思われる。にもかかわらず、理系の研究現場において重要視される
ことは少なく、、むしろ「今を温（たず）ねて新しきを知る」ことが尊ばれる。
しかし、現実は、そう単純ではない。「故（ふる）きを温（たず）ねなかった」
ばかりに「世紀の大発見」の登場が１６０年遅れた事例が実際にある。
１９６５年に発表された高速フーリエ変換(Fast Fourier Transform通称
FFT)は２０世紀で最も偉大な工学上の発見とまで称えられたが、実は
１８０５年にガウスが考案していたことが現在では知られている。他にも、
ニュートンのプリンキピアには人工衛星の着想が描かれていたとか、
ラプラスはブラックホールの半径を計算していたとか、この種のエピソード
は枚挙にいとまがない。どうすれば「車輪の再発明」のような愚行を避ける
ことができるのであろうか。それには、故（ふる）きを温（たず）ねて、
温（たず）ねて、温（たず）ね抜くしかない。幸い、Googleに代表される
高速検索技法やProject Gutenbergに代表される無料電子図書館の
発展により、事態は改善されつつある。ただ文献量の一方的な増大に
どのように対処するかは今後の課題であり、このままでは学問の最前線に
たどり着くまでに一生を費やしかねない。我々にはＡＩの進展に望みを
つなぐほか道はないのであろうか。
*** Title: The Wolfe Disk: ALMA Discoveries of Distant, HI-selected Galaxies [#ff566700]
Abstract: I will review our series of successful programs to dissect
the interstellar medium of distant, star-forming galaxies with the
Atacama Large Millimeter Array (ALMA). In particular, I will discuss
surveys of the set of HI-selected galaxies known as the damped
Lya systems (DLAs). We resolve, in part, a decades old struggle to
identify the galactic counterparts of these DLAs and thereby place
them firmly in the modern picture of galaxy formation. I will also highlight
high spectral and spatial resolution observations of the Wolfe Disk,
a z~4 galaxy with a Milky Way-like rotation curve.
** No. 346: 27 June, 2019 (Thu) 15:30 - 16:30 [#xb7a91df]
*** Speaker: Toshio FUKUSHIMA (NAOJ) [#jb196055]
*** Speaker: Dr. Yuu NIINO (IoA/U. Tokyo) [#m2d19922]
*** Title: Study Old and Find New [#bca9fee8]
Abstract: "Study Old and Find New" is a Confucian advice to beginners. Although
it is a general principle, this motto is not so advocated in natural sciences.
Rather, we are told to "Study Now and Find New." However, the reality
is not so simple. Indeed, there exists an educative specimen that a great
discovery was delayed to be popularized because nobody did study old.
The well-known FFT (Fast Fourier Transform) was said to be invented
by Cooley and Tukey in 1965. Nevertheless, Gauss did propose the exact
same method in 1805. An older example is Newton's cannon ball depicted
in Vol. 3 of PRINCIPIA, which is nothing but the artificial satellites. Also,
Laplace estimated an upper bound of Sun's density by using the fact
that its escape velocity is less than the speed of light. This means that
the Sun is never a black hole, which the general theory of relativity was
said to have discovered. Then, how can we avoid such a re-invention
of the existing but not popular idea? The only solution may be to
"Study Old, Study Old, and Study Old". Fortunately, the development
of searching engines as the Google and the spread of free electronic
library systems like the Project Gutenberg seem to have improved
the situation. Having said so, we must admit that remained is a big
issue: exponentially increasing literature. It might mean that the whole
lifetime of a researcher is spent before reaching the cutting-edge.
Is there any other way to resolve this problem than relying on the
advancement of the Artificial Intelligence?
*** Title: The origin of short and intense explosions in the universe [#o3b19aac]
** No. 324: 14 May, 2018 (Mon) 15:30 - 16:30 [#kc329cd6]
Abstract: Short and intense transients like gamma-ray bursts (GRBs), and fast radio bursts (FRBs) provide us with irreplaceable laboratories of physics and unique probes of the evolution of the universe. However, observationally obtaining a direct evidence that clarifies the nature of those transients is often difficult due to their short timescale and large distance toward them. In this talk, I will discuss how the origin of GRBs has been unveiled via observationally available clues, and what can we learn about FRBs from the limited information currently available.
*** Speaker: Susanne Aalto (Chalmers University of Technology) [#mb5213bf]
*** Title: Hidden outflows and obscured nuclei in Luminous Infrared Galaxies - Starbursts or AGNs? [#y17c92bc]
Abstract:
Cold gas plays a central role in feeding and regulating star formation and growth of supermassive black holes (SMBH) in galaxy nuclei. Particularly powerful activity occurs when interactions of gas-rich galaxies funnel large amounts of gas and dust into nuclei of luminous and ultra luminous infrared galaxies (LIRGs/ULIRGs). These dusty objects are of key importance to galaxy mass assembly over cosmic time.
It is also increasingly clear that feedback from star formation and AGNs is fundamental to regulating the evolution of galaxies in the nearby Universe as well as at earlier epochs.
Mechanical feedback occurs in the form of winds (stellar, AGN, galactic), turbulence, supernova bubbles and superbubbles, AGN jets and backflows. With the advent of ALMA and the NOEMA telescopes we can now study the extent, morphology, velocity structure, physical conditions and even chemistry of these cold flows at unprecedented sensitivity and resolution.
I will focus on recent ALMA and NOEMA studies of AGN and starburst outflows from dusty galaxies.
I will for example present recent ALMA studies with resolutions of 20-30 milli arcseconds (2 – 7 pc) of the dusty cores and molecular outflows and jets in the nearby LIRGs NGC1377 and IC860. The relation between collimated molecular flows and nuclear growth will be discussed. Recent developments on the
physical and chemical conditions in outflow will be presented. How can we connect the properties of
the outflowing gas to the nature of the driving source and the origin of the outflowing gas?
I will also show how one can use the JVLA telescope for high-resolution molecular observations of nuclear outflows.
** No. 325: 16 May, 2018 (Wed) 15:30 - 16:30 [#h91bd6d4]
*** Speaker: Shuta J. Tanaka (Aoyama Gakuin University) [#fd7b782d]
*** Title: Blocking Metal Accretion onto Population III Stars by Stellar Wind [#fde909a4]
Abstract: Recent studies of the formation of first stars (PopIII stars) show that low-mass PopIII stars could be formed via the fragmentation of the circumstellar disk around the primary proto-first-stars, although the initial mass function (IMF) of PopIII stars are considered to be top-heavy compared with the IMF of the present stars. Because low-mass PopIII stars of < 0.8 M could survive up until the present, the non-detection of them in our Galaxy has already put a stringent constraint on the IMF of PopIII. On the other hand, some claim that the lack of such stars stems from the metal enrichment of their surfaces by the accretion of heavy elements from the interstellar medium (ISM). In this study, we investigated the effects of the stellar wind on metal accretion onto low-mass PopIII stars because accretion of the local ISM onto the Sun is prevented by the solar wind, even for neutrals. We found that the stellar wind and radiation block the metal accretion if the wind has the similar power to that of the Sun. This demonstrates that low-mass PopIII stars remain pristine and will be found as metal-free stars and that further searches for them are valuable in constraining the IMF of PopIII stars.
Language: English
** No. 326: 24 May, 2018 (Mon) 15:00 - 16:00 [#lc30d2cb]
*** Speaker: Ronin Wu (Paris Observatory Meudon) [#nd99c148]
** No. 347: 2 July, 2019 (Tue) 16:00 - 17:00 [#x16dff39]
*** Title: Physical conditions of the PDR: a case study of the PDRs of Trumpler 14 in the Carina Nebula [#j63f44b3]
*** Speaker: Dr. Wako ISHIBASHI (University of Zurich) [#t7a3021e]
Abstract: We investigate the physical conditions of molecular clouds near the young star cluster, Trumpler 14 of the Carina Nebula. The observations presented in this work are taken with the Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) onboard the Herschel Space Observatory. Our field of view covers the edge of a cavity carved by Trumpler 14 about 1 Myr ago and marks the transition from HII regions to photo-dissociation regions. With the state-of-the-art Meudon PDR code, we successfully derive the physical conditions from the observed CO spectral line energy distributions~(SLEDs) in the observed region.
*** Title: How AGN radiative feedback may shape black hole-galaxy co-evolution [#l7d06ec9]
In this talk, I will discuss (1) the relationship between the derived physical conditions and the environments; (2) the reliability of tracing the physical conditions of PDRs with CII 158, OI 63 and 145 micron lines; (3) the empirical relationship between the thermal pressure (P) and the radiation fields strength (G_UV) and its implication.
Abstract: Active Galactic Nucleus (AGN) feedback is widely invoked in galaxy evolutionary models, while evidence of such AGN feedback in action is now observed in the form of galactic outflows. However, the physical mechanism driving AGN feedback remains ill-understood, and whether galactic outflows are powered by jets, winds, or radiation, is still a source of much debate. We consider AGN feedback driven by radiation pressure on dust. We show that such radiative feedback is capable of accounting for the observed dynamics and energetics of galactic outflows, provided that radiation trapping is properly taken into account.
** No. 327: 31 May, 2018 (Thu) 15:30 - 16:30 [#a95ebe6a]
Feedback from the central black hole is usually invoked to quench star formation in galaxies (the standard negative feedback paradigm). We consider the alternative possibility of triggering star formation in the host galaxy, within the feedback-driven outflows (a form of positive feedback). Such "AGN feedback-driven star formation" may contribute to the size and morphological evolution of galaxies over cosmic time. Recently, there has been growing observational evidence for such star formation occurring inside galactic outflows. I will discuss the multiple roles of AGN feedback in galaxy evolution, and how radiative feedback may ultimately shape the co-evolutionary path.
*** Speaker: 飯野孝浩 (東京農工大学) [#g9d2d2b5]
*** Title: Sub-millimeter/millimeter single-dish and interferometric observation of solar system planetary atmosphere for the new constraint of the origin, chemistry and dynamics [#f0e17ea1]
Abstract: 太陽系内惑星の大気は，組成や温度構造，ダイナミクスにおいて大きなバリエーションを持ち，各天体固有の多様な化学・物理過程を反映している．その観測的解明には，探査機のみならず，地上大型望遠鏡による全球観測が非常に重要であり，探査機との相補性を発揮しながら，欧米を中心に多様な成果が生み出されてきた．ALMA,ASTEといったサブミリ波測器を用いた太陽系惑星大気観測は，惑星大気組成カタログの構築にとどまらず，分子ガスの3次元分布やダイナミクス，連続波すなわち温度分布の直接取得など，惑星大気環境の観測的制約において大きな強みを持つ．中でも，ガス惑星大気成層圏に偏在する揮発性分子の検出や，地球以上に豊潤かつダイナミックな土星衛星Titanの大気組成とその変動，ハビタブル天体である土星衛星Enceladusトーラス組成の直接観測などが近年のトピックである．私はASTEを用いた観測的研究に2010年から取り組み，木星以遠天体の大気組成と時間変動の研究を進めてきた(Iino+ 2014, 2016a, b)．近年は特にALMAデータの解析に注力しており，莫大な量(>100 TB!)の絶対強度較正データを科学研究用に転用し，Titanや海王星の大気組成，時空間変動，温度構造の研究に取り組んでいる(Iino+ 2018b etc)．本発表では，惑星大気観測で得られる物理量から，特に90年代初頭から英仏を中心に展開されてきた観測的研究成果の紹介，そしてASTE, ALMAを用いた我々の観測成果と今後の計画について紹介しつつ，星惑星形成研究やアストロバイオロジーとの接点について議論したい．
** No. 348: 4 July, 2019 (Thu) 15:30 - 16:30 [#xb7a91df]
*** Speaker: Prof. Hidenobu YAJIMA (University of Tsukuba) [#m2d19922]
*** Title: Cosmological simulations of galaxy formation at the epoch of reionization [#j9f68317]
Language: Japanese
Abstract: 近年の観測機器の目覚ましい発展により、数多くの遠方銀河が検出された。それにより、塵に覆われた爆発的星形成銀河（サブミリ波銀河）、ライマンアルファ輝線を強く放射する銀河（ライマンアルファエミッター）、超巨大ブラックホールを持つ銀河など、宇宙年齢わずか１０億年未満に銀河の多様性がすでに生まれている事が明らかとなった。そして、現在すばるHSC銀河サーベイによって、原始銀河団の候補が多数見つかってきている。初代銀河形成からわずか１０億年の間に、このような銀河の多様性を引き起こしたメカニズムは何だったのか？ そして、原始銀河団のような超高密度領域で銀河進化はどのように進んだのか？ これらを明らかにするため、我々は近年大規模な宇宙論的流体シミュレーションを進めている。結果として、初期宇宙の銀河は超新星爆発のフィードバックにより、星形成が間欠的になること、それにともなって輻射特性も大きく変化する事が分かった。フィードバックによるガスアウトフローとともに、紫外線連続波やライマンアルファ光子は効率良く脱出し、銀河はライマンアルファエミッター・ブロッブとなる。また、原始銀河団領域では、サブミリ波銀河がフィラメント構造にそって複数形成されることが分かった。本講演では、これらのシミュレーション結果について紹介するとともに、銀河とブラックホールの共進化についても議論する。
** No. 328: 14 June, 2018 (Thu) 15:30 - 16:30 [#p638efc8]
*** Speaker: 馬場俊介 (宇宙科学研究所) [#b89c173b]
** No. 349: 11 July, 2019 (Thu) 15:30 - 16:30 [#xb7a91df]
*** Speaker: Dr. Fumihiko USUI (Kobe University) [#m2d19922]
*** Title: 近赤外線分光観測による小惑星の含水鉱物探査 [#ff566700]
*** Title: CO近赤外線吸収バンドで探る活動銀河核トーラスの状態と構造 [#w0f91b6b]
Abstract: 太陽系にはさまざまな形態の水が広く存在しているが、特に小惑星には、含水鉱物として水が保持されていると考えられている。この含水鉱物は液体の水と無水鉱物が反応して生成されるが、水氷の昇華温度以上でも比較的安定であるため、水の存在を示す重要なトレーサーである。含水鉱物は近赤外線の波長2.7 µm付近に吸収フィーチャーを持つことが知られているが、この波長域は地球大気の吸収のために、地上望遠鏡では観測できていなかった。我々は赤外線天文衛星「あかり」を用いて、地球大気に影響されることなく小惑星の近赤外線分光観測を行い、小惑星66天体のスペクトルを得ることに成功した。その結果、多くのC型小惑星には含水鉱物に起因する顕著な吸収が見られること、一方ほとんどのS型小惑星にはそのような吸収が見られないことがわかった。本講演では、「あかり」による小惑星の近赤外線分光観測の概要とその結果から考えられる小惑星の形成進化過程について紹介し、さらにTAO/MIMIZUKUを用いた世界初の小惑星母天体の内部構造探査計画について議論する。
Abstract: 活動銀河核（AGN）の多様性を統一的に理解するには、AGN統一モデルの鍵 である核周囲のトーラス状分子雲（AGNトーラス）を観測し、その存在を実証すること、またその形態を調べることが重要である。しかし、考えられているトーラスは数pcスケールと物理的に小さく、直接の空間分解はごくごく近傍の銀河でしか期待できない。そこで我々は、近赤外線領域における一酸化炭素（CO）の振 動回転吸収バンド（4.7 µm）の分光観測に取り組んできた。分子雲が中心核の手前にあれば、中心核周辺からの熱放射を吸収する。吸収線観測のため母銀河から の寄与を受けず、背景光源がコンパクトなため実効的に高い空間分解能で観測できる。この手法はガスの分布を直接調べられないものの系統的な研究を行うことができ、ALMAなどによるCO純回転輝線の直接空間分解観測と相補的である。これまでに天文衛星「あかり」を用いて近赤外線CO吸収バンドを数十の赤外線銀河で観測した結果、トーラスに相当する高温・大柱密度の分子ガスが実際に存在すること、その分布形態が中心核の光度や核周辺での星形成活動に依存することが分かってきた。本講演では、これらの研究成果を報告し、JWST時代における本手法の展望についても紹介したい。
** No. 350: 26 August 2019 (Mon) 15:30 - 16:30 [#xb7a91df]
*** Speaker: Dr. Glenn Orton (Jet Propulsion Laboratory, California Institute of Technology) [#id03825f]
*** Title: The Exploration of Jupiter by the Juno Mission [#h6d4bf63]
Language: Japanese
Abstract: The Juno spacecraft was launched in August of 2011 and was placed into orbit around Jupiter in July of 2016. It is the first solar-powered spacecraft in the outer solar system and the first to be placed into polar orbits. Its primary goals are (1) to determine the O/H ratio from the abundance of water in the atmosphere to discriminate between alternatives for its origin, (2) to understand Jupiter's interior structure and dynamical properties by mapping its gravitational and magnetic fields, (3) to map variations in atmospheric composition, cloud opacity and dynamics to depths of over 100 atmospheres of pressure at all latitudes, and (4) to characterize the 3-dimensional structure of Jupiter's polar magnetosphere and its auroras. Juno is also the first mission to include a public-outreach camera on its instrument payload, which has been providing stunning images of Jupiter at nearly unprecedented spatial resolutions. This talk will survey those results and identify ways in which the general public, as well as space scientists, can become involved in this mission directly.
** No. 329: 21 June, 2018 (Thu) 15:30 - 16:30 [#v7109702]
** No. 351: 2 October 2019 (Wed) 13:15 - 14:15 [#xb7a91df]
*** Speaker: 吉田健二 (芝浦工業大学) [#id03825f]
*** Title: Correlations between Optical/Infrared and Gamma-ray Variability in Bright Well-Monitored Blazars 2008-2017 [#z720d980]
*** Speaker: 林田将明 (甲南大学) [#v25a8448]
Abstract: We present cross correlations of the SMARTS optical/infrared and
Fermi-LAT gamma-ray light curves for 8 bright blazars that have been
monitored with 1 day time bin over the past decade. For the temporal
correlation analysis of unevenly sampled variability data, we use the
Discrete Correlation Function (DCF), creating an empirical bootstrapping
method to assess the significance of the DCF amplitude for each blazar.
Our results are perhaps surprising. Early on in the Fermi mission, the
brightest gamma-ray blazar 3C 454.3 showed zero lag between
optical/infrared and gamma-ray fluxes as reported by Bonning et al.
(2012), which was consistent with the leptonic model that
optical/infrared photons are produced by synchrotron radiation of
relativistic electrons and gamma rays are produced by inverse Compton
scattering of ambient photons by the synchrotron-emitting electrons.
However, among the 8 blazars, only one blazar ― 3C 454.3 ― shows a
significant peak at zero lag, and the other 7 blazars show no
significant peak at zero lag. Some blazars show broad peaks at tens of
days of lags at or just below 3 sigma significance. In addition, for a
given blazar, strong changes of the DCFs from one epoch to the next are
shown by the analyses of time periods of one or two year. These results
make it complicated to understand blazar emission mechanisms. Possible
physical explanations are discussed.
*** Title: 高エネルギーニュートリノ観測とマルチメッセンジャー天文学 [#k1074196]
Abstract: 高エネルギーニュートリノはその優れた透過性から、宇宙空間伝搬中にエネルギー情報を失うことなく遠方天体から直進して地球まで到達できる。特に、天体での発生過程からも、長年の謎である「宇宙線陽子(核子)起源」を突き止められる。南極点氷河に埋設された1立方キロメートルの検出容量を持つニュートリノ観測装置「IceCube」は2012年以降、数十TeV以上の高エネルギー宇宙ニュートリノ候補を100事象近く報告しているが、それら事象の到来方向分布に既知天体との相関は見られず、起源天体は謎のままである。そこで、2016年春に始動した「ニュートリノ速報システム」に対して、光赤外やガンマ線を含む多波長電磁波追観測を実施する体制を整え「マルチメッセンジャー」の視点で起源天体の解明に取り組んでいる。その結果、2017年9月22日に検出された高エネルギーニュートリノ事象「IceCube-170922A」に対して、フェルミ衛星LAT検出器によるGeVガンマ線帯の追跡観測から、ニュートリノ事象到来方向の誤差領域内(約1平方度)にフレアしているブレーザーTXS 0506+056が確認され(ATel#10791)、初の起源天体同定の可能性が盛んに議論されている。
本講演では、高エネルギーニュートリノ観測の現状を紹介するとともに、IceCube-170922Aに対する「マルチメッセンジャー観測」の結果を解説する。
Language: Japanese
** No. 330: 28 June, 2018 (Thu) 15:30 - 16:30 [#nb78895f]
** No. 352: 24 October 2019 (Thu) 15:30 - 16:30 [#je71137c]
*** Speaker: Tetsuya Hashimoto (National Tsing Hua University) [#p446196c]
*** Title: Recent three discoveries from NTHU cosmology group [#gd344d07]
*** Speaker: Eduardo Ibar (Universidad de Valparaiso) [#if3b7b62]
Abstract: I will present my recent papers on (i) the luminosity-duration
relation of fast radio bursts (FRBs), (ii) ALMA observations of
Gamma-Ray Burst (GRB) host galaxies, and (iii) a blue cluster
in the local Universe. Brief summaries of each paper are as follows.
*** Title: The VALES survey: a new look to the molecular gas content in low-redshift galaxies [#m60d8a38]
(i) Luminosity-duration relation of fast radio bursts
We discovered an empirical correlation between luminosity and duration
of FRBs. We propose a new distance measure using the relation of FRBs,
which can reach more distant Universe than type Ia supernovae in quantity.
This method can potentially reveal the time variability of the dark energy,
which is one of the central foci of observational cosmology.
Abstract: In this talk, I will present a new extragalactic survey that characterise dusty galaxies at low redshifts: the Valparaíso ALMA Line Emission Survey (VALES). I will introduce the use of ALMA Band-3 CO(1-0) and APEX SEPIA Band-5 CO(2-1) observations to study the molecular gas content in a sample of ~100 main-sequence (and starburst) star forming galaxies up to z=0.35. The galaxies are far-IR bright [L_IR/Lo = 10^(10-12)Lo] emitters selected from the H-ATLAS survey over ∼160 deg^2 and present a rich wavelength coverage. We have spectroscopically detected (>5sigma in a previous Herschel campaign) 27 galaxies in [CII] and ~60 galaxies in CO, facilitating a characterisation of the ISM state in some of these galaxies via PDR modelling. One third of the ALMA targets are spatially resolved in CO, facilitating an exploration of the global Schmidt-Kennicutt law, and a kinematic interpretation for the star-formation activity. A non negligible fraction of galaxies is found to be molecular gas-rich (f_gas>30%), fractions which are similar to those found in normal high-redshift star-forming galaxies. I will show the future prospects of this campaign by introducing the follow-up campaigns we are leading from Valparaíso.
(ii) SFRs of two GRB host galaxies at z~2 and a [CII] deficit observed with
ALMA
We discovered a new parameter to characterize GRB host galaxies, [CII]
deficit, by overcoming a serious dust-extinction problem of GRB host
galaxies. Possible parameters controlling the deficit include the metallicity,
initial mass function, and gas density.
Language: English
(iii) A young galaxy cluster in the old Universe
We discovered a 'blue cluster', that is a local galaxy cluster with an
unprecedentedly high fraction of blue star-forming galaxies yet hosted
by a massive dark matter halo. The blue cluster challenges the current
standard understanding of galaxy formation under the Lambda CDM
Universe.
** No. 332: 19 July, 2018 (Thu) 15:30 - 16:30 [#p5c43ab0]
*** Speaker: 星野洋輔（Georgia Institute of Technology） [#t552ee61]
*** Title: 宇宙の中の生命 [#lfae78fa]
Abstract: 生命がどのようにして生まれたのか？生命は我々以外にも存在するのか？という問いは今も科学における最大の未解決問題の一つである。地球上の生命はこの宇宙の中で現在知られている唯一の生命現象の例である。この地球上の生命の多様性、進化の流れが宇宙という大きな文脈の中でどのように位置付けられるのか見ていきたい。
Language: Japanese
*** Speaker: Tyler Pritchard (New York University) [#g1c96d3e]
*** Title: Wider, Faster - A Simultaneous Multi-wavelength Survey for Fast Transients [#y930d9a7]
Abstract: The combination of modern advancements in electronics and
ever-increasing telescope apertures have resulted in the dawn of a new
era. One where once rarely detected astrophysical transients are
becoming increasingly commonplace and previous purely theoretical
objects are now on the cusp of (potential) detection. In this talk I
will discuss the burgeoning list of theoretical and observed fast
transients and the “Deeper, Wider, Faster” survey; a simultaneous
multi-wavelength high cadence survey featuring simultaneous radio to
gamma-ray observations that has been designed to probe new parameter
spaces and observe them.
Language: English
** No. 334: 13 September, 2018 (Mon) 15:30 - 16:30 [#k31fb066]
** No. 353: 28 October 2019 (Mon) 13:00 - 14:00 [#xb7a91df]
*** Speaker: Kevin Fogarty (Caltech) [#j23dfdbb]
*** Title: Cooling and Condensation in Cool-Core Galaxy Clusters: the Case of MACS 1931.8-2635 [#ob2bc123]
*** Speaker: Prof. Jari Kotilainen (Turku observatory) [#i13f0589]
Abstract: Cool-core clusters of galaxies were originally predicted to form massive (~10^2 - 10^3 Msun/yr) cooling flows as the intracluster medium (ICM) radiatively dissipates thermal energy and descends the gravitational potential well of the cluster. However, mechanical mode feedback from the active galactic nuclei (AGN) of the brightest cluster galaxies (BCGs) in cool-core clusters has sufficient energy to offset cooling in the core, and suppresses cooling flows. Residual ICM condensation gives rise to spectacular starbursts in the normally "red-and-dead" BCG and cold molecular gas reservoirs that can be several 10^10 Msun, and observations of condensed material provides important clues for how feedback moderates cooling in galaxy clusters. In this talk, I will focus on our observations of star formation and condensed material in the CLASH (Cluster Lensing And Supernova survey with Hubble) sample of galaxy clusters, with particular focus on our recent study of dust and molecular gas in the BCG of MACS 1931.8-2635 conducted with ALMA. MACS 1931 hosts one of the most extreme BCG starbursts known in a cool-core cluster, with a star formation rate of ~250 Msun/yr, and multiphase gas filaments extending ~30 kpc from the center of the BCG. Our observations in MACS 1931 reveal a massive (~2 x 10^10 Msun) molecular gas reservoir that is highly excited (R_31 = 0.93 +/- 0.16), suggesting that gas excitation is being partially driven by non-photodissociation region- related processes, while continuum observations of dust allow us to constrain the temperature of several dust clumps to <10 K, which is too cold to be directly interacting with the surrounding ~4.8 keV intracluster medium (ICM). Excitingly, our findings imply a scenario where BCG dust, which is not predicted to survive on longer than Myr timescales in hot ICM environments, can be shielded from ICM sputtering. I conclude by discussing how observations like our observation of MACS 1931 constrain the formation and evolution of dust and gas in the extreme feedback-regulated environments of cool-core clusters.
*** Title: Powerful relativistic jets from disk galaxies [#k7fa0f5a]
Abstract: The launch of powerful relativistic jets has been exclusively associated with giant elliptical galaxies. However, the recent detection of gamma−ray emission from Narrow-Line Seyfert 1 (NLSy1) galaxies raises doubts on this jet paradigm. We use deep NOT and ESO VLT near-IR imaging to characterize the morphology of 26 radio–loud (R-L) NLSy1s, including nine gamma−ray emitting NLSy1s (gamma−NLSy1s) to elucidate the conditions for AGN to produce radio jets. We resolved 20/26 host galaxies (6/9 of the gamma−NLSy1s). Consistent with radio-quiet NLSy1s and contrary to the jet paradigm, the host galaxies of R-L NLSy1s are disky systems with pseudobulges. In half of the host galaxies, we detect long and weak bars, which may promote inflow of gas to trigger nuclear activity. Majority of the galaxies show signs of mergers or interactions, consistent with models of bar formation and AGN activity. The bulge near-IR colours of gamma−NLSy1s are much redder than the rest of the R-L NLSy1s, suggesting recent star formation activity. The nuclear and bulge luminosities of R-L NLSy1s are correlated, indicating positive feedback by the powerful radio jets on the host galaxies.
Language: English
** No. 335: 11 October, 2018 (Mon) 15:30 - 16:30 [#md96d697]
** No. 354: 31 October 2019 (Thu) 15:30 - 16:30 [#ja6cd708]
*** 講師: 徳田一起（大阪府立大学） [#aae24360]
*** 題目: ALMAによる大小マゼラン雲とM33の巨大分子雲観測 [#lf3f0b7f]
*** Speaker: Tetsuya Hashimoto (National Tsing Hua University) 橋本哲也(国立清華大学) [#kdafe115]
要旨：
星間空間に多大な影響を及ぼし銀河進化を規定する大質量星の形成条件を探るためにはその主たる前駆体である巨大分子雲の理解が重要となる。これまでは分子雲を空間分解した観測は単一電波望遠鏡による銀河系内の分子雲のみに限定されてきたが、ALMAの登場により星形成の直接母体となる分子雲コア/クランプ(数pc~0.1pc)を空間分解可能な観測は系外銀河(大小マゼラン雲やM33)の分子雲に拡大されつつある。これらの観測は、視線方向上の重なりを考慮する必要がほとんどないことに加えて、金属量による違いや銀河スケールの構造/現象による星形成への影響を調べる上でも重要であり、宇宙進化史における星形成の一般的な理解に向けてさらなる飛躍をもたらすと期待される。
*** Title: A new parameter in the fundamental metallicity relation of star-forming galaxies [#w35680fd]
本講演では主に、ALMAによる0.”2(～0.07 pc)の高分解能観測によって得られた大マゼラン雲N159領域の結果について紹介する。EとW領域にて、~0.1 pc 幅のフィラメント状分子雲と大質量原始星からのアウトフロー、わし座で見られる”創造の柱”構造などを系外銀河の分子雲で初めて同定した。この2つの領域は互いに 50 pc以上離れているにも関わらず、非常に似た性質/進化段階を示すことから、銀河規模の大局的なガスフローが同時多発的なフィラメント状分子雲/大質量星形成に重要な役割を果たしたと考えられる。
Abstract: Star-forming galaxies display a close relation among stellar mass, metallicity, and star formation rate (or molecular-gas mass). This is known as the fundamental metallicity relation (FMR) (or molecular-gas FMR), and it has a profound implication on models of galaxy evolution. However, there still remains a significant residual scatter around the FMR. We show here that a fourth parameter, the surface density of stellar mass, reduces the dispersion around the molecular-gas FMR. In a principal component analysis of 29 physical parameters of 41,338 star-forming galaxies, the surface density of stellar mass is found to be the fourth most important parameter. The new 4D fundamental relation forms a tighter hypersurface that reduces the metallicity dispersion to 50 per cent of that of the molecular-gas FMR. We suggest that future analyses and models of galaxy evolution should consider the FMR in a 4D space that includes surface density. The dilution time-scale of gas inflow and the star-formation efficiency could explain the observational dependence on surface density of stellar mass.
この他マゼラン雲やM33に対するALMAを用いた観測の進行状況を簡単に紹介し、今後の展望について議論する。
** No. 336: 8 November, 2018 (Mon) 15:30 - 16:30 [#v8000119]
*** 講師: 岡本丈典 (国立天文台) [#ofd8fa73]
*** 題目: 太陽観測史上最強の黒点磁場 [#g163bc16]
要旨:
黒点は太陽を代表する構造の 1つであり、その正体は強い磁場の集合体である。
一般的に黒点磁場は 3,000 ガウスと言われているが、
それでは一番強い磁場はどれくらいの強度を持つのだろうか。
これに答えるべく、太陽観測衛星「ひので」が 10年に渡って撮りためたデータを
全て調べてみたところ、太陽観測史上最大となる 6,250 ガウスの磁場を発見した。
典型的な強度の 2倍というのも驚きであるが、
さらに興味深いのは黒点内における最強磁場の存在場所である。
黒点の磁場は通常最も暗い部分（暗部の中心）が一番強いのだが、この黒点は
そのルールに反し、暗くない部分（暗部以外）に存在するという特異な性質を示している。
なぜ暗部以上に強い磁場が暗部以外に作られるのか。
これは過去にも類似の報告例があるが、その成因については長年謎であった。
そこで、「ひので」の安定した長時間観測の利点を活かし、
今回発見された超強磁場を持つ黒点の数日間に渡る観測データを解析した結果、
最強磁場の地点に向かって、太陽面上にガスの強い流れが存在することを明らかにした。
これは、地球のプレート境界で地震を引き起こす歪が溜まるのと同様に、
磁極の異なる2つの暗部が近接しているとき、片方の暗部から延びるガスの流れが
他方の暗部を強く圧迫し、その衝突点で磁場が強められると我々は考えている。
他の黒点においても同様の傾向が見られ、我々は暗部より強い磁場領域形成の
メカニズムに初めて一貫した説明を与えるに至った。
** No. 337: 19 November, 2018 (Mon) 15:00 - 16:00 [#ke9b5a31]
*** different from the regular IoA seminar, so please make sure the date and starting time [#x4e74ef4]
** Talk1 [#r7a4396b]
*** Speaker: Veronique Buat (Laboratoire d'Astrophysique de Marseille) [#g25923e6]
*** Title: The HELP Project, massive SED fitting and dust obscuration in galaxies [#gb125baa]
Abstract:
I will present the European/ FP7 HELP project aimed at delivering homogeneous panchromatic data on cosmological Herschel fields. After a description of the deliverables I will illustrate the massive SED fitting performed on each field by the case of the ELAIS N1 field. The last part of my talk will be devoted to the analyses we performed with these data to characterize dust attenuation, and the impact of its variation on stellar masses determination.
** Talk2 [#ia8bc6aa]
*** Speaker: Denis Burgarella (Laboratoire d'Astrophysique de Marseille) [#mf46a1fe]
*** Title: Hi-z SMGs, Hi-z LBGs and low-zZ galaxies (TBC) [#fa9aea83]
Abstract: (TBA)
** No. 338: 29 Nov, 2018 (Thu) 15:30 - 16:30 [#i11511b1]
*** Speaker: 金子紘之 (国立天文台野辺山宇宙電波観測所) [#g11b228c]
*** Title: What makes a variety of galaxies? -a view from environmental effects- [#j0f96715]
Abstract: 銀河の多様性が如何にして獲得されたのかという疑問は、銀河進化と結びつく大きな問題の一つである。
銀河進化は星形成を、星形成は分子ガスを介して行われることから、
銀河の分子ガスの性質を知ることがその解明に本質的であると言える。
近年の受信機の性能向上により、ケーススタディー的に過ぎなかった分子ガス撮像観測が多数の銀河に対しても行えるようになってきた。
我々は野辺山45m電波望遠鏡を用いた複数CO輝線撮像観測サーベイであるCOMINGを実施し、140以上の銀河のCO撮像に成功した。
本発表では、こうした状況を概観しつつ、COMINGデータを用いた環境効果、
特に銀河のおよそ半数が属する銀河群における分子ガスの性質について議論したい。
Language: Japanese
** No. 355: 7 November 2019 (Thu) 15:30 - 16:30 [#je71137c]
*** Speaker: Dr. Satoru Takakura (IPMU/U.Tokyo) [#e84a2194]
*** Title: A measurement of the degree-scale CMB polarization with POLARBEAR [#v4a81a80]
** No. 339: 06 Dec, 2018 (Thu) 15:30 - 16:30 [#wee83da0]
*** Speaker: 坂野正明 (Wise Babel Ltd.) [#o427a28c]
*** Title: 「理にそった英作文、英語発表」—— 筋立ての表現、主語、否定、冠詞 [#ceb145b6]
Abstract: 科学の世界の「作文」あるいは口頭発表において最も重要なのは、主張が明快で誤解なく伝わり、論理の筋が一貫していることなのは言を待ちません。日本語でもさることながら、英作文や英語発表の場合、それが決定的に重要なポイントになります。言うは易し行うは難し、本セミナーでは、論文の実例も採り上げながら、筆者(話者)の頭の中の筋を読者(聞き手)に伝わるように再構成して英文を紡ぐためのポイントを解説します。関連して、主語、否定文、冠詞について、特に日本語話者が陥りやすい誤りや誤読される文例を見ていきます。加えて、それらが、口頭発表(あるいは会話)の際にどのように応用でき、どこに特に注意すべきかを例示します。伝えたいことが伝わり、読者や聴衆をより惹きつけるものを提供できるようになる一助になることが、本セミナーの目標です。
Abstract: Polarization anisotropies on the cosmic microwave background (CMB) is an interesting target for cosmology. Especially, the parity-odd component, the so-called B-mode, in degree scale is a unique probe of primordial gravitational waves from the cosmic inflation. The POLARBEAR experiment is a ground-based CMB polarization measurement at the Atacama Desert in Chile with 1,274 transition-edge-sensor (TES) bolometers sensitive to the 150 GHz band on a 2.5 m aperture off-axis Gregorian type telescope. Since 2014, POLARBEAR has started observations of a 670 square degree patch of the sky using a continuously rotating half-wave plate, which is located at the prime focus to suppress the detector noise below ~0.1 Hz by modulating polarization signal. In this talk, I present the characterization of the instruments including studies about detector nonlinearities and atmospheric clouds. Then, I report the result of the B-mode angular power spectrum measurement.
Language: Japanese
** No. 340: 15 Jan., 2019 (Tue.) 15:30 - 16:30 [#s6b65ab9]
** No. 356: 14 November 2019 (Thu) 14:30 - 15:30 [#t237a3d8]
*** Speaker: Prof. Ewine F. van Dishoeck (Leiden Observatory, Leiden University) [#u65882a9]
*** Title: Molecules from clouds to disks and planets [#s1b242d1]
*** Speaker: David Elbaz (CEA-Saclay) [#d1e5af74]
Abstract: The discovery of thousands of planets around stars other than our Sun
has revived age-old questions on how these exo-planets form and which
chemical ingredients are available to build them. Star formation and
chemistry start in the cold and tenuous clouds between the stars. New
facilities such as ALMA allow us to zoom in on dense cloud cores and
planetary system construction sites with unprecedented sharpness and
sensitivity. Spectral scans of young disks contain tens of thousands
of rotational lines, revealing water and a surprisingly rich variety
of organic materials, including simple sugars and high abundances of
deuterated species. Yet more mature protoplanetary disks show very
few lines. How are these molecules formed and what chemical and
physical processes play a role? How common are they? And how do they
compare with the inventory in comets such as come 67P/C-G?
*** Title: An ALMA view on the formation of massive galaxies and galaxy clusters [#s00395c8]
** No. 357: 5 December 2019 (Thu) 15:30 - 16:30 [#je71137c]
*** Speaker: Dr. Hiroaki Sameshima (IoA/U.Tokyo) [#e84a2194]
*** Title: Spectroscopic studies on quasars and stars [#n1cdb512]
Abstract:
Our understanding of galaxy formation is largely based on the use of the Lyman discontinuity in the ultraviolet spectrum of galaxies. Discovering "Lyman break galaxies" revolutionized our vision of the distant Universe, providing a "complete" picture of the cosmic history of star formation and offering the best candidates for reionizing the Universe.
However, there are signs that pieces of the puzzle may be missing. The progenitors of massive ellipticals with compact stellar cores found at z~2 remain elusive; quasars and other distant monsters seem to hide most of their activity by dust attenuation; the density of cosmic star formation deduced from distant gamma-ray bursts suggests that much of the history of galaxy growth is still elusive.
Is a major episode of our series on the history of the universe missing?
I will present recent results obtained largely with the Atacama Large Millimeter Array, ALMA, that change our understanding of the history of galaxy formation and evolution, including the discovery of HST-dark galaxies, invisible to even the deepest images of the Hubble Space Telescope. Using ALMA to dissect galaxies, I will show a clear dichotomy between transparent UV regions and opaque regions in distant galaxies. Finally, I will use distant dusty galaxies as probes to search for distant galaxy clusters in formation.
** No. 341: 24 Jan., 2019 (Thu.) 15:30 - 16:30 [#p5cbc88b]
*** Speaker: 小麦真也(工学院大学) [#ga11a24b]
*** Title: On the relation between ISM and star formation at molecular cloud scales [#td94ea49]
Abstract:
Star formation is a local process occurring at the scale of less than
100 parsecs over several 10 Myrs, while collectively, it can drive
galaxy evolution at much larger scales. Various relations exist between
quantities of the ISM, but we do not know which are the fundamental ones
that drive galaxy evolution. Using a sample of GMCs in the nearby
spiral galaxy M33 and NGC300 and utilizing the principle component
analysis, we have identified two parameters which best express the
properties of GMCs; one can be interpreted as "ISM content", and the
other as "star formation activity". GMCs at different evolutionary
stages have distinct values of ISM content and SF activity, with
implications on how the GMCs and the surrounding environment evolve over
several 10 Myrs. The analyses also reveal that at the scale of GMCs,
dust mass correlates with star formation better than CO, and that an
extended form of the Kennicutt-Schmidt relation holds regardless of GMC
age.
I will talk about two topics related to spectroscopic studies of quasars and stars in the optical and near-infrared regions:
(1) Quasar elemental abundances are expected to provide unique probes of high-redshift star formation and galaxy formation. Using the archival optical spectra of SDSS quasars at 0.7 < z < 1.6, we measured Fe II and Mg II emission-line strengths and estimated [Mg/Fe] abundance ratios from them in combination with photoionization simulations. The derived abundance ratios are consistent with chemical evolution models, which validates our abundance estimate. However, because chemical evolution models are degenerated at 0.7 < z < 1.6 regardless of the star formation history, we could not put any strong constraints on it. Future observations with the forthcoming TAO instruments (NICE, SWIMS) would shed light on the evolution of [Mg/Fe] abundance ratio at 3 < z < 7.
(2) WINERED is a near-infrared high-resolution echelle spectrograph that simultaneously covers the wavelength range of 0.91-1.35 micron with a resolving power of ~28000 (WIDE mode). As a member of the WINERED team, I have tackled correction of an observed spectrum for telluric absorption, which is an unavoidable problem for ground-based telescopes. We succeeded to correct telluric absorption with high accuracy by using the spectrum of a telluric standard star whose stellar features were carefully removed. By applying this method to a spectrum of the A-type star 21 Lyn obtained with WINERED, we identified 219 atomic lines. Intriguingly, a curve of growth created from the measured C I lines showed large scattering that cannot be explained by measurement errors. This result, combined with other near-infrared spectroscopic studies, implies that not a few of oscillator strengths of near-infrared lines need calibrations based on astronomical observation.
** No. 342: 31 Jan., 2019 (Thu.) 15:30 - 16:30 [#k3203b31]
Language: slides in English, talk in Japanese
*** Speaker: 竹腰達哉(東京大学天文学教育研究センター) [#fe9fb230]
*** Title: Dust-selected molecular clouds in the Small Molecular Cloud [#x3c8d0e3]
** No. 358: 12 December 2019 (Thu) 15:30 - 16:30 [#je71137c]
*** 講師: 坂野正明 (ワイズバベル) [#r29897e5]
*** 題目: 「英語の『数』を考える —— 冠詞、単数複数、非可算」 [#p0a05ad3]
Abstract:
小マゼラン雲は距離60 kpc にある極近傍の矮小銀河であり、低金属量環境下での星形成や銀河形成過程を明らかにするうえで重要な天体である。星形成の母体となる分子雲観測は、NANTEN やMopra 望遠鏡によるCO分子輝線のサーベイ観測が行われているが、非常にコンパクトなCO 分布を示すなど、我々の銀河系とは異なった分子雲の描像を示している。我々は、低金属量環境の観測に最適な新たな分子雲同定手法として、ダスト連続波を用いた分子雲同定手法を提案し、直径10mのサブミリ波望遠鏡ASTE を用いた1.1mm 帯全面サーベイとハーシェル宇宙望遠鏡のデータを組み合わせることで、銀河系内の分子雲と同程度のガス質量、サイズ、密度を持つ天体を同定することに成功した。これらの天体にはCO ではこれまで発見されていない星形成活動を示さない天体も含まれており、星形成を伴うものより有意に質量やサイズが小さかった。またALMA/ACAによるCO観測で得られた結果についても紹介する。
要旨:
** No. 343: 13 Feb., 2019 (Wed.) 15:30 - 16:30 [#u7f57fe1]
科学論文の英文校閲の現場で遭遇する多種多様な問題の中で、修正する箇所として最も多いのは、ほぼ例外なく冠詞と可算非可算、単数複数の用法です。筆者が相当の英語上級者であっても、いやむしろあればこそ、割合的にその点が頻出修正事項になります。不幸なことに、冠詞と名詞の単複ほど本質的に校閲が難しい点はありません。なぜならば、基本的な誤りでない限り、文法的にはどちらでも正当であることが普通だからです。
*** Speaker: S. R. Kulkarni (Zwicky Transient Facility, Caltech) [#b3ccb1a8]
しかし、いかに文法的に正しくても、冠詞と単複を誤ると、文意が筆者の意図と大きく異なってしまうことがままあります。正確さと精密さとが命の科学論文においては、書く場合はもちろん読む場合でさえ、これは致命的になりかねません。そんな時、文法的には正しい以上、読者が読み取る判断の拠り所は、文章の背景知識に基づいた「常識」だけになります。ところが、例えば「太陽は1個」が世の常識であっても、天文屋の常識は異なることもありましょう。あるいは自ら開発した装置の「常識」を読者に要求するのは無理難題というものです。究極的には、筆者の意図に沿った「正しい」冠詞や単複は、筆者にしか説明できないものなのです。
*** Title: The Restless Universe (How the Periodic Table Got Built up) [#za9d449d]
本講演では、自身かつては天文学研究者であり、近年は一流の天体物理論文の校閲を数多く請負った講演者により、日本人科学者による誤用の実例も使いながら、英語の冠詞と数詞のテーマに構造的に切り込みます。日本語ネイティブならではの視点から、実用的な対策も提案します。
Abstract: The Universe began only with hydrogen and helium. It is cosmic
explosions which build up the periodic table! Astronomers have now
identified several classes of cosmic explosions of which supernovae
constitute the largest group. The Palomar Transient Factory was
an innovative 2-telescope experiment, and its successor, the Zwicky
Transient Factory (ZTF), is a high tech project with gigantic CCD
cameras and sophisticated software system, and squarely aimed to
systematically find "blips and booms in the middle of the night".
The speaker will talk about the great returns and surprises from
this project: super-luminous supernovae, new classes of transients,
new light on progenitors of supernovae, detection of gamma-ray
bursts by purely optical techniques and troves of pulsating stars
and binary stars. ZTF is poised to become the stepping stone for
the Large Synoptic Survey Telescope.
--
Masa Sakano, PhD
Wise Babel Ltd
URI: http://www.wisebabel.com/
Twitter/Facebook: @WiseBabel
http://www.astro.caltech.edu/~srk/PalomarObs.jpg
An areal view of the Palomar Observatory (California). The discovery
engine is the 48-inch telescope (extreme left) and the photometric
classification is done at the 60-inch telescope (extreme right).
Spectral classification is undertaken at the 200-inch telescope
(center). The very first synoptic survey undertaken with a wide
field Schmidt telescope was F. Zwicky's 18-inch and is the small
dome to the right of the 200-inch.
** No. 344: 14 Feb. 2019 (Thu.) 15:30 - 16:30 [#k329e7a0]
*** Speaker: 百瀬莉恵子（東京大学） [#x9b64e42]
*** Title: Evolution of galaxies traced by Lyman-alpha halos [#o0b6fc1c]
要旨：銀河の基本的な活動は、ガスから星を形成し星質量を獲得していくことである。
銀河におけるガスは銀河間空間から銀河とその周辺環境の境であるハローを介し
銀河本体（銀河円盤）に供給される。ガスの供給によって銀河円盤では活発な
星形成活動が行われ、その後、形成された星からのアウトフローにより銀河円盤
からハローへガスが流出される。このように銀河円盤での星形成はハローを介した
ガス供給・流出によって促進・抑制される。銀河円盤でのガス収支の痕跡は
ハローを構成する淡いガス（銀河周辺物質 CGM）の観測から探ることができる。
CGM の形状や密度等の物理状態はガス収支を反映するため、その形状・性質の
理解は銀河の星形成史やそれに伴う銀河進化の解明への一助となる。近年、この
CGM のトレーサーとして水素の再結合線である Lyα 輝線が注目されている。Lyα
輝線によって観測される CGM は Lyα halo と呼ばれており、その性質は、
Lyα 輝線銀河（LAE）やクェーサー（QSO）という銀河種族において特に調べられている。
本セミナーでは、LAE、QSO の Lyα halo に関して、これまでの研究をレビューする。
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