Theoretical Astrophysics Seminars

42nd Seminar

Computing the Universe: from Intergalactic to Interstellar Medium

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Renyue Cen

Princeton University

This talk will highlight some progress made based on our efforts of computing the universe, in order to understand the dynamics of gas in the universe, from intergalactic to interstellar medium. Select observables presented include the cosmic web from redshift zero to z=2-4, and the escape fraction of Lyman continuum...

41st Seminar

Probing dust aggregate structure in protoplanetary disks by millimeter-wave polarization

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Ryo Tazaki

University of Tohoku

Dust coagulation in protoplanetary disks is the first step of planetesimal formation. However, a pathway from dust aggregates to planetesimals remains unclear. Both laboratory and numerical studies have so far shown that the structure of a dust aggregate plays important roles in planetesimal formation. However, the aggregate structure has been...

40th Seminar

Radiation hydrodynamical simulations of first-star binaries including radiative feedback

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Kazuyuki Sugimura

University of Tohoku

The formation of the first stars after the big bang is one of the most important outstanding problems in modern astrophysics. While recent theoretical studies of the formation of individual first stars revealed the importance of radiative feedback and led to estimates first star the masses of first stars, studies...

39th Seminar

Uncovering the formation of extremely distant galaxies with ALMA

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Takuya Hashimoto

Osaka Sangyo University / NAOJ

電波干渉系 ALMA の登場によって、宇宙再電離時代 (宇宙年齢がおそよ2-10億年) にある銀河の研究は新時代を拓いた。サブミリ波帯に赤方偏移した遠赤外の微細構造輝線 ([OIII] 88μm, [CII] 158μm など) を ALMA で観測することで、再電離時代の星形成銀河を分光同定することが可能になったのである (e.g., Inoue et al. 2016, Science)。さらに、このような宇宙初期の時代、既に豊富なダストが存在することも明らかになってきた (e.g., Watson et al. 2015, Nature)。  本発表では、私たちのグループが推進している超遠方銀河の微細構造輝線 (主に [OIII] 88 μm) およびダスト連続光の観測結果を紹介する。まず私たちは、重力レンズ効果によって明るく見えている遠方銀河1天体を観測した。この結果、赤方偏移 z = 9.11 (宇宙年齢 5.5億年) にある [OIII] 88 μm の分光検出に成功した (Hashimoto et al. 2018a, Nature)。これは現在最も遠い輝線天体である。さらに、ハッブル宇宙望遠鏡やスピッツァー宇宙望遠鏡のデータも組み合わせた多波長データ解析から、観測時点よりも過去の星形成の歴史を遡った。この結果、この銀河が星形成を開始したのは z ~ 15 (宇宙年齢2.5億年) の頃だと推定され、宇宙最初期の星形成に知見を得た。次に、z...

38th Seminar

The most rapidly growing black holes: Narrow Line Seyfert 1s across cosmic time

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Chris Done

University of Durham

Narrow Line Seyfert 1s (NLS1) are the lowest mass, highest mass accretion rate Active Galactic Nuclei (AGN) in the local Universe, with black hole masses of 1-10 million x Msun, accreting at the Eddington limit or beyond. These properties are similar to those expected for the majority of the first...

37th Seminar

Fragmentation in self-gravitating accretion disks; Influence of binary systems

Image

Jannes Klee

University of Kiehl

Self-gravitation can play a role in protoplanetary- and AGN-disks. If they are massive enough, gravitoturbulence sets in and acts as a strong driver for angular momentum redistribution. Thereby it moves large amounts of gas from the outer parts of the disk to the central object. However, if the disk cools...

36th Seminar

A New Stellar Population in the Bulge, and a new survey

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R. Michael Rich

University of California, Los Angeles (UCLA)

By mass, the Galactic bulge is actually dominated by a relatively metal rich bar. This population exhibits relatively rapid rotation that reflects a pattern speed independent of Galactic latitude. We have completed a survey of 955 RR Lyrae stars in the bulge region, and find a remarkable population that does...

35th Seminar

What young stars' infrared variability reveals about protoplanetary disks

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Neal Turner

Jet Propulsion Laboratory, Caltech

Young stars' infrared emission shows several puzzling features: variability uncorrelated with visible-light changes, foreground extinction that recurs erratically on weekly timescales, and excesses over the stellar photosphere too large to explain with starlight absorbed and re-emitted by a hydrostatic protostellar disk. I will discuss how each of these features can...

42nd Seminar

Image

Computing the Universe: from Intergalactic to Interstellar Medium

Renyue Cen

Princeton University

This talk will highlight some progress made based on our efforts of computing the universe, in order to understand the dynamics of gas in the universe, from intergalactic to interstellar medium. Select observables presented include the cosmic web from redshift zero to z=2-4, and the escape fraction of Lyman continuum...

June 2019   13 : 30     computational fluid dynamics, galaxy evolution, and cosmological simulations
41st Seminar

Image

Probing dust aggregate structure in protoplanetary disks by millimeter-wave polarization

Ryo Tazaki

University of Tohoku

Dust coagulation in protoplanetary disks is the first step of planetesimal formation. However, a pathway from dust aggregates to planetesimals remains unclear. Both laboratory and numerical studies have so far shown that the structure of a dust aggregate plays important roles in planetesimal formation. However, the aggregate structure has been...

May 2019   13 : 30     dust and protoplanetary discs
40th Seminar

Image

Radiation hydrodynamical simulations of first-star binaries including radiative feedback

Kazuyuki Sugimura

University of Tohoku

The formation of the first stars after the big bang is one of the most important outstanding problems in modern astrophysics. While recent theoretical studies of the formation of individual first stars revealed the importance of radiative feedback and led to estimates first star the masses of first stars, studies...

February 2019   15 : 15     numerical simulations, radiative transfer, and first stars
39th Seminar

Image

Uncovering the formation of extremely distant galaxies with ALMA

Takuya Hashimoto

Osaka Sangyo University / NAOJ

電波干渉系 ALMA の登場によって、宇宙再電離時代 (宇宙年齢がおそよ2-10億年) にある銀河の研究は新時代を拓いた。サブミリ波帯に赤方偏移した遠赤外の微細構造輝線 ([OIII] 88μm, [CII] 158μm など) を ALMA で観測することで、再電離時代の星形成銀河を分光同定することが可能になったのである (e.g., Inoue et al. 2016, Science)。さらに、このような宇宙初期の時代、既に豊富なダストが存在することも明らかになってきた (e.g., Watson et al. 2015, Nature)。  本発表では、私たちのグループが推進している超遠方銀河の微細構造輝線 (主に [OIII] 88 μm) およびダスト連続光の観測結果を紹介する。まず私たちは、重力レンズ効果によって明るく見えている遠方銀河1天体を観測した。この結果、赤方偏移 z = 9.11 (宇宙年齢 5.5億年) にある [OIII] 88 μm の分光検出に成功した (Hashimoto et al. 2018a, Nature)。これは現在最も遠い輝線天体である。さらに、ハッブル宇宙望遠鏡やスピッツァー宇宙望遠鏡のデータも組み合わせた多波長データ解析から、観測時点よりも過去の星形成の歴史を遡った。この結果、この銀河が星形成を開始したのは z ~ 15 (宇宙年齢2.5億年) の頃だと推定され、宇宙最初期の星形成に知見を得た。次に、z...

October 2018   13 : 30     reionization, ALMA, first galaxies, and first stars
38th Seminar

Image

The most rapidly growing black holes: Narrow Line Seyfert 1s across cosmic time

Chris Done

University of Durham

Narrow Line Seyfert 1s (NLS1) are the lowest mass, highest mass accretion rate Active Galactic Nuclei (AGN) in the local Universe, with black hole masses of 1-10 million x Msun, accreting at the Eddington limit or beyond. These properties are similar to those expected for the majority of the first...

September 2018   13 : 30     seyfert galaxies, NLS1, AGN, and black holes
37th Seminar

Image

Fragmentation in self-gravitating accretion disks; Influence of binary systems

Jannes Klee

University of Kiehl

Self-gravitation can play a role in protoplanetary- and AGN-disks. If they are massive enough, gravitoturbulence sets in and acts as a strong driver for angular momentum redistribution. Thereby it moves large amounts of gas from the outer parts of the disk to the central object. However, if the disk cools...

August 2018   13 : 30     accretion discs, computational fluid dynamics, and numerical simulations
36th Seminar

Image

A New Stellar Population in the Bulge, and a new survey

R. Michael Rich

University of California, Los Angeles (UCLA)

By mass, the Galactic bulge is actually dominated by a relatively metal rich bar. This population exhibits relatively rapid rotation that reflects a pattern speed independent of Galactic latitude. We have completed a survey of 955 RR Lyrae stars in the bulge region, and find a remarkable population that does...

March 2016   10 : 30     galaxy formation and observations
35th Seminar

Image

What young stars' infrared variability reveals about protoplanetary disks

Neal Turner

Jet Propulsion Laboratory, Caltech

Young stars' infrared emission shows several puzzling features: variability uncorrelated with visible-light changes, foreground extinction that recurs erratically on weekly timescales, and excesses over the stellar photosphere too large to explain with starlight absorbed and re-emitted by a hydrostatic protostellar disk. I will discuss how each of these features can...

October 2015   15 : 30     protoplanetary discs and MHD

42nd Seminar Computing the Universe: from Intergalactic to Interstellar Medium

Renyue Cen (Princeton University)
June 2019   13 : 30     computational fluid dynamics, galaxy evolution, and cosmological simulations

41st Seminar Probing dust aggregate structure in protoplanetary disks by millimeter-wave polarization

Ryo Tazaki (University of Tohoku)
May 2019   13 : 30     dust and protoplanetary discs

40th Seminar Radiation hydrodynamical simulations of first-star binaries including radiative feedback

Kazuyuki Sugimura (University of Tohoku)
February 2019   15 : 15     numerical simulations, radiative transfer, and first stars

39th Seminar Uncovering the formation of extremely distant galaxies with ALMA

Takuya Hashimoto (Osaka Sangyo University / NAOJ)
October 2018   13 : 30     reionization, ALMA, first galaxies, and first stars

38th Seminar The most rapidly growing black holes: Narrow Line Seyfert 1s across cosmic time

Chris Done (University of Durham)
September 2018   13 : 30     seyfert galaxies, NLS1, AGN, and black holes

37th Seminar Fragmentation in self-gravitating accretion disks; Influence of binary systems

Jannes Klee (University of Kiehl)
August 2018   13 : 30     accretion discs, computational fluid dynamics, and numerical simulations

36th Seminar A New Stellar Population in the Bulge, and a new survey

R. Michael Rich (University of California, Los Angeles (UCLA))
March 2016   10 : 30     galaxy formation and observations

35th Seminar What young stars' infrared variability reveals about protoplanetary disks

Neal Turner (Jet Propulsion Laboratory, Caltech)
October 2015   15 : 30     protoplanetary discs and MHD

34th Seminar Density scratches and formation processes of primordial dark matter haloes via dry mergers

Go Ogiya (LMU/MPI)
October 2015   13 : 30     DM Halo, N-body simulation, and structure formation

33rd Seminar The composition of interstellar molecular gas in galaxies

Nanase Harada (Academia Sinica Institute of Astronomy and Astrophysics (ASIAA))
September 2015   13 : 00     ULIRG, IR, radiative transfer, and protostellar disc

32nd Seminar Radiation transport calculation of the thermal radiation from gamma-ray burst jets

Sanshiro Shibata (Konan University)
March 2015   13 : 30     GRB

31st Seminar (Part 1) Dancing in the dark: galactic properties trace spin swings along the cosmic web

Yohan Dubois (IAP)
October 2014   13 : 30     SMBH and galaxy formation

31st Seminar (Part 2) Exploring the Role of AGN Feedback in Galaxy Formation

Rebekka Bieri (IAP)
October 2014   14 : 30     AGN feedback and galaxy evolution

30th Seminar The Epoch of Reionization: observations and simulations

Benoît Semelin (LERMA, Observatoire de Paris)
September 2014   13 : 30     reionization

29th Seminar A Dynamically Collapsing Cloud Core and a Precursor of a Core in a Filament Supported by Turbulent and Magnetic Pressures

Rei Furuya (Tokushima University)
July 2014   13 : 30     GMC, turbulence, MHD, star formation, molecular cores, and observations

28th Seminar Watching a Little Gas Cloud on its Way into the Galactic Supermassive Black Hole

Andreas Burkert (Ludwig Maximilians Universität München)
February 2014   17 : 00     hydrodynamics, G2, clouds, Galactic center, SMBH, AGN, and accretion discs

27th Seminar (Part 1) Puzzling Features of Quasar Accretion

Charles Steinhardt (Kavli IPMU)
August 2013   15 : 00     quasars, SMBH, and AGN

27th Seminar (Part 3) The Evolution of Star-Forming Galaxies Over Cosmic Time

Josh Speagle (Harvard University, Kavli IPMU)
August 2013   16 : 20     quasars, SMBH, and AGN

27th Seminar (Part 2) How Does Galaxy Environment Influence AGN Activity?

Emil Khabiboulline (Caltech, Kavli IPMU)
August 2013   15 : 40     quasars, SMBH, and AGN

26th Seminar Relativistic Jets and Black Hole Accretion Disks

Geoffrey Bicknell (The Australian National University)
July 2013   14 : 00     AGN, AGN feedback, AGN jets, SMBH, M-sigma relation, MHD, accretion discs, radio galaxies, and Hydra A

25th Seminar 1. The effects of Chern-Simons Gravity and Electromagnetic fields in Blach Hole space-time 2. Space-time rotation induced Landau quantization

Takahashi Rohta (Tomakomai National College of Technology)
March 2012   13 : 30     black holes, general relativity, and radiative transfer

24th Seminar Are Lyman alpha emitters the building blocks of the Milky Way?

Hidenobu Yajima (Pennsylvania State University)
March 2012   13 : 30     LAE, cosmology, radiative transfer, and Milky Way

23rd Seminar The AGN/Starburst connection at z~2 from an IR/submillimeter point of view

Laurie Riguccini (Ehime University)
February 2012   13 : 30     AGN, starbursts, high-z galaxies, galaxy formation, IR, and submm

22nd Seminar The effect of photo-dissociation in the mass accretion phase of PopIII.1 stars

Hajime Susa (Konan University)
December 2011   13 : 30     PopIII stars, accretion discs, radiative feedback, and star formation

21st Seminar The formation of the first stars and galaxies

Thomas Greif (Max Planck Institut für Astrophysik)
September 2011   15 : 00     first stars and first galaxies

20th Seminar (Part 2) Modeling the Electromagnetic Signature of Merging Supermassive Black Holes

Takamitsu Tanaka (Max Planck Institut für Astrophysik)
August 2011   15 : 00     SMBH, SMBH mergers, and accretion discs

20th Seminar (Part 1) A Road to Supermassive Black Hole Merger

Kimitake Hayasaki (Kyoto University)
August 2011   15 : 00     SMBH, SMBH mergers, accretion discs, SPH, and X-rays

19th Seminar Relativistic Jet Feedback in Evolving Galaxies

Alexander Wagner (The Australian National University)
October 2010   15 : 00     AGN jets, AGN feedback, galaxy formation, m-sigma relation, and hydrodynamics

18th Seminar Massive stars in galaxies: their Feedback over their Lives

Gerhardt Hensler (University of Vienna)
September 2010   15 : 00     massive stars and supernovae

17th Seminar The Chemo-dynamical Treatment of Galaxy Evolution

Gerhardt Hensler (University of Vienna)
September 2010   15 : 00     chemodynamics, massive stars, and supernovae

16th Seminar Physics and Fluid-Dynamical Simulations Using GPUs

Muranushi Takayuki (University of Kyoto)
July 2010   15 : 00     GPU and hydrodynamics

15th Seminar Numerical Simulations of High-energy Phenomena in the Universe

Shigehiro Nagataki (Yukawa Institute for Theoretical Physics, Kyoto University)
June 2010   15 : 00     high-energy astrophysics
  1. Computing the Universe: from Intergalactic to Interstellar Medium, Renyue Cen (Princeton University)   June 2019  
  2. Probing dust aggregate structure in protoplanetary disks by millimeter-wave polarization, Ryo Tazaki (University of Tohoku)   May 2019  
  3. Radiation hydrodynamical simulations of first-star binaries including radiative feedback, Kazuyuki Sugimura (University of Tohoku)   February 2019  
  4. Uncovering the formation of extremely distant galaxies with ALMA, Takuya Hashimoto (Osaka Sangyo University / NAOJ)   October 2018  
  5. The most rapidly growing black holes: Narrow Line Seyfert 1s across cosmic time, Chris Done (University of Durham)   September 2018  
  6. Fragmentation in self-gravitating accretion disks; Influence of binary systems, Jannes Klee (University of Kiehl)   August 2018  
  7. A New Stellar Population in the Bulge, and a new survey, R. Michael Rich (University of California, Los Angeles (UCLA))   March 2016  
  8. What young stars' infrared variability reveals about protoplanetary disks, Neal Turner (Jet Propulsion Laboratory, Caltech)   October 2015  
  9. Density scratches and formation processes of primordial dark matter haloes via dry mergers, Go Ogiya (LMU/MPI)   October 2015  
  10. The composition of interstellar molecular gas in galaxies, Nanase Harada (Academia Sinica Institute of Astronomy and Astrophysics (ASIAA))   September 2015  
  11. Radiation transport calculation of the thermal radiation from gamma-ray burst jets, Sanshiro Shibata (Konan University)   March 2015  
  12. The Epoch of Reionization: observations and simulations, Benoît Semelin (LERMA, Observatoire de Paris)   September 2014  
  13. A Dynamically Collapsing Cloud Core and a Precursor of a Core in a Filament Supported by Turbulent and Magnetic Pressures, Rei Furuya (Tokushima University)   July 2014  
  14. Watching a Little Gas Cloud on its Way into the Galactic Supermassive Black Hole, Andreas Burkert (Ludwig Maximilians Universität München)   February 2014  
  15. How Does Galaxy Environment Influence AGN Activity?, Emil Khabiboulline (Caltech, Kavli IPMU)   August 2013  
  16. Relativistic Jets and Black Hole Accretion Disks, Geoffrey Bicknell (The Australian National University)   July 2013  
  17. 1. The effects of Chern-Simons Gravity and Electromagnetic fields in Blach Hole space-time 2. Space-time rotation induced Landau quantization, Takahashi Rohta (Tomakomai National College of Technology)   March 2012  
  18. Are Lyman alpha emitters the building blocks of the Milky Way?, Hidenobu Yajima (Pennsylvania State University)   March 2012  
  19. The AGN/Starburst connection at z~2 from an IR/submillimeter point of view, Laurie Riguccini (Ehime University)   February 2012  
  20. The effect of photo-dissociation in the mass accretion phase of PopIII.1 stars, Hajime Susa (Konan University)   December 2011  
  21. The formation of the first stars and galaxies, Thomas Greif (Max Planck Institut für Astrophysik)   September 2011  
  22. Modeling the Electromagnetic Signature of Merging Supermassive Black Holes, Takamitsu Tanaka (Max Planck Institut für Astrophysik)   August 2011  
  23. Massive stars in galaxies: their Feedback over their Lives, Gerhardt Hensler (University of Vienna)   September 2010  
  24. The Chemo-dynamical Treatment of Galaxy Evolution, Gerhardt Hensler (University of Vienna)   September 2010  
  25. Physics and Fluid-Dynamical Simulations Using GPUs, Muranushi Takayuki (University of Kyoto)   July 2010  
  26. Numerical Simulations of High-energy Phenomena in the Universe, Shigehiro Nagataki (Yukawa Institute for Theoretical Physics, Kyoto University)   June 2010  
  27. Performance of Godunov SPH Schemes, Tsukamoto Yusuke (University of Tokyo)   June 2010  
  28. Late-type stars in the Andromeda galaxy, Andreas Koch (Leicester University, UK)   June 2010  
  29. Black Hole Flywheel Engine Theory and Applications to statistical AGN characteristics, Nitta Shinya (Tsukuba University of Technology)   February 2010  
  30. Magnetic field amplification and turbulence in supernova remnants, Tsuyoshi Inoue (National Astronomical Observatory Japan)   February 2010  
  31. The other dynamical friction: Supression of dynamical friction by the core structure of a halo, Shigeki Inoue (Tohoku University)   November 2009  
  32. Galaxy evolution and cosmic reionization probed through Lyman alpha galaxies, Kazuaki Oota (Riken)   October 2009  
  33. Fast Reionization Simulations for LOFAR, Rajat Mani Thomas (IPMU)   September 2009  
  34. Escape fraction of ionizing photons in high-z galaxies: implications on DLAs and LAEs, Kentaro Nagamine (Unversity of Nevada)   August 2009  
  35. Evolution of SMBH binaries through interaction with stellar systems, Masaki Iwasawa (NAOJ, Theory Group)   June 2009  
  36. Testing the black hole paradigm with future observations of SgrA*, Cosimo Bambi (IPMU)   June 2009  
  37. A New Perspective on the Complex Halo of M31, R. Michael Rich (University of California)   June 2009  
  38. One-dimensional steady-state solution of the black hole accretion disc taking into account the magnetic field, Hiroshi Oda (University of Chiba)   May 2009  
  39. Numerical simulations with GPU, Naohito Nakasato (University of Aizu)   April 2009  
  40. A submm exploration of the protocluster SSA22, Yoichi Tamura (NAOJ Nobeyama)   April 2009