Home > ALMA Jセミナー | 太陽系小天体セミナー | 科学研究部コロキウム | 総研大コロキウム > 2022.7.4-2022.7.10


July 5 Tue 10:00~11:30 太陽系小天体セミナー Solar System Minor Body Seminar zoom

July 6 Wed 10:30~12:00  SOKENDAI Colloquium            zoom

July 6 Wed 14:30~15:30  ALMA-J seminar               zoom

July 6 Wed 15:30~17:00  NAOJ Science Colloquium          zoom






Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:July 6th, 2022 10:30-12:00

Speaker 1: Suzuka Nakano
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Kouichiro Nakanishi, Takashi Sekii, Masayuki Tanaka)
Title: Mm/submm Energy Diagnostics & Non-LTE Modeling of the AGN-Starburst Composite Galaxy NGC 7469 with ALMA

Speaker 2: Shun Hatano
Affiliation: SOKENDAI 1st year (M1) (Supervisor: Masami Ouchi, Yusei Koyama, Takashi Moriya)
Title: Unknown Ionization Source in Extremely Metal Poor Galaxies

-Name:Matsuda, Graduate Student Affairs Unit


Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and Time: 2022 July 6 14:30-15:30
Place: Zoom
Speaker: Tom Bakx
Affiliation: Nagoya University/NAOJ
Title: More for less: Boosting two key high-redshift science drivers through efficient observation set-ups with ALMA
Abstract: ALMA has fundamentally improved the quality and resolution of studies of galaxies in the early Universe. Crucially, it offers spectroscopic capabilities, revealing the properties of the gas inside and surrounding galaxies from low to very dense environments. In this talk, I expand on two techniques that take the efficiency of ALMA (and other interferometer) to its extreme; 1. ensuring robust spectroscopic redshifts with minimum observation time and 2. providing hyper-efficient snapshot observations of spectral lines. Even Cycle 0 demonstrated ALMA’s power as a redshift hunter, exploiting a full coverage of band 3 to detect at least a single CO line of high-redshift galaxies, however often one has to rely on photometric redshifts as a guide. Using public code, I provide a method to determine the quality of redshift identifications and use this to optimize future observations to robustly identify redshifts through multiple lines. This simple method enables twice as efficient observations as previous band 3 redshift studies. Meanwhile, follow-up of galaxies with robust redshifts have revealed the internal gas properties of galaxies across cosmic time. However, often such observations require re-tuning, leading to overheads that fundamentally limit ALMA’s spectroscopic capabilities to several tens of sources per project. Instead, I explore a method to use fixed spectral windows that include as many lines as possible. We successfully target 85 lines within just 6 hours of observation time; a five-time improvement compared to existing line surveys. This method can be extended to improve the science output of any future continuum snapshots of sources with known redshifts that could, for free, pick up additional lines.
Daisuke Iono, Andrea Silva


Seminar:NAOJ Science Colloquium
Regularly Scheduled/Sporadic:Every Wednesday
Date and time:2022 July 6, 15:30-17:00
Speaker:Raiga Kashiwagi
Affiliation:NAOJ (D2)
Title:Numerical study on star formation process induced by collisions between filamentary molecular clouds
Abstract:Recent observations have revealed that filamentary molecular clouds are closely related to star formation. In particular, where the filaments appear to overlap, active star formation has been observed. One possible interpretation is that the filaments collide with each other and then star formation is triggered. Therefore, we focus on collisions between filamentary molecular clouds and investigate these evolutionary processes by using 2D hydrodynamical simulations. We assumed a head-on collision of isothermal filaments in hydrostatic equilibrium. One of the main results is that the critical line mass, which governs the radial gravitational instability of the filament, also governs the radial gravitational instability of the shocked region, which is formed by the collision. In other words, if the total line mass of the initial filaments exceeds the critical line mass, we can expect that filament-filament collisions trigger a radial gravitational collapse of the shocked region. On the other hand, when the total line mass is less than the critical line mass, the equilibrium filament will be formed in the shocked region. In this presentation, I will report not only the results of the hydrodynamic calculation but also the magnetohydrodynamic calculation and discuss the properties of the magnetic field in filament-filament collisions.

Speaker:Yuta Tashima
Affiliation:NAOJ (D2)

-Name:Akimasa Kataoka

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