カテゴリー別アーカイブ: 研究紹介

On-sky Closed-loop Atmospheric Dispersion Compensation: Demonstration of Sub-milliarcsecond Residual Dispersion Across H-band. / Chemical Abundances of Extremely Metal-Poor Turn-Off Star

[Speaker1]
Pathak Prashant, SOKENDAI D3 (Supervisor; Prof. Hideki Takami)
[Title]
On-sky Closed-loop Atmospheric Dispersion Compensation: Demonstration of Sub-milliarcsecond Residual Dispersion Across H-band.

[Speaker2]
Tadafumi Matsuno, SOKENDAI D1 (Supervisor; Wako Aoki)
[Title]
Chemical Abundances of Extremely Metal-Poor Turn-Off Star
[Abstract]
I will start my talk with introduction to the
Galactic Archaeology and metal-poor stars. In the latter part, we
present our latest results of abundance analysis for extremely
metal-poor turn-off stars. The discussion includes i) lithium
abundance below [Fe/H]=-3.5, ii) chemical inhomogeneity in the early
Universe in comparison to supernova yield with special focus on
[Na/Fe] bimodality, and iii) binary mass transfer of materials
enriched with slow neutron capture process elements enhancement and
thermohaline mixing.

Dense molecular outflows from the merging LIRG NGC3256 / Lyman-alpha emission as a tool to probe galaxy formation

[Speaker1]
Tomonari Michiyama, SOKENDAI D2 (Supervisor; Daisuke Iono)
[Title]
Dense molecular outflows from the merging LIRG NGC3256
[Abstract]
We report the new ALMA Cycle 3 results of line survey towards a late stage merging galaxy NGC 3256. NGC 3256 hosts two merging nuclei and the starburst and AGN activities are strongly affecting the chemical and physical properties of the ISM. We have detected more than 20 molecules (e.g., c-C3H2, H13CN, H13CO+, SiO, CCH, HCN, HCO+, HNC, CH3OH, CS, HC3N, CH3CCH, C18O, 13CO) at 2” angular resolution, which is high enough to resolve the double nuclei. In this presentation, we focus on CO, HCN and HCO+ to discuss the high velocity components detected only by those bright molecular lines. Such high velocity components are though to be molecular gas outflow from northern and southern nuclei. Including the CO(1-0) and CO(3-2) archived data, the line ratios suggest that (1) The excitation condition become weak towards edge of the outflow in the starburst triggered outflow. (2) In the case of low luminous AGN like southern nucleus in NGC 3256, the outflowing gas is associated with AGN jet, and warm and dense gas can be newly formed due to interaction between jet and ISM interaction.
(3) The HCN is enhanced due to shock especially in red-shifted outflow. In addition, we conducted radiative transfer modeling. By using a Bayesian likelihood analysis, we found that the CO column density and filling factor of outflowing gas is smaller than the gas around nuclei.

[Speaker2]
Satoshi Kikuta, SOKENDAI D1 (Supervisor; Masatoshi Imanishi)
[Title]
Lyman-alpha emission as a tool to probe galaxy formation
[Abstract]
Lyman-alpha emission line is the strongest line from astrophysical sources and can be used to probe galaxy formation especially at high-redshift (z>2) Universe. In this talk, I will review the basic physics about Lyman-alpha line and recent works on galaxy formation which used the line. Finally I will also talk about my research plan using the Lyman-alpha line from the gas in young galaxies around bright QSOs at z~3 to study the importance of gas in galaxy formation.

The Galaxy-Halo Connection Across Cosmic History / Radiation-MHD Simulation of Clumpy Outflow from Supercritical Accretion Flow / S-Cam and HSC Search of z>6 Quasars

[Speaker1]
Shogo Ishikawa, D3, SOKENDAI (Supervisor; Nobunari Kashikawa)
[Title]
The Galaxy-Halo Connection Across Cosmic History

[Speaker2]
Hiroshi Kobayashi, D3, SOKENDAI (Supervisor: Ken Ohsuga)
[Title]
Radiation-MHD Simulation of Clumpy Outflow from Supercritical Accretion Flow

[Speaker3]
Masafusa Onoue, D2, SOKENDAI (Supervisor; Nobunari Kashikawa)
[Title]
S-Cam and HSC Search of z>6 Quasars
[Abstract]
I will present several updates on our high-redshift (z>6) quasar search projects using Subaru/S-Cam and HSC.
In short, our constraints on the quasar luminosity function at z~6 suggest that quasars have only a moderate contribution on the total photons required to re-ionize the universe at z~6.
From the HSC-Wide survey, we have found ~30 low-luminosity quasars
at z>6 in ~100 deg^2 of the HSC-SSP coverage. Their NIR follow-up observation is
now ongoing with Gemini and VLT, which is for the BH mass and metallicity measurements.
Moreover, the HSC-Deep survey enables us to find much fainter quasar candidates down to z~25 AB mag.