Jan. 23 Mon 14:00-16:00 SOKENDAI Doctoral Thesis Defense Zoom
Jan. 23 Mon 15:00-17:00 Solar and Space Plasma Seminar Zoom/Insei Seminar Room(hybrid)
Jan. 24 Tue 10:00-11:30 太陽系小天体セミナー Zoom
Jan. 25 Wed 10:00-12:00 SOKENDAI Colloquium Zoom
Jan. 25 Wed 14:30-15:30 ALMA-J seminar Zoom
Jan. 25 Wed 15:30-17:00 NAOJ Science Colloquium Zoom
Jan. 27 Fri 13:30-15:00 Solar and Space Plasma Seminar Zoom/Insei Seminar Room(hybrid)
詳細は下記からご覧ください。
=============== Jan 23 Mon ===============
Campus：Mitaka
Seminar：SOKENDAI Doctoral Thesis Defense
総研大博士学位論文審査会
Regularly Scheduled/Sporadic: Sporadic
Date：January 23(Mon)
Time：14:00-14:40 Presentation
14:40-15:00 Q&A
15:00-16:00 Judging (Not open to public)
Place：Zoom
Speaker：Hideaki Takemura
Title：Study of Dense Core Property and Core Mass Function with Simulation and Observation Data to Reveal and Observation Data to Reveal the Core Growth with Observations
Examiner：Hideko Nomura, Doris Arzoumanian, Tomoko Takahashi, Toshikazu Ohnishi（Osaka Metropolitan University), Koji Sugitani（Nagoya City University)
Facilitator:
-Name：Hideyuki Kobayashi, Yumiko Omura (Graduate Student Affairs Unit)
=============== Jan 23 Mon ===============
Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：23th Jan (Mon), 15:00-17:00
Place： hybrid, Subaru Building / Insei Seminar Room or Zoom
Speaker：Shun Ishigami
Affiliation：SOKENDAI
Title：Study of Heating Distributions along Coronal Loops Using Emission Line Spectroscopy and Bayesian Analysis
Abstract：It is not fully understood that what heats the corona to hotter than 10^6 K. It is thought that main building blocks of corona are coronal loops which are bright semicircular structures observed by using extreme ultraviolet (EUV) or X-ray. The purpose of this presentation is to study the heating mechanism of coronal loops. To study the heating mechanism, we use the relation among the heating flux F_H, the magnetic field strength at the base of the loop B_base and the half-length of loop L_half: F_H ∝ B_base^β L_half^λ. Since β and λ are different for each theoretical heating mechanism, the heating mechanism can be investigated by these exponents. F_H can be determined by the spatial heating distribution along the loop. In this study, we assume the heating distribution along the loop position s is E(s) = E_0 exp(−s/s_H) and estimate the heating scale height s_H and the base heating rate E_0 by the observed temperature/density distributions. EUV spectroscopic data is analyzed to measure the temperature/density distributions of 8 active region loops by using the intensity ratio of emission lines. As a result, it is found that obtained heating scale height, s_H = 3–21 Mm, seems to be similar or shorter than the value suggested by previous work, even if we consider the inaccuracy of the starting position of the loop. In addition, by using the relation: F_H ∝ B_base^β L_half^λ, we obtained β = 0.8±0.3, λ = −0.9±0.3. Our result appears to be plausible for the reconnection heating model (β = 1, λ = −1: Parker 1983). However, it is not appropriate to reject other theoretical heating models as impossible, because the obtained β and λ have large error.
Facilitator
-Name：Takayoshi oba
Comment：in Japanese
=============== Jan 24 Tue ===============
キャンパス：三鷹
セミナー名：太陽系小天体セミナー
定例・臨時の別：定例
日時：1月24日（火曜日）10時00分～11時30分
場所：zoom
講演者：大坪貴文
世話人の連絡先
名前：渡部潤一
備考：テレビ会議またはスカイプによる参加も可
=============== Jan 25 Wed ===============
Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：January 25, 2023 10:00-12:00
Place：Zoom
Speaker : Yuta Tashima
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Mami Machida, Fumitaka Nakamura, Tomoya Takiwaki)
Title: Elucidation of galactic magnetic field structure by pseudo-observation using N-body simulation
Speaker: Hideaki Takemura
Affiliation: SOKENDAI 5th year (D3) (Supervisor: Fumitaka Nakamura, Tomoya Hirota, Akimasa Kataoka)
Title: Revealing the core growth with numerical simulation data and observation data in Orion A
Speaker: Umi Kobayashi
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Masayuki Tanaka, Koichiro Nakanishi, Masatoshi Imanishi)
Title: TBA
Facilitator
-Name：Matsuda, Graduate Student Affairs Unit
=============== Jan 25 Wed ===============
Campus：Mitaka
Seminar：ALMA-J seminar
Regularly Scheduled/Sporadic： Every Wednesday
Date and time：25th January (Wed), 14:30 – 15:30
Place：Zoom
Speaker: Takuma Izumi
Affiliation: NAOJ
Title: Resolving supermassive black hole feeding and feedback down to sub-parsec scales
Abstract:
Mass accretion is a fundamental process for the growth of supermassive black holes and activating the central engines. However, detailed accretion properties have not been observationally identified at the central ~10 parsec of active galaxies due to the compactness. Here we report the first robust identification of a sub/parsec-scale (i.e., 0.01% scale of the host galaxy) dense molecular inflow toward the active nucleus of the Circinus galaxy. Only a tiny portion (< 3%) of this inflow is consumed in the actual black hole growth but a bulk portion is blown-out by multiphase outflows. The observed dense gas disk is gravitationally unstable and drives accretion down to the central ~1 parsec. However, a complete solution to the long-standing fuel supply problem requires a further understanding of the mechanism in the inner sub-parsec region.
Facilitator: Shun Ishii , Jorge Zavala
=============== Jan 25 Wed ===============
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2023 January 25, 15:30-17:00
Place：zoom
Speaker：Tomomi Sunayama
Affiliation：Nagoya Univ.
Title：Towards an accurate cluster cosmology with photometric galaxy surveys
Abstract：Galaxy clusters are the most massive gravitationally self-bound objects in the Universe. These clusters form at the rare high peaks of the primordial density fluctuations, and they subsequently trace the growth of structure in the Universe as they grow in mass and abundance. As such, clusters constitute a natural cosmological probe for constraining the properties of the primordial fluctuations as well as cosmological parameters including the nature of dark energy. Clusters are, however, also known to be susceptible to many systematics such as selection biases and projection effects.We develop a new analysis pipeline which is full forward modeling of cluster observables (abundance, clustering, and lensing signals) with an empirical model for the projection effects (i.e., interloper galaxies along the line-of-sight are misidentified as genuine members of the cluster). The projection effects alter the mass-observable relation as well as boost the amplitude of clustering and lensing signals due to the anisotropic distribution of optical clusters. We validate our model on simulations and then apply it to the SDSS redMaPPer cluster catalog whose result favors low Omega-m and high sigma8. We discuss possible implications using Subaru HSC lensing measurements.
Facilitator
-Name：Akimasa Kataoka
Comment：in English
=============== Jan 27 Fri ===============
Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：27th Jan (Fri), 13:30-15:00
Place： hybrid, Subaru Building / Insei Seminar Room or Zoom
Speaker：Kakeru Fukumitsu
Affiliation：University of Tokyo
Title：Image Restoration Based on Deep Learning for High-Resolution Solar Images
Abstract：The Earth’s turbulent atmosphere is an obstacle to obtain high-resolution solar images with a ground based telescope. One possible solution to remove seeing is Adaptive Optics (AO), but it is difficult to correct high-order aberrations. And particularly in a case of solar observation, the Field of View (FOV) is limited because it is difficult to apply to objects with a spreading structure. Another method is post-processing image restoration such as Multi-frame Blind Deconvolution (MFBD) and Speckle Masking Method, but these methods are insufficient for bad seeing. And it requires a huge computational cost and is not possible to analyze the images in real-time. Therefore, several studies to use deep learning for image restoration have been proposed in recent years although quantitative evaluation of the accuracy of restored images is still insufficient. It is important to demonstrate reliability that the restored images represent the true solar images in order to use the method based on deep learning for actual observations. In this study, I develop a method to remove seeing using deep learning and evaluate its performance. I use simulated solar images and simulated wavefront errors and perform quantitative evaluation of the accuracy of the restored images by the network by comparing these images to the target images before degradation, i.e., the ideal images without seeing (diffraction-limited images). In addition, I investigate the relationship between various observation conditions and the accuracy of the image restoration by changing the telescope aperture, atmospheric turbulence (Fried parameter), observation objects (granule, sunspots), and observation wavelengths. As a consequence, in a visual comparison, I confirm that the network improves the resolution of the restored images. However, according to quantitative evaluation, the accuracy of the image restoration is still insufficient and it is more difficult especially for large aperture telescopes, short observation wavelengths, and bad seeing.
Facilitator
-Name：Takayoshi oba
Comment：in Japanese