カテゴリー: ALMA Jセミナー

2023/10/16~2023/10/22

Oct 17 Tue 　10:00-11:30 　 太陽系小天体セミナー Zoom

Oct 17 Tue 　13:30-14:30 NAOJ Seminar zoom/ Large seminar room in Subaru Building

Oct 18 Wed 　10:30-12:00 　 SOKENDAI Colloquium Hybrid;Large Seminar Room in Subaru Building and Zoom

Oct 18 Wed 　14:30-15:30 ALMA-J seminar hybrid (ROOM102 in ALMA building and ZOOM)

Oct 18 Wed　 15:30-16:30 NAOJ Science Colloquium The large seminar room / Zoom (hybrid)

詳細は以下をご覧下さい。

=============== October　17　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：10月17日（火曜日）10時00分～11時30分
場所：zoom
講演者：藤原康徳

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

=============== October　17　Tue===============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regularly Scheduled Date and time：2023 Oct 17, 13:30-14:30
Place：zoom/ Large seminar room in Subaru Building

Speaker：Dr,Bruno Dias
Affiliation: President, Sociedad Chilena de Astronomía (SOCHIAS) Professor, Institute of Astrophysics, Department of Physics, Faculty of Exact Sciences, Universidad Andrés Bello (UNAB), Chile

Title:　The Chilean Astronomical Society (SOCHIAS)

Abstract: The Chilean Astronomical Society (SOCHIAS) was founded on May 31, 2000 with the goals of boosting Astronomy in Chile, managing the interests of Chilean astronomers, organising scientific meetings, establishing and maintaining contact with organizations in Chile and abroad, and supporting Astronomy education, among other related objectives. In this context, two representatives of the current SOCHIAS board are visiting Japan, and in this presentation we will show some information about SOCHIAS as well as some of our initiatives. We hope to keep and strengthen the relationship among Japanese and Chilean astronomical communities.

Facilitator
-Name：Izumi Takuma

=============== October　18　Wed===============

Campus： Mitaka
Seminar： SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：October 18, 2023 10:30-12:00
Place： hybrid; Large Seminar Room in Subaru Building and Zoom

Speaker: Moka Nishigaki
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Masami Ouchi, Tadafumi Takata, Kimihiko Nakajima)
Title: Modeling the Mass-Metallicity Relation with Dark Matter Halo Assembly from z=0–10

Speaker: Kuria Watanabe
Affiliation: SOKENDAI 2nd year (M2) (Supervisor: Masami Ouchi, Nozomu Tominaga, Masato Onodera)
Title: The Chemical enrichment and origin of Nitrogen-Rich Galaxies at High Redshift

Facilitator
-Name：Matsuda, Graduate Student Affairs Unit

=============== October　18　Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 18th (Wed) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)

Speaker: Pei-Ying Hsieh
Affiliation: NAOJ

Title:The circumnuclear disk revealed by ALMA – environments of star formation in the inner 10 pc of the Galaxy

Abstract:The molecular 2-pc circumnuclear disk (CND) immediately around the Milky Way supermassive black hole (SMBH), SgrA, resembles the “molecular torus” in AGNs, providing a unique opportunity to study SMBH accretion and nuclear star formation at sub-parsec scales. In recent years, I have been studying the key question of how much of the available gas can actually form stars in the environment around Sgr A, and how material is being moved around and accreted in this region. The lifetime of the CND has been a long-standing debate over the past decade. The CND can not live longer than 10^5 years if the gas density is under the tidal threshold of SgrA/nuclear star clusters, thus depleting the source of fuel and star formation. Utilizing the ALMA and various single-dish telescopes, we present CS line maps toward the CND of the Galactic Center. Our primary goal is to resolve the compact structures within the CND and the streamers, in order to understand the stability conditions of molecular cores in the vicinity of Sgr A. Our data provide the first homogeneous high-resolution (1.3″ = 0.05 pc) observations aiming at resolving density and temperature structures. A stability analysis based on the unmagnetized virial theorem including tidal force shows that 84 (+16/-37) % of the total gas mass (2.5X10^4 Msun) is tidally stable, which accounts for the majority of gas mass. Turbulence dominates the internal energy and thereby sets the threshold densities 10-100 times higher than the tidal limit at distance >1.5 pc to Sgr A*, and therefore, inhibits the clouds from collapsing to form stars near the SMBH.

Organizers: Gianni Cataldi , Hiroshi Nagai

=============== October　18　Wed===============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Oct. 18 (Wed.), 15:30-16:30
Place: The large seminar room / Zoom (hybrid)

Speaker: Yoshiaki Misugi
Affiliation: NAOJ

Title: Evolution of the Angular Momentum of Molecular Cloud Cores in Filamentary Molecular Clouds

Abstract:
The angular momentum of molecular cloud cores plays a key role in the star formation process. However, the evolution of the angular momentum of molecular cloud cores formed in magnetized molecular filaments is still unclear. We perform three-dimensional magnetohydrodynamics simulations to reveal the evolution of the angular momentum of molecular cloud cores formed through filament fragmentation. As a result, we find that the angular momentum decreases by 30% and 50% at the mass scale of
1 Msun in the case of weak and strong magnetic field, respectively. By analyzing the torques exerted on fluid elements at different mass scales, we identify the magnetic tension as the dominant process for angular momentum transfer for mass scales < 3 M sun for the strong magnetic field case. This critical mass scale can be understood semi-analytically as the time scale of magnetic braking. We show that the anisotropy of the angular momentum transfer due to the presence of strong magnetic field changes the resultant angular momentum of the core only by a factor of two. We also find that the distribution of the angle between the direction of the angular momentum and the magnetic field is random even just before the first core formation. Our results also indicate that the variety of the angular momentum of core inherited from the difference of the phase of the initial turbulent velocity field could contribute to the diversity in size and other properties of protoplanetary disks recently reported by observations.

Facilitator
-Name: Kanji Mori
Comment: English

2023.10.9-2023.10.15

Oct 10 Tue 　　　 10:00-11:30 　　　太陽系小天体セミナー Zoom

Oct 11 Wed 　　　13:30-15:00 Solar and Space Plasma Seminar 　 hybrid; Subaru Building / Insei Seminar Room or Zoom

Oct 11 Wed 　　　14:00-15:00 　 Tea Talk 輪講室（＋Zoom）

Oct 11 Wed 　　　14:30-15:30 　　 ALMA-J seminar hybrid (ROOM102 in ALMA building and ZOOM)

Oct 11 Wed 　　　15:30-16:30 　　 NAOJ Science Colloquium Zoom / the large seminar room (hybrid)

Oct 13 Fri 　 16:00-17:00 NAOJ Seminar zoom/ Large seminar room in Subaru Building

詳細は以下をご覧下さい。

=============== October　10　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：10月10日（火曜日）10時00分～11時30分
場所：zoom
講演者：秋澤宏樹

Abstract：『COMETS III』より、著者による先行公開されている２つの章、
「彗星大気の化学」
https://www.research.ed.ac.uk/en/publications/chemistry-of-comet-atmospheres
「遠隔観測による彗星核の物理・表面特性」
https://arxiv.org/abs/2304.09309
の内容を紹介したいと思います。

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

=============== October　11　Wed===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：11th Oct (Wed), 13:30-15:00
Place： hybrid; Subaru Building / Insei Seminar Room or Zoom
Speaker： Stanislav Gunar
Affiliation：Astronomical Institute of the Czech Academy of Sciences
Title：What is important for robust inversions of spectroscopic observations of chromospheric and coronal structures?
Abstract：In this presentation, we will discuss what is hidden behind the term “robust spectroscopic inversions” and what we need to achieve them. We will focus on the use of UV spectral data, such as the Lyman line series and the Mg II h&k lines.

There are several necessary ingredients needed to produce high-fidelity spectroscopic inversions. The first is high-resolution multi-wavelength observations. The second are realistic radiative transfer models encompassing dominant processes forming the observed spectra. The third component is sophisticated inversion methods that allow us to find a realistic fit between the observed and synthetic spectra. And there is another necessary component – a good understanding of all important boundary conditions.

We will demonstrate the importance of boundary conditions on the example of the so-called incident radiation. This is the radiation coming from the solar surface, which illuminates chromospheric and coronal structures, such as prominences or spicules. We will show that variations in this boundary condition have a strong impact on the shape and intensity of Lyman lines and the Mg II h&k lines. This impact is then responsible for significantly different outcomes of spectroscopic inversions.

Facilitator
Name：Takayoshi oba
Comment：in English

=============== October　11　Wed===============

キャンパス：三鷹　野辺山 水沢 岡山 ハワイ
セミナー名：Tea Talk
定例・臨時の別：臨時
日時：10/11（水）14：00～15：00
場所：輪講室（＋Zoom）
講演者：渡部　潤一
所属：天文情報センター
タイトル：APRIM2023の顚末記

世話人の名前：藤田登起子

=============== October　11　Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 11th (Wed) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)
Speaker: Tetsu Kitayama
Affiliation: Toho University
Title: High-resolution measurements of the Sunyaev-Zel’dovich effect toward galaxy clusters
Abstract:
The Sunyaev-Zel’dovich effect (SZE) provides a unique probe of cosmic plasma up to high redshifts. We first review briefly the progress of high-resolution SZE observations over the past two decades. We then present the measurements made by the Atacama Large Millimeter/submillimeter Array (ALMA); we have obtained SZE images toward four galaxy clusters with 5″ resolution, while retaining extended signals out to 40″. We also discuss implications of these results on the evolution of galaxy clusters as well as prospects for further SZE measurements.

=============== October　11　Wed===============

Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday Date and time：2023 Oct. 11, 15:30-16:30
Place：Zoom / the large seminar room (hybrid)

Speaker：Daichi Kashino
Affiliation：NAOJ
Title：Witnessing Galaxies Reionizing the Intergalactic Medium with JWST
Abstract：
Cosmic reionization is the last major phase transition of the universe, occurring in the first billion years after the Big Bang.
Understanding this process is one of the pivotal goals in modern astrophysics. The commissioning of JWST heralded a new era in investigating the roles of galaxies in reionizing the intergalactic medium, thanks to its unprecedented high sensitivity and dispersing power in near infrared.

In the presentation, I will present early results from our ongoing EIGER (Emission-line galaxies and Intergalactic Gas in the Epoch of
Reionization) survey, a JWST/NIRCam WFSS campaign in the fields of luminous z>6 quasars. The existence of these background quasars enables us to determine the ionization condition along their lines of sight from analysis of the high signal-to-noise quasar spectra. The primary objective of the project is to characterize the cross correlation between galaxies (as pinpointed by JWST) and the IGM conditions during the tail end of the epoch of reionization. In the first quasar field, we confirmed roughly 150 [OIII]5008-emitting galaxies over the redshift range of z=5.3–6.9. Through analyzing the distribution of these galaxies and the transmission spectrum of this corresponding quasar, we identified individual spatial coincidence between the groups of galaxies and highly ionized regions, as well as a mean excess IGM transmission in both Lyman-alpha and Lyman-beta around ~6 cMpc away from the galaxies at z~6. This is interpreted as direct evidence of local reionization by galaxies — indicating that we are witnessing galaxies reionizing the surrounding IGM. I may also showcase further preliminary results from other quasar fields currently being analyzed.

Facilitator
Name：Haruka Kusakabe
Comment：English

=============== October　13　Fri===============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regularly Scheduled Date and time：2023 Oct 13, 16:00-17:00
Place：zoom/ Large seminar room in Subaru Building

Speaker: Cristian Eduard Rusu, PhD
Affiliation: Axelspace Corporation
Title: Opportunities and Challenges for Space Observations with Commercial Satellites
Abstract：Over the past decade, the number of satellites launched into orbit for commercial
purposes has increased exponentially. Nonetheless, these have had virtually no usage for
astronomical observations, due to the still prohibitive cost of launching large mirrors and
achieving scientific-level tolerances. In recent years however, governments as well as private
companies have become interested in Space Situation Awareness, or gaining insights from
optical monitoring from space of artificial satellites and space debris as faint as the 14th magnitude.
This renewed interest in space observations has the potential of reducing the cost of dedicated
astronomical satellites and bringing them within the reach of commercial companies.
I will explore these topics as experienced from the point of view of Axelspace, a Japanese commercial
satellite manufacturer and provider of satellite imagery.

Facilitator
-Name：Moriya, Takashi

2023.9.26-2023.10.1

September　26　Tue　 10:00-11:30 　　太陽系小天体セミナー　zoom

September　27　Wed　 14:30-15:30 　　 ALMA-J seminar  ALMA building #102 / Zoom (hybrid) 　　　　　　　　　　　　　　　

September 　29　Fri　 　　 16:00-17:00　　　　 　NAOJ Seminar 　　　　　　　　　　　Zoom / the large seminar room (hybrid)　　　　　　　　　　　　　　

詳細は下記からご覧ください。

=============== September　26　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：9月26日（火曜日）10時00分～11時30分
場所：zoom

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

=============== September　27　Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: September 27, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Kana Morokuma-Matsui
Affiliation: Tsukuba University
Title: Star-formation quenching in galaxies in the Virgo, Fornax and Antlia clusters
Abstract:
Understanding how star formation (SF) is suppressed in galaxies is a crucial aspect of galaxy evolution research.
The cosmic SF rate (SFR) density has a peak around z~1-2, and the last half of the universe is the history of SF quenching in galaxies.
In this talk, we present our findings on how the galaxy-cluster environment affects SF activity in galaxies by observing molecular gas in cluster galaxies.
We investigate three nearby galaxy clusters, the Virgo, Fornax, and Antlia clusters. Our results show that SF activity is low in cluster galaxies due to the depletion of cold gas reservoirs rather than the decrease in star-formation efficiency.
We find that the molecular gas in Virgo galaxies is likely to be removed in a shorter timescale than the typical gas depletion timescale of ~1-3 Gyr.
We also discuss the similarities and differences between the three clusters.

Facilitator: Bunyo Hatsukade and Kouichiro Nakanishi

=============== September　29　Fri===============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regularly Scheduled Date and time：2023 Sep 29, 16:00-17:00
Place： Zoom / Large Seminar Room (hybrid)

Speaker: Kazunori Kohri, Ph. D
Affiliation: Division of Science, NAOJ
Title: What is Dark Matter? From the Standpoint of Particle Cosmology
Abstract：
What is the nature of dark matter? Observations have determined that dark matter is approximately 25% of the total energy in the Universe today. However, its true nature is still unknown. Only when we uncover its true nature, we can call it a triumph of science. We do not have to say there is no argument that this is beyond the scope of astronomy. In particle physics, for example, the LHC experiment at CERN in Geneva, Switzerland, was expected to reveal a new particle, dark matter, but it did not. The energy of particle physics experiments cannot be dramatically increased in a short period of time. Therefore, there is a growing trend to use future astronomical/cosmological observations to uncover the true nature of dark matter. In this talk, I will introduce my lifeworks for candidates for dark matter, 1) WIMPs, 2) axions, 3) primordial black holes, 4) right-handed neutrinos and so on, and show how they can be constrained by using cosmology, particle physics, gravity, high-energy astrophysics or multi-messenger astronomy. I will also explain how they may be elucidated in the future.

Facilitator
-Name：Takuma Izumi

2023.9.11-2023.9.17

Sep　11　Mon　 　15:00-16:30　　Solar and Space Plasma Seminar
　　　　　　　　　　　　　　　　hybrid; Central Building (North) / 310 or Zoom

Sep　13　Wed　　　　14:30-15:30 　　 ALMA-J seminar 　
　　　　　　　　　　　　　　　　　　　ALMA building #102 / Zoom (hybrid)　　　　　　　　　　　　　　

詳細は下記からご覧ください。

=============== Sep　11　Mon===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Sep 11th (Sep), 15:00-16:30
Place： hybrid; Central Building (North) / 310 or Zoom
Speaker：Teodora Mihailescu
Affiliation：Mullard Space Science Laboratory, University College London
Title：Intriguing Plasma Composition Pattern in a Solar Active Region: a Result of Non-Resonant Alfvén Waves?

Abstract：The plasma composition of the solar corona is different from that of the solar photosphere. Elements that have a low first ionisation potential (FIP) are preferentially transported to the corona and, therefore, show enhanced abundances in the corona compared to the photosphere. The level of enhancement is measured using the FIP bias parameter. The highest FIP bias values are typically observed in active regions, but they also vary at sub-active region level. In this work, we use data from the EUV Imaging Spectrometer (EIS) on Hinode to study the plasma composition in an active region following an episode of significant new flux emergence into the pre-existing magnetic environment of the active region. We use two FIP bias diagnostics: Si X 258.375 Å/S X 264.233 Å (formation temperature of 1.5 MK) and Ca XIV 193.874 Å /Ar XIV 194.396 Å (formation temperature of 4 MK). We observe different plasma composition patterns in the newly emerging loops and the preexisting loops (those that had been formed before the flux emergence). This result can be interpreted in the context of the ponderomotive force model, which proposes that the enhancement of low-FIP elements in the corona is generally driven by Alfvén waves. We suggest that the low-FIP elements enhancement pattern observed in the emerging loops could be driven by resonant waves originating in the active region core loops. Conversely, we suggest that the pattern observed in preexisting loops could be driven by non-resonant waves and we discuss potential sources of these waves. This different type of wave activity is what could explain the different patterns of low-FIP elements enhancement in these two sets of loops.

Facilitator
Name：Takayoshi oba
Comment：in English

=============== Sep 13　Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: September 13, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Kaho Morii
Affiliation: The University of Tokyo/NAOJ
Title: Unveiling Early Stages of High-Mass Star Formation: Insights from Infrared Dark Clouds

Abstract:
Physical properties in infrared dark clouds (IRDCs) provide insights into the initial conditions of high-mass star and stellar cluster formation. We have conducted the ALMA Survey of 70 µm Dark High-mass Clumps in Early Stages (ASHES) on thirty-nine high-mass clumps, which are the dense parts of IRDCs. These targets are dark at 24 µm and 70 µm and have low temperatures, high masses, and high density, best candidates to investigate the earliest stages of high-mass star formation. Our ALMA observations reveal their internal structure and have identified an unprecedented number of 839 cores from dust continuum emission.  We find that less than 1% (7/839) of the cores possess masses exceeding 27 Msun. All of these cores are gravitationally bound and associated with molecular outflows. No high-mass prestellar core has been observed. Furthermore, among our sample, 90%  (35 out of 39) only host low- to intermediate-mass cores, indicating the necessity of additional mass input for high-mass star formation. Observed core properties generally follow the thermal Jeans fragmentation of the clumps. In this talk, I will present the first results of the statistical study of the 839 cores as well as a summary of the pilot survey, and discuss the characteristics of the initial stages of high-mass star formation.

Facilitator: Bunyo Hatsukade and Kouichiro Nakanishi

2023.8.28-2023.9.3

August　30　Wed　 　13:30-15:00　　Solar and Space Plasma Seminar
　　　　　　　　　　　　　　　　　　　　 hybrid; Central Building (North)310 or Zoom

August　30　Wed　　　14:30-15:30 　　 ALMA-J seminar 　
　　　　　　　　　　　　　　　　　　　　 Zoom / ALMA building #102 (hybrid)　　　　　　　　　　　　　　　

詳細は下記からご覧ください。

=============== August　30　Wed===============

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Aug 30th (Wed), 13:30-15:00
Place： hybrid; Central Building (North) / 310 or Zoom
Speaker：Dr. Masahito Kubo
Affiliation：NAOJ
Title：Comparison of polar magnetic fields derived from MILOS and MERLIN inversions for Hinode/SOT-SP data


Abstract：The detailed investigation of the polar magnetic field and its time evolution is one of the major achievements of Hinode. Precise measurements of the polar magnetic field are essential for understanding the solar cycle, and they provide important constraints for identifying the source regions of the solar wind. The Spectropolarimeter (SP) of the Solar Optical Telescope (SOT) on board Hinode has been the instrument best suited to make such measurements. In this study, we compare SOT-SP data for the polar regions as processed using two representative Milne-Eddington inversion codes, MILOS and MERLIN. These codes are applied to the same level-1 SOT/SP data, and the same disambiguation algorithm is used on the maps that go through the two inversions. We find that the MERLIN inversion tends to give the radial magnetic flux density (the magnetic flux density with respect to the local vertical) that is about 20% larger than the MILOS inversion. The somewhat higher radial magnetic flux density from MERLIN appears to be common to the polar magnetic fields observed at different phases of the solar cycle. We attribute the difference in the radial magnetic flux density to different filling factors adopted by the two inversions, based on different assumptions of the scattered light profiles. The relationship between the radial magnetic flux density and the magnetic filling factor could be more complex in the polar (limb) observations due to the possible contributions of the transverse magnetic field component that may affect the estimated radial magnetic flux density.

Facilitator
-Name：Takayoshi oba
-Comment：in English

=============== August 　30　Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: August 30, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Jan-Willem Steeb
Affiliation: National Radio Astronomy Observatory
Title: AstroHACK: Holography Antenna Commissioning Kit

Abstract: Correcting the surface of a dish antenna by adjusting the panels can significantly improve the dish’s performance. For instance, the VLA panel adjustments completed in 2000 more than doubled the high-frequency sensitivity of the VLA dishes. The software presently utilized by ALMA and VLA is written in Fortran and is becoming challenging to maintain. Consequently, the CASA team is developing AstroHACK, which generates antenna aperture images and calculates antenna panel adjustment corrections from calibrated holography measurement sets. AstroHACK is the first non-prototype software package developed using the Python-based VIPER (Visibility and Image Parallel Execution Reduction) Framework, previously known as the CASA Next Generation Infrastructure Software Framework. This framework was designed to meet the requirements of the ngVLA and the ALMA Wideband Sensitivity upgrade. In this seminar, I will provide an overview of the VIPER Framework and the functionalities of AstroHACK, followed by a live demonstration.