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2018.05.21-05.27

5月22日(火)13:30~14:30   理論コロキウム         輪講室  
May 22 Tue          DTA colloquium       Rinko-room 

5月23日(水)10:30~12:00  総研大コロキウム        講義室
May 23 Wed        SOKENDAI colloquium    Lecture Room

5月24日(木)16:00~17:00  国立天文台談話会        大セミナー室  
May 24 Thu        NAOJ Seminar         Large Seminar Room 

5月25日(金)13:30~15:00  太陽天体プラズマセミナー    院生セミナー室   
May 25 Fri       Solar and Space Plasma Seminar Student Seminar Room, Subaru Bldg. 

5月25日(金)16:00~17:00  国立天文台談話会        大セミナー室  
May 25 Fri         NAOJ Seminar        Large Seminar Room 

詳細は以下をご覧下さい。

5月22日(火)

Campus
Mitaka
Seminar
DTA colloquium
Regularly Scheduled/Sporadic
Regularly Scheduled
Date and time
May 22, 2018, 13:30-14:30
Place
Rinko room
Speaker
Kazumi Kashiyama
Affiliation
University of Tokyo
Title
The repeating fast radio burst and the young neutron star model
Abstract
Fast radio bursts (FRBs) are enigmatic radio transients with large dispersion measure. There are ~ 30 of FRBs discovered so far and only one of them, FRB121102, repeats. Recently, the host galaxy and persistent radio counterpart have identified for this repeating FRB.
First, I will overview the observational results and the general implications. Then, I will focus on the young neutron star model for FRBs and discuss how one can test the model observationally. In particular, I will discuss the possible connection between FRBs and energetic supernovae.
Facilitator
-Name:Tomoya Takiwaki
Comment
in English

5月23日(水)

Campus
Mitaka
Seminar
SOKENDAI colloquium
Regularly Scheduled/Sporadic
Regular
Date and time
May 23, 2018, 10:30 -12:00

Place
Lecture Room

Speaker
Satoshi Tanioka
Affiliation
SOKENDAI 3rd year (D1)(Supervisor: Yoichi Aso,Ryutaro Takahashi,Tomotada Akutsu)
Title
bKAGRA Phase 1 From Kamioka with Love
Abstract (if you like):bKAGRA Phase 1 operation was held in April 28th to May 6th. I will report the overview.

Speaker
zhao yuhang
Affiliation
SOKENDAI 3rd year (D1)(Supervisor: Matteo Leonardi,,)
Title
status of the frequency dependent squeezing experiment at TAMA
Abstract (if you like):It is expected that the second-generation gravitational wave detectors will be quantum noise limited in the whole detection frequency band. This expectation was partially confirmed by the LIGO-Virgo O1 and O2 runs. KAGRA will be the first 2.5-generation GW detector, and the quantum noise limit is expected to be even more severe than the second-generation detectors. The implement of frequency dependent squeezed(FDS) light source is one of the most promising solutions to this problem. After several years of table top experiments and proof of principle experiments, the implement of squeezing into GW detector is a mature technique. The most studied solution to realize an FDS is the coupling between a frequency independent squeezer to a Fabry-Perot cavity(usually addressed as filter cavity). One of the main parameter of this kind of experiment is the intra-cavity losses per meter of the filter cavity. One solution to mitigate this problem is to use hundred-meter scale filter cavity.

The purpose of our experiment, that is in the TAMA300 facility, is to realize FDS with a 300m long filter cavity. The filter cavity is hosted in an arm of the former TAMA300 interferometer. As of today, the filter cavity has been installed and is locked stably with a green field. The characterization work of the filter cavity is ongoing but almost finished. The assembling of the frequency independent squeezer is on going. The next step will be the characterization of the frequency independent squeezing and its injection into the filter cavity.

Please note that the presenter information posted here is not necessarily listed in order of presentation.

Facilitator
-Name:Yoshiki Hatta
Comment
TV conference system is available connecting from Nobeyama, Hawaii, Mizusawa, and Okayama.

5月24日(木)

Campus
Mitaka
Seminar
NAOJ seminar
Regularly Scheduled/Sporadic
Scheduled
Date and time
Thu 24 May. 16:00~17:00
Place
Large Seminar Room
Speaker
Brian Day (NASA SSERVI) / Emily Law (NASA JPL)
Title
” Mission Planning, Planetary Science, and Public Outreach with NASA’s Solar System Treks”
Abstract
NASA’s Solar System Treks Project provides a suit of online, web-based portals for visualizing
and Analyzing planetary surfaces. These portals allow mission planners, planetary scientists, students,
and the general public to explore planetary surfaces as seen through the eyes of many different instruments
aboard a wide range of spacecraft for a growing number of planetary bodies. Portals for the Moon, Mars,
and Vesta are currently online, with new portals now being developed for additional planetary bodies.

Facilitator
-Name: Matsuda, Yuichi

5月25日(金)

Campus
Mitaka
Seminar
Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic
Regular
Date and time
25 May (Fri), 13:30-15:00
Place
Student Seminar Room, Subaru Bldg.
Speaker
Satoko Nakamura
Affiliation
Kyoto University
Title
Time domain simulation of geomagnetically induced current (GIC) flowing in 500 kV power grid in Japan including a three-dimensional ground inhomogeneity
Abstract
We performed time domain simulation of geomagnetically induced currents
(GICs) flowing in the Japanese 500 kV power grid. The three-dimensional distribution of the geomagnetically induced electric field (GIE) was calculated by using the finite-difference time-domain (FDTD) method with a three-dimensional electrical conductivity model constructed from a global relief model and a global map of sediment thickness. First, we imposed a uniform sheet current at 100 km altitude with a sinusoidal perturbation to illuminate the influence of the structured ground conductivity. The simulation result shows that GIE exhibits localized, the uneven distribution that can be attributed to charge accumulation due to the inhomogeneity below the Earth’s surface. The charge accumulation becomes large when the conductivity gradient vector is parallel, or anti-parallel to the incident electric field. For given GIE, we calculated the GICs flowing in a simplified 500 kV power grid network in Japan. The influence of the structured ground conductance on GIC appears to depend on a combination of the location of substations and the direction of the source current. Uneven distribution of the power grid system gives rise to an intensification of the GICs flowing in remote areas where substations/power plants are distributed sparsely.
Secondly, we imposed the equivalent sheet current inferred from the ground magnetic disturbance for the magnetic storm of 27 May 2017 as a source current of the FDTD simulation. The calculated GIC agrees well with the observations at substations around Tokyo when the uneven distribution of GIE is incorporated into the simulation.

Facilitator
-Name:Shin Toriumi
Comment

5月25日(金)

Campus
Mitaka
Seminar
NAOJ seminar
Regularly Scheduled/Sporadic
Scheduled
Date and time
Fri 25 May. 16:00~17:00
Place
Large Seminar Room
Speaker
Vikram Ravi (Caltech)
Title
“Fast Radio Bursts / 瞬発電波バースト””
Abstract
Ten years after their discovery, fundamental questions on the extragalactic fast radio bursts (FRBs) remain open:
(1) what are their progenitors? (2) what is the nature of the medium through which they propagate?
The extreme diversity of the FRB sample in the estimated burst energies, temporal profiles, and polarization properties
makes it difficult to identify individual populations. Similarly, the diversity of propagation signatures (including dispersion,
scattering, and Faraday rotation in intervening inhomogeneous, magnetized plasma) prevents us from identifying
the typical FRB distance scale and progenitor environment. Accurate localization of FRBs, which is technically difficult
when they are first detected, is therefore crucial for further progress. I shall describe efforts at Caltech to construct
a dedicated FRB localization instrument. The successful deployment of a ten-antenna prototype has motivated us to begin
construction of a 110-antenna array (the Deep Synoptic Array; DSA) that will localize >100 FRBs/year to <3 arcseconds.
I will outline the expected outcomes of the DSA, focusing on its potential for the study of physical conditions in the
circum-/intergalactic medium.

Facilitator
-Name: Matsuda, Yuichi

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