研究紹介」カテゴリーアーカイブ

VERA observatons of SiO masers toward Symbiotic star R Aquarii – Determination of orbital parameters etc.

[Speaker 1]
Min Cheul Hong D2, SOKENDAI, Mitaka(supervisor : Mareki Honma)
[Title]
VERA observatons of SiO masers toward Symbiotic star R Aquarii – Determination of orbital parameters
[Abstract]
Symbiotic stars are now generally understood as binary systems comprising a cool late-type star and a hot compact companion.
Interacting between the components presents a good laboratory for studying variety of physical processes, and their study gives important implications for the binary evolution.
R Aquarii (R Aqr) is one of the closest and most studied symbiotic star, but its orbital parameters are still under debated.
In order to extract the orbital parameters, we have been observing the R Aqr system of the SiO maser with the VERA (VLBI Exploration of Radio Astrometry) which can allows us to conduct precise astrometry of the maser sources.
Here, I will report observational results of the preliminary orbital parameters for R Aqr system.

[Speaker 2]
Onitsuka Masahiro M2, SOKENDAI, Mitaka(supervisor : Tomonori Usuda)
[Title]
Infrared Transit Observations of the Very Young Hot Jupiter CVSO30b
[Abstract]

Experimental confirmation for CLASP’s spectrograph alignment procedure etc.

[Speaker 1]
Giono Gabriel D1, SOKENDAI, Mitaka(supervisor : Yoshinori Suematsu)
[Title]
Experimental confirmation for CLASP’s spectrograph alignment procedure
[Abstract]

[Speaker 2]
Onoue Masfusa M1, SOKENDAI, Mitaka(supervisor : Nobunari Kashikawa)
[Title]
High-z Quasar Selection with Hyper Suprime-Cam
[Abstract]
Quasars at high (>6) redshift are one of the best tracers of early Universe,
thanks to its high luminosity and characteristic spectrum.
However, quasars are very rare objects and it is important to establish a method to
select quasars effectively.
Based on the above, I will present the strategy for identifying high-z quasars by using SED fitting (#HSC project 47).
The goal of this study is to effectively isolate high-z quasars from contaminating sources such as brown dwarfs.
We are going to apply SED fitting method for quasar selection along with conservative two-color selection.
I will report the current status of SED fitting code development, and preliminary results of its application.
In addition, I would like to introduce the recently found three z~7 quasars (Venemans+13).

Temporal evolution of the Sun’s Polar Magnetic Patches as observed with Hinode etc.

[Speaker 1]
Anjali John K D3, SOKENDAI, Mitaka(supervisor : Suematsu Yoshinori)
[Title]
Temporal evolution of the Sun’s Polar Magnetic Patches as observed with Hinode
[Abstract]
The Sun’s polar region is covered by countless discrete flux elements called as magnetic patches. The magnetic patches are believed to be formed from the remnant magnetic flux from the active latitudes which is transported to the polar region through diffusion and meridional circulation. It is likely that large unipolar patches with magnetic flux >10^18 Mx determine the magnetic polarity of each poles and their total flux is modulated by the solar cycle. It is important to understand the temporal evolution of these large patches to derive information of magnetic activities in the polar region, especially, the mechanism of magnetic polarity reversal. We also like to investigate the interaction between magnetic patches and the polar faculae whose occurrence tends to be associated with the large magnetic patches, according to our previous study. We obtained Hinode/SP and FG data for six hours of the south polar region in March 2013. We will show results obtained from this analysis.

[Speaker 2]
Ayumu Matsuzawa D1, SOKENDAI, Mitaka(supervisor : Satoru Iguchi)
[Title]
Absorbing spectrum in galactic nucleus of M87 from VLBA archive data
[Abstract]
Super Massive Black Hole (SMBH) in Active Galactic Nuclei (AGN) attracts matters to form an accretion disk by its strong gravity. AGN is very bright than normal galaxy due to huge luminosity of accretion disk. In order to emit the huge luminosity, that requires a lot of accretion matter accreting to SMBH. The absorption was seen in spectrum of VLBI observation near SMBH. There are the two possibilities that absorption as synchrotron-self-absorption (SSA) from optically thin region of AGN jet or free-free-absorption (FFA) from cold dense plasma around SMBH. This cold dense plasma (we called FFA plasma) was considered as accreting matter to SMBH. The analysis of FFA around SMBH has been used to investigate this kind of accretion process at very vicinity (~pc-scale) of the BH. The purpose of my research is probing the FFA plasma around SMBH of M87. M87 is one of very important object, because M87 has the second-largest apparent Schwarzschild radius next to SrgA*.In order to probe the FFA plasma around SMBH of M87, we required the absorption spectrum of VLBI observation near SMBH of M87.We make the SED with seven frequencies (0.324, 1.6, 2.2, 4.9, 8.4, 15, 22GHz) on SMBH of M87 from VLBA archive data to confirm the absorption spectrum and the SED shown absorption spectrum.

Mass map measurement for Deep Lens Survey Field

[Speaker 1]
Junya Sakurai M2, SOKENDAI, Mitaka(supervisor : Satoshi Mitayaki)
[Title]
Mass map measurement for Deep Lens Survey Field
[Abstract]
Measurement the evolution of dark matter distribution is the important
cosmological probe. For this probe, one of the promising techniques is
weak gravitational lensing. This measurement is sensitive to any
systematic biases in measured quantities. lensfit (L. Miller et al., 2007)
we use is able to yield unbiased measurement. Since lensfit has
recognized as one of the most reliable tools based on mock simulation
data analysis, we try to apply lensfit to Subaru Suprime-Cam data
analysis.

We get optical imaging data of Deep Lens Survey Field 2 from SMOKA. We
select galaxies with 23

An energetics study of X-ray jets etc.

[Speaker 1] Sukom Amnart
AffiliationD3, SOKENDAI, Mitaka(supervisor : Saeko Hayashi)
[Title]TBA
[Abstract]TBA

[Speaker 2]Sako Nobuharu
AffiliationD3, SOKENDAI, Mitaka(supervisor : Tetsuya Watanabe)
[Title]
An energetics study of X-ray jets
[Abstract]For plasma acceleration in X-ray jets, three mechanisms have been considered, based on the reconnection model of X-ray jets; The reconnection jet produced by magnetic tension, the evaporation flow produced by pressure gradient, and the twisted jet produced by magnetic pressure. There are some evidences of X-ray jets in active regions (ARs) produced by pressure gradient. On the other hands, there is no observational evidence of X-ray jets by the other forces. In order to distinguish the evaporation flow from the other types of jets, I have studied the energetics of the X-ray jets.
Using over 100 X-ray jets greater than 3×104 km in length in ARs, quiet regions (QRs), and coronal holes (CHs), I have find no large differences in the life time, the width of the jets, and the area of the footpoint flares in such regions. On the other hands, the plasma number density of the X-ray jets and flares in ARs is ten times larger than those in QRs and CHs. From a comparison of the energy flux of the jets with the energy flux from the reconnection sites, which is estimated from the footpoint flares, I have found that the some events are consistent with the prediction from the evaporation flow. The energy fluxes of the other events are larger than the energy flux from the reconnection site. The kinetic energy fluxes of these jets are larger than the thermal fluxes. In my presentation, I will discuss the details.