• 천문학회보
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• 제35권1호
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• pp.83.1-83.1
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• 2010

In the last meeting of KAS, we reported the first statistical study of Faraday rotation measure (RM) in the large-scale structure of the universe using the data of cosmological structure formation simulations. With a turbulence dynamo model for the intergalactic magnetic field (IGMF), we predicted that the root mean square of RM through filaments is \sim 1 rad/m^2. Future radio observatories such as the Square Kilometer Array (SKA) could detect this signal level. However, it is known that the typical foreground galactic RM is a few tens and less than ten rad/m^2 in the low and high galactic latitudes, respectively. So the RM in the large-scale structure could be detected only after the foreground galactic RM is removed. In this talk, we show how we remove the foreground galactic RM and what we obtain from the masked data, by using some noise models and masking techniques. Our results can be used to simulate future RM observations by SKA, and eventually to constrain the origin and evolution of the IGMF in the large-scale structure.

• Journal of Magnetics
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• 제11권3호
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• pp.139-142
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• 2006

We fabricated new one-dimensional magnetophotonic crystal (1D-MPC) utilizing the second and third photonic band gaps where localized modes existed. Structure of the 1D-MPC was $(Ta_{2}O_{5}/SiO_{2})_{5}/Bi:YIG/(SiO_{2}/Ta_{2}O_{5})_{5}$ with optical thicknesses of 3$\lambda$ /4 for $Ta_{2}O_{5} and $SiO_2$ dielectric layers and $\lambda$ /2 for Bi:YIG defect layer, where $\lambda$ is a wavelength of a localized mode in the second photonic band gap. Faraday rotation at the localized mode in the second photonic band gap was enhanced, which was confirmed by calculation using 4${\times}$4 matrix method.

• Journal of Magnetics
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• 제2권2호
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• pp.46-49
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• 1997

This paper reports the first success in enhancement of the magneto-optic figure of merit of garnet films in blue wavelengths. The maximum of the absolute value of the Faraday rotation angle observed at about 500 nm for the films with no La substitution shifted toward shorter wavelength as La content increased, that leads the increase of the absolute value of the Faraday rotation angle in the wavelengths shorter than about 480 nm. The optical absorption coefficient at the wavelengths shorter than 500 nm decreased as La content increased. As a result the magneto-optic figure of merit increased in the wavelengths shorter than 470 nm as La content increased and was about two times larger for the film with La content of 0.6 in formular unit compared to that of the film without La substitution. This might be attributed to the shift of the centers of the charge transfer and crystal field transitions by La substitution.

• 한국자기학회지
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• 제5권5호
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• pp.720-725
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• 1995

Bi-substituted gadolinium iron garnet films were deposited on GGG(111) and NGG (111) substrates by irradiating KrF excimer laser onto targets having compositions of $Bi_{x}Gd_{3-x}Fe_{5}O_{12}$ ($2.0{\leq}x{\leq}3.0$) under substrate temperature of $580~620^{\circ}C$. Analysis on structure, composition and angle of Faraday rotation, ${\theta}_{F}$, were carried out. The composition, the structure and the magneto-optical properties of the obtained films were found to be strongly dependent both on the compositions of the targets and on the pressure of oxygen. Before annealing in air, all films showed ${\theta}_{F}{\geq}0$ at ${\lambda}=6328{\AA}$, while several films showed ${\theta}_{F}{\leq}0$ after the annealing. The highest value of Bi-substitution up to x = 1.76 with uniform composition was obtained.

• 천문학회보
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• 제44권2호
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• pp.51.3-51.3
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• 2019

Its ability to measure the polarization of light at four frequencies makes the KVN a "plasma physics observatory" that can probe the internal physics (e.g., magnetic fields, outflow geometries) of AGN radio jets and cores. We initiated a Key Science Program, the Plasma-physics of Active Galactic Nuclei (PAGaN) project, dedicated to polarimetric monitoring of 14 radio-bright AGN. We have been able to measure the Faraday rotation measure of the cores of our targets as function of frequency; the observed scaling relation is in good agreement with conically expanding outflows to first order. We are further probing a polarized hotspot in the jet of 3C84 and possible systematic differences in the Faraday rotation in BL Lacertae objects and flat spectrum radio quasars.

• 천문학회보
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• 제46권2호
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• pp.39.3-40
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• 2021

The Faraday rotation measure (RM) of extragalactic radio sources is one of tools that can explore the magnetic field in the cosmic web. We have investigated the statistical properties of the RM using the data of simulations for the large-scale structure formation of the universe. Various modelings for the cosmic magnetic field including the redshift dependence, and the intrinsic RM of radio sources have been considered. We here present the structure functions (SFs) of simulated RMs for small angular separations, and compare the SFs with observations, specifically those from the NRAO VLA Sky Survey (NVSS) and LOFAR Two-Metre Sky Survey (LoTSS). We then discuss the implications of our work.

• 천문학회보
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• 제32권1호
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• pp.96.2-96.2
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• 2007

• 천문학회보
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• 제34권2호
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• pp.54.2-54.2
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• 2009

• 천문학회보
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• 제31권2호
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• pp.71.1-71.1
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• 2006

• 한국자기학회지
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• 제2권1호
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• pp.61-68
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• 1992

전이 금속(Ni, Co), 희토류(Ce, Pr, Eu) 및 Al이온 치환 Ba 훼라이트박막을 스퍼터법으로 제조하여, 그 구조, 자기적 및 자기광학적 성질(1.0eV~3.2eV)을 조사하였다. 막 제작시의 투입 rf 전역 밀도를 조절하는 것에의해, 막 중의 결정립의 크기를 수 100 nm-수 nm로 제어하는데 성공했다. Fe를 Al으로 치환하는 것에의해 각형 히스테리시스 루우프를 얻는데 성공했다. Ni이온이 가시역에서 페러데이 회전을 크게 증가시키는 것을 발견했다. Co이온이 근적외선 영역에서 페러데이 회전을 크게 증가시키는것을 확인했다. Ce, Pr, Eu이온데 의한 페러데이 회전의 증가는 관찰되지 않았다. 이들 이온 치환 막의 자기적 및 자기광학적 성질의 기원에 대해 고찰했다.