Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in McConnachie et al. (2009), we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range 0.01 < z < 0.22. This large redshift sample shows that the interloper fraction in the McConnachie et al. (2009) compact group candidates is  42%. A secure sample of 332 compact groups includes 192 groups with four or more member galaxies and 140 groups with three members. The fraction of early-type galaxies in these compact groups is 62%, higher than for the original Hickson compact groups. The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than 100 h−1 kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The abundance of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the abundance for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale.

이 연구의 목적은 중학교 천문 수업에 대한 과학 교사의 교수 실행에서 나타나는 시스템 사고를 분석하는 것이 다. 이를 위해 4명의 중학교 8학년 과학 교사의 천문 단원 수업을 녹화하였고 녹화된 수업은 모두 전사하였으며, 선행 연구의 시스템 사고 위계 구조를 수정하여 개발한 시스템 사고 분석틀을 적용하여 이들을 분석하였다. 또한, 수업 분석 후 참여 교사의 과학 수업에 대한 지향과 교수학적 생각을 심층적으로 분석하기 위해 비디오 자극 회상 면담을 실시하 였다. 연구 결과는 다음과 같다: 모든 참여 교사들은 천문 수업에서 시스템 사고의 위계를 제대로 반영하지 못하였으며, 낮은 수준의 시스템 사고만을 활용하는 것으로 나타났다. 또한, 교사가 학생 중심의 교수 지향을 지녔다 하더라도 시스 템 사고의 교수 실행은 교사 중심으로 진행되는 것으로 나타났다. 천문 수업의 교수 실행에서 시스템 사고가 부족하게 나타나는 것은 공간적 사고에 보다 집중하는 것과 지구과학 비전공 교사로서의 천문 내용 및 형성 평가 지식 부족 때 문인 것으로 판단된다. 이러한 연구 결과를 바탕으로 천문 수업에서 효과적인 시스템 사고의 도입 방안을 논의하였다.

The Horizon Run 4 is a cosmological N-body simulation designed for the study of coupled evolution between galaxies and large-scale structures of the Universe, and for the test of galaxy formation models. Using 63003 gravitating particles in a cubic box of Lbox = 3150 h−1Mpc, we build a dense forest of halo merger trees to trace the halo merger history with a halo mass resolution scale down to Ms = 2.7 × 1011h−1M⊙. We build a set of particle and halo data, which can serve as testbeds for comparison of cosmological models and gravitational theories with observations. We find that the FoF halo mass function shows a substantial deviation from the universal form with tangible redshift evolution of amplitude and shape. At higher redshifts, the amplitude of the mass function is lower, and the functional form is shifted toward larger values of ln(1/σ). We also find that the baryonic acoustic oscillation feature in the two-point correlation function of mock galaxies becomes broader with a peak position moving to smaller scales and the peak amplitude decreasing for increasing directional cosine μ compared to the linear predictions. From the halo merger trees built from halo data at 75 redshifts, we measure the half-mass epoch of halos and find that less massive halos tend to reach half of their current mass at higher redshifts. Simulation outputs including snapshot data, past lightcone space data, and halo merger data are available at http://sdss.kias.re.kr/astro/Horizon-Run4.

We search for misclassified type 1 AGNs among type 2 AGNs identified with emission line flux ratios, and investigate the properties of the sample. Using 4 113 local type 2 AGNs at 0.02 < z < 0.05 selected from Sloan Digital Sky Survey Data Release 7, we detected a broad component of the Hα line with a Full-Width at Half-Maximum (FWHM) ranging from 1 700 to 19 090 km s−1 for 142 objects, based on the spectral decomposition and visual inspection. The fraction of the misclassified type 1 AGNs among type 2 AGN sample is 3.5%, implying that a large number of missing type 1 AGN population may exist. The misclassified type 1 AGNs have relatively low luminosity with a mean broad Hα luminosity, log LHα = 40.50 ± 0.35 erg s−1, while black hole mass of the sample is comparable to that of the local black hole population, with a mean black hole mass, log MBH = 6.94 ± 0.51 M⊙. The mean Eddington ratio of the sample is log Lbol/LEdd = −2.00±0.40, indicating that black hole activity is relatively weak, hence, AGN continuum is too weak to change the host galaxy color. We find that the Oiii lines show significant velocity offsets, presumably due to outflows in the narrow-line region, while the velocity offset of the narrow component of the Hα line is not prominent, consistent with the ionized gas kinematics of general type 1 AGN population.

A focal reducer is developed for CQUEAN (Camera for QUasars in EArly uNiverse), which is a CCD imaging system on the 2.1 m Otto Struve telescope at the McDonald observatory. It allows CQUEAN to secure a wider field of view by reducing the effective focal length by a factor of three. The optical point spread function without seeing effects is designed to be within one pixel (0.28300) over the field of view of 4.82' × 4.82' in optimum wavelength ranges of 0.8 − 1.1 μm. In this paper, we describe and discuss the characteristics of optical design, the lens and barrel fabrications and the alignment processes. The observation results show that the image quality of the focal reducer confirms the expectations from the design.