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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Publications of The Korean Astronomical Society
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Journal DOI :
The Korean Astronomical Society
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Volume & Issues
Volume 25, Issue 4 - Dec 2010
Volume 25, Issue 3 - Sep 2010
Volume 25, Issue 2 - Jun 2010
Volume 25, Issue 1 - Mar 2010
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SOME CURRENT ISSUES IN GALAXY FORMATION
Silk, Joseph ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 53~58
DOI : 10.5303/PKAS.2010.25.3.053
The origin of the galaxies represents an important focus of current cosmological research, both observational and theoretical. Its resolution involves a comprehensive understanding of star formation and evolution, galaxy dynamics, supermassive black holes, and the cosmology of the very early universe. In this paper, I will review our current understanding of galaxy formation and review some of the challenges that lie ahead. Specific issues that I address include the galaxy luminosity function, feedback by supernovae and by AGN, and downsizing. I argue that current evidence favours two distinct modes of star formation in the early universe, in order to account for the origin of disk and massive spheroidal galaxies. However perhaps the most urgent need is for a robust theory of star formation.
CORE AND GLOBAL PROPERTIES OF EARLY-TYPE GALAXIES AND THEIR GLOBULAR CLUSTER SYSTEMS
Cote, Patrick ; The Acs Virgo And Fornax Cluster Survey Teams, The Acs Virgo And Fornax Cluster Survey Teams ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 59~64
DOI : 10.5303/PKAS.2010.25.3.059
The core and global properties of the early-type ("red sequence") galaxies in the Virgo and Fornax clusters are examined using high-quality HST/ACS imaging for 143 galaxies. Rather than dividing neatly into disparate populations having distinct formation and/or evolution histories, many of the core and global properties of these galaxies show smooth and systematic variations along the galaxy luminosity function. The few examples of the rare class of compact elliptical galaxies in our sample all show properties that are strongly suggestive of tidal stripping by massive galaxies; if so, then these systems should not be viewed as populating the low-luminosity extension of so-called "normal" elliptical sequences. These results demonstrate that complete and/or unbiased samples are a pre-requisite for identifying the physical mechanisms that gave rise to the early-type galaxies we observe locally, and how these mechanisms varied with mass and environment.
A FULLY EMPIRICAL APPROACH TO GALAXY EVOLUTION
Renzini, Alvio ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 65~69
DOI : 10.5303/PKAS.2010.25.3.065
Observations of large samples of galaxies from low to high redshifts are composing a picture of remarkable simplicity: (1) The star formation rate (SFR) of starforming galaxies scales almost linearly with mass, strongly decline with cosmic time, and exhibits very small scatter around the average relation. (2) Due to the high observed SFRs the mass of galaxies at high redshifts must increase very rapidly, and yet the mass function of star forming galaxies evolves only very slightly with redshift. (3) At all redshifts the fraction of quenched (passively evolving) galaxies increases with galactic stellar mass and with local overdensity, with the remarkable property that the relative efficiency of "mass quenching" is independent of environment, and that of "environment quenching" is independent of mass. In a recent paper by the zCOSMOS collaboration, Peng et al. (2010) demonstrate that these three empirical facts suffice to account for the observed evolution of the galaxy mass function and naturally generate the "double-Schechter" mass function for quenched galaxies.
NUMERICAL SIMULATIONS OF GALAXY FORMATION
Peiran, Sebastien ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 71~76
DOI : 10.5303/PKAS.2010.25.3.071
The current status of numerical simulations of galaxy formation is reviewed. After a description of the main numerical simulation techniques, I will present several applications in order to illustrate how numerical simulations have improved our understanding of the galaxy formation process.
THE GALAXY-BLACK HOLE CONNECTION IN THE LOCAL UNIVERSE
Schawinski, Kevin ; Fellow, Einstein ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 77~82
DOI : 10.5303/PKAS.2010.25.3.077
Recent results from large surveys of the local universe show that the galaxy-black hole connection is linked to host morphology at a fundamental level and that there are two fundamentally different modes of black hole growth. The fraction of early-type galaxies with actively growing black holes, and therefore the AGN duty cycle, declines significantly with increasing black hole mass. Late-type galaxies exhibit the opposite trend: the fraction of actively growing black holes increases with black hole mass. Issues of AGN selection bias and prospects for near-future efforts with high redshift data are discussed.
HISTORY OF STAR FORMATION OF EARLY TYPE GALAXIES FROM INTEGRATED LIGHT: STELLAR AGES AND ABUNDANCES
Schiavon, Ricardo P. ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 83~90
DOI : 10.5303/PKAS.2010.25.3.083
I briefly review what has been learned from determinations of mean stellar ages and abundances from integrated light studies of early-type galaxies, and discuss some new questions posed by recent data. A short discussion of spectroscopic ages is presented, but the main focus of this review is on the abundances of Fe, Mg, Ca, N, and C, obtained from comparisons of measurements taken in integrated spectra of galaxies with predictions from stellar population synthesis models.
OBSERVATIONAL EVIDENCE OF MULTIPLE STELLAR POPULATIONS IN STAR CLUSTERS
Piotto, Giampaolo ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 91~99
DOI : 10.5303/PKAS.2010.25.3.091
An increasing number of observations have confirmed the presence of multiple stellar populations in Galactic globular clusters. Multiple populations evidence come from the complex chemical pattern of stars hosted in GCs and from the split or broadening of different evolutionary sequences in the color-magnitude diagrams. Multiple stellar populations have been identified in Galactic and Magellanic Cloud clusters, as well as in external galaxies. In this paper I will summarize the observational facts.
PANORAMIC VIEWS OF GALAXY CLUSTER EVOLUTION: GALAXY ECOLOGY
Kodama, Tadayuki ; Koyama, Yusei ; Hayashi, Masao ; Ken-ichi, Tadaki ;
Publications of The Korean Astronomical Society, volume 25, issue 3, 2010, Pages 101~105
DOI : 10.5303/PKAS.2010.25.3.101
Taking the great advantage of Subaru`s wide field coverage both in the optical and in the near infrared, we have been providing panoramic views of distant clusters and their surrounding environments over the wide redshift range of 0:4 < z < 3. From our unique data sets, a consistent picture has been emerging that the star forming activity is once enhanced and then truncated in galaxy groups in the outskirts of clusters during the course of cluster assembly at z < 1. Such activity is shifted into cluster cores as we go further back in time to z ~ 1.5. At z