2008.4 ~ 2009.3

The astrophysics and cosmology group of Korea Institute for Advanced Study consists of Prof. Changbom Park, and six research fellows. Prof. Park has organized a Korean Scientist Group (KSG) to participate in the new international consortium for the Sloan Digital Sky Survey III (SDSS-III). This survey is a legacy survey of the previous SDSS survey. KIAS, in partnership with ARCSEC of Sejong University, has joined the SDSS-III in March, 2008. The new survey will continue through 2014, and consists of the massive survey of high-redshift luminous red galaxies (BOSS), structure, dynamics and chemical evolution study of the Milky Way Galaxy (SEGUE-II, APOGEE), and the search for exoplanets (MARVELS).

Individual members of the astrophysics and cosmology group have been active in his/her research in 2008. Dr. Yun-Young Choi and Prof. Park have studied the effects of environments, namely, the nearest neighbor galaxy and large-scale density, on the galaxy properties using the SDSS data. They have also studied the effects of the host galaxy and large-scale background density on the satellite galaxies in isolated galactic satellite systems. They measured the topology of the large-scale distribution of the luminous red galaxies observed by the SDSS. An astonishing agreement between the observed genus and the genus from a LCDM model simulation was found. Dr. Choi moved to ARCSEC in Sejong University.

Dr. Juhan Kim and Prof. Park have run the Horizon Run N-body Simulation, the biggest cosmological N-body simulation till date, on a supercomputer at Korea Institute for Science and Technology Information. The evolution of matter fluctuation is shown from the present epoch all the way out to the horizon (the Big bang surface) for the first time. Massive dark matter halos are identified for a comparison with observations of the forthcoming BOSS of the SDSS-III project. The simulation is used to accurately measure the non-linear systematic effects such as gravitational evolution, redshift space distortion, past light cone space gradient, and galaxy biasing, and to calibrate the baryon oscillation scale and the genus topology. Dr. Kim moved to CITA in University of Toronto in Aug. 2008.

Dr. Prava Chingangbam studied models of inflation which give rise to features in the primordial power spectrum. It was found that a particular model, motivated by MSSM in particle physics, with potential having an inflection point provides a much better fit to CMB data compared to the usual power-law spectrum, particularly for the low multipoles. She also worked on possible scenarios where the amplitude of curvature perturbation on super-horizon scales can be modified during reheating. Further, she has calculated the trispectrum in axion-type curvaton model and found that it can be relevant for non-Gaussianity in the CMB. Dr. Chingangbam and Prof. Park developed codes for simulation of non-Gaussian CMB maps and are computing Minkowski Functionals from these maps. She gave a series of lectures on cosmological perturbation theory and a seminar at National Taiwan University.

Dr. Ho Seong Hwang and Prof. Park studied the effects of galaxy-galaxy and galaxy-cluster interactions on galaxy properties, and found that the galaxy-galaxy interaction has been one of the main driving causes for galaxy evolution in the cluster environment and also at high redshifts. The SDSS galaxies in the massive Abell clusters, and high redshift (z<1) galaxies in the Hubble Space Telescope archival data and ground-based spectroscopic data, were used. They investigated the kinematics of satellite galaxies using the SDSS data.

Dr. Young-Rae Kim and Prof. Park are continuing their research on topology and large scale structure as a probe of cosmology. They have formulated the estimated genus value at a given cosmology by using a volume factor with respect to a reference cosmology and genus values at scaled smoothing length for the new cosmology and the reference smoothing length. They estimated how well their method can constrain cosmology once SDSS-III is completed. They are now using the Horizon Run to measure the non-linear corrections and calibrate their analysis.

Dr. Pascale Hibon has joined KIAS astrophysics group in June 2008. She has been searching for high redshift (z=7.7) Lyman-alpha Emitters from Narrow-Band Imaging Survey. She visited NAOJ in Sept. 2008, where she created a new collaboration, resulting in two new observational projects. Dr. Pascale Hibon and Prof. Park have also been investigating the interactions of galaxy-galaxy pairs using the GOODS data.

Dr. Graziano Rossi, who joined KIAS astrophysics group in Sept. 2008, studied the statistics of the cosmic microwave background fluctuations such as the higher order correlations and peak statistics using the five-year WMAP data. He also worked on deconvolution techniques for galaxy scaling relations and statistical estimation problems.


  1. Adelman-McCarthy, J. K. et al., The Sixth Data Release of the Sloan Digital Sky Survey, 2008, ApJS, 175, 297
  2. Hwang, Ho Seong, & Lee, M. G., Galaxy Orbits for Galaxy Clusters in Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey, 2008, ApJ, 676, 218
  3. Kim, Juhan, Park, Changbom, & Choi, Y.-Y., A Subhalo-Galaxy Correspondence Model of Galaxy Biasing, 2008, ApJ, 683, 123
  4. Cervantes-Sodi, B., Hernandez, X., Park, Changbom, & Kim, Juhan, Environment and mass dependencies of galactic λ spin parameter: cosmological simulations and observed galaxies compared, 2008, MNRAS, 388, 863
  5. Ann, H. B., Park, Changbom, & Choi, Yun-Young, Galactic satellite systems: radial distribution and environment dependence of galaxy morphology, 2008, MNRAS, 389, 86
  6. Lee, J. H., Lee, M. G., Park, Changbom, & Choi, Y.-Y., The nature of the Sloan Digital Sky Survey galaxies in various classes based on morphology, colour and spectral features - I. Optical properties, 2008, MNRAS, 389, 1791
  7. Park, Changbom, & Choi, Yun-Young, Combined Effects of Galaxy Interactions and Large-Scale Environment on Galaxy Properties, 2009, ApJ, 691, 1828
  8. Cho, J., & Park, Changbom, Internal Extinction in the SDSS Late-Type Galaxies, 2009, ApJ, 693, 1045
  9. Wang, Y., Park, Changbom, Yang, X., Choi, Yun-Young, & Chen, X., Alignment between the host and the nearest neighbor Groups, 2008, ApJ, submitted (arXiv0810.3359)
  10. Kim, Juhan, Park, Changbom, Gott, J. R., & Dubinski, J., The Horizon Run N-body Simulation: Baryon Acoustic Oscillations and Topology of Large Scale Structure of the Universe, 2008, ApJ, submitted (arXiv0812.1392)
  11. Gott, J. R., Choi, Yun-Young, Park, Changbom, & Kim, Juhan, 3D Genus Topology of Luminous Red Galaxies, 2008, ApJ, submitted (arXiv0812.1406)
  12. Jain, R. K., Chingangbam, Pravabati, Gong, J. O., Sriramkumar, L. & Souradeep, T.,  Punctuated inflation and the low CMB multipoles, 2008, JCAP, in press, astro-ph/0809.3915
  13. Jain, R. K., Chingangbam, Pravabati & Sriramkumar, L., Reheating in tachyonic inflationary models: Effects on the large scale curvature perturbations, 2008, JCAP, submitted, astro-ph/0902.1067
  14. Chingangbam, Pravabati and Huang, Q.G., The curvature perturbation in the axion-type curvaton model, 2009, JCAP, accepted, astro-ph/0902.2619
  15. Ko, J., Im, M., Lee, H. M., Lee, M. G., Hopwood, R., Serjeant, S., Smail, I., Hwang, H. S., Hwang, N., Shim, H., Kim, S. J., Lee, J. C., Lim, S., Seo, H., Goto, T., Hanami, H., Matsuhara, M., Takagi, T., Wada, T., The Mid-infrared View of Red Sequence Galaxies in Abell 2218 with AKARI, 2009, ApJL, accepted
  16. Park, Changbom & Hwang, Ho Seong, Interactions of Galaxies in the Galaxy Cluster Environment, 2008, ApJ, submitted (arXiv0812.2088)
  17. Hwang, Ho Seong, & Lee, M. G., Galaxy Activity in Merging Binary Galaxy Clusters, 2008, MNRAS, submitted
  18. Choi, Y.-Y., Woo, J.-H., & Park, Changbom, Environment Dependence of AGN Activity. I: The Effects of Host Galaxy, 2008, ApJ, submitted
  19. Lee, J. H., Lee, M. G., Park, Changbom, Choi, Y.-Y., The Nature of the SDSS Galaxies in various classes based on morphology, colour and spectral features - II. Multi-wavelength properties, 2008, MNRAS, submitted
  20. Hernandez-Toledo, H. M., Martinez-Vazquez, J. A., Choi, Y.-Y., & Park, Changbom, The UNAM-KIAS Catalog of Isolated Galaxies, 2008, ApJ, submitted
  21. Hwang, Ho Seong, & Park, Changbom, Evidence for Morphology and Luminosity Transformation of Galaxies at High Redshifts, 2008, ApJ, submitted

Presentations at Meetings

  1. Park, C., The New Era of Large-Scale Survey of the Universe, Korea Astronomical Society Meeting, KIAS, Seoul, Apr. 11, 2008 (opening plenary talk)
  2. Hwang, H. S. (speaker), Lee, J. C., Lee, M. G., Serjeant, S., Nakagawa, T., Jeong, W.-S., Pearson, C., Progress Report of AKARI NIR Spectroscopy of Ultraluminous Infrared Galaxies at Intermediate Redshift, Korea Astronomical Society Meeting, KIAS, Seoul, Apr. 11, 2008
  3. Kim, Juhan (speaker), & Park, Changbom, Cosmological N-body Simulation Powered by the Graphics Processing Unit -- I. A Progress Report, Korea Astronomical Society Meeting, KIAS, Seoul, Apr. 11, 2008
  4. Park, C., Dark Energy Constraints from the Large Scale Structure of the Universe, Korean Physics Society Meeting - International session, Daejeon, Apr. 17, 2008 (invited)
  5. Park, C., Effects of Interactions and Large-Scale Environment of Galaxy Properties, East Asian Young Astronomers Meeting 2008, Jiayugwan, China, Jul. 30, 2008 (invited)
  6. Park, Changbom, Galaxy-Galaxy Interactions in the General Environment and Clusters of Galaxies, An International Symposium. The Sloan Digital Sky Survey: From Astroids to Cosmology, The Kavli Institute for Cosmological Physics, Chicago, USA, Aug. 15-18, 2008
  7. Hwang, H. S. (speaker), Park, C., Effects of Galaxy-Galaxy Interaction on Morphology and Luminosity of High redshift Galaxies, Korea Astronomical Society Meeting, Gyungju, Oct. 10, 2008
  8. Hwang, H. S., & Park, C., Kinematics of Satellite Systems of Galaxies: Prograde and Retrograde Motion, Korea Astronomical Society Meeting, Gyungju, Oct. 10, 2008 (poster)
  9. Choi, Y.-Y. (speaker), Park, C., Woo, J.-H., Environmental Dependence of AGN Activity. I: The Effects of Host Galaxy, Korea Astronomical Society Meeting, Gyungju, Oct. 10, 2008
  10. Ann, H. (speaker), Park, C., Choi, Y.-Y., Morphology Conformity in Galactic Satellite Systems, Korea Astronomical Society Meeting, Gyungju, Oct. 10, 2008
  11. Park, C., How galaxy interaction and large-scale environment jointly determine galaxy properties?, Korea Astronomical Society Meeting, Gyungju, Oct. 10, 2008
  12. Kim, Y.-R. (speaker), & Park, C., Cosmological Parameter Estimation from Large Scale Structure Topology, Korea Astronomical Society Meeting, Gyungju, Oct. 10, 2008
  13. Park, C., Spatial and Temporal Environmental Effects on Galaxy Properties, KIAS Workshop on Cosmology and Structure Formation, KIAS, Oct. 27-28, 2008
  14. Park, C., Cosmology from Topology of Large Scale Structure of the Universe, RESCEU Symposium on Astroparticle Physics and Cosmology, The University of Tokyo, Tokyo, Japan, Nov. 11-14, 2008 (invited)
  15. Rossi, G., Peak Statistics in the WMAP Sky: Non-Gaussianity?, RESCEU Symposium on Astroparticle Physics and Cosmology, The University of Tokyo, Tokyo, Japan, Nov. 11-14, 2008
  16. Rossi, G., Hunting for non-Gaussianity: Clustering Statistics in the WMAP5 Sky, 24th Texas Symposium on Relativistic Astrophysics, Vancouver, Canada, Dec. 8-12, 2008
  17. Hwang, H. S. (speaker), & Park, C., Environment Dependent Evolution of High-redshift Galaxies, American Astronomical Society Meeting, Long Beach, USA, Jan, 5, 2009
  18. Park, C., Galaxy Properties in Dark Matter Halo Evironments, The 8th Sino-German workshop on the tumultuous lives of gaalxies, supermassive blackholes and their dark halos, Kunming, China, Feb. 23-28, 2009 (invited)
  19. Rossi, G., Primordial non-Gaussianity in the CMB: Theoretical and Observational Challenges, Workshop on Connecting Fundamental Physics with Observations, Kavli Institute for Theoretical Physics (KITCP), Beijing, China, Feb. 16 - Apr. 30 (invited)