“Galaxies formation theory and observation research” wins first prize of Shanghai natural and science awards

  

 

   On Mar.24, 2010. Shanghai science and technology awards conference was hold in shanghai exhibition center. Conference was presided by SHANGHAI Mayor Han Zheng. Party secretary Yu Zhengsheng attended and gave key speech. “Galaxies formation theory and observation research”, recommended by Shanghai Astronomical Observatory, wins first prize of Shanghai natural and science awards.

   This project was finished in Shanghai Astronomical Observatory and the principal achievers are Yipeng JING, Donghai ZHAO, Cheng LI, Xi KANG and Weipeng LIN. The project is focused on studies of galaxies and cosmology in the field of astrophysics. Many physical processes including accretion and mergers of dark matter haloes, cooling and condensation of gas, formation of stars, and growth and feedback of black holes are believed to play decisive roles in galaxy formation and evolution. They are, however, closely coupled. Quantitatively predicting and understanding these processes are therefore very important and challenging tasks in studies of astrophysics. Using high-resolution numerical simulations and observational data from large galaxy redshift surveys, this project has made a systematical study of the relationship between the formation of galaxies and their environment. Some of the major representative results of the project are, (1) we found that the mass assembly history of dark matter haloes consists of two phases which are distinct in their physical characteristics: an early phase of fast growth and a late phase of slow growth. The concentration parameter of dark matter haloes remains a constant during the early fast phase as matter within haloes mixes rapidly through violent relaxation while it increases steadily with time during the slow phase because the newly-accreted matter is mostly added into the outskirt. A scaling relation between the concentration of dark haloes and their growth history, and a method of accurately predicting the structure of dark haloes are proposed. (2) By tracing the motion and evolution of dark matter subhaloes resolved in high-resolution cosmological simulations, we show that the merger time scale of galaxies in previous semi-analytical models for galaxy formation was underestimated by a factor of two or so. The semi-analytic model with the corrected merger time scale can better reproduce the observed abundance and color of massive galaxies, helping solve the long-standing problems in previous studies. The formation of massive red galaxies in the early Universe can be naturally explained by including physical models of formation and energy feedback of supermassive black holes. The semi-analytic model of galaxy formation was thus developed in which galaxy mergers and black hole formation are treated in a reasonable and careful way. (3) Using a set of N-body/SPH cosmological simulations, we self-consistently study for the first time the influence of physical processes of baryonic matter on the dark matter distribution overall as well as within dark matter haloes. The effect of these processes on the forecast accuracy of future weak-lensing experiments is quantified. (4) Using data from galaxy redshift surveys, we extensively study the connection between the physical properties of galaxies and their surrounding environment. We found that the pairwise velocity dispersion of galaxies exhibits a non-monotonic dependence on galaxy luminosity. For the first time, the clustering strength of galaxies is accurately measured as a function of their stellar mass. The dependences of the clustering on many other important physical properties of galaxies were obtained.

   During a relatively short period between 2003 and 2006, 42 papers have been published with this project in SCI journals, of which 19 were in Astrophysical Journal, 20 in Monthly Notices of Royal Astronomical Society, 2 in Astronomy and Astrophysics, and 1 in Astronomical Journal. These papers are of high impact in the international community, with 846 independent citations by SCI papers. By Jan. 15, 2010, there have been 312 citations for the 8 representative papers and 107 for the most cited one. All these numbers are still growing rapidly. The results produced by this project have been included in the famous textbook Galactic Dynamics (2nd edition) to demonstrate the correlation of the structure of dark matter haloes with their formation history, were reviewed by NEWS & VIEWS of the Nature Physics as “Some of the semi-analytical models of galaxy formation are become powerful tools in their own right”, were quoted by ESA/ESO in their white paper for the long-term planning in the next fifteen years and by the LSST project in its science book as the strong evidence that the influence of baryonic matter cooling must be properly taken into account in future weak-lensing observations, and finally were taken as important observational measurements for testing theoretical models and for comparisons with other observations (e.g. “a high-quality reference to which high-redshift measurements can be compared to test evolution” as said by the deep galaxy survey working group of the VLT, currently the largest optical telescope of the world). The results of this project were also included in 《10 years: a selection of achievements of the 973 program》(the 973 program is the biggest national key program in basic sciences in the last ten years) by the Ministry of Science and Technology, which is the only project selected in the field of astrophysics.

   Because of the outstanding success of the project, it was awarded “Top 10 Astronomical achievements in China” of 2009.  


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