Multi-wavelength Investigations of Galaxy-Hot Plasma Interactions in Clusters of Galaxies

2014 Fiscal Year Annual Research Report

• Project/Area Number: 25887013
• Research Institution: The University of Tokyo
• Principal Investigator: 顧 力意 東京大学, 理学(系)研究科(研究院), 研究員 (20713308)
• Project Period (FY): 2013-08-30 – 2015-03-31
• Keywords: X-ray astrophysics / optical astronomy / cosmology / plasma physics / 国際研究者交流

Outline of Annual Research Achievements

We have continued and extended the research topic, the cosmological infall of galaxies into the centre of galaxy clusters (originally proposed by Makishima et al. 2001), by carrying out a much more comprehensive study on the three main mass components i.e., galaxies, hot ICM, and dark matter, in the galaxy clusters.
In collaborating with optical astronomers (Prof. Han and Dr. Wen) in National Observatory of China, we compiled a sample of 340 galaxy clusters in redshift range of 0.1-0.5. The size of the sample is 10 times as the one used in Gu et al. (2013). In this work I played a central role in analyzing both X-ray and optical data. We have detected, following Gu et al. (2013), a significant evolution on a cosmological timescale: galaxies have been centrally concentrated with time relative to the ICM and dark matter, while the ICM has been expanding compared to dark matter even they keep radiating. This evolution is not solely driven by gravitational effects such as dynamical friction between galaxies and cluster matters. The result will be submitted soon to the Astrophysical Journal.

References: Makishima, K. et al. 2001, PASJ, 53, 401; Gu, L. et al. 2013, ApJ, 767, 157; Gu, L. et al. 2014, in prep.

Research Progress Status

26年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

26年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Discovery of nine extended ionized gas clouds in a z=0.4 cluster (2015)
  • Author(s): Yagi, M., Gu, L., Koyama, Y., Nakata, F., Kodama, T., Hattori, T., Yoshida, M.
  • Journal Title: Astronomy Journal Volume: in press Pages: in press
  • Peer Reviewed
• [Presentation] the Important Role of Dark Matter Halo in Retaining Hot Gas Content in Early-Type Galaxies (2014)
  • Author(s): Su, Y., Irwin, J., White, R., Buote, D., Gu, L.
  • Organizer: American Astronomical Society, HEAD meeting
  • Place of Presentation: Chicago, US
  • Year and Date: 2014-08-17 – 2014-08-21
• [Presentation] Probing of Interactions between the Hot Plasmas and Galaxies in Clusters over a Cosmological Timescale (2014)
  • Author(s): Gu, L., Makishima, K.
  • Organizer: X-ray Universe 2014
  • Place of Presentation: Dublin, Ireland
  • Year and Date: 2014-06-16 – 2014-06-19