Letters of Intent received in 2019

LoI 2021-2075
GA Focus Meeting: Galaxy evolution in clusters

Topics

1.Galaxy evolution in various environments
2.Galaxy cluster surveys
3.Galaxy cluster simulations
4.Numerical techniques
5.Cluster formation and evolution in the cosmological context
6.Interplay between dark matter and baryon particles

Rationale

The cluster environment is an important driver of galaxy evolution. The high density of galaxies and surrounding medium can leave great impacts on galactic properties as revealed by much observational evidence accumulated to date. Thanks to both new observations and the progress in simulations, our understanding of the physics behind environmentally-driven galaxy evolution has been improved for the last few decades. At the same time, however, further challenges are emerging as we look deeper, and the answers to where and how galaxies are affected in clusters still depend on the wavelength of the data and the simulation tool in hand. Therefore, we propose a focused meeting among observers and theorists to get a more comprehensive understanding of galaxy evolution in the cluster environment. There has not been an IAU conference or focused meeting on this topic in the last 10 years. The closest one was Focused Meeting 22 in 2015 GA on “The Frontier Fields: Transforming our understanding of cluster and our understanding of cluster and galaxy evolution”. Following are the key topics to be discussed in this meeting.

1)A panchromatic view of cluster galaxies: Brand new instruments and telescopes are now allowing for the large surveys of galaxy clusters with good resolution in a broad range of wavelengths from radio to X-ray (e.g., CLASH-VLT, GASP, GOGREEN, HeViCS, HiFLUGS, HSC SSP, LoCuSS, NGVS, VERTICO, VESTIGE, VIVA, WINGS). However, surveys are still time consuming and in-depth studies on coherent samples are yet limited in the number of galaxies and/or in the range of wavelengths. This meeting aims to bring cluster galaxy survey communities of various wavelengths together to better understand the detailed evolutionary processes in the cluster environment, i.e. from gas stripping to consequent star formation quenching.

2)Theoretical perspectives: The recent progress in large-volume simulations (e.g., Eagle, Horizon-AGN, and Illustris) and cluster simulations (e.g., Cluster-Eagle, Romulus-C, and YZiCS) has been greatly helpful in understanding what galaxies may undergo in the cluster environment, yet there are still compromises to be made due to computing power and numerical techniques. This meeting aims to discuss how different simulation tools handle various galactic components in distinct scales from individual galaxies to clusters, and what should be improved to leverage our current understanding.

3)The real vs. the virtual universe: With recent progress from both sides, it will be very timely for observers and theorists to get together to discuss the next challenges and future directions in this field. Simulators must go from gas density and temperature, and stellar mass and ages to mock observations, while observers must use limited wavelength data to deduce inherent galaxy properties (such as mass) and formation history (such as stripping timescales). Understanding the assumptions and limitations of either process is critical for useful interactions between the observational and theoretical community.