Extreme galaxies and extreme environments have long served as key benchmarks for models of galaxy formation. The mere existence of such galaxies and environments creates significant challenges to physical models of galaxy formation, as such models must be able to explain the formation of “normal galaxies” in “normal environments” as well as the extreme tail of the galaxy and environmental distribution.  For example, massive and quenched/strongly star-forming galaxies have long placed significant constraints on quenching models.  Likewise, the existence of proto-clusters containing both strongly starbursting and quenched galaxies are forcing us to reevaluate the effect of environment on galaxy evolution at high redshift.  Studies at 1 < z < 2 have raised a host of new questions about galaxy evolution that can only be answered by turning our gaze to even higher redshift.  Fortuitously, the coming of observatories such as JWST, ALMA and the upcoming Euclid and Roman Missions are opening up the study of the z > 2 universe with large surveys that make possible the study of extreme galaxies and extreme environments at the very highest redshifts.  The goal of this meeting is to bring together theoreticians and observational astronomers working on extreme galaxies in extreme environments at z > 2 to summarize the state of these fields and discuss how they are pushing forward our understanding of the physics of galaxy formation.

This 5-day meeting will focus on 4 key themes under the general topic of extreme objects. The four topics that will be discussed in the meeting are: 

1. Extreme galaxies: Massive galaxies, dusty-star-forming galaxies, high/low mass quiescent galaxies, AGN, and other extreme objects

2. Extreme environments: Proto-clusters, galaxy overdensities, and voids

3. Extreme galaxies in extreme environments: Is the evolution of extreme galaxies and environment linked at high-redshift and if so, how? 

4. The evolution with time of extreme galaxies and environments: How do these extreme environments/objects connect to lower-redshift descendants (z < 2) and what does this tell us about the physics of galaxy formation? 

The “extreme” landscape and environment of Iceland should provide the ideal backdrop for lively discussion and debate!

We envisage an engaging and lively meeting in which we discuss the status, challenges and prospects for these specific areas of galaxy evolution. We also envisage intense discussion/brainstorming sessions to summarize where we are, what we do not understand, what is controversial and how we can make progress in the next few years.

This is meant to be a mid-sized conference with ~100-120  participants.