PI: Andra Stroe (she/her, astroe@stsci.edu, STScI research profile, webpage under construction)
Group: You will be a founding member for a new STScI research group (named TBD), focused on understanding galaxy cluster physics through multiwavelength astronomy.
Project duration: 1-year rotation project for a graduate student, which could evolve into a full thesis project.
Background
Galaxy cluster mergers, the most energetic events since the Big Bang, represent an intermediate evolutionary stage between lower-density environments, such as fields and groups, and bona-fide, relaxed clusters, and thus provide an important missing link for how galaxies evolve as function of local density. Unlike relaxed clusters, which are dominated by passive ellipticals, merging clusters have large populations of highly-efficient, star-forming galaxies. The increase in star formation activity in disturbed, young, massive galaxy clusters could be triggered by interactions between gas-rich galaxies and shocks and/or the intra-cluster medium.
In Cairns et al. (2019), we completed the first survey for molecular gas in galaxies located in Antlia, nearest merging galaxy cluster. Given its proximity, Antlia has rich multi-wavelength data which give us an unprecedented view on the interaction between the large-scale disturbed environment and the cluster galaxies. We found that galaxies in the Antlia cluster have surprisingly large molecular gas reservoirs, which could fuel and sustain high star formation and black hole activities. In the Antlia cluster, we might be seeing the intermediate step in the evolution of galaxies between fields and dense clusters, where the effects of the intracluster medium are just beginning to operate.
Project description
Are galaxies in merging clusters just beginning to experience ram pressure? Or are they interacting with a cluster-wide process triggering star-formation and black hole activity, such as a large-scale shock or turbulence caused by the disturbed cluster environment? Are galaxies interacting more with each other because of the dense environments? You will explore already awarded ALMA and SMA observations to spatially resolve the molecular gas reservoirs in Antlia galaxies and test whether typical environmental effects, such as ram pressure stripping, operate at intermediate cluster evolution stages. You will look for signs of gas removal and/or galaxy-galaxy interactions and unveil the physical mechanism at play in disturbed galaxy clusters and compare to the more evolved Fornax cluster and field star-forming galaxies.
You will work with PI Dr. Andra Stroe (Associate Astronomer at STScI) and collaborate with fantastic staff, postdocs, and students from both STScI and JHU, including experts in galaxy evolution and black hole physics, such as Drs. Katey Alatalo, Kate Rowlands, and Andreea Petric, as well as collaborators at other institutes in the US and abroad. You will have the opportunity to work on topics related to galaxy evolution, interstellar medium physics and cluster astrophysics and apply a number of techniques, including statistical methods, radio/sub-mm interferometry, 3D spectroscopy, as well as get familiarized with multiwavelength observations and Python coding as part of the project. With the required sub-mm datasets already in hand (ALMA and SMA, PI Stroe), you will be able to quickly progress towards achieving the goals of the project. Full financial support is available for one year, covering JHU tuition, salary and benefits, conference travel, a laptop, and publication charges.
Planned work
- Get familiar with the relevant literature, data, methods and tools, including concepts of radio/sub-mm interferometry and specific tools used for radio astronomy (e.g. CASA).
- Compile any archival ground-based and Hubble imaging and available measurements of galaxy properties
- Reduce the SMA observations and reprocess the ALMA data to optimize for the science goals, and produce high-level science products including CO maps and cubes.
- Search for signatures of disturbance in the molecular gas reservoirs in the sub-mm data
- Spearhead a comparative analysis of the molecular gas distribution and the galaxy morphologies (from Hubble or ground-based observations) as a function of galaxy mass and star-formation, black hole activity, local environment, and compare with studies of relaxed clusters from the literature
- Write and publish one paper and present the results at an international conference.
- Release the ALMA and SMA cubes and maps of molecular gas lines, and galaxy property catalogs for the Antlia star-forming galaxies on a public facing repository.
