Project:	Multiple Projects in Astrophysics
Disciplines:	Astronomy, Computer Science, Physics
Mentor:	Charles Steinhardt, Professor of Physics, (PMA), csteinhardt@missouri.edu, Phone: 609-672-9866
Background:	NOTE: This project is being offered by a Caltech postdoc alum and is open only to Caltech students. The project will be conducted at the University of Missouri in Columbia, Missouri. This is one of several projects available at the University of Missouri this summer, and we expect that in total 6-8 students (some from Caltech and some from elsewhere) will come to Columbia, MO. We have been running a similar program for a decade, previously in Copenhagen. Other projects in physics with different mentors will also be available. We hope to finalize who will be coming by mid-January, so that there will be plenty of time to both write a SURF proposal and find housing.
Description:	A range of projects in galaxy evolution and cosmology, ranging from observational to computational depending upon your background and interest. In addition, there is funding available for an entirely unrelated data science project. Much of the recent focus of the group has been on improved techniques for inferring the properties of high-redshift galaxies. Analysis of high-redshift galaxies can often only be done from very limited data, in many cases using only the colors of galaxies in very broad filters (called photometry). Everything we learn about these galaxies therefore comes from fitting models derived from local galaxies to photometric data. However, there are several good reasons to think that the first galaxies to form in the Universe actually aren’t exactly like local galaxies, and therefore we would need to use different models. A few related projects could include: 1) The James Webb Space Telescope has observed an increasingly large sample of very high-redshift galaxies. We can apply these new models for the first galaxies to determine their properties, hopefully also discovering unexpected features of the assembly and evolution of the first galaxies. 2) More locally, these same techniques have allowed us to develop improved models of star formation, including several papers SURF students have been involved in. One of the most surprising is that galaxies previously thought to be “dead” might instead be responsible for a majority of the star formation in the history of the Universe. Several different projects are possible to investigate this possibility. Another possible direction would involve recent observations suggesting the possibility that dark energy might not be a cosmological constant, but instead something more complex. 3) A recent SURF project found mathematical improvements in the techniques used for inferring cosmological parameters from a set of observational constraints. We would like to turn these into a code that can be released to the broader community, so that other groups can use these improved techniques. 4) The current “generic” version of a dynamical model for dark energy is not physically well motivated. Choosing a more natural model finds a somewhat difficult result, including the possibility of a preference for models in which the future of the Universe is far different than under the current concordance cosmological model. A next step would be to look for other consequences of this class of models, including possible observational tests that could falsify them. 5) If we observe the same object for an extended period of time, the redshift should be slowly evolving as the Universe expands. Measuring this cosmological redshift drift would be an independent probe of the composition of the Universe. However, the effect is very small, and proposals exist to perhaps measure this with an intensive effort over the next few decades. A possible project would be to try to design an experiment to measure the effect more quickly than current proposals.
References:	https://arxiv.org/abs/2205.11536 https://arxiv.org/abs/2205.14161 https://arxiv.org/abs/2206.01750 https://arxiv.org/abs/2208.07879 https://arxiv.org/abs/2301.01774 https://arxiv.org/abs/2402.03423 https://arxiv.org/abs/2404.03002 https://arxiv.org/abs/1907.04495
Student Requirements:	Variable, depending upon the project, but some computational background is strongly recommended. Some projects will be suitable for frosh, and others will require a more formal astronomy, physics, computer science, or even math background.
Programs:	This AO can be done under the following programs:   Program    Available To        SURF    Caltech students only  Click on a program name for program info and application requirements.