PI: Nimisha Kumari (PI website)
Duration: 9 months
Description:
One of the frontier goals of observational cosmology is to understand the epoch of reionization (Fig 1, Robertson+2010) and its connection to the early star-forming galaxies. It is a popular belief that metal-poor dwarf galaxies were either the primary source or at least resemble those sources of ionizing photons that led to the reionization of the Universe. Characterizing the properties of the interstellar medium (ISM) of these metal-poor dwarfs is essential to understand the pristine conditions which existed within the first galaxies. Integral Field Spectroscopy is a very powerful technique combining imaging and spectroscopy that allows us to map the properties encoded in the emission lines emanating from the ionized gas within galaxies and hence perform a detailed spatially-resolved study. The technique has been used via integral field units (IFU) within several world-class ground-based and space-borne telescopes (e.g., Keck, VLT, JWST). The proposed project involves the analysis of the IFU data of a few dwarf galaxies to map the physical and chemical properties of the ISM. The project is timely because of the link between the dwarf galaxies and reionization-era galaxies, which are being routinely observed with the recently-launched JWST (Robertson+2022).
Fig 1 (Robertson+2010) shows the cosmic history. This project focuses on dwarf galaxies which are similar to sources that reionized the Universe.
Data: Proprietary IFU data from ground-based telescopes.
Student's work: The work mainly includes reducing the IFU data, creating emission line maps, and then analyzing them. The analysis will include mapping different physical properties of the ionized gas (both dense and diffuse, Kumari+2019a), such as extinction, electron temperature, density, chemical abundances, and velocity fields. These maps will allow us to characterize the properties of the ISM of dwarf galaxies sample, and then study their spatial variation and correlation (e.g. Kumari+2017, 2018, 2019b) to go beyond characterization and understand more global phenomena via comparison with early star-forming galaxies discovered with JWST.
All the tools required to do the work already exist, which include the publicly-available data-reduction pipeline and some of the codes which I have written myself. The student may need to modify the tools. Familiarity with python and idl will help the student to progress quickly. However, I am mainly looking for an enthusiastic student who is keen to learn. My collaborators and I will be available to help.
Publications: At least one refereed article is expected from the project. The student will be the lead author.
