Team Members

Get to know us!

Galaxy with a purple circumgalactic medium, blue
	     accretion, and white outflows

Circumgalactic Medium Group

We are a growing group in the Homer L. Dodge Department of Physics and Astronomy at the University of Oklahoma led by Asst. Prof. Nikki Nielsen. We currently consist of 3 graduate students, 3 undergraduate students, and 2 incoming postdoctoral research associates.

We collaborate closely with astronomers around the world, including at Swinburne University of Technology in Australia, and US universities New Mexico State University and Pennsylvania State University.

The team regularly uses some of the largest telescopes in the world, including the twin Keck Observatory telescopes in Hawaii, the Very Large Telescope in Chile, and the Hubble Space Telescope.

Asst Prof Nikki Nielsen

Assistant Professor Nikki Nielsen

Dr Nielsen joined OU in August 2024. After obtaining her PhD at New Mexico State University in 2015, she was a postdoctoral resesarch associate in the Centre for Astrophysics and Supercomputing at Swinburne University of Technology in Melbourne, Australia. She then became the Swinburne ASTRO 3D Fellow in 2021, which was an independent fellowship funded by the Australian Research Council Centre of Excellence for All-Sky Astrophysics in 3 Dimensions.

Nikki's hobbies include knitting, gardening, baking, and consuming sci-fi and fantasy stories.

Postdocs

Dr
				      Sameer

Dr Sameer

Dr Sameer will be joining the group in August 2025!

He is currently a postdoc at the University of Notre Dame. He completed his PhD at Pennsylvania State University in 2022.

Website


Dr Grecco Oyarzun

Dr Grecco Oyarzún

Dr Oyarzún will be joining the group in September/October 2025!

He is currently a postdoc at Johns Hopkins University. He completed his PhD at the University of California, Santa Cruz in 2022.

Graduate Students

Imran Hossain

Imran Hossain

Imran is a 4th-year PhD student. His research focuses on the circumgalactic medium and quasar absorption lines, exploring how galaxies acquire and lose gas over cosmic time. He is specifically studying the kinematics of the cool CGM to understand how gas flow properties change with star formation rate.

Outside of research, Imran enjoys playing cricket, watching movies with his family, listening to classic rock, and reading short stories by Alice Munro and Haruki Murakami.

Kaitlyn Linder

Kaitlyn Linder

Kaitlyn is a 2nd year astrophysics PhD student. She is currently working with Keck/MOSFIRE spectroscopy to identify the host galaxies of cool CGM absorption at z=1-2.

Kaitlyn enjoys knitting, cooking, reading and unicycling.

Amisha Rane

Amisha Rane

Amisha just wrapped up her first year as a PhD student! She's broadly interested in how gas flows through the universe. During her Master's program, Amisha worked on analyzing and modeling methanol spectral lines toward ionized jet candidates in high-mass star-forming regions. Now she's expanding that passion to larger scales, studying the CGM to understand how galaxies acquire, recycle, and lose their gas.

Amisha genuinely loves working with telescopes – that hands-on experience is a big part of why she jumped at the chance to host star parties this past year. Outside of research, Amisha makes it a point to swim every day or at least try to! She absolutely loves vibing to music and dancing – it's her go-to way to unwind and reset!

Undergraduate Students

Jaden Cooper

Jaden Cooper

Jaden is a junior majoring in astrophysics, with interests in extragalactic astronomy and cosmology.

Jaden loves to stargaze, taking photos of the Moon and planets with her Celestron refractor telescope. She currently serves as the Treasurer for OU Women in Physics.

Isabella
				      Hildinger

Isabella Hildinger

Isabella is a junior astrophysics major.

She loves all things astronomy, and in her free time composes and plays a little piano.

Emily Thrun

Emily Thrun

Emily is a second year studying astrophysics and Japanese.

Outside of research, Emily works as a consultant at the OU Writing Center. She is passionate about music, and loves collecting vinyls and going to concerts.