Hee-Jong Seo

Hee-Jong Seo, portrait
Associate Professor
Clippinger 274, Athens Campus
Astrophysical Institute
Physics and Astronomy
seoh@ohio.edu
740-593-1714

News

Education

  • Ph.D. Astronomy, University of Arizona. Fall 2001 - Aug 2007
  • B.S. Astronomy, Summa Cum Laude, University of Arizona. Spring 1999 - Fall 2001
  • B.S. Physics, Summa Cum Laude, University of Arizona. Spring 1999 - Fall 2001
  • B. in Pharmacy, Pusan National University (South Korea). Spring 1990 - Spring 1994

Professional Membership

Research Interests

Dr. Seo's Google Scholar Page

Cosmology, galaxy surveys:

  • Baryon acoustic oscillations and redshift-space distortions from galaxy redshift surveys
  • Large scale clustering from cosmic shear
  • Mitigation of observational systematics in galaxy surveys using deep learning methods
  • Baryon acoustic oscillations from the 21cm intensity mapping.

My research interests are in high precision cosmology with large scale structure. I study the distributions of galaxies and matter on very large scales to infer how our Universe has expanded, what our Universe is composed of, and therefore to collect observational clues to identify dark energy and dark matter, which together makes up 95% of Universe while still being quite mysterious.

The main topics of my work involve the detection of the Baryon Acoustic Oscillations (BAO) from the large scale structure of galaxies and matter. This feature was formed in the very early, hot Universe by the sound waves propagated in the plasma of photons and baryons due to the interaction between photon pressure and gravity. The propagating sound waves have been frozen near the epoch of so called 'Recombination' when the baryons and photons are effectively separated.

The current distribution of galaxies and matter still trace the imprint of this primordial sound saves on very large scales. The true size of this feature is known quite accurately; therefore, by comparing the observed size and the known true size, we can estimate the distance to various cosmic epochs. This relation of distance to cosmic epoch encodes the expansion history of the Universe and therefore the properties of dark energy that drives the expansion faster and faster.

The enormous size of this feature (~0.5 billion light years) requires very large galaxy surveys, such as Baryon Oscillations Spectroscopic Survey (BOSS) which has been completed, producing a series of papers recently (https://sdss3.org//science/boss_publications.php), eBOSS (extended BOSS) which is ongoing , Dark Energy Spectroscopic Instrument (DESI) which will start in 2018.

I have been and am actively involved in all these missions.

Along with the BAO features, these surveys also intend to study the large scale streams of the galaxies (i.e, galaxies move around) to study the nature of Gravity, dark matter, and dark energy. My work involves various methods of analyzing the large scale structure of galaxies and matter, including analytical, numerical, observational studies, as a dark energy probe. I am also interested in relating observed galaxies to the underlying dark matter halo distributions, finding the upper limit on neutrino mass using the large scale structure, weak gravitational lensing signal of the dark matter distribution.

Synergistic Activities

  • Co-Convener for DESI Y1 BAO Key Project, Feb 2020 - Present
  • Co-Chair of the Galaxy Quasar Clustering Science Working Group for DESI, Feb 2017- Mar 2020
  • European Research Council: Starting Grant Panel, Peer Review Panels, 2020
  • Architect of SDSS-IV, July 2015-
  • Tiling coordinator for the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), July 2013-2019
  • Development of a public BAO forecasting code with Prof. Daniel Eisenstein, 2007

Selected Publications

Grants

  • “Improving Dark Energy Constraints Using Low-Redshift Large-Scale Structures,”DE-SC, (PI), 9/1/2022-4/30/2024, Department of Energy, Office of Science, Office of High Energy Physics, $150,000
  • “Optimal and robust reconstruction of BAO, redshift-space distortions and the Alcock-Paczynski effect,” DE-SC0019091 (PI), 9/2018-8/2023, Department of Energy, Office of Science, Office of High Energy Physics, Early Career Award, $750,000
  • “Improving Dark Energy Constraints Using Low Redshift Large Scale Structures,” DE-SC0014329 (Co-PI), 4/2018-3/2021, Department of Energy, Office of Science, Office of High Energy Physics, ($335,000)
  • “Improving Dark Energy Constraints Using Low Redshift Large Scale Structures,” DE-SC0014329 (Co-PI), 4/2017-3/2018, Department of Energy, Office of Science, Office of High Energy Physics, ($140,000)
  • “Improving Dark Energy Constraints Using Low Redshift Large Scale Structures,” DE-SC0014329 (Co-PI), 7/2015-3/2017, Department of Energy, Office of Science, Office of High Energy Physics, ($240,000)

Courses Taught

Undergraduate: Introduction to Physics: you can explain many of the everyday physical phenomena if you take this course *well*, Kinematics, Newton's laws, circular motions, fluids, thermodynamics; Fundamentals of Astrophysics: Introduction to celestial Mechanics, stellar astrophysics, telescope, galaxies, cosmology

Undergraduate/Graduate: Interstellar Medium and Galaxies: An advanced lecture focusing on galaxies and cosmology