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Research Areas

Cosmology

Questions

  • How did our Universe begin? How did our Universe evolve into the current state? What will be the fate of the Universe?
  • What is dark energy? How does it evolve? Is the Cosmological Constant an accurate model for dark energy?
  • What is dark matter? How does it affect the astronomical observables on all scales?
  • Are there systematic errors in the extragalactic distance scale and the Hubble Constant?
  • What is the expansion history of the universe?
  • How did the first galaxies and quasars form and evolve? What are the observational signatures of these first luminous objects?
  • How did the stars and galaxies we know today arise from the initial conditions of the Big Bang, and how did the process of Cosmic Reionization unfold?
  • What are the properties of the supermassive black holes that power the most distant quasars? How did they form at the cosmic dawn?
  • What is the relationships between supermassive black holes and host galaxies?

Discoveries and Milestones

  • Don Schneider played a leading role in the development of the Sloan Digital Sky Survey Catalog, which contains over 105,000 spectroscopically-confirmed quasars found during the first two phases of the Sloan Digital Sky Survey (1999-2008).
  • Yuexing Li has pioneered the numerical modeling of the formation, evolution, and multi-band properties of the most distant galaxies and quasars by combining multi-scale cosmological simulations with multi-wavelength radiative transfer calculations. She has developed essential models of quasar formation, as well as a comprehensive radiative transfer code ART2 ,which has a wide range of applications in modeling both continuum and emission lines from galaxies and quasars.
  • Derek Fox and collaborators discovered the most distant gamma-ray burst at redshift z=8.2, when the Universe was only a few hundred million years old.
  • Robin Ciardullo pioneered the technique of using the Planetary Nebulae Luminosity Function for extragalactic distance measurements, which is only method that can be applied to all large galaxies within ~ 20 Mpc, regardless of Hubble type or stellar population.
  • Donghui Jeong pioneered the dark-matter origin of sub-solar mass black holes, whose binary coalescence can imprint a distinctive signature in LIGO/Virgo/Kagra gravitational-wave observatories. If 0.1-0.001 percent of dark matter is locked in the black holes, we should be able to detect them with current facilities.
  • Joel Leja’s research team plays a leading role in modeling the early universe with JWST, including exotic objects like very massive galaxies and the first black holes. His team recently took deep JWST spectroscopy to discover and confirm the second most distant galaxy observed to date.

Current Projects

  • The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) galaxy survey is currently 70 % complete and will measure dark energy density between 1.9 < z < 3.5, which will be an earliest ever measurement of the mysterious entity. Robin Ciardullo, Caryl Gronwall, Donghui Jeong, and Don Schneider are playing an important role in the data taking and analysis of the survey.
  • Yuexing Li is conducting computational work to investigate the formation of the first quasars, accretion onto black holes, Lyman-alpha emission from high-redshift galaxies, fossils of the first black holes and galaxies in the Milky Way, and large-scale structure formation.
  • Don Schneider uses data gathered by the Sloan Digitial Sky Survey, the Chandra satellite, and the Hobby-Eberly Telescope to investigate the properties of active galactic nuclei and the large-scale properties of the universe.
  • Donghui Jeong is studying cosmologically viable scenarios for sub-solar mass black hole binary formation, including both Fermionic and Bosonic dark matter as well as primordial black holes.
  • Robin Ciardullo is using integral field unit spectrographs to extend Planetary Nebula Luminosity Function measurements to distances of almost 40 Mpc. Such data can be used to obtain a ~ 4 % Hubble Constant measurement that is independent of the Cepheid calibration of Type Ia supernova. The goal of this program is to address the current tension between measurements of H0 made locally and that determined from the microwave background (under the assumption of a Cosmological Constant).
  • Joel Leja combines large-scale Bayesian and machine learning techniques with models for stars, gas, dust, and black holes, and compares them with deep (JWST) and wide (SDSS, upcoming PFS) surveys of the universe, with the ultimate goal of understanding the formation and evolution of galaxies.

Participants

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