Khee-Gan Lee


As of October 2015, I have moved to Lawrence Berkeley National Lab as a Hubble Fellow. Please see my new homepage.

I am a postdoctoral researcher in the Galaxies and Cosmology department at the Max Planck Insitute for Astronomy. in Heidelberg, Germany. Previously, I did my PhD in Princeton University and my undergraduate studies in University College London.

Research Interests

My research focuses on using the Lyman-alpha forest absorption in the line-of-sight to distant quasars and galaxies to study the intergalactic medium and associated large-scale structure.

I am the Principal Investigator of the COSMOS Lyman-Alpha Mapping And Tomography Observations (CLAMATO) survey, which will use faint star-forming galaxies (LBGs) as background lightsources to study the Lyman-alpha forest. LBGs are much more common than the quasars traditionally used for Lyman-alpha forest analysis, and at a magnitude limit of g<24 are separated by only ~3Mpc/h on the sky. This will allow us to `tomographically' reconstruct the 3D distribution of the absorbing gas --- since this traces large-scale structure, we will provide the first direct 3D maps of the z~2 Universe.

(Left) Smoothed 3D Lyman-alpha forest absorption field from a N-body simulation. (Right) Tomographic reconstruction using a set of 1D sightlines probing the same simulated volume, with noise properties expected from CLAMATO.
A whole bunch of CLAPTRAP

CLAMATO will yield a rich and unique set of science results. It will allow the characterization of z~2 galaxy properties (morphology, star-formation, metallicity etc) as a function of their large-scale gas environment. We also hope to identify progenitors of present-day massive galaxy clusters through intersections of the cosmic web. The data will also be powerful for Lyman-alpha forest correlation analysis: we will be able to measure the 3D Lyman-alpha forest auto-correlation at <10Mpc/h scales, which is sensitive to neutrino mass. The cross-correlation between the Lyman-alpha forest with, e.g., Type-2 AGN, LAEs, sub-MM galaxies etc will yield bias estimates for these objects.

Other than CLAMATO, I am also part of the Baryonic Oscillations Sky Survey (BOSS) collaboration. My interest has been on studying the global statistics of the BOSS Lyman-alpha forest data set to constrain the thermal history of the intergalactic medium.

Contact me

Max Planck Institute for Astronomy
Königstuhl 17
69117 Heidelberg

Email: lee at
Phone: +49 (0)6221-528 476


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