After getting my Ph.D. in 2005 I arrived in JHU as the Keck Fellow, and continue to work as an Associate Research Scientist. My research interests are galaxy formation, computational astrophysics, and data-intensive sciences.

Galaxies in 3D

Galaxies are composite systems in 3 spatial dimensions (3D). They are inclined at different angles on the sky and located at various distances from us. I am combining spectra and images from sky surveys to reconstruct spectra of galaxies in 3D, with the goal to understand properties of galaxies in a new dimension.

Inclination Effect on Galaxy Properties

The observed spectra of disk galaxies change with inclination. This effect can be used to probe dust in the galaxies. Many derived galaxy parameters are impacted, including star formation rate and photometric redshift. Illustrations of the inclination effect can be found here and here.

Galaxy Formation using N-Dimensional Grid

The derivation of galaxy properties relies on parameter estimation of spectra and images. I have developed the N-dimensional Grid to accommodate multiple stellar population parameters. Interpolations can be carried out on-the-fly to obtain model spectra at fine computational resolutions, necessary for precise parameter estimates.

Finding Informative Features in Big Data

Principal Component Analysis (PCA) has been used to parametrize large samples of spectra in astronomy. The idea is to reduce the dimension of the data space, while leaving the wavelength sampling intact. With Michael Mahoney at Berkeley, we are using the CUR Matrix Decomposition to compress galaxy spectra in wavelengths as well. Our algorithm has automatically found a set of informative wavelength regions that are sensitive to stellar age and metallicity, analogous to the well-known Lick/IDS Indices.

Super-Resolution of Galaxy Integral Field Unit Spectra

With Emmanuel Candes & Carlos Sing-Long.

Mining Human Genome

With Sarah Wheelan & Craig Bohrson.


Data Mining in Modern Astronomy Sky Surveys Course

Photo Projects

Miguel Calvo's Universe Visualization
Mark Neyrinck's Cosmic Origami

Other Things

Galaxy PCA Eigenspectra
Quasar PCA Eigenspectra
1 Angstrom Resolution SDSS Galaxy Spectral Atlas
SDSS-III DR8 Photo-z
Laszlo Dobos's Spectrum Services
Scot Kleinman's SDSS DR7 White Dwarf Catalog