I am a postdoctoral fellow at Johns Hopkins University in Baltimore, Maryland, USA since late 2016. Prior to this, I briefly held a position at the University of Tokyo in Japan as a JSPS fellow. I received my Ph.D. in Astronomy from the University of Texas at Austin in the Spring of 2016. I grew up in Taiwan, where I received a B.S. in Computer Science with Physics minor and a M.S. in Astronomy from National Tsing Hua University.

Building Ancient Cosmic Cities

Galaxy Protoclusters are large overdense structures in the early Universe from which galaxy clusters gravitationally collapse. They represent an unique interface between the subjects of galaxy formation and cosmology, and a key laboratory to study both in their extreme conditions. A major part of my work has been pioneering the numerical modeling, observations, and physical inferences of protoclusters and their relations to both large and small scale astrophysics.

Dissecting The 3D Universe

Extragalactic Background Light in Broad Band Intensity Mapping. Most of the photons ever recorded by astronomical instruments are in the form of images—or broad-band intensity maps. Usually a large fraction of these photons are in the diffuse field, or pixels outside individual objects. They are often discarded during the process of background removal (by e.g., SExtractor), which is an unfortunately waste of information. I developed an angular cross correlation technique to recover the redshift of the diffuse extragalactic background light (EBL), and has potential to recover its spectral energy distribution (SED) with a spectral resolution much higher than the original bandwidth. Such a time and frequency dependent radiation output will provide a critical summary statistics of cosmological galaxy formation.

Clustering Redshift Estimation is a powerful technique to obtain distance distributions of extragalactic objects or photons using their angular fluctuations on the sky. Utilizing the fact that extragalactic objects are gravitationally clustered in the filamentary cosmic web, we can propagate information from a spatially 3D data set (the "reference" sample with RA, Dec, redshift available) to a 2D one (the "unknown"). This is achieved by a series of angular cross correlations. The applications include inferring the redshift distribution of photometrically selected galaxies, and deprojecting various cosmic intensity fields from 2D back to 3D.

Contact Information

Address:
3400 N. Charles Street
Baltimore, MD 21218
United States

Email:
ykchiang@jhu.edu

Research Gallery


Recovering redshift & spectral energy distributions of extragalactic background light
Dissecting Galactic dust maps using angular cross-correlations with cosmic web tracers
Visualizing the drastically evolving Lagrangian volumes of simulated galaxy protoclusters
Protoclusters are expected to be the key drivers of early cosmic star formation history and reionization
Three-stage scenario of galaxy cluster formation: inside-out, extended growth, and infalling
Discovery of a massive protocluster at z=2.44 in a blind Lya emitter search in the HETDEX Pilot Survey
Discovery of 36 protocluster candidates at z=2~3 using photometric redshifts in the COSMOS field
Mass and size evolution of protoclusters predicted in the Millennium simulation