Post Doctoral Research

Adrian Liu, Postdoctoral Fellow

Although I am broadly interested in astrophysics and cosmology, my recent work has focused on using the 21cm hyperfine transition of neutral hydrogen atoms to map our Universe. This technique, known as 21cm tomography, will eventually survey the distribution of matter in a larger faction of our observable Universe than current cosmological probes such as galaxy surveys and the cosmic microwave background. In addition to providing better constraints on cosmological parameters, this will allow precision tests of inflation and competitive bounds on the neutrino mass. Crucially, 21cm tomography will also be the only direct observational probe the Epoch of Reionization (EoR), during which the first stars and galaxies formed. Understanding how these first structures formed will help to complete the story of our Universe's transformation from a set of primordial fluctuations to the rich collection of astronomical structures that we see today. Unfortunately, 21cm tomography is technically challenging and has yet to mature into a practical probe of cosmology. My recent research has thus focused on bridging the gap between the theoretical promise and observational reality of 21cm tomography. This has led to algorithm development for radio telescope calibration, studies of Galactic and xtragalactic foreground contamination, and methods for foreground subtraction. Experimental design and a critical examination of observationally measurable statistics have also been recent considerations. I am also part of a number of observational groups, including the MWA, GMRT-EoR, and PAPER, and am involved in data analysis efforts. Early attempts at detecting a genuine cosmological signal from the data have been encouraging, if challenging, and suggest that 21cm tomography will soon be able to live up to its great potential.

Publications

Lawrence Berkeley National Laboratory 1 Cyclotron Rd., MS 50R5004 Berkeley, CA 94720

Marcel Schmittfull, Postdoctoral Fellow

I am a BCCP Fellow at UC Berkeley and Lawrence Berkeley National Lab working on cosmology, especially on non-Gaussianity of large-scale structures and on gravitational lensing of the CMB. Before moving to California in Fall 2013, I obtained my PhD from DAMTP at the University of Cambridge, where I worked with Paul Shellard and Anthony Challinor. I will add more content soon.

Hee-Jong Seo, Postdoctoral Fellow

My research interests are in high precision cosmology with large scale structure. I have studied analytically and numerically the performance of the BAO in large galaxy surveys as a dark energy probe. I also worked on the evolution of galaxy clustering and halo occupation distribution, using dissipationless N-body simulations. My recent research have aimed at extending my previous work as well as expanding to observational and experimental studies and to weak lensing study: I have worked on nonlinear effects on BAO in depth with various high-resolution simulations, the effect of galaxy bias and redshift distortions on BAO, a feasibility of a BAO survey in radio bands, and combining BAO with SN data from SDSS. The ongoing projects are

1. measuring the power spectrum of cosmic shear from SDSS Stripe 82

2. re-capturing more cosmic information by Gaussianizing the convergence field

3. deriving a BAO constraint from the SDSS III imaging data.

Publications Hee-Jong  Seo will start at The Astrophysical Institute, Ohio University in 2014 hee-jongseo@lbl.gov