Post Doctoral Research

BCCP Fellows

Beth Reid, Cosmology Data Science Fellow

Galaxy redshift surveys trace out the three-dimensional structure of the cosmic web.  The rich structure we observe in these maps depends on the expansion history of the universe (measured using the baryon acoustic oscillation [BAO] standard ruler), the rate at which matter perturbations are growing (measured using redshift space distortions), and the complex relationships between galaxies and the underlying matter fluctuations.  My work focuses many aspects of turning raw data into insights about cosmology.

* I am primarily responsible for generating, documenting, and publicizing the final SDSS-III BOSS large scale structure catalogs.

* I use perturbation theory techniques to build models of the clustering structure in galaxy maps and infer cosmological parameters

* I use simulations to understand the small-scale clustering properties of our galaxies, thus providing a better understanding of how galaxies trace out the underlying density and velocity structures of matter.

Yu Feng, Cosmology Data Science Fellow

I am a BCCP Cosmology Data Science fellow. I mainly study the formation of galaxies in the large scale structure of the Universe with computer simulations. The physics of galaxies involves gravity, hydrodynamics, radiative transfer, atomic physics, and feedback from star formation and black hole accretion. The next generation surveys like DESI and WFIRST will give us better observational constraints on how and where these galaxies are formed. Cosmologists do not experiment with universes: we would rather experiment with computer simulations. Simulation of this kind requires the full capability of state of art super-computers, and produces data measured in petabytes. Operating such computational experiments, identifying valuable scientific information from the data are challenges that I face everyday.

Some of the largest simulations I was involved are:

  • the MassiveBlack-I and MassiveBlack-II simulation (http://mbii.phys.cmu.edu) at Kraken in National Institute for Computation Sciences, and
  • the BlueTides simulation at BlueWaters in National Center for Supercomputing Applications.

In addition to first principles simulation of galaxies, I also work on producing `simulated` mock catalogues of galaxies, Lyman-Alpha forest and quasars for surveys such as SDSS. These simulated mock catalogues are crucial in understanding the systematics and errors in the measurements of cosmological parameters from observational data.

Adrian Liu, Postdoctoral Fellow

Adrian Liu, BCCP Postdoctoral Fellow

We are now in an era of precision cosmology, with increasingly rich data emerging from the Cosmic Microwave Background (CMB) and galaxy surveys. While exciting work remains to be done with these probes, it is timely to look towards qualitatively different probes of our Universe. I am excited to be leading efforts to make one such probe—the highly redshifted 21 cm line of hydrogen—a reality. In 21cm cosmology, one traces the distribution of matter using the spin-flip hyperfine transition of hydrogen. Due to the ubiquity of hydrogen, this in principle allows us to survey an enormous fraction of our Universe.

Crucially, the 21cm line may be the only way to directly observe the Epoch of Reionization (EoR), when the first luminous galaxies formed and ionized the intergalactic medium around them. Within the next few years, the first generation of 21cm cosmology experiments will make a positive detection of the 21cm line from the EoR, and I am currently working with the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) and the Hydrogen Epoch of Reionization Array (HERA) collaborations to achieve this. Doing so will provide answers to some basic questions in a currently unobserved portion of our cosmic timeline: how did the first generation of stars and galaxies form? What were their properties, and how did they affect the structures around them? I also work on methods for using 21cm cosmology to constrain “basic”/fundamental cosmological parameters such as spatial curvature and the neutrino mass.

Marcel Schmittfull, Postdoctoral Fellow

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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.
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Andreu Font, Postdoctoral Fellow

Study of the Large Scale Structure of the universe using spectroscopic data from the BOSS collaboration. In particular, study of the Lyman alpha forest and quasars as tracers of the density field. Baryon Acoustic Oscillations (BAO) at high redshift, providing constraints to the expansion history of the Universe. For a recent press release visit http://newscenter.lbl.gov/news-releases/2014/04/07/boss-quasars-measure-expansion.

Florian Beutler, Postdoctoral Fellow

I am a postdoctoral fellow at the Lawrence Berkeley National Lab and a member of the BOSS collaboration. The BOSS collaboration has produced the largest galaxy redshift catalogue available right now with the aim to measure the Baryon Acoustic Oscillation (BAO) signal. BAO are a special scale in the distribution of galaxies, which can be used to measure the geometry of the Universe and learn more about dark matter and dark energy.

Beside BAO I am working on constraints on the neutrino masses using redshift-space distortions. Redshift-space distortions are deviations between the inferred position of a galaxy, derived from its redshift, and the true position, which is caused by the underlying peculiar velocity field.

Before my postdoc position here in Berkeley I did my PhD at the University of Western Australia, working with the 6-degree Field Galaxy Survey.

 

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