Axions are a hypothetical new particle introduced to explain why there is not more charge-parity symmetry violation in the theory of the strong interaction. Depending on precise parameters, ultra-light axions () can act as dark matter or dark energy. For masses , axions behave more like dark energy, while if , axions behave more like […]
Working with Duncan Hanson,we used the WMAP 9-year maps to search for evidence of compensated isocurvature perturbations (CIPs) using the techniques outlined in arXiv:1107.5047. We find that baryons do trace dark matter at the ~10% level (expressed as a limit on the CIP amplitude). Results published in arXiv:1306.4319 (Phys. Rev. D 89, 023006). Collaborators: Duncan […]
Unlike isocurvature perturbations between photons and neutrinos, CDM, or baryons, isocurvature perturbations between dark matter and baryons are surprisingly poorly constrained. In this work, we show that such perturbations do have observable effects on the CMB due to higher-order effects that induce off-diagonal correlations and non-Gaussianity in the CMB. Results published in arXiv:1107.5047 (Phys. Rev. […]
Working with Yacine Ali-Haïmoud and Prof. Chris Hirata, we included the effect of Lyman line-overlap at high n in computations of recombination, finding, that along with a slew of other previously unconsidered radiative transfer effects, that they do not need to be included in recombination calculations at the levels of precision needed for Planck data […]
Properly interpreting precise CMB data (like that obtained from the Planck mission) requires a precise treatment of atomic hydrogen recombination (the formation of the first atoms at redshift (. Working with Chris Hirata, I computed the recombination of atomic hydrogen including very highly excited Rydberg states of hydrogen, establishing that the computation is sufficiently converged […]
I showed that if the radiation domination era began not long before big-bang nucleosynthesis (a novel but empirically allowed possibility), constraints to thermally produced axions are significantly relaxed. Results published in arXiv:0711.1352 (Phys. Rev. D 77, 085020). Collaborators: Tristan Smith and Prof. Marc Kamionkowski. Most experimental searches for axions and astrophysical constrains depend on their […]
I successfully proposed ~20 hours of observation time to look for decaying relic axions in the high-z galaxy cluster RDCS 1252. The resulting upper limits are the best in existence in the mass window from 8-14 eV. In the course of project, I mentored Princeton undergraduate student Kai Zhong Khor (shown below). Collaborators: Kai Zong […]
In this work, I led a team that used spectra of the galaxy clusters A2667 and A2390 obtained at the VLT in Chilé using the VIMOS IFU to look for thermally-produced axions in the 4.5-7.7 eV mass window, using their monochromatic decays to photons. If extant, such axions would produce a line signature in the […]
You must be logged in to post a comment.