Research Assistant Professor at the Institute for Nuclear Theory at the University of Washington
My research demonstrates that neutron star observations can be used to understand how neutrons and protons interact. Also, I have shown that nuclear physics is critical for describing neutron star observations and many astrophysical processes including core-collapse supernovae, X-ray bursts and giant flares in magnetars. Recently, I determined how neutron star radius observations improve our knowledge of nuclear three-body forces, the neutron skin thickness of lead, and the nuclear symmetry energy.
Five of my papers are listed in the top 100 articles cited by nucl-th preprints in 2013 (#13, #29, #33, #35, and #64). My 2005 review appeared as #13 on this list.
In work led by Alex Deibel and in collaboration with Ed Brown (both at Michigan State), we show that superfluid entrainment resolves the standing issue of observed magnetar QPO frequencies predicting anomalously small values of the nuclear symmetry energy. Our work is now published in Physical Review C and available on the arXiv.
In a new article, at arXiv:1407.0100, I describe how Bayesian analysis has been used to analyze neutron star observations and why the best fit and a covariance matrix is not enough to describe the likelihood. This leads to a proposal on improving fits to low-energy nuclear data and a method for modern constraints on the nuclear symmetry energy.
See also my CV.
In a collaboration with Stefano Gandolfi, Farrukh Fattoyev, and William Newton, we predicted neutron star tidal deformabilities and neutron star moments of inertia using
My analysis (with Jim Lattimer) of distance and X-ray absorption uncertainties in quiescent low-mass X-ray binaries (QLMXBs) is now published in Ap. J 784 (2014) 123 (also at arXiv:1305.3242). We show how mass and radius constraints from QLMXBs can be reconciled with what we know about neutron star crusts from nuclear physics experiments. We also identify X-ray abosrption as the key systematic uncertainty for connecting observations to neutron star structure.
Our review on the nuclear symmetry energy is featured on the front cover of the European Physical Journal A. See the contents of the full issue or just the article itself. I was also happy to be involved in a separate and also excellent invited review in the same issue led by Stefano Gandolfi.
See our work as published in Nature, the arXiv version, a summary for non-specialists, an article on the Chandra website, the press releases at Los Alamos and MSU Today, the article at Ars Technica, or the Astronomy magazine article.
We present our new constraints on the neutron star mass-radius curve and the equation of state (EOS) of dense matter which shows that almost all neutron stars in the universe mostly likely have radii between 10 and 13 km. Our work was featured on the Chandra website, and described at Astronomy magazine. A more technical summary and the associated EOS table are also available.
In collaboration with Matthias Hempel and Tobias Fischer, we release two new supernova equation of state tables, SFHo and SFHx, which are more consistent with modern nuclear experiments and neutron star mass and radius observations.
I show that the nuclear symmetry energy can modify the amount of deep crustal heating in an accreting neutron star by a factor of two.
In my new article with Stefano Gandolfi in Physical Review Letters, we show that neutron star mass and radius observations can constrain the three-neutron force and the density dependence of the symmetry energy.