Earlier Research Results

Back to Andrew W. Steiner at the University of Tennessee.


Jan. 2015: Predicting neutron star tidal deformabilities and moments of inertia

 

In a collaboration with Stefano Gandolfi, Farrukh Fattoyev, and William Newton, we predicted neutron star tidal deformabilities and neutron star moments of inertia using

  • up-to-date nuclear physics near the saturation density, and
  • recent neutron star mass and radius measurements.
We found that neutron star tidal deformabilities are less than \( 3 \times 10^{36}~\mathrm{g}~\mathrm{cm}^2~\mathrm{s}^2 \) to 95% confidence. Also, the fraction of the neutron star's moment of inertia contained in the crust can be as much as 10-11% of the total, depending on one's current interpretation of the mass and radius data. Our work is published in Phys. Rev. C and is also available on the arXiv.

Aug. 2014: How superfluidity affects magnetar flare oscillations

 

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.

Mar. 2014: Systematic uncertainties in masses and radii from QLMXBs

Mass and radius constraints from the five QLMXBs
		    for the Dickey et al. (1990) N_H values and
		    H or He atmospheres

 

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 absorption as the key systematic uncertainty for connecting observations to neutron star structure.

Feb. 2014: Our invited review article is on the front cover

The cover of EPJA, 
	       volume 50 number 2

 

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.

Dec. 2013: Discovery of a new cooling process in accreting neutron stars

A plot of the nuclides
		 showing the new cooling process from Schatz et al.
		 (2013)

 

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.

Aug. 2013: New equation of state tables for core-collapse supernovae released

The M-R curves for several EOS tables from
		      Steiner, Hempel, and Fischer (2013)  

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.

More information

Feb. 2013: Probing extreme matter through observations of neutron stars

My EOS constraints from Steiner, Lattimer, and
		      Brown (2013)  

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. This paper continues to be the second most cited article in Astrophys. J. Lett from 2013 (first place is taken from the 2012 Hubble Deep Field)!

May 2012: Nuclear reactions in the inner neutron star crust

The properties of the accreted crust
		 from Steiner (2012)  

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.

More information

Feb. 2012: Nuclear symmetry energy and three-body forces in Phys. Rev. Lett.

Constraints on beta, b, and L from Steiner and
		      Gandolfi (2012)  

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.

More information