Prof. Charles J. Horowitz

Center for the Exploration of Energy and Matter and Department of Physics,

Indiana University, 701 E. Third St., Bloomington, IN 47405

Swain Hall West Room 233 or Indiana University Cyclotron Facility 1215

Phone: 812 855-2959 or 855-0303

Email: horowit at Indiana dot edu   




I am a theoretical nuclear physicist working on dense nuclear matter in the laboratory and in astrophysics.  Some of my publications are listed on SPIRES


Conferences I have co-organized in Nuclear Physics, Astrophysics, and Fundamental Symmetries.


Research topics:

The Equation of State (pressure versus density) of dense and or neutron rich nuclear matter.

Supernovae are giant stellar explosions.  I am interested in how supernovae depend on neutrino interactions and the properties of dense matter.

Neutron stars are collapsed stars that are the densest macroscopic objects this side of black holes.

Laboratory measurements of nuclear properties important for astrophysics, such as

Measuring the neutron radius of the heavy nucleus 208Pb via parity violating electron scattering.  This is the Pb Radius Experiment (PREX) at Jefferson lab.


PREX target vesselPhysicists measure skin of nucleus

A Sciencemag web article by Adrian Cho highlights our recent paper: A large atomic nucleus is like a chocolate truffle with a gooey interior and a harder shell. Inside, the nucleus contains a mixture of protons and neutrons. Outside, it's covered with a nearly pure layer of neutrons—the "neutron skin." Now, for the first time, nuclear physicists have measured the thickness of that skin in a fairly direct way. More-precise future measurements could transform the study of all nuclei and even of neutron stars. (Illustration is target vessel for PREX experiment at JLAB from R. Michaels) See Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering by Abrahamyan et al., Phys. Rev.Lett. 108, 112502 (2012).


 Star crust is 10 billion times stronger than steel

A NewScientist Web article by Rachel Courtland highlights our recent paper:

The crust of neutron stars is 10 billion times stronger than steel, according to our large scale computer simulations. That makes the surface of these ultra-dense stars tough enough to support long-lived bulges that could produce gravitational waves detectable by experiments on Earth. Neutron stars are the cores left behind when relatively massive stars explode in supernovae. They are incredibly dense, packing about as much mass as the sun into a sphere just 20 kilometres or so across, and some rotate hundreds of times per second. Because of their extreme gravity and rotational speed, neutron stars could potentially make large ripples in the fabric of space but only if their surfaces contain bumps or other imperfections that would make them asymmetrical. (Illustration: Casey Reed/Penn State University.)

See The breaking strain of neutron star crust and gravitational waves by C. J. Horowitz, and Kai Kadau, Phys Rev. Letters 102, 191102 (2009).






 Chemistry of neutron stars modeled for first time

A NewScientist Web article by David Shiga highlights our recent paper on phase separation in neutron star crusts.  We find, based on large scale molecular dynamics simulations, that when material falls on a neutron star and freezes, the lighter Z elements tend to remain behind in a liquid ocean.  This chemical separation may change many properties of neutron stars and could explain how carbon is concentrated until it can ignite in a great thermonuclear explosion known as a superburst.  It could also lead to a layered structure for neutron stars with larger bumps that may efficiently radiate gravitational waves.


See Astro-ph/0703062 Phase separation in the crust of accreting neutron stars by C. J. Horowitz, D. K. Berry, E. F. Brown, Phys Rev. E 75, 066101, 2007.


A neutron star that siphons material from a partner has a solid crust of heavy elements topped by an ocean of lighter elements. Occasionally, the ocean erupts in a nuclear explosion (Illustration: Ed Brown, MSU)    




Fall of 2012 Electricity and Magnetism I: P506

Spring 2011 Electricity and Magnetism II: P507

Fall of 2010 Electricity and Magnetism I: P506

Fall of 2009 Classical Mechanics: P521  Click here for information

Spring 2009, P630, Nuclear Astrophysics

Spring 2008, P621 Relativisatic Quantum Field Theory
I have also tought in recent years:

P110/ P120, Energy
P111, The Physics of Extraterrestrial Life and Death
P453 Quantum Mechanics
P556, Statistical Physics


I organize the Indiana University Physics Journal Club.   Here graduate students make informal presentations on exciting recent papers in any area of physics.