Why do you think your paper is highly cited?

The SIDM paper describes the growing evidence that standard models of weakly interacting cold dark matter models predict a density of dark matter in the cores of galaxies that is too high and then suggests a possible solution—the dark matter may have strong self-interactions. 

  Does it describe a new discovery or new methodology that's useful to others?

We think that there are several factors that have contributed to the level of interest in the paper. These are as follows:

1. It addresses an important scientific question: what is the nature of the dark matter?
2. It suggested a departure from the standard picture of weakly interacting dark matter with testable consequences.
3. It showed how changing the nature of dark matter could resolve a number of different puzzles that have arisen in comparing observations and simulations.
4. There are several intellectual communities that can contribute to understanding the physics of self-interacting dark matter. There have been papers on SIDM written by dynamicists, cosmologists, and particle physicists. Many people have tools-numerical simulations or physical models-that can be used to understand dark matter. The model makes a number of calculable and observable predictions.

We should note that Nature rejected the paper as "overly speculative" because strongly self-interacting dark matter was not already predicted by present particle physics models. We are grateful the PRL did not adopt this conservative stance.

Professor David N. Spergel
Department of Astrophysical Sciences
Princeton University 

Professor Paul J. Steinhardt
Department of Physics
Princeton University