It is my pleasure to inform you that my work (by S. Wanajo) with a Kyoto group (of Y. Sekiguchi) was featured as a press release of RIKEN on July 17th (http://www.riken.jp/pr/press/2014/20140717_2/). A brief summary of the press release, which was presented by myself during the iTHES coffee meeting on July 18th, is as follows. Origin of heavy elements such as gold and uranium (made by the rapid neutron-capture or r-process) has been one of the greatest mysteries in astrophysics. The scenario of supernovae, the best studied candidate for the r-process, is now facing severe problems. Another scenario, the mergers of two neutron stars in binary systems, has also encountered a problem; extremely neutron-rich ejecta make only heavy r-process elements. Our study is the first one implementing both general relativistic and neutrino effects for the modeling of neutron star mergers. We find that the weak interaction induced by these effects moderates the neutron-richness and results in making the r-process elements that closely follow the solar abundance distribution over all the mass range. This strongly suggests that neutron star mergers are the origin of the r-process elements. Future observation of radioactively powered emission from a neutron star merger associated with a gravitational wave signal will be a “smoking gun” of r-processing in such an event. This work was published on July 10th in Astrophysical Journal Letters (http://iopscience.iop.org/2041-8205/789/2/L39/).

My name is Tsutomu Momoi. I am a member of Condensed Matter Theory Laboratory. I finished my Ph.D in the University of Tokyo. I have worked in the University of Tsukuba and Harvard University before I moved to RIKEN.

My main research interest is the search for novel quantum states of matters in many-body systems. For example magnetism in “frustrated spin systems” is one of my research fields. This “frustrated spin systems” is a terminology for the spin systems that have competing spin interactions and hence have highly degenerate ground states in the classical approximation. A fundamental ｑuestion for this situation is what happens when quantum effect is introduced to this system or how a new quantum state is reorganized from the degenerate classical ground states. I am studying this problem using both analytical method and numerical approach.

Besides research, I am recently enjoying hiking with my son and also planning to start biking (cycling). My immediate plan (dream?) is to bike to Tokyo bay from RIKEN through Arakawa Cycling Road and to have a lunch in Tokyo bay area.