Scientists puzzled over neutron stars` x-ray superbursts origin

Washington: Scientists are trying to find what exactly powers neutron stars` x-ray superbursts. Peter Moller of Los Alamos National Laboratory`s Theoretical Division, said that understanding this would yield important insights about the fundamental forces in nature, especially on the astronomical/cosmological scale.

A neutron star is created during the death of a giant star more massive than the Sun, compressed to a tiny size but with gravitational fields exceeded only by those of black holes. And in the intense, neutron-rich environment, nuclear reactions cause strong explosions that manifest themselves as X-ray bursts and the X-ray superbursts that are more rare and 1 ,000 times more powerful. Moller, who coauthored the paper with a multidisciplinary team including former Los Alamos postdoctoral researchers Sanjib Gupta, now a faculty member at the Indian Institute of Technology (IIT), Ropar, and Andrew Steiner , now a research assistant professor at INT, Seattle, said that the terrestrial experimental study of weak interactions in highly deformed, neutron-rich nuclei that FRIB can potentially provide is lent support by this ground-breaking Nature letter, since Los Alamos has been one of the few homes to theoretical studies of deformed nuclei and their role in astrophysics, and remains so to this day. At Los Alamos scientists have carried out detailed calculations of the specific, individual beta-decay properties of thousands of nuclides, all with different decay properties, and created databases with these calculated properties. The databases are then used at MSU as input into models that trace the decay pathways with the passage of time in accreting neutron stars and compute the total energy that is released in these reactions. The new, unexpected result is that so much energy escapes by neutrino emission that the remaining energy released in the beta decays is not sufficient to ignite the X-ray superbursts that are observed. Thus the superbursts` origin has now become a puzzle. The study has been published online in journal Nature. Pic courtesy: NASA