A bosenova or bose supernova is a very small, supernova-like explosion, which can be induced in a Bose–Einstein condensate (BEC) by changing the magnetic field in which the BEC (Bose-Einstein Condensate) is located so that the BEC quantum wavefunction's "self-scattering" interaction due to the Feshbach resonance transitions from repulsive to attractive, causing the BEC to "collapse and bounce" or "rebound."
Although the total energy of the explosion is very small, the "collapse and bounce" scenario superficially and quite vaguely resembles (albeit is physically quite unrelated to) a tiny core-collapse supernova, hence the term 'bosenova'. (The nomenclature is also partly a play on the Brazilian music style, bossa nova.)
In the particular experiment when a bosenova was first detected, transitioning the self-interaction from repulsive to attractive caused the BEC to implode and shrink to a size smaller than the optical detector's minimum resolution limit, and then suddenly "explode." In this explosion, about half of the atoms in the condensate superficially seemed to have "disappeared" from the experiment altogether, i.e., they were not detected in either the cold particle remnants nor in the expanding gas cloud produced.
"The 'missing' atoms are almost certainly still around in some form, but just not in a form that we can detect them in our current experiment," Carl Wieman told SPACE.com. "The two likely possibilities are that they have formed into molecules of two rubidium atoms stuck together, or they have gotten enough energy from somewhere to fly away fast enough that they are out of our observation region before we look for them."
Under current BEC theory (which only very crudely account for the interactions between the particles composing the BEC), the "bosenova" phenomenon remains unexplained, because the energy available to the individual atoms of the condensate near absolute zero appears to be insufficient to cause the observed implosion. However, subsequent mean-field theories have been proposed to explain "bosenovas" as a "collective phenomenon."
The "bosenova" behaviour of a BEC may provide insights into the behaviour of a neutron star or pulsar, as well as into the possible properties of still-hypothetical "Boson Stars," and into the quantum theory of "collective phenomena" in general.