mercoledì 1 marzo 2017

Supercomputing Superluminous Supernovae


First 2-dimension simulations shed new light on superluminous stellar explosions, which are up to 100 times brighter than regular supernovae
Scientists recently used a supercomputer to run two-dimensional simulations of superluminous supernovae – which are explosion of stars that are up to 100 times brighter than normal – in hopes of better understanding how they form.
An international research team, led by astrophysicist Ken Chen of the National Astronomical Observatory of Japan, ran the 2D simulations to learn more about the physical characteristics that create superluminous supernovae.
These extremely bright supernovae were only first spotted in the past decade and has confounded scientists, according to a recent press release by Lawrence Berkeley National Laboratory (LBNL).
The researchers ran the simulations using the Intel Xeon-based Edison supercomputer at LBNL’s National Energy Research Scientific Computing Center (NERSC).
“This is the first time that anyone has simulated superluminous supernovae in 2D. Previous studies have only modeled these events in 1D,” Ken said in the release. “By modeling the star in 2D, we can capture detailed information about fluid instability and mixing that you don’t get in 1D simulations. These details are important to accurately depict the mechanisms that cause the event to be superluminous and explain their corresponding observational signatures such as light curves and spectra.”
Chen said one leading theory is that superluminous supernovae are powered by highly magnetized neutron stars, called magnetars. They spin several hundred times per second and are extremely dense. In fact, a sugar-cube-sized amount of material from these neutron stars weighs more than 1 billion tons. The combination of the fast rotation, density and physics in the core creates extreme magnetic fields, according to the press release.
A magnetic field, in turn, takes out the rotational energy of the neutron star and turns the energy into energetic radiation. Some researchers believe this radiation powers a superluminous supernova, the release said.
“By doing a more realistic 2D simulation of superluminous supernovae powered by magnetars, we are hoping to get a more quantitative understanding about its properties,” Chen said in a statement. “So far, astronomers have spotted less than ten of these events. As we find more, we’ll be able to see if they have consistent properties. If they do and we understand why, we’ll be able to use them as standard candles to measure distance in the universe.”

Chen adds that further research into these supernovae could also provide insights into the conditions of the distant universe.

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