Researchers 'clear away the dust,' get better look at
youngest supernova remnant
Supernova Remains G1.9+0.3
Thursday, April 23, 2009
Researchers at North Carolina State University have used a
mathematical model that allows them to get a clearer picture of the
galaxy's youngest supernova remnant by correcting for the
distortions caused by cosmic dust. Their new data provides evidence
that this remnant is from a type Ia supernova - the explosion of a
white dwarf star - and raises questions about the ways in which
magnetic fields affect the generation of the remnant's cosmic ray
particles.
NC State physicists Dr. Stephen Reynolds and Dr. Kazimierz
Borkowski, with colleagues from Cambridge University and NASA,
re-examined their original X-ray images of supernova remnant
G1.9+0.3 in an attempt to glean more information about the
remnant's origins, rate of expansion, and any cosmic particles that
may have resulted from the explosion. Scientists know that
supernovae create cosmic rays - fast-moving subatomic particles
that play a role in the formation of stars - but they aren't sure
how this occurs or what other functions the particles may
serve.
"We knew the dust was a problem - it's why we never saw the
original supernova light in Victorian times," Reynolds says. "Our
high-powered orbiting telescopes use X-rays to take pictures of
these objects, and the dust scatters these X-rays, so in order to
get data that might be helpful to us, we first had to correct for
the dust distortion."
A mathematical model allowed the scientists to deduce how many
X-rays from each part of the remnant were scattered from another
part. After this correction, they found that the "bright" and "dim"
sides of the remnant had more and fewer of the highest-energy
X-rays, respectively. Reynolds says that this pattern is best
explained by a type Ia supernova, and that the difference in
brightness corresponds to the level of synchrotronic X-rays
present. Synchrotronic X-rays (like those produced by terrestrial
synchrotron particle accelerators) are produced by high-energy
cosmic particles, making this remnant one of the best examples of a
cosmic ray accelerator that scientists have.
In addition, the location of the bright and dim sides point to the
presence of a magnetic field that is affecting the remnant's
acceleration process, and the distribution of cosmic rays.
The results were published in the April 20 edition of Astrophysical
Journal Letters.
"We use supernovae as flashbulbs across the universe (a means to
make assumptions about how the universe works," Reynolds says.
"Shockwaves from the explosions and the fast-moving cosmic
particles that come from them play roles in galaxy formation. If we
can figure out how these particles are energized, and how magnetic
fields affect them, we'll be able to answer all sorts of questions
about our universe."
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North Carolina State University
Thanks to North Carolina State University for this article.