VLT/VIMOS observations of the shock front in the remnant of the supernova SN 1006
The remnant of the supernova SN 1006 seen at many different wavelengths
Part of the supernova remnant SN 1006
seen with the NASA/ESA Hubble Space Telescope
VLT probes remains of medieval supernova
Very detailed new observations with ESO’s
Very Large Telescope (VLT) of the remains of a thousand-year-old
supernova have revealed clues to the origins of cosmic rays. For the
first time the observations suggest the presence of fast-moving
particles in the supernova remnant that could be the precursors of such
cosmic rays. The results are appearing in the 14 February 2013 issue of
the journal Science.
In the year 1006 a new star was seen in the southern skies and widely
recorded around the world. It was many times brighter than the planet
Venus and may even have rivaled the brightness of the Moon. It was so
bright at maximum that it cast shadows and it was visible during the
day. More recently astronomers have identified the site of this
supernova and named it SN 1006. They have also found a glowing and
expanding ring of material in the southern constellation of Lupus (The
Wolf) that constitutes the remains of the vast explosion.
It has long been suspected that such supernova remnants may also be
where some cosmic rays — very high energy particles originating outside
the Solar System and travelling at close to the speed of light — are
formed. But until now the details of how this might happen have been a
long-standing mystery.
A team of astronomers led by Sladjana Nikolić (Max Planck Institute for Astronomy, Heidelberg, Germany [1])
has now used the VIMOS instrument on the VLT to look at the
one-thousand-year-old SN 1006 remnant in more detail than ever before.
They wanted to study what is happening where high-speed material ejected
by the supernova is ploughing into the stationary interstellar matter —
the shock front. This expanding high-velocity shock front is similar to
the sonic boom produced by an aircraft going supersonic and is a
natural candidate for a cosmic particle accelerator.
For the first time the team has not just obtained information about
the shock material at one point, but also built up a map of the
properties of the gas, and how these properties change across the shock
front. This has provided vital clues to the mystery.
The results were a surprise — they suggest that there were many very rapidly moving protons in the gas in the shock region [2].
While these are not the sought-for high-energy cosmic rays themselves,
they could be the necessary “seed particles”, which then go on to
interact with the shock front material to reach the extremely high
energies required and fly off into space as cosmic rays.
Nikolić explains: “This is the first time we were able to take a
detailed look at what is happening in and around a supernova shock
front. We found evidence that there is a region that is being heated in
just the way one would expect if there were protons carrying away energy
from directly behind the shock front.”
The study was the first to use an integral field spectrograph [3]
to probe the properties of the shock fronts of supernova remnants in
such detail. The team now is keen to apply this method to other
remnants.
Co-author Glenn van de Ven of the Max Planck Institute for Astronomy, concludes: “This
kind of novel observational approach could well be the key to solving
the puzzle of how cosmic rays are produced in supernova remnants.”
Notes
[1] The new evidence emerged during
analysis of the data by Sladjana Nikolić (Max Planck Institute for
Astronomy) as part of work towards her doctoral degree at the University
of Heidelberg.
[2] These protons are called suprathermal as they are
moving much quicker than expected simply from the temperature of the
material.
[3] This is achieved using a feature of VIMOS called
an integral field unit, where the light recorded in each pixel is
separately spread out into its component colours and each of these
spectra recorded. The spectra can then be subsequently analysed
individually and maps of the velocities and chemical properties of each
part of the object created.
More information
This research was presented in a paper “An
Integral View of Fast Shocks around Supernova 1006” to appear in the
journal Science on 14 February 2013.
The team is composed of Sladjana Nikolić (Max Planck Institute for
Astronomy [MPIA], Heidelberg, Germany), Glenn van de Ven (MPIA), Kevin
Heng (University of Bern, Switzerland), Daniel Kupko (Leibniz Institute
for Astrophysics Potsdam [AIP], Potsdam, Germany), Bernd Husemann (AIP),
John C. Raymond (Harvard-Smithsonian Center for Astrophysics,
Cambridge, USA), John P. Hughes (Rutgers University, Piscataway, USA),
Jesús Falcon-Barroso (Instituto de Astrofísica de Canarias, La Laguna,
Spain).
ESO is the foremost intergovernmental astronomy organisation in
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operates the Very Large Telescope, the world’s most advanced
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works in the infrared and is the world’s largest survey telescope and
the VLT Survey Telescope is the largest telescope designed to
exclusively survey the skies in visible light. ESO is the European
partner of a revolutionary astronomical telescope ALMA, the largest
astronomical project in existence. ESO is currently planning the
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E-ELT, which will become “the world’s biggest eye on the sky”.
Links
Contacts
Sladjana NikolićMax Planck Institute for Astronomy
Heidelberg, Germany
Tel: +49 6221 528 438
Email: nikolic@mpia.de
Glenn van de Ven
Max Planck Institute for Astronomy
Heidelberg, Germany
Tel: +49 6221 528 275
Email: glenn@mpia.de
Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
