Page 32 - EngineerIT April 2022

SPACE SCIENCE

Astronomers reveal best image yet of

mysterious ORCs in space

stronomy’s newest mystery objects,
odd radio circles or ORCs, have
Abeen pulled into sharp focus by an
international team of astronomers using the
world’s most capable radio telescopes.
First revealed by the ASKAP radio
telescope, owned and operated by
Australia’s national science agency CSIRO,
odd radio circles quickly became objects of
fascination. Theories on what caused them
ranged from galactic shockwaves to the
throats of wormholes.
A new detailed image, captured
by the South African Radio Astronomy
Observatory’s MeerKAT radio telescope
and published in the monthly notices of the
Royal Astronomical Society (DOI 10.1093/
mnras/stac701), is providing researchers
with more information to help narrow down
those theories.
There are now three leading theories to
explain what causes ORCs.
To date ORCs have only been detected
using radio telescopes, with no signs
of them when researchers have looked The MeerKAT Stokes-I image of ORC1, superimposed on optical data from the Dark Energy Survey
DR1(Abbott et al. 2018), both spanning the same field of view. A square root transfer function was
for them using optical, infrared or X-ray applied to the radio data of the field of view and this gray-scale image was then adjusted for contrast.
telescopes. An image of the radio data confined to the ORC region was assigned mint green. This region was
blended with the grey-scale radio continuum field of view image and the DES optical image of the same
Dr Jordan Collier of the Inter-University field, so that faint radio sources outside the ORC appear as faint grey diffuse patches, often surrounding
Institute for Data Intensive Astronomy, who their host galaxies. The filters used in the DES image were assigned turquoise, magenta, yellow and red,
with the result that DES sources mainly appear in this image as white. The layering schema employed is
compiled the image from MeerKAT data, described in English (2017). This figure is optimised to convey the structure of the ORC, and quantitative
said that continuing to observe these odd information should be taken from Figure 1 or from the FITS files in the Supplementary Information.
radio circles would provide researchers with
more clues.
“People often want to explain
their observations and show that they
align with our best knowledge. To me,
it’s much more exciting to discover
something new, that defies our current
understanding,” Dr Collier said.
The rings are enormous – about a
million light years across, which is 16 times
bigger than our own galaxy. Despite this,
odd radio circles are hard to see.
Professor Ray Norris from Western
Sydney University and CSIRO, one of the
authors of the paper, said only five odd radio
circles have ever been revealed in space. Dr Jordan Collier

EngineerIT | April 2022 | 30