Credit: X-ray: NASA/CXC/Leiden Univ./F. de Gasperin et al;
Optical: SDSS; Radio: LOFAR/ASTRON, NCRA/TIFR/GMRT
Enterprise NCC 1701
USS Enterprise NCC 1701
Credit: Smithsonian National
Air & Space Museum
Hidden in a distant galaxy cluster collision are wisps of gas resembling the starship Enterprise — an iconic spaceship from the "Star Trek" franchise.
Galaxy clusters — cosmic structures containing hundreds or even
thousands of galaxies — are the largest objects in the Universe held
together by gravity. Multi-million-degree gas fills the space in between
the individual galaxies. The mass of the hot gas is about six times
greater than that of all the galaxies combined. This superheated gas is
invisible to optical telescopes, but shines brightly in X-rays, so an X-ray telescope like NASA's Chandra X-ray Observatory is required to study it.
By combining X-rays with other types of light, such as radio waves, a
more complete picture of these important cosmic objects can be
obtained. A new composite image of the galaxy cluster Abell 1033,
including X-rays from Chandra (purple) and radio emission from the
Low-Frequency Array (LOFAR) network in the Netherlands (blue), does just
that. Optical emission from the Sloan Digital Sky Survey is also shown.
The galaxy cluster is located about 1.6 billion light years from Earth.
Using X-ray and radio data, scientists have determined that Abell
1033 is actually two galaxy clusters in the process of colliding. This
extraordinarily energetic event, happening from the top to the bottom in
the image, has produced turbulence and shock waves, similar to sonic booms produced by a plane moving faster than the speed of sound.
In Abell 1033, the collision has interacted with another energetic
cosmic process — the production of jets of high-speed particles by
matter spiraling into a supermassive black hole,
in this case one located in a galaxy in one of the clusters. These jets
are revealed by radio emission to the left and right sides of the
image. The radio emission is produced by electrons spiraling around magnetic field lines, a process called synchrotron emission.
The electrons in the jets are traveling at very close to the speed of
light. As the galaxy and its black hole moved toward the lower part of
the image, the jet on the right slowed down as it crashed into hot gas
in the other galaxy cluster. The jet on the left did not slow down
because it encountered much less hot gas, giving a warped appearance for
the jets, rather than the straight line that is typically seen.
This image of Abell 1033 also provides an example of "pareidolia",
a psychological phenomenon where familiar shapes and patterns are seen
in otherwise random data. In Abell 1033, the structures in the data
create an uncanny resemblance to many of the depictions of the fictional
Starship Enterprise from Star Trek.
In terms of astrophysical research, a detailed study of the image
shows that the energy of the electrons in the "saucer section" and neck
of the starship-shaped radio emission in Abell 1033 is higher than that
found in the stardrive section towards the lower left (see labels). This
suggests that the electrons have been reenergized, presumably when the
jets interact with turbulence or shock waves in the hot gas. The
energetic electrons producing the radio emission will normally lose
substantial amounts of energy over tens to hundreds of millions of years
as they radiate. The radio emission would then become undetectable.
However, the vastly extended radio emission observed in Abell 1033,
extending over about 500,000 light years, implies that energetic
electrons are present in larger quantities and with higher energies than
previously thought. One idea is that the electrons have been given a
further boost in energy by extra bouts of shocks and turbulence.
Other sources of radio emission in the image besides the
starship-shaped object are the shorter jets from another galaxy (labeled
"short jets") and a "radio phoenix" consisting of a cloud of electrons
that faded in radio emission but was then reenergized when shock waves
compressed the cloud. This caused the cloud to once again shine at radio
frequencies, as we reported back in 2015.
The team who made this study will use observations with Chandra and
LOFAR to look for further examples of colliding galaxy clusters with
warped radio emission, to further their understanding of these energetic
objects.
A paper describing this result was published in the October 4th, 2017 issue of Science Advances and is available online.
The authors of the paper are Francesco de Gasperin, Huib Intema,
Timothy Shimwell (Leiden University, the Netherlands), Gianfranco
Brunetti (Institute of Radio Astronomy, Italy), Marcus Bruggen
(University of Hamburg, Germany), Torsten Enblin (Max Planck Institute
for Astrophysics, Germany), Reinout van Weeren (Leiden), Annalisa
Bonafede (Hamburg), and Huub Rottgering (Leiden).
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages
the Chandra program for NASA's Science Mission Directorate in
Washington. The Smithsonian Astrophysical Observatory in Cambridge,
Massachusetts, controls Chandra's science and flight operations.
Fast Facts for Abell 1033:
Scale: Image is about 7.4 arcmin across (about 3.3 million light years)
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 10h 31m 33.70s | Dec +35° 04´ 33.96"
Constellation: Leo Minor
Observation Date: 19 and 21 Feb 2013
Observation Time: 17 hours 35 min
Obs. ID: 15084, 15614
Instrument: ACIS
References: de Gasperin, F et al., Sci. Adv. 2017, 3, 1701634; arXiv:1710.06796
Color Code: X-ray (Pink); Optical (Red, Green, Blue); Radio (Blue)
Distance Estimate: About 1.62 billion light years (z=0.1259)
Scale: Image is about 7.4 arcmin across (about 3.3 million light years)
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 10h 31m 33.70s | Dec +35° 04´ 33.96"
Constellation: Leo Minor
Observation Date: 19 and 21 Feb 2013
Observation Time: 17 hours 35 min
Obs. ID: 15084, 15614
Instrument: ACIS
References: de Gasperin, F et al., Sci. Adv. 2017, 3, 1701634; arXiv:1710.06796
Color Code: X-ray (Pink); Optical (Red, Green, Blue); Radio (Blue)
Distance Estimate: About 1.62 billion light years (z=0.1259)
Source: NASA’s Chandra X-ray Observatory
