A gigantic and resilient "cold front" hurtling through the Perseus galaxy cluster has been studied using data from NASA's Chandra X-ray Observatory. This cosmic weather system spans about two million light years and has been traveling for over 5 billion years, longer than the existence of our Solar System.
This graphic shows the cold front in the Perseus cluster. The image
above contains X-ray data from Chandra — for regions close to the center
of the cluster —along with data from ESA's XMM-Newton and the
now-defunct German Roentgen (ROSAT) satellite for regions farther out.
The Chandra data have been specially processed to brighten the contrast
of edges to make subtle details more obvious.
The cold front is the long vertical structure on the left side of the
image (rollover the image above to view labels). It is about two
million light years long and has traveled away from the center of the
cluster at about 300,000 miles per hour.
The inset below shows a close-up view of the cold front from Chandra.
This image is a temperature map, where blue represents relatively
cooler regions (30 million degrees) while the red is where the hotter
regions (80 million degrees) are.
Close-up view of the cold front;
Credit: NASA/CXC/GSFC/S.Walker, ESA/XMM, ESA/ROSAT
The cold front has not only survived for over a third of the age of
the Universe, but it has also remained surprisingly sharp and split into
two different pieces. Astronomers expected that such an old cold front
would have been blurred out or eroded over time because it has traveled
for billions of years through a harsh environment of sound waves and turbulence caused by outbursts from the huge black hole at the center of Perseus.
Instead, the sharpness of the Perseus cold front suggests that the
structure has been preserved by strong magnetic fields that are wrapped
around it. The comparison of the Chandra X-ray data to theoretical
models also gives scientists an indication of the strength of the cold
front's magnetic field for the first time.
While cold fronts in the Earth's atmospheres are driven by rotation
of the planet, those in the atmospheres of galaxy clusters like Perseus
are caused by collisions between the cluster and other clusters of
galaxies. These collisions typically occur as the gravity of the main
cluster pulls the smaller cluster inward towards its central core. As
the smaller cluster makes a close pass by the central core, the
gravitational attraction between both structures causes the gas in the
core to slosh around like wine swirled in a glass. The sloshing produces
a spiral pattern of cold fronts moving outward through the cluster gas.
Aurora Simionescu and collaborators originally discovered the Perseus
cold front in 2012 using data from ROSAT (the ROentgen SATellite),
ESA's XMM-Newton Observatory, and Japan's Suzaku X-ray satellite.
Chandra's high-resolution X-ray vision allowed this more detailed work
on the cold front to be performed.
The results of this work appear in a paper that will be published in the April issue of Nature Astronomy and is available online.
The authors of the paper are Stephen Walker (Goddard Space Flight
Center), John ZuHone (Harvard-Smithsonian Center for Astrophysics),
Jeremy Sanders (Max Planck Institute for Extraterrestrial Physics), and
Andrew Fabian (Institute of Astronomy, Cambridge, England.)
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 Perseus Cluster:
Scale: Image is about 42 arcmin (about 3 million light years) across.
Category: Groups & Clusters of Galaxies, Cosmology/Deep Fields/X-ray Background
Coordinates (J2000): RA 03h 19m 47.60s | Dec +41° 30´ 37.00"
Constellation: Perseus
Observation Date: Nov 13, 2016
Observation Time: 25 hours 50 min (1 day 1 hour 60 minutes)
Obs. ID: 19565, 19938
Instrument: ACIS
Also Known As: Abell 426
References: S. Walker et al., 2018, Nature Astronomy, arXiv:1803.00898
Color Code: X-ray (intensity)
Distance Estimate: About 250 million light years
Source: NASA’s Chandra X-ray Observatory
