Perseus Cluster
Credit: X-ray: NASA/CXO/Oxford University/J. Conlon et al. Radio: NRAO/AUI/NSF/Univ. of Montreal/Gendron-Marsolais et al.
Optical: NASA/ESA/IoA/A. Fabian et al.; DSS
An innovative interpretation of X-ray data from a galaxy cluster could help scientists understand the nature of dark matter, as described in our latest press release.
The finding involves a new explanation for a set of results made with
NASA's Chandra X-ray Observatory, ESA's XMM-Newton and Hitomi, a
Japanese-led X-ray telescope. If confirmed with future observations,
this may represent a major step forward in understanding the nature of
the mysterious, invisible substance that makes up about 85% of matter in the Universe.
The image shown here contains X-ray
data from Chandra (blue) of the Perseus galaxy cluster, which has been
combined with optical data from the Hubble Space Telescope (pink) and
radio emission from the Very Large Array (red). In 2014, researchers detected an unusual spike of intensity,
known as an emission line, at a specific wavelength of X-rays (3.5 keV)
in the hot gas within the central region of the Perseus cluster. They
also reported the presence of this same emission line in a study of 73
other galaxy clusters.
In the subsequent months and years, astronomers have tried to confirm
the existence of this 3.5 keV line. They are eager to do so because it
may give us important clues about the nature of dark matter. However, it
has been debated in the astronomical community exactly what the
original and follow-up observations have revealed.
A new analysis of Chandra data by a team from Oxford University, however, is providing a fresh take on this debate. The latest work shows that absorption of X-rays at an energy of 3.5 keV is detected when observing the region surrounding the supermassive black hole at the center of Perseus. This suggests that dark matter particles in the cluster are both absorbing and emitting X-rays (see our artist's impression above for a diagram helping to explain this behavior, where 3.5 keV X-rays are shown). If the new model turns out to be correct, it could provide a path for scientists to one day identify the true nature of dark matter. For next steps, astronomers will need further observations of the Perseus cluster and others like it with current X-ray telescopes and those being planned for the next decade and beyond.
A paper describing these results was published in Physical Review D on December 19, 2017 and a preprint is available online.
The authors of the paper are Joseph Conlon, Francesca Day, Nicolas
Jennings, Sven Krippendorf and Markus Rummel, all from Oxford University
in the UK. 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 3.87 arcmin (about 280,000 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: 2009
Observation Time: 55 hours 33 minutes (2 days 7 hours 33 minutes)
Obs. ID: 11713,12025,12044, 12036
Instrument: ACIS
Also Known As: Abell 426
References: Conlon et al. 2017 Physical Review D, 90, 123009; arXiv: 1086.01684
Color Code: X-ray (Blue); Optical (Pink); Radio (Red)
Distance Estimate: About 250 million light years
Source: NASA’s Chandra X-ray Observatory
