Images by Date
Images by Category
Solar System
White Dwarfs
Neutron Stars
Black Holes
Milky Way Galaxy
Normal Galaxies
Galaxy Clusters
Cosmology/Deep Field
Images by Interest
Space Scoop for Kids
Sky Map
Photo Blog
Top Rated Images
Image Handouts
Fits Files
Image Tutorials
Photo Album Tutorial
False Color
Cosmic Distance
Look-Back Time
Scale & Distance
Angular Measurement
Images & Processing
Image Use Policy
Web Shortcuts
Chandra Blog
RSS Feed
Email Newsletter
News & Noteworthy
Image Use Policy
Questions & Answers
Glossary of Terms
Download Guide
Get Adobe Reader
Perseus Cluster: Mysterious X-ray Signal Intrigues Astronomers

  • A mysterious signal has been seen in X-ray data from a study of over 70 galaxy clusters with Chandra and XMM-Newton.

  • This spike of intensity at a specific wavelength of X-ray light has several intriguing explanations.

  • More data and investigation will be needed to confirm both the signal's existence and nature.

  • This image shows a new view of the Perseus cluster, one of the galaxy clusters included in the new study.

A new study of the central region of the Perseus galaxy cluster, shown in this image, using NASA's Chandra X-ray Observatory and 73 other clusters with ESA's XMM-Newton has revealed a mysterious X-ray signal in the data. This signal is represented in the circled data points in the inset, which is a plot of X-ray intensity as a function of X-ray energy. The signal is also seen in over 70 other galaxy clusters using XMM-Newton. This unidentified X-ray emission line - that is, a spike of intensity at a very specific energy, in this case centered on about 3.56 kiloelectron volts (keV) - requires further investigation to confirm both the signal's existence and nature as described in the latest Chandra press release.

One intriguing possible explanation of this X-ray emission line is that it is produced by the decay of sterile neutrinos, a type of particle that has been proposed as a candidate for dark matter. While holding exciting potential, these results must be confirmed with additional data to rule out other explanations and determine whether it is plausible that dark matter has been observed.

There is uncertainty in these results, in part, because the detection of this emission line is pushing the capabilities of both Chandra and XMM-Newton in terms of sensitivity. Also, there may be explanations other than sterile neutrinos if this X-ray emission line is deemed to be real. For example, there are ways that normal matter in the cluster could have produced the line, although the team's analysis suggested that all of these would involve unlikely changes to our understanding of physical conditions in the galaxy cluster or the details of the atomic physics of extremely hot gases.

This image is Chandra's latest view of hot gas in the central region of the Perseus Cluster, where red, green, and blue show low, medium, and high-energy X-rays respectively. It combines data equivalent to more than 17 days worth of observing time taken over a decade with Chandra. The Perseus Cluster is one of the most massive objects in the Universe, and contains thousands of galaxies immersed in an enormous cloud of superheated gas. In Chandra's X-ray image, enormous bright loops, ripples, and jet-like streaks throughout the cluster can be seen. The dark blue filaments in the center are likely due to a galaxy that has been torn apart and is falling into NGC 1275 (a.k.a. Perseus A), the giant galaxy that lies at the center of the cluster. A different view of Perseus, shown below, combines data from Chandra in the inner regions of the cluster and XMM data in regions further out.

A paper describing the detection of this mysterious emission line was published in the July 1st issue of The Astrophysical Journal and a preprint is available online. The first author is Esra Bulbul of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, MA, and NASA's Goddard Space Flight Center (GSFC) in Greenbelt, MD. The co-authors are Maxim Markevitch from GSFC, Adam Foster and Randall Smith from CfA, Michael Loewenstein from University of Maryland in College Park MD and GSFC, and Scott W. Randall from CfA.

Only a week after Bulbul et al. placed their paper on the arXiv, a different group, led by Alexey Boyarsky of Leiden University in the Netherlands, placed a paper on the arXiv reporting evidence for an emission line at the same energy in XMM-Newton observations of the galaxy M31 and the outskirts of the Perseus cluster. This strengthens the evidence that the emission line is real and not an instrumental artifact.

Fast Facts for Perseus Cluster:
Credit  X-ray: NASA/CXC/SAO/E.Bulbul, et al.
Release Date  June 24, 2014
Scale  Image is about 11 arcmin across (about 768,000 light years)
Category  Groups & Clusters of Galaxies, Black Holes
Coordinates (J2000)  RA 03h 19m 47.60s | Dec +41° 30´ 37"
Constellation  Perseus
Observation Date  25 pointings between Sep 1999 and Dec 2009
Observation Time  416 hours 32 min (17 days 8 hours 32 min).
Obs. ID  502, 503, 1513, 3209, 3404, 4289, 4946-4953, 6139, 6145, 6146, 11713-11716, 12025, 12033, 12036, 12037
Instrument  ACIS
Also Known As Abell 426
References Bulbul, E. et al, 2014, ApJ (accepted); arXiv:1402.2301
Color Code  X-ray (Red = 0.5-1.2 keV, Green = 1.2-2.0 keV, Blue = 2.0-7.0 keV)
Distance Estimate  About 250 million light years
distance arrow
Visitor Comments (13)

Proud to have been the NASA Flight Director to lead this great Shuttle mission STS-93.
My Flight Director call sign is Perseus Flight. How about that?
Keep up the good work.
Bryan Austin

Posted by Bryan Austin on Monday, 10.31.16 @ 14:34pm

So much wars and suicides and self torturing in the space...

Posted by Pijush Banerjee on Wednesday, 06.17.15 @ 09:22am

Howdy. Would you mind if I share your blog with my twitter group? There's lots of people that I believe would really enjoy your content. Please let me know. Thanks

Posted by Smithg508 on Wednesday, 12.31.14 @ 00:50am

Thank you so much.

Posted by geethika on Wednesday, 07.16.14 @ 05:32am

If I am not mistaken, Manuel, Gravitational energy is a form of electromagnetic energy. Therefore, one has no greater significance than the other.
Marv, I am certain that this would not be the first contact with an extraterrestrial species, if in fact it is a form of communication being picked up in these emissions. Through historical analysis of evidence left by earlier humans of their experiences with other-than-Earthbound species, we can reach the conclusion that contact has been previously made.
I hope these comments are helpful and useful.

Posted by Bill Allbritten on Sunday, 07.6.14 @ 12:13pm

Hi. Is gravity force more powerful than
electromagnetic force? What is the main equation relating these two forces?

Posted by manuel gomes on Thursday, 07.3.14 @ 13:39pm

What is radiation - a light, what is its source?

Posted by Stacey on Thursday, 06.26.14 @ 13:13pm

If it can't be seen "or even proven to exist" how can we say it makes up 85% of the universe?
And why dark matter? Why not un-matter... I kind of like that. sounds a little more intriguing...

Posted by cliff brannick on Wednesday, 06.25.14 @ 22:18pm

Those are great.

Posted by Chris West on Wednesday, 06.25.14 @ 21:26pm

Great story. Keep us posted.

Posted by charlena on Wednesday, 06.25.14 @ 19:40pm

I hope this signal indicates first contact with another intelligence. We are not alone.

Posted by Marv Brilliant on Wednesday, 06.25.14 @ 19:01pm

Hello, is it not possible that the idea is wrong with the "photon" being the only one in its group? how about an anti-photon and or an neutral photon or other kind of photons? Could his help explain the dark matter or in whatever it is...

Posted by Bernhard Edgren on Wednesday, 06.25.14 @ 16:50pm

Thank you.

Posted by Adriana Amor on Wednesday, 06.25.14 @ 16:07pm

Rate This Image

Rating: 3.8/5
(896 votes cast)
Download & Share


1024x768 - 540.6 kb
1280x1024 - 823.4 kb
1680x1050 - 1.1 MB
More Information
More Images
X-ray Image of Perseus Cluster
Jpg, Tif

More Images
Animation & Video
Tour of Perseus Cluster

More Animations
More Releases
Perseus Cluster
Perseus Cluster
(19 Mar 20)

Perseus Cluster
Perseus Cluster
(03 Apr 18)

Perseus Cluster
Perseus Cluster
(19 Dec 17)

Perseus Cluster
Perseus Cluster
(02 May 17)

Perseus Cluster
Perseus Cluster
(27 Oct 14)

Perseus Cluster
Perseus Cluster
(01 Dec 05)

Perseus Cluster
Perseus Cluster
(01 Sep 03)

Related Images
(18 Aug 10)
Centaurus A Jet
Centaurus A Jet
(23 Apr 03)

Related Information
Related Podcast
Top Rated Images
Chandra Releases 3D Instagram Experiences

Timelapses: Crab Nebula and Cassiopeia A

Brightest Cluster Galaxies