At the core of a newly found dwarf galaxy, astronomers discovered a mysterious source of gamma rays that may signal the presence of the mysterious dark matter. If this is confirmed, then it would be the first time we see dark matter through anything else than its gravitational pull.
Dark matter is a hypothetical kind of matter that cannot be seen with telescopes but accounts for most of the matter in the Universe – we know this because we observe its gravitational pull. But dark matter neither emits nor absorbs light, and we can’t see it, basically. Whatever it may be, we don’t know anything about it, other than we can see its effects. Understanding it would enable us to see the Universe in a new way, unlocking one of its biggest mysteries.
Now astronomers have reported that a small, newly discovered galaxy orbiting the Milky Way is emitting a surprising amount of electromagnetic radiation in the form of gamma rays. What does this have to do with dark matter? Well, dwarf galaxies have so little atomic (“normal”) matter that astronomers use them as hunting grounds for dark matter. If the gamma-ray signal is confirmed, this would first confirm the existence of dark matter (something which some astrophysicists still doubt) and provide some information about it. But while this evidence is “tantalizing” Alex Geringer-Sameth of Carnegie Mellon University and colleagues from Brown and Cambridge Universities say that it is still premature to draw conclusions.
“They are very quiet systems, just containing some old stars and a lot of dark matter,” Dr. Geringer-Sameth said in an email. “If you see any excess gamma rays coming from them, something intriguing is going on.”
Neal Weiner, a dark matter theorist at New York University, agreed, saying that this study has quite a lot of potential.
“If you see gamma rays in a dwarf galaxy, it would be a good way to make a case that you are seeing dark matter.”
It’s not the first time astronomers hoped they have found dark matter though, and no one wants to get too excited. In December last year, astronomers believed they found X-Ray signals of dark matter, while in April 2014, a different team found other interesting signals. But for now, nothing is confirmed. Dark matter, one of the biggest Universal mysteries, still has to wait.
Source: Carnegie Mellon University.
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