The Unsolved Mystery of the Galactic Centre GeV Excess of Gamma Rays

AD | Join me in reading Nautilus in 2025, by heading to http://joinnautilus.com/drbecky you can get 15% off a membership to Nautilus, a perfect new years treat for any science enthusiast. | Us astrophysicists love a good unsolved mystery - because when you can’t explain something you’ve observed you know that eventually you’ll learn something new about the Universe. Now one of the biggest unsolved mysteries still in astrophysics is dark matter - matter that doesn’t interact with light at all, but does with gravity so that we know it’s there. In the same way we can’t see the wind, but know that its windy because we can see the trees move. There has been a pile of evidence growing over the past century in favour of dark matter, and yet we still don’t know what its made of. So while the particle physicists are fiddling with their big particle colliders trying to make or detect some dark matter, us astrophysicists are also constantly looking for new ways to detect it out in the universe and test if its there. The problem comes when you end up with another unsolved mystery in the process, like the Galactic Centre GeV excess - an as yet unexplained surplus of gamma rays, the highest energy light there is, that’s was discovered right at the centre of the Milky Way back in 2007. And what’s exciting is this could be a signal that there’s a surplus of dark matter at the centre of the Milky Way, which would make it the first direct detection of dark matter. But this gamma ray excess could also be something else entirely, and not actually to do with dark matter at all... My previous video on all the evidence we have for dark matter - https://youtu.be/nbE8B7zggUg?si=m0RS8Ak-_ouLVnp0 My previous video on anti-matter - https://www.youtube.com/watch?v=hzioEVQN4Dg More about the Fermi Gamma Ray Space Telescope - https://fermi.gsfc.nasa.gov/ More about the Cherenkov Telescope Array - https://www.ctao.org/ More about the Square Kilometre Array - https://www.skao.int/en Goodenough & Hooper (2009) - https://arxiv.org/pdf/0910.2998 Hooper & Goodenough (2011) - https://arxiv.org/pdf/1010.2752 Navarro, Frenk & White (1996) - https://articles.adsabs.harvard.edu/pdf/1996ApJ...462..563N Baltz, Taylor & Wai (2007) - https://arxiv.org/pdf/astro-ph/0610731 Mirabel et al. (2013) - https://arxiv.org/pdf/1309.3428 Bartels et al. (2016) - https://arxiv.org/pdf/1506.05104 Hooper & Linden (2018) - https://arxiv.org/pdf/1803.08046 Leane & Slayter (2019) - https://arxiv.org/pdf/1805.10305 Gautam et al. (2022) - https://arxiv.org/pdf/2106.00222 00:00 Introduction 03:16 What is the Galactic Centre GeV excess? 06:33 Dark matter annihilation explanation 10:26 Milli-second pulsars explanation 13:32 How will we figure out which is the right explanation? 15:48 Bloopers Video filmed on a Sony ⍺7 IV Video edited by Martino Gasparrini: https://www.fiverr.com/mgs_editing --- 📚 My new book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): http://lnk.to/DrBecky --- 👕 My new merch, including JWST designs, are available here (with worldwide shipping!): https://dr-becky.teemill.com/ --- 🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive --- 🔔 Don't forget to subscribe and click the little bell icon to be notified when I post a new video! --- 👩🏽‍💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford (Christ Church). I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars. http://drbecky.uk.com