96 | Lina Necib on What and Where the Dark Matter Is
May 11, 2020
01:21:43
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Lina Necib discusses the concept and significance of dark matter, theories and candidates for dark matter, detecting dark matter through missing energy and gamma rays, prospects of gamma ray telescopes, advancements in astronomy with Gaia satellite, and exploration of the complex nature of dark matter.
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Quick takeaways
Dark matter accounts for 25% of the universe and understanding its distribution and properties is crucial for detection.
Prominent candidates for dark matter composition include WIMPs, axions, and primordial black holes, which are being investigated through various detection methods.
Direct and indirect detection methods, such as particle collision experiments and astrophysical observations, provide insights into the presence and nature of dark matter.
Deep dives
Dark Matter Inventory
Cosmologists have determined that ordinary matter, like atoms and particles, only makes up about 5% of the universe, while dark matter accounts for 25% and dark energy for 70%. Understanding the distribution and properties of dark matter is crucial for detecting it.
Unveiling the Nature of Dark Matter
Researchers are actively studying dark matter to determine its composition, with prominent candidates including WIMPs (weakly interacting massive particles), axions, and primordial black holes. These particles have distinct properties and are being investigated through various detection methods.
Direct Detection Experiments
Direct detection experiments involve large tanks of material, such as xenon, deep underground. These experiments search for interactions between dark matter particles and ordinary matter, looking specifically for signals like missing energy in particle collisions.
Indirect Detection and Galactic Center Excess
Indirect detection methods involve searching for astrophysical signals caused by dark matter annihilations or decays. Observations of the galactic center, dwarf galaxies, and cosmic rays can provide insights into the presence of dark matter, although distinguishing it from other astrophysical sources can be challenging.
Prospects for Gamma Ray Telescopes and Other Experiments
Gamma ray telescopes like Fermi provide valuable data for understanding astrophysics and the Milky Way. Upcoming telescopes like the Lassistis and the Gaia space telescope offer exciting possibilities for gaining more insights into the universe.
Impact of Gaia's 3D Stellar Map on Dark Matter Studies
Gaia's 3D stellar map of a billion stars aids in studying the interplay between the location of dark matter in the Milky Way and its detection on Earth. The map helps understand the distribution, velocities, and interactions of dark matter particles, which has implications for theories such as warm dark matter and self-interacting dark matter.
The past few centuries of scientific progress have displaced humanity from the center of it all: the Earth is not at the middle of the Solar System, the Sun is but one star in a large galaxy, there are trillions of galaxies, and so on. Now we know that we’re not even made of the same stuff as most of the universe; for every amount of ordinary atoms and other known particles, there is five times as much dark matter, some kind of stuff we haven’t identified in laboratory experiments. But we do know a great deal about the behavior of dark matter. I talk with Lina Necib about why we think there’s dark matter, what it might be, and how it’s distributed in the galaxy. The latter question has seen enormous recent progress, especially from high-precision measurements of the distribution of stars in the Milky Way.
Lina Necib received her Ph.D. in physics from the Massachusetts Institute of Technology. She is currently a Sherman Fairchild Postdoctoral Scholar in Theoretical Physics at Caltech, and will be an Assistant Professor of Physics at MIT starting in the fall. Her research spans issues in particle physics and astrophysics, especially concerning the nature and distribution of dark matter, as well as techniques for detecting it and constraining its properties.