Cosmic journey at SISSA

1. Cosmic journey at SISSA

2. The astrophysics sector at SISSA • Science: processes relevant in cosmlogy and astrophysics, from big bang to black holes • Training: students go from passive learning to active research in three or four years • www.sissa.it/ap • www.sissa.it/app

3. Astrophysics • Limits in technology and funding prevent us to make particle physics experiments as we like on earth • An example? In order to see unification of all forces, one should build an accelerator with the radius of the solar system! • The universe around us provides an ideal laboratory, from big bang to black holes…so… • Let’s look at it!

4. Journeying in the cosmos

5. Journeying in the cosmos The worm Ouroboros

6. Why do we care? • Spending our life and money to think about these things, building strange and expensive machines to probe extreme physics… • Why? Only for the sake of knowledge? Pleasure for few? Is there something for the community?

7. Why do we care? • Spending our life and money to think about these things, building strange and expensive machines to probe extreme physics… • Why? Only for the sake of knowledge? Pleasure for few? Is there something for the community? • The good answer? It’s in the switch for the light, turn it on!

8. Why do we care? • Spending our life and money to think about these things, building strange and expensive machines to probe extreme physics… • Why? Only for the sake of knowledge? Pleasure for few? Is there something for the community? • The bad answer? It’s in the worst weapon ever (so far)

9. The big bang • Ehm…simply, what the hell was it? physical laws we know fail there, help! • Things that we may reproduce on earth happened 10-28 after the bang • Our guesses reach a tiny fraction of a second…but… • What was spacetime there? • Did space get stretched immediately after the bang? • Do we see it? Well, no, but we see (and measure, very well actually) its echo, through the relic radiation • Contacts: Carlo Baccigalupi, Stefano Liberati Courtesy of the NASA WMAP team

10. The aftermath: darkness and first light • When the relic radiation is rarefied enough, the universe is smoothly expanding in the dark, but without hot radiation structures may grow… • Eventually dense regions light up, and we see their signature today, as their energy extracted the electrons from hydrogen in the cosmic medium • When did this happen exactly? • What were the engines of first light? Primordial giant stars? Primeval quasi-stellar objects powered by black holes? • Contact: Andrea Ferrara

11. The galaxies: isles… • Hundreds of billions of stars in each of them, and we see billions… • How do they work? • Ellipticals, starburst, spirals, ghost, and…? • What is their central engine? maybe a black hole for all of them? • Contact: Luigi Danese, Paolo Salucci

12. …in an invisible ocean • Galaxies rotate too fast…stars orbit more mass than we see, much more, and dark… • The relic radiation is also a spy of darkness…hot and cold spots come from invisible wells and hills in the early universe… • Our guess…a dark network of unknown particles is all around us…but… • What are those? Super-world particles? Or new forces? • Let’s simulate their graitational forces, and compare what we get with what we see… • Contact: Paolo Salucci, Riccardo Valdarnini

13. Galactic violence • The milky way is our home, it looks quiet and steady… • But other galaxies are violent, they have active nuclei, not to say catastrophic…and… • Some of them, once per day in the sky, shine of the most violent event ever observed, a gamma-ray burst • What’s the mechanics of active galactic nuclei? How exactly the central black holes power them? • How many different kinds of them exist? • What are the gamma-ray burst? Super-supernovae? Why we see only explosions in the early universe? Are we in danger? • Contact: Annalisa Celotti

14. Challenging Einstein • General relativity (Einstein, 1916): gravity as geometry, perhaps the most elegant theory ever formulated • But also the wildest beast ever! • Don’t try to match it with quantum gravity, you’ll hurt yourself! • Theories to go beyond that have failed so far! • But the sky is full of objects under extreme gravity conditions, let’s study and model them, for different gravity models… • And even try to reproduce them here, at least on super-computers… • Extreme gravity excites spacetime, producing ripples in spacetime…can we try to see those? • Contacts: Stefano Liberati, John Miller, Luciano Rezzolla

15. What? Big Bang today? • Mysteries are not enough, so let’s get another one • A mysterious force, the dark energy, discovered in 1998, is stretching space apart, today, as it probably did at the Big Bang • It seems to come from a form of energy in the empty space… • No idea of what it is, scientists are trying all possible explanation, failing completely so far • The universe will bang again in a few billions years… • Contact: Carlo Baccigalupi

16. The sky: a cornucopia for physics • Where from now? • The road will be decided substantially by the results of observations, in just a few years from now • Which ones? The Planck satellite (relic radiation) the Large Hadron Collider (elementary particles), the Herschel space telescope (physics of galaxies), gravity wave detectors, galactic surveys (dark matter) • The final message: stay tuned…or help!!!