Events: Colloquia

KICP Colloquium: James Bock (California Institute of Technology)

3:30–4:30 pm ERC 161

“SPHEREx: An All-sky Infrared Spectral Survey Explorer Satellite”

Feb 19

Special A&A Colloquium: Azadeh Maleknejad (Max Planck Institute for Astrophysics)

12:00–1:00 pm ERC 576

A new paradigm for particle cosmology

Modern cosmology has been remarkably successful in describing the Universe from a second after the Big Bang until today. However, our current understanding of the cosmos before that time is less precise. Moreover, cosmology profoundly involves particle theory beyond the Standard Model to explain its long-standing puzzles: the origin of the observed matter asymmetry, particle nature of dark matter, and cosmic inflation. In this colloquium, I will explain that relic axion-gauge fields in fractions of a second after the Big Bang can relate and explain these seemingly unrelated puzzles in early and late cosmology. As a smoking gun, such relics would provide a new window into the early Universe through primordial gravitational waves. Therefore, they are testable by future CMB missions.

Feb 25

A&A Colloquium - Marco Velli (UCLA)

3:30–4:30 pm ERC 161

“Parker Solar Probe:  Understanding Coronal heating and Solar Wind Acceleration”

The magnetic field is fundamental to solar activity and shapes the inter-planetary environment, as shown by the full three dimensional monitoring of the heliosphere provided by measurements from many past and present interplanetary and remote sensing spacecraft. Magnetic fields are also the source for coronal heating and the very existence of the solar wind; produced by the sun’s dynamo and emerging into the corona, magnetic fields become a conduit for waves, act to store energy, and then propel plasma into the Heliosphere in the form of Coronal Mass Ejections (CMEs). Magnetic fields are also at the heart of the generation and acceleration of Solar Energetic Particle (SEPs) that modify the space weather environment of the Earth and other planets.

Parker Solar Probe (PSP) was launched in August 2018 to carry out the first in situ exploration of the outer solar corona and inner Heliosphere. Direct measurements of the plasma in the closest atmosphere of our star should lead to a new understanding of the questions of coronal heating, solar wind acceleration, and the generation, acceleration and propagation of SEPs.

In this lecture I will start with an introduction to our present knowledge of the magnetized solar corona and wind before describing the PSP scientific objectives, orbit, and instrument suites, and showing results from the first three orbits. Emphasis will be on how PSP will confirm or falsify present wind models as well as the potential new discoveries stemming from the first exploration of the space inside the orbit of Mercury. I will also discuss how synergies with Solar Orbiter might lead us to accurately understand the state of the solar wind all the way from the corona into interplanetary space, a stepping stone for understanding the dynamics of active magnetized plasmas throughout the universe.

Feb 26

A&A Colloquium - Peng Oh (UC Santa Barbara)

3:30–4:30 pm ERC 161

Cold Gas in Hot Halos: The Formation and Survival of Cold Gas in Galactic Halos

In recent years, observations of the circumgalactic medium has undercovered a large reservoir of T ~ 10^4 K, photoionized gas in the much hotter halos of galaxies. Inflowing cold gas in galactic halos helps fuel star formation, whilst outflowing cold gas is our primary observational marker of feedback. However, the formation and survival of dense cold gas in the atmospheres of galaxy halos is still poorly understood. For instance, we do not yet understand how cold gas can be entrained in a hot wind, as is observed; most simulations indicate it should be shredded by hydrodynamic instabilities. The small scale structure of the cold gas is also poorly understood; galaxy formation simulations show CGM properties which are not converged numerically, and it is not clear what scales need to be resolved to achieve convergence. In this talk I will highlight some recent progress on these questions.

Mar 18

Brinson Lecture: Carlos Frenk (University of Durham)

6:00–7:00 pm SAIC MacLean Ballroom

How our universe was made: all from nothing

Cosmology addresses some of the most fundamental questions in science. How and when did our universe begin? What is it made of? How did galaxies and other structures form? There has been enormous progress in the past few decades towards answering these questions. For example, recent observations have established that our universe contains an unexpected mix of components: ordinary atoms, exotic dark matter and a new form of energy called dark energy. Gigantic surveys of galaxies reveal how the universe is structured. Large supercomputer simulations can recreate the evolution of the universe in astonishing detail and provide the means to relate processes occurring near the beginning with observations of the universe today. A coherent picture of cosmic evolution, going back to a tiny fraction of a second after the Big Bang, is beginning to emerge. However, fundamental issues, like the identity of the dark matter and the nature of the dark energy, remain unresolved.Large supercomputer simulations can recreate the evolution of the universe in astonishing detail and provide the means to relate processes occurring near the beginning with observations of the universe today. A coherent picture of cosmic evolution, going back to a tiny fraction of a second after the Big Bang, is beginning to emerge. However, fundamental issues, like the identity of the dark matter and the nature of the dark energy, remain unresolved.

May 14