Session D08: DAP/DPF Awards Session

Live

The Hubble tension between early universe and local measurements of H0 can be resolved by a brief episode of dark energy contributing about 10% of cosmic energy density at redshift z ∼ 3500. New N-body simulations have shown that this Early Dark Energy scenario predicts earlier structure formation, e.g. 50% more clusters than ΛCDM at redshift z ∼ 1. Galaxies were long thought to start as disks, but HST images show that most galaxies instead start prolate (pickle shaped). Galaxy simulations can explain this as a consequence of the filamentary nature of the ΛCDM dark matter distribution. But comparisons between simulations and observations using novel machine learning methods reveal other potential challenges. Earth may be a radioactively Goldilocks planet, with just the right amount of radiogenic heating by Th and U for plate tectonics and a magnetic field both of which may be necessary for the evolution of complex life. Production of these elements in rare neutron star mergers implies incomplete mixing. A factor of 2 increase would have stopped Earth’s magnetic dynamo for hundreds of millions of years and also caused widespread vulcanism. A factor of 2 decrease could have stopped plate tectonics   

Live

In this talk, I discuss ongoing efforts to understand axion and axion-like particle (ALP) dark matter. I will give some insight into how I am using a range of tools -- model building, computation, and high energy astrophysics -- to get at the basic question of “what is the statistical mechanics of axion dark matter?” I will also make some comments along the way about the challenges we face in making physics reflect the best of humanity.   

Live

Astrochemistry is the study of the elementary chemical reactions that produce and destroy the molecules observed in astronomy. Sixty years ago, there were only a few atoms, diatomic, and triatomic molecules observed in astronomy. Most of these were in comets such as O, Na, K C2,CN, OH, CO+, OH+, N2+, C3, NH2, and CO2+ through their emission spectra excited by resonance fluorescence of sunlight in the atmosphere surrounding a comet. In this atmosphere there is also gas, dust and magnetic fields. The laboratory studies of the spectroscopy of these species had been known for a long time and it was also known that the atoms and radicals could not be stored for long periods of time, even at liquid He temperatures. If they are not evaporating from the cometary nucleus, how are they being produced? The method of production has to be consistent with the astronomical environment they are found in. I will chronicle how certain laboratory techniques have helped us to determine the precursors of some atoms and radicals observed in comets, planetary atmospheres and other astronomical bodies.   

Live

The accelerated expansion of the Universe is the most surprising cosmological discovery in decades. It has inspired a new generation of ambitious surveys which will soon map billions of galaxies and probe cosmic structure formation with high statistical precision. In my talk, I will introduce the landscape of current and near-future wide-field galaxy surveys and the different measurement techniques used by these experiments. I will describe opportunities and challenges of cosmological analyses in the presence of complex systematic effects, using recent results from the Dark Energy Survey as pathfinder examples. I will further give an outlook on cosmology analysis plans upcoming experiments, such as Rubin Observatory and Roman Space Telescope, and synergies with multi-wavelength observations.