High Energy and Particle Astrophysics

A computer simulates a jet of gamma-rays protruding from a dying star. The jet is created from the rotating material just outside the newly formed black hole. The jet will produce a GRB once it escapes the stellar atmosphere. Weiqun Zhang and Stan Woosley (University of California, Santa Cruz)

Astrophysical sources such as neutron stars, black holes, supernovae, and even the big-bang itself require a thorough understanding of high-energy and particle physics to interpret.  Likewise, such phenomena can be used as testing arenas for cutting edge-fundamental physics.

Research in high energy and particle astrophysics is divided at UCSC between the Physics Department (especially the Santa Cruz Institute for Particle Physics) and the Astonomy Department. The two departments are located in the same building and collaborations are common.

Some of the key high-energy and particle astrophysics projects ongoing at UCSC are:

Gamma rays and cosmic rays

The Physics Department and SCIPP have played a leading role in the Fermi Gamma Ray Space Telescope , having largely built the observatory's primary instrument . The UCSC Fermi team, including faculty Steve Ritz, Bill Atwood, Robert Johnson, Hartmut Sadrozinski, Terry Schalk, Tesla Jeltema,  Stefano Profumo, Joel Primack, and Enrico-Ramirez Ruiz, have actively gathering and interpreting data from the spacecraft for better understanding of AGN, compact objects, dark matter, and other potential sources of high-energy particles.

SCIPP members and physics faculty have played key roles in the Milagro and Veritas  high-energy gamma-ray and cosmic-ray experiments. Physicist David Smith is a co-investigator on the RHESSI solar X-ray satellite.  UCSC is also part of several future missions.

Supernovae, hypernovae, and Gamma-ray bursts

Stan Woosley and Enrico Ramirez-Ruiz have an active research program in nucleosynthesis and computational supernova and gamma-ray burst astrophysics. Woosley is the developer of the collapsar/hypernova model of gamma-ray bursts (GRB), which has become the canonical picture. He is also a co-investigator on the HETE-2 GRB satellite mission.  Ramirez-Ruiz  uses simulations and theory to study the role of compact binary coalescences as gravitational wave sources, short gamma-ray burst and type Ia supernova progenitors

Black Holes and Neutron stars

Astronomy faculty Enrico Ramirez-Ruiz and Piero Madau specialize in the complex physics of accretion and merging in black holed and neutron stars.  Tying these objects to both high-energy obervational astronomy and to contextual models of cosmology and galaxy formation, these researchers and their teams seek to understand both these objects themselves, and the role they play in the wider universe.

X-ray Astrophysics

Understanding the physics and evolution of thermal X-ray emission from hot gas in galaxies and galaxy clusters is another productive research area at UCSC. Observational work by Tesla Jeltema and others on the dynamics and evolution of this gas is closely linked with cosmological studies with DES and other surveys".

Particle astrophysics, and the early universe

High-energy theorists Stefano Profumo, Michael Dine, Tom Banks, Joel Primack and Anthony Aguirre seek to connect fundamental particle physics to both high-energy observations (such as those from Fermi), to particle physics experiments (such as at the LHC) and to cosmological observables.  These researchers tackle questions such as the origin of dark matter and dark energy, the orgin of baryonic matter, the formation of gravitational waves, and even the formation of our observable universe itself.