Astrophysics

UCR has an active program in space physics, high energy astrophysics, and extragalactic astronomy. Much of this research is performed with the Institute of Geophysics and Planetary Physics (IGPP) at UCR.

Theoretical Space Physics

Our activities encompass the physics of the solar corona and solar wind acceleration, the interaction of the solar wind with the non-magnetized bodies, the interplanetary medium (turbulence, shock waves, solar wind composition, neutral and charged particle transport, particle acceleration, solar energetic particles and cosmic rays, dust, etc.), and the interaction of the heliosphere with the local interstellar medium (LISM). We maintain an active research program in several areas of plasma astrophysics, focusing primarily but not exclusively on galactic cosmic rays, the interstellar medium, galactic magnetic fields, and the interaction of stellar winds with their local interstellar environment. For more information on individual projects see the IGPP website.

High Energy Astrophysics

High energy astrophysics involves the observation and understanding of the most energetic and violent physical processes in the universe. X- and gamma-ray continuum emissions can be observed from supernovae, rotating neutron stars/pulsars and the accretion disks surrounding black holes. Gamma-ray line emission is seen from the nucleosynthesis of radioactive isotopes that takes place in violent supernovae. Annihilation radiation at 0.511 MeV is seen from matter-dominated relativistic plasmas at the center of our Milky Way galaxy. The origin of cosmic gamma ray bursts remains one of the greatest enigmas of all time in astronomy. X- and gamma-rays resulting from the accretion of matter onto massive black holes at the core of active galactic nuclei represent the highest energy processes yet seen in the early universe.

In high energy astrophysics, UCR is well known for its development of Compton telescopes and balloon-borne observations with these instruments. They have initiated the development of technology for a new Compton telescope for the 21st century. This is called the Tracking and Imaging Gamma-Ray Experiment (TIGRE). UCR researchers are active in the analysis of data from NASA's Compton Gamma-Ray Observatory which is presently in space. They are also analyzing data from the recently launched Rossi X-ray Timing Explorer mission. Balloon and space observations of gamma rays have been successful up to energies of about 20 GeV. Above this energy fluxes are too low and detectors are too large for space. UCR researchers are involved in several techniques using the earth's atmosphere as the interaction medium to detect these higher energy photons. One method involves using large-area solar energy concentrators to detect flashes of Cerenkov radiation produced by single gamma-ray-initiated air showers in the Earth's upper atmosphere. A second method is the LANL MILAGRO air shower experiment. Here, the charged particles from an extended air shower are detected on a large covered water detector near Los Alamos.

Extragalactic Astronomy

One of the main subjects of our research at UCR is the study of Active Galactic Nuclei (AGN) in the near and distant universe. AGN are centers of galaxies containing supermassive black holes that are actively accreting matter at relatively high rates. Much of the gravitational energy of the infalling material is transformed into radiative energy across the electromagnetic spectrum, making AGN some of the most powerful and luminous objects in the universe. Quasars are of particular interest since they represent the family of AGN with the highest luminosities and can therefore be observed at the greatest distances, when the universe was only a small fraction of its present age. There are many outstanding fundamental questions regarding the origins and astrophysics of quasars, such as determining the most common triggering mechanisms, the duty cycle, and the mass of the central black hole. We investigate these topics through the detailed study of the environments and the quasar host galaxies, as well as establishing relationships between observable parameters in the hosts and fundamental parameters in their active nuclei. Our research also involves the study of large scale starbursts in distant galaxies, galaxy formation and evolution, as well as mergers and interactions of galaxies.

The observational extragalactic astronomy group at the UCR is heavily involved in a number of research projects addressing formation and evolution of galaxies, search for the most distant galaxies, star formation in galaxies, Dark Matter and Dark Energy. These are among the most fundamental questions in Astronomy today, and are studied using multi-waveband galaxy surveys obtained with 8-10 meter ground-based telescopes (Keck, VLT, Subaru) and space facilities (HST, Spitzer, GALEX, Chandra).

UCR astronomy group plays an active role in the largest and most ambitious cosmological surveys currently in progress, including the Great Observatories Origin Deep Survey (GOODS), Cosmic Evolution Survey (COSMOS) and the Hubble Ultra-Deep Field (HUDF). Using deep, multi-waveband (from UV to radio wavelengths) data from these surveys, we examine current theories for formation of galaxies -- if galaxies we see today were formed by merger of smaller sub-units throughout the age of the Universe or, were formed in a monolithic collapse when the Universe had a fraction of its present age. We explore the origin of the morphology of galaxies and how they came to have their observed shape. By searching for the most distant galaxies in the Universe, we study very early epoch in the Universe, and the first generation of stars and galaxies and how they were formed. Using the multi-waveband data from the GOODS, COSMOS and HUDF we investigate the most fundamental parameters which govern star formation activity in galaxies and how the observed star formation depends on the redshift, environment, mass, color, dust content and type of galaxies.

We are an active member of the SuperNovae Acceleration Probe (SNAP) space project. This is a future mission aimed to study the existence and nature of Dark Energy and its equation of state.