Science

Interdisciplinary Scientists

Four interdisciplinary scientists (IDS) were chosen whose scientific interests Fermi observations will impact significantly. Below the IDS's are listed with a brief paragraph about their scientific interests and how they relate to Fermi.

Charles Dermer

Dr. Charles Dermer is a theoretical astophysicist whose research covers some of the most exotic topics in astronomy, ranging from the evolution of the universe and the formation of black holes, to collisions between clusters of galaxies and sites where the highest energy cosmic-ray particles are accelerated. Dr. Dermer studies the feasibility of the Fermi mission to reveal the universe in its nonthermal, energetic phases where powered by exploding stars, accreting black holes, and galaxy cluster mergers. As demonstrated by the pioneering EGRET experiment on the Compton Gamma Ray Observatory, gamma-ray astronomy provides a fundamental tool to probe the very large and very small: the diffuse radiations in our universe and the compact objects that populate it. Dermer is an expert on radiation mechanisms, including nonthermal electron and proton collision events, and photon and neutrino production processes in the explosive outflows from supernovae, gamma-ray bursts, and astrophysical jets.

Brenda Dingus

Brenda Dingus, a staff scientist at Los Alamos National Laboratory, is interested in high energy gamma-rays from transient sources. Using data from EGRET, she found gamma rays as high an energy as 20 GeV from a gamma-ray burst and has recently discovered a gamma-ray burst with a higher energy spectral component of longer duration that could be indicative of ultra high energy cosmic ray acceleration in gamma-ray bursts. Dr. Dingus also is a collaborator on the Milagro TeV gamma-ray observatory located in the mountains above Los Alamos, NM. Milagro is a unique TeV detector because of its large field of view (~2 sr) and high duty factor (~90%). Both of these qualities allow Milagro to perform the most sensitive survey of the sky for transient sources of TeV gamma-rays. Dr. Dingus is using her expertise with EGRET and Milagro to enhance the capabilities of Fermi for observing transient sources and to insure the usefulness of Fermi observations for scientists studying TeV gamma ray emission.

Martin Pohl

At Iowa State University, Martin Pohl as one of the four Fermi Interdisciplinary Scientists selected by NASA conducts his long-term research program on modeling the diffuse galactic gamma-ray emission. This emission tells us about the physical conditions in the Galaxy as seen by cosmic ray particles, and it may also reveal previously hidden gas, i.e. baryonic dark matter. Galactic diffuse emission is both a burden as it provides background, and a valuable tracer of cosmic rays and the interstellar medium. He intends to provide a) an extensive physical analysis of diffuse Galactic gamma-ray emission, and b) a continuously refined model of the Galactic gamma-ray emission to be used for foreground estimation by the Fermi team and the Fermi guest observers.

Stephen Thorsett

Rotation-powered pulsars are often misleadingly called radio pulsars, after the spectral region where they were first discovered. However, known "radio" pulsars are actually most efficient in the hard x-ray and gamma-ray bands, where Fermi operates, and some (such as the Geminga pulsar) can't be detected in radio at all. Because of the relatively poor sensitivity of early gamma-ray telescopes, only a handful of pulsars have been studied in this band, but Fermi should increase the number by an order of magnitude or more. It is often said that we know why pulsars pulse (their rotation sweeps lighthouse beams across the sky), but we don't really know how they shine (what makes the lighthouse beam?). Nearly four decades after their discovery, Fermi promises to test pulsar emission theories. My own interest is primarily in the geometry of the pulsar beams. Knowing the size of the lighthouse beam is crucial to estimating the number of neutron stars in the Galaxy, the rate at which they are born, and the nature of compact x-ray sources in supernova remnants. I will help facilitate the coordinated radio and gamma-ray observations needed to make the most sensitive possible Fermi observations of pulsars and to compare radio and gamma-ray beam shapes.