Tim Linden

The Galactic Center Gamma-Ray Excess

The Milky Way Galactic Center

High Mass X-Ray Binaries

X-Ray Binaries

X-Ray binaries are formed when a compact object, either a neutron star or black hole, comes into close contact with an ordinary star. Material from the stars surface is either ejected or ripped onto the compact object. As this material falls, it heats up rapidly, eventually forming a bright accretion disk around the compact object which glows in X-Ray radiation. These systems can be among the brightest X-Ray emitters in the sky. The formation, evolution and X-Ray emission from these objects provide us insight into how binary stars evolve and die.

Here we see a wind-accretion X-Ray binary. In this case, the strong stellar winds from the companion star push material out in all directions, the material that is pushed in the direction of the compact object gets pulled and eventually falls into an accretion disk around the compact object. As material from the accretion disk heats up and falls into the object, bright X-Ray jets are formed.

This is a Roche Lobe X-Ray binary. In this case, the compact object has gotten so close that the stellar surface of the companion star is disrupted, causing material to be pulled off of the surface of the star and onto the compact object. These X-Ray binaries are typically much brighter than the wind-accretion systems.

Latest Results

TeV Halos

TeV electrons accelerated by pulsars may explain the diffuse TeV excess observed by Milagro.

Dark Kinetic Heating

Dark Matter collisions with neutron stars set a minimum neutron star temperature. This may be observable with next-generation instruments.

Star-Forming Galaxies

An analysis of 584 SFGs finds significant dispersion in their far-IR to gamma-ray correlation. SFGs significantly contribute to the IGRB.