Physicists Find Evidence for Highest Energy Photons Ever Detected From Milky Way's Equator

Dec 14, 2005
The Milky Way Galaxy

Physicists at nearly a dozen research institution have discovered evidence for very high energy gamma rays emitting from the Milky Way, marking the highest energies ever detected from the galactic equator. Their findings, published in the Dec. 16 issue of the Physical Review of Letters, were obtained using the Milagro Gamma Ray Observatory, a new detector located near Los Alamos, N.M., that allows monitoring of the northern sky on a 24-hour, 7-day-per-week basis.

Gamma rays are considered by scientists to be the best probe of cosmic rays outside the solar neighborhood.

The research team, which includes nearly 40 physicists, reported that Milagro, positioned at an altitude of 8600 feet in the Jemez Mountains, detected a signal along the galactic equator region and interpreted it as arising from gamma rays with a median energy of 3.5 trillion electron-volts, or 3500 times the mass-energy of a proton. Previous satellite experiments have seen gamma-ray emissions along the galactic equator reaching up to energies of only 30 billion electron-volts.

These emissions are understood to be produced by interactions of cosmic-ray particles with the abundant interstellar medium near the galactic equator. Previously, some researchers had speculated that additional mechanisms were needed to explain the large number of particles observed at high energies. However, the measurements by Milagro can be understood by assuming a cosmic ray energy spectrum near the galactic center similar to that in the solar system and the standard properties of particle interactions.

The results presented in the Physical Review of Letters paper were gathered over a three-year period, beginning in July 2000.

Source: New York University

Explore further: 'Comb on a chip' powers new atomic clock design

add to favorites email to friend print save as pdf

Related Stories

Newly merged black hole eagerly shreds stars

Apr 08, 2011

A galaxy's core is a busy place, crowded with stars swarming around an enormous black hole. When galaxies collide, it gets even messier as the two black holes spiral toward each other, merging to make an even ...

Explaining the mystery of the missing sunspots

Apr 05, 2011

Sunspots have been observed for about four centuries, since they were first reported by Galileo. Appearing in roughly eleven-year cycles of activity, sunspots are regions of strong and complex magnetic fields ...

Recommended for you

'Comb on a chip' powers new atomic clock design

8 hours ago

Researchers from the National Institute of Standards and Technology (NIST) and California Institute of Technology (Caltech) have demonstrated a new design for an atomic clock that is based on a chip-scale ...

Quantum leap in lasers brightens future for quantum computing

8 hours ago

Dartmouth scientists and their colleagues have devised a breakthrough laser that uses a single artificial atom to generate and emit particles of light. The laser may play a crucial role in the development of quantum computers, ...

Technique simplifies the creation of high-tech crystals

8 hours ago

Highly purified crystals that split light with uncanny precision are key parts of high-powered lenses, specialized optics and, potentially, computers that manipulate light instead of electricity. But producing ...

A new multi-bit 'spin' for MRAM storage

11 hours ago

Interest in magnetic random access memory (MRAM) is escalating, thanks to demand for fast, low-cost, nonvolatile, low-consumption, secure memory devices. MRAM, which relies on manipulating the magnetization ...

User comments : 0