Universe ID: 12376

Fermi Finds Record-breaking Gamma-ray Binary

Released on September 29, 2016

Using data from NASA's Fermi Gamma-ray Space Telescope and other facilities, scientists have found the first gamma-ray binary in another galaxy and the most luminous one ever seen. The dual-star system, dubbed LMC P3, contains a massive star and a crushed stellar core that interact to produce a cyclic flood of gamma rays, the highest-energy form of light.

Gamma-ray binaries are rare -- only six are known in our own galaxy, and one remains undetected by Fermi. The systems are prized because their gamma-ray output changes significantly during each orbit and sometimes over longer time scales. This variation lets astronomers study many of the emission processes common to other gamma-ray sources in unique detail.

The systems contain either a neutron star or a black hole and radiate most of their energy in the form of gamma rays. Remarkably, LMC P3 is the most luminous such system known in gamma rays, X-rays, radio waves and visible light, and it's only the second one discovered with Fermi.

LMC P3 lies within a supernova remnant located in the Large Magellanic Cloud (LMC), a small nearby galaxy about 163,000 light-years away. In 2012, scientists using NASA's Chandra X-ray Observatory found a strong X-ray source within the remnant and showed that it was orbiting a hot, young star many times the sun's mass. The researchers concluded the compact object was either a neutron star or a black hole and classified the system as a high-mass X-ray binary (HMXB).

In 2015, a team led by Robin Corbet at NASA's Goddard Space Flight Center began looking for new gamma-ray binaries in Fermi data by searching for the periodic changes characteristic of these systems. The scientists discovered a 10.3-day cyclic change centered near one of several gamma-ray point sources recently identified in the LMC. One of them, called P3, was not linked to objects seen at any other wavelengths but was located near the HMXB. Were they the same object?

Observations from NASA's Swift satellite clearly reveal the same 10.3-day cycle seen in gamma rays by Fermi. They also indicate that the brightest X-ray emission occurs opposite the gamma-ray peak, so when one reaches maximum the other is at minimum. Radio data exhibit the same period and out-of-phase relationship with the gamma-ray peak, confirming that LMC P3 is indeed the same system investigated by Chandra.

Prior to Fermi's launch, gamma-ray binaries were expected to be more numerous than they've turned out to be. It's a puzzle because hundreds of HMXBs are cataloged, and all of them are thought to have originated as gamma-ray binaries following the supernova that formed the compact object. Its possible gamma-ray binaries may form only from neutron stars born with the fastest spins, which would enhance their ability to produce gamma rays.

Observations from Fermi's Large Area Telescope (magenta line) show that gamma rays from LMC P3 rise and fall over the course of 10.3 days. The companion is thought to be a neutron star. Illustrations across the top show how the changing position of the neutron star relates to the gamma-ray cycle.

Credit: NASA's Goddard Space Flight Center

LMC P3 (circled) is located in a supernova remnant called DEM L241 in the Large Magellanic Cloud, a small galaxy about 163,000 light-years away. The system is the first gamma-ray binary discovered in another galaxy and is the most luminous known in gamma rays, X-rays, radio waves and visible light.

Credit: NOAO/CTIO/MCELS, DSS

Binary animation, version with a moving camera. This animation of LMC P3 illustrates how the position of the neutron star (magenta) modulates the system's gamma-ray brightness. The neutron star accelerates high-energy electrons. When these particles collide with the star's visible light, it receives a boost up to gamma-ray levels. This process produces more gamma rays when the companion passes near the star on the far side of its orbit as seen from our Earth.

This animation of LMC P3 illustrates how the position of the neutron star (magenta) modulates the system's gamma-ray brightness. The neutron star accelerates high-energy electrons. When these particles collide with the star's visible light, it receives a boost up to gamma-ray levels. This process produces more gamma rays when the companion passes near the star on the far side of its orbit as seen from our Earth.

This map, produced using seven years of data from Fermi's Large Area Telescope, shows the entire sky in gamma rays and locates all known gamma-ray binary systems. Fermi has detected five of these binaries within our galaxy, the lone exception being HESS J0632+057. LMC P3 is the first gamma-ray binary found in a galaxy beyond our own. Brighter colors indicate greater numbers of gamma rays with energies above 1 billion electron volts (GeV). The central plane of our galaxy, the Milky Way, is the bright band running across the center.

Credit: NASA/DOE/Fermi LAT Collaboration

This map, produced using seven years of data from Fermi's Large Area Telescope, shows the entire sky in gamma rays with energies above 1 billion electron volts (GeV). Brighter colors indicate greater numbers of gamma rays. The central plane of our galaxy, the Milky Way, is the bright band running across the center.

Credit: NASA/DOE/Fermi LAT Collaboration

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For More Information

http://www.nasa.gov/feature/goddard/2016/nasas-fermi-finds-record-breaking-binary-in-galaxy-next-door

Credits

Scott Wiessinger (USRA): Lead Producer
Scott Wiessinger (USRA): Lead Animator
Francis Reddy (Syneren Technologies): Lead Science Writer
Francis Reddy (Syneren Technologies): Graphics

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NASA's Goddard Space Flight Center. However, individual items should be credited as indicated above.

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Mission:
Fermi Gamma-ray Space Telescope

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Keywords:
SVS >> Galaxy
SVS >> HDTV
SVS >> Neutron Star
SVS >> X-ray
GCMD >> Earth Science >> Spectral/Engineering >> Gamma Ray
SVS >> Gamma Ray Burst
SVS >> Astrophysics
SVS >> Space
SVS >> Fermi
SVS >> Supernova
SVS >> Star
NASA Science >> Universe

GCMD keywords can be found on the Internet with the following citation: Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 8.0.0.0.0