Two mysterious globular structures were spotted in the galaxy NGC 3079, located 67 million light years from Earth. Scientists unveiled nuclear “superbubbles” thousand of light years wide that act like particle accelerators 100 times more powerful than the Large Hadron Collider, and are around 2,000 times longer, on average, than our solar system.The “bubbles,” according to a new study led by University of Michigan astronomer Jiangtao Li, are made of high-energy particles that stretch out across 4,900 light years on one side of the galaxy, and 3,600 light years on the other. To put that into perspective, the Sun’s influence extends for about two light years.
The extreme properties of the superbubbles suggest that they are produced by cataclysmic events like starbirth, or jets emitted from the galaxy’s central supermassive black hole. The structures may also be a source of cosmic rays, which are high-energy particles that originate outside the solar system and constantly hit Earth’s atmosphere.
A team of astronomers led by Jiangtao Li, an assistant research scientist from the University of Michigan, has described the results of their observations and research on galactic bubbles in a paper that was recently published in The Astrophysical Journal.
Galaxy NGC 3079, which is located approximately 67 million light years from earth, contains two galactic bubbles – one that is 4,900 light years across, and another that is 3,600 light years. These bubbles give off light in the form of X-ray, optical and radio emission, which make them detectable by NASA telescopes, such as those at the NASA Chandra X-ray Observatory.
New observations from Chandra by Dr. Li and his team of researchers show that a cosmic particle accelerator is producing ultra-energetic particles on the edges of NGS 3079’s cosmic bubbles, therefore providing evidence that these bubbles – and structures like them – may be the source of “cosmic rays.”
As the outer regions of galactic bubbles expand and collide with surrounding gas, researchers believe that charged particles scatter and bounce off magnetic fields in the shock waves. When the particles cross the shock front, they are super accelerated to energies about 100 times stronger than those generated by the world’s most powerful human-made particle accelerator. Some of these energy particles may escape and even strike Earth’s atmosphere in the form of cosmic rays.
The amount of radio waves generated by one of the galactic bubbles suggest that the source of the X-ray emission is electrons swirling around the magnetic fields of the shock waves on the rim of the bubble. The electrons are radiated by a process called synchrotron radiation, and these observations by Dr. Li and his team present the first direct evidence of synchrotron radiation in high energy X-rays from a massive galactic bubble.
The radio emission has been detected on both sides of the bubble, but the hard X-ray emission is detected only on the SW side. It is strange that the NE side, which is brighter in every other wavelength (radio, Halpha, soft X-ray), is not detected in hard X-ray. It is not yet understood why synchrotron emission has not been detected from the other bubble.
NASA Chandra image at top of the page of NGC 3079 shows X-ray and optical wavelengths.
The Daily Galaxy, Max Goldberg, via University of Michigan