A galaxy about 23 million light-years away is the site of impressive, ongoing, fireworks. Rather than paper, powder, and fire, this galactic light show involves a giant black hole, shock waves, and vast reservoirs of gas.
A new study of these anomalous arms made with Spitzer shows that shock waves, similar to sonic booms from supersonic planes, are heating large amounts of gas — equivalent to about 10 million suns. What is generating these shock waves? Radio data shows that the supermassive black hole at the center of NGC 4258 is producing powerful jets of high-energy particles. Researchers think that these jets strike the disk of the galaxy and generate shock waves. These shock waves, in turn, heat some of the gas — composed mainly of hydrogen molecules — to thousands of degrees. As shown in our additional, composite image, part of the evidence for this heating process comes from the similarity in location between the hydrogen and X-ray emission, both thought to be caused by shocks, and the radio jets.
The ejection of gas from the disk by the jets has important implications for the fate of this galaxy. Researchers estimate that all of the remaining gas will be ejected within the next 300 million years — very soon on cosmic time scales — unless it is somehow replenished. Because most of the gas in the disk has already been ejected, less gas is available for new stars to form. Indeed, the researchers used Spitzer data to estimate that stars are forming in the central regions of NGC 4258, at a rate which is about ten times less than in the Milky Way galaxy.
What would life in a pyrotechnic galaxy look like? Is it even possible?
I wonder about the sonic booms. Would they be felt on any planets within the galaxy? Or would the size and physics of their orbit make such phenomenon barely noticeable — the way we do not notice that we are flying around the sun at a horrifying rate of speed? What would normal look like in this galaxy?
Could a planet be protected enough that life could exist within the range of these high-energy particles? Would energy be readily available? Would these theoretical beings be used to the concept of energy being freely available? Would they see energy the way we see oxygen? Would they take it for granted? Would they build ships that would fly using this energy? What would happen if they came to our galaxy? Would they find our own radiation compatible?
What inter-cultural adventures might arise as they tried to understand humanity and its approach to energy?