Something came out of galaxy M87 moving faster than the speed of light.
Or at least that's what it looked like. Indeed, the Hubble Space Telescope has shown that it is almost five times faster. This feat was initially detected in 1995 in galaxy M87 and has subsequently been confirmed in a large number of other galaxies. It may cause you to doubt your whole reality. Nothing, after all, can exceed the cosmic speed limit, correct? You cannot just disregard the rules of physics... can you?
If you want to just enjoy the illusion from your audience seat, please stop reading. Otherwise, I'd like to invite you behind the scenes to see how the trick works – and how it's assisting astronomers in their quest to comprehend the destiny of whole galaxies.
Since 1918, when astronomer Heber Curtis saw a beam of light associated with the galaxy, we have known about the jet of plasma flowing from the center of M87. To be seen from such a great distance, it needed to be enormous — around 6000 light-years in length.
As contemporary astronomers have discovered, almost all galaxies have a core black hole that attracts stars and gas clouds on a cyclical basis. When gas starts to swirl down the drain, it warms up and is focused into jets of hot plasma by magnetic fields. These jets travel at speeds close to – but not beyond – the speed of light.
If you point a telescope towards M87, you will see that this plasma lance is twisted. Rather than directly into our line of sight, it is slanted slightly to the right.
To see the illusion, consider a single incandescent blob of plasma beginning at the base of this route and emitting a beam of light toward Earth. Now, wait ten years. During that time period, the blob has approached a significant fraction of the speed of light. This provides the photons released from the later location advantage of a few light-years on their journey to us.
When comparing the first and second photographs from Earth's viewpoint, it seems as if the blob has merely migrated to the right across the sky. However, since the second point is likewise closer to us, the light from it has traveled less distance than looks. This implies that it arrived sooner than it really did - as if the blob spent those ten years traveling at breakneck speed.
According to Eileen Meyer of the University of Maryland, Baltimore County, the jet from M87 is more than a curiosity.
Throughout the cosmos, outflows of energy from enormous black holes have the potential to halt or restart the birth of stars in galaxies. However, the mechanism by which these fluxes occur and the amount of energy contained inside them are unknown.
Jets such as the M87 one shift significantly over a few years due to their appearance to travel faster than light, which is rare for distant objects such as galaxies. This enables astronomers to make exact estimations of the plasma's velocity and consequently the process's power.
M87 is unique in that it is near in comparison to other galaxies, making it simple to examine. In 1999, scientists saw the plasma ripple outwards using Hubble images acquired over a four-year period of the jet. Meyer extended that to 13 years of photos in 2013, which seemed to indicate that the plasma may possibly move in corkscrew-like spirals — as if it wasn't confusing enough already.
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Meyer's latest findings, which are now being processed for publication, extend that baseline to more than two decades and may reveal fresh surprises. “Over 20 years, you know, things go bump in the night,” she says.
And, although she is well aware of the faster-than-light impact, she sometimes pauses to admire it. The majority of objects visible in the sky, such as planets and comets, are quite near to us. However, M87 is millions of light-years distant. “We can see, over a human lifetime, things moving,” she says. “Which is crazy.”
Reference(s): Peer-Reviewed Research