Hercules A, a supermassive-blackhole situated in the galaxy 3C 348, emits Plasma as far as 1.5 million light years away !! Although the cause is poorly understood, what could be the possible cause for this, and why it is so long ?

Links: Hercules a huge black hole emits two beams of matter into space

A Multi-Wavelength View of Radio Galaxy Hercules A

Hercules A

  • 1
    $\begingroup$ @uhoh Links Added ! $\endgroup$ Commented Jan 1, 2022 at 9:27
  • 1
    $\begingroup$ That's great, thank you! $\endgroup$
    – uhoh
    Commented Jan 1, 2022 at 10:33
  • 1
    $\begingroup$ Are you asking what is causing the astrophysical jets in principle, or what could be causing the jets to be so long? $\endgroup$ Commented Jan 1, 2022 at 18:22
  • $\begingroup$ @DaddyKropotkin Both ! $\endgroup$ Commented Jan 2, 2022 at 4:26

2 Answers 2


Hercules A can not emitt plasma or anything. Any matter within the event horizon will stay within the event horizon forever.

So the matter in the jets must come from outside the event horizon.

Matter orbiting Hercules A just above the event horizon must have speeds just slightly below the speed of light. Matter orbiting Hercules A farther out will have orbital speeds which are lower than that, but still extremely fast.

If matter fell to Hercules A from an infinite distance it would take an infinite time to arrive and would be travelling at the escape velocity, the speed of light, when it crossed the event horizon. Actual matter falling into Hercules A will be travelling slower than the speed of light, but still extremely fast.

So matter in the neighborhood of Hercules A will tend to be travelling very fast, at significant fractions of the speed of light. A lot of that material will be ionized and so will react to the strong magnetic fields which should be in the vicinity of Hercules A.

So it is common for matter located near Hercules A to have its speed and direction of travel changed radically by gravitational and magnetic interactions with Hercules A and/or with other matter near Hercules A.

In some cases the new velocity will make the matter more likely to enter the event horizon, in other cases the new velocity will make it more likely to move away from Hercules A.

Suppose that partcle travels at 0.95 of the speed of ligth and passes so close to Hercules A that at the closest point the escape velocity will be 0.90 of the speed of light. The particle will have 0.05 of the speed of light more than the escape velocity and so willl not fall into Hercules A at the closest pass but will continue on its course getting farther and farther away from Hercules A and slowing down more and more, so that theoreticallly it would eventually be travelling away from Hercules A at a speed of 0.05 of the speed of light.

Obviously jets of material travelling away from black holes have high speeds relative to the black holes. And they will be slowing down as they get farther and farther away from the black hole. Either they are travelling slower than the escape velocity of the black hole, and will eventually fall back toward the black hole, or they wiil be traveling faster than the escape velocity of the black hole and will continue to move farther away forever.

The great galaxy M8 has a giant black hole at its center with a mass of about 6.5 billion solar masses. The black hole has a jet of ejected material extending at least 5,000 light years from the black hole. According to this online calaculator, the escape velocity from an object with a mass of about 6,500,000,000 suns at a distance of about 5,000 light years is about 191.009 kilometers per second, which is only 17.075 times the escape velocity of Earth.


The velocity of the jet is apparently many times 191.009 kilometers per second, so the matter in the jet will never slow down, stop, and then begin to fall into the black hole.

The Black Hole at the center of Hercules A is believed to have a mass of about 4 billion solar masses. Since the jets extend over 1 million light years from the black hole, the escape velocity from the Black hole at that distance should be about 10.5953 kiometers per second, less than the escape velocity of the Earth. The galaxy Hercules A is in has about 1,000,000,000,000,000 times the mass of the Sun. At a distance of 1,000,000 light years, it should have an escape veloctiy of about 5,257.65 kilometers per second.


Clearly for matter to be ejected from near a black hole, and to reach distances of thousands of ligth years, or even a million light years, from that black hole, it must have been given a speed that was close to the escape velocity at that distance from the black hole

Thus it could travel for many thousands or millions of years, and reach distances of thousands or millions of light years from the black hole, before being slowed down enough to stop and then fall toward the black hole. And if its speed is over the escape velocity from the black hole at the distance it is ejected from, it will keep on getting farther and farther from the black hole forever.

What is really wonderfull about the jets from Hercules A is that they contain so much matter, and so energetic, that they don't dissapate and fade into the intertellar medium at distances of just a few thouand light years from the black hoole, but continue to be detectable when they are a million light years from it.


Records show that the spin of S.M.Black holes lie between 0.5 - 0.8C. Matter/energy entering the ergosphere can be redirected to to poles and onwards at these speeds; versions of the Penrose effect. Nature, August 2013 updates spin rate to above 90% C. Read Penrose Effect and subsequent related material applying to S.M.B.Hs to understand Ergosphere. Basically active SMBHs have an accretion ring of stellar objects that can feed the SMBH for millions of years emitting polar streams at near C producing filaments approaching a Mpc. Coherence may not be fully understood.

  • $\begingroup$ Where did you get this information from? $\endgroup$
    – WarpPrime
    Commented Jan 19, 2022 at 13:39

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .