How Are Heavy Nuclei Produced in Black Hole Jets?

[anorlunda]

A recent APOD page discussed jets ejected from black holes. It said, "Recent evidence indicates that these jets are composed not only electrons and protons, but also the nuclei of heavy elements such as iron and nickel."

What is thought to be the mechanism of production of these heavy nuclei?

 

[phyzguy]

The jets they are referring to are from the collapse of the cores of massive stars. The cores of these massive stars are composed primarily of heavy iron-group elements that were built over time from nuclear fusion of hydrogen and helium during the life of the star. Try looking up stellar nucleosynthesis.

 

[anorlunda]

The APOD page is not talking about a supernova event. Rather talks about about accretion disks in binary systems as the source of the jet material.

 

[Chronos]

Chances are good its something they ate. Black holes are not yet proven to synthesize heavy nuclei, but that is certainly a possibility. The accretion disk of black holes [which is the obvious source of particles in jets] is basically a particle accelerator on steroids. Synthesis of heavy nuclei is easily achieved on Earth using particle accelerators. Alternatively, it could merely be burping the core of some hapless star it had shredded. See http://kipac.stanford.edu/kipac/tidbits2012/?GRMHD2a for discussion.

 

[phyzguy]

Chances are good its something they ate. Black holes are not yet proven to synthesize heavy nuclei, but that is certainly a possibility. The accretion disk of black holes [which is the obvious source of particles in jets] is basically a particle accelerator on steroids. Synthesis of heavy nuclei is easily achieved on Earth using particle accelerators. Alternatively, it could merely be burping the core of some hapless star it had shredded. See http://kipac.stanford.edu/kipac/tidbits2012/?GRMHD2a for discussion.

Yes. Please ignore my earlier post. I thought they were talking about jets from core collapse supernovae, which is not the case here. In addition to what you mentioned, could the densities and temperatures in black hole accretion disks be high enough for nuclear fusion to occur?

 

[anorlunda]

I didn't know that about particle accelerators.

The APOD article specifically mentioned nickel. Nickel is heavier than iron and therefore cannot be produced by normal fission. The cores of companion stars should not contain nickel either.

So, perhaps the particle accelerator analogy to the accretion disk is the best guess. I've always been taught that supernova remnants are the only source of elements heavier than iron, which is why the article about the BH jets caught my eye because it could mean a second mechanism.

In terms of abundance of elements heavier than iron, such as in our solar system, would it be correct to say that the abundance of heavy elements formed in BH jets would be tiny compared to those ejected from supernovas? The jets do continue churning out stuff for billions of years.

 

[Chronos]

That's a good question, phyzguy. I would say no, but, with certain caveats. Accelerator synthesized nuclei are indistinguishable from those forged by stellar processes. Stellar fusion is gravity assisted, and accelerator synthesis only requires high input energy. In the end, its not actually clear there is any real difference between the tow, you just need a whole bunch of kinetic energy, and the resulting nuclei are utterly indifferent to its source. A sort of 'tomato, tomato' thing.

Actually, anorlunda, nickel 56 is readily produced by massive stars. Only heavier isotopes require supernova production. The production rate of heavy nuclei in accretion disks has not been quantified to my knowledge, which is understandable considering their presence in BH jets is a recent discovery. The potential for nickel 56 production in an accretion disk is discussed in this paper http://arxiv.org/abs/1112.2673.

 

[WSTrood]

This is my first post on here. It is a Black Hole question but not sure if this is the right place.
Bomb me if not acceptable.

Most artist impressions of Black Holes, show them double ended.
NASA and others photos of Black Holes usually show the Galaxy facing you and the Black Hole in the centre.
I cannot find any actual photographs, showing an indication of two ended Black Holes.
Are there such things, and if so, do both ends act in the same way.

If I have posted wrongly, could you tell me where I should post.
Thank you.