Recently, new observations show that the jets of black hole 4U 1630-47, in the direction of the constellation Norma, carry massive particles, such as iron and nickel atoms, instead of the typical low-mass particles such as electrons. The fast-moving, heavy-particle jets, which move at two-thirds the speed of light, have more power than spurts of only low-mass particles, astronomers report November 14 in Nature..
The question is why and how is this jet formed and why this high speed of heavy particles?
As a layman I can't answer that but can contribute
some reading material. It has to do with magnetic fields.
http://arxiv.org/abs/1211.3651
http://www.eurekalert.org/pub_releases/2013-11/icfr-ar111113.php
http://www.eurekalert.org/pub_releases/2013-11/uoc--eoj112213.php
http://www.eurekalert.org/pub_releases/2013-10/e-apm101413.php
http://www.eurekalert.org/pub_releases/2011-05/nsfc-rtc052011.php
Regards,
Joachim
I can only offer a conjecture - that only relatively light elementary particles (electrons and quarks) are ejected via the relativistic polar jets, but as they dissipate and cool, more massive compound particles are formed by condensation. The more massive particle condense as the greater initial velocity is diminished...
Arno,
As I understand, polar jets are a common phenomena associated with a diverse group of objects undergoing gravitational collapse. Please see http://en.wikipedia.org/wiki/Polar_jets
"A polar jet is a phenomenon often seen in astronomy, where streams of matter are emitted along the axis of rotation of a compact object. It is usually caused by the dynamic interactions within an accretion disc. When matter is emitted at speeds approaching the speed of light, these jets are called relativistic jets. The largest polar jets are those seen in active galaxies such as quasars. Other systems which often contain polar jets include cataclysmic variable stars, X-ray binaries and T Tauri stars. Herbig–Haro objects are caused by the interaction of polar jets with the interstellar medium. Bipolar outflows or jets may also be associated with protostars (young, forming stars),[1] or with evolved post-AGB stars (often in the form of bipolar nebulae).
"... Accretion discs around many stellar objects are able to produce jets, although those around a black hole are the fastest and most active. This is because the speed of the jet is around the same speed as the escape velocity of the central object."
The Wikipedia entry already includes mention of this new observation and a link to an informative news report: http://www.sciencedaily.com/releases/2013/11/131113132200.htm.
The research report is available at http://dx.doi.org/10.1038/nature12672 or http://arxiv.org/abs/1311.5080.
Please see my prior comment regarding a potential explanation that IMO is consistent with established theories.
Walid,
the current paradigm is that of magnetic launching. It has been known for few decades that spinning magnetic sources, such as a dipole, create a twisted spiraling magnetic field around the rotation axis. It is not hard to show that the magnetic pressure decreases quite fast with the distance to the object. If you assume the plasma is coupled to the field lines, this pressure gradient ends up accelerating the fluid. It is also possible to show that acceleration occurs up to ultra-relativistic speeds. Please, check the book of Beskin (MHD flows in compact astrophysical objects). The energy released to the jet is basically the Poynting flux. However 2 problems still need some attention. The first is the magnetic field configuration, since the Grad-Shafranov equation can lead to very different field configurations depending on boundary conditions and geometries assumed. This have implications on the precise location of some critical points along the jet, such as the sonic and the Alfvén points. The second is the origin of the magnetization of the black-hole. This second problem is bypassed if the accretion disk is magnetized. Even though, it is not yet clear how these disks would support strong magnetic fields without breaking or driving MHD instabilites that could easily destroy the needed configuration.
To conclude... the acceleration is the least of our problems... ;)
Diego,
Good comment, but this still seems to be any area of active research where no clear consensus has been reached and no single source is likely to provide a complete perspective. For example, please see http://xxx.lanl.gov/abs/astro-ph/9908283, http://dx.doi.org/10.1088/1742-6596/355/1/012016, http://arxiv.org/abs/1303.3004 and http://arxiv.org/abs/1301.6771.
What seems clear is that it is the black hole gravitation that is the ultimate source of expulsion energy - but the precise mechanism by which accretion disk and black hole rotation, along with MHD effects contribute to particle velocity is not fully understood.
This implies that the heavy nucleus are formed inside a quasi-black hole before a jet explosion or supernova explosion is triggered, and the strong magnetic field of a quasi-black hole comes from the intrinsic magnetic dipole fields of neutrons. A true black hole can not be formed, no matter how heavy it is.
Yes, in order to solve the cosmological puzzles, a new cosmological model is necessary.
- Badges
- Science topic
- Similar topics
- Philosophy
- Esthetics
- Interpretation