Relation Between Black Hole and Supernova Actions

Scientific Paper
Title	Relation Between Black Hole and Supernova Actions
Read in full	Link to paper
Author(s)	Arnold G Gulko
Keywords	black hole, Black Holes, action
Published	2008
No. of pages	11

Read the full paper here

Abstract

Black holes are the most massive and most mysterious objects in the cosmos, and this writer considers them of great importance to the existence and character of the cosmos. Supernovas are the most powerful explosive releases of energy near us and are now considered to be the only observable event which might form a black hole.  Despite the fact that black holes are formed by supernovas, astrophysics ignores the possibility that the actions of black holes and the supernova event might involve the same mechanism.

To consider the respective actions, we must establish the structure of a black hole, for we cannot consider how a black hole functions without understanding the structure of the hole.  We must also consider the action of black holes in ejecting polar jets, for these jets and their formation is filled with mystery.  Then we must consider the supernova event, for it also contains much that is confused.  With these preliminaries in hand we must compare the formation and characteristics of the jets with the supernova event and its ejecta in order to ascertain the extent to which the two are the same or different.  Lastly, we shall explain the common mechanism of action which this writer believes accounts for both the supernova event and the jets of black holes. 

Overview

Gulko's paper is an argument by analogy, pressed hard. He observes that a Supernova and the polar jets of a Black Hole share a striking list of features — matter first accelerated inward by gravity, then turned around and thrown outward against that same gravity, arriving gamma-ray active when it went in inert — and he concludes that the two must run on one mechanism. Mainstream astrophysics, he says, treats them as unrelated problems and has a satisfying account of neither.

The mechanism he proposes is nuclear fragmentation of collapsed matter. In his picture a black hole is not a singularity but a body of collapsed matter with real size, real poles and a real surface; matter falling onto that surface shatters it, and the shards — heavy, neutron-rich, and still expanding — are what get ejected. The same shattering, occurring at the surface of a collapsed stellar core when the outer layers implode onto it, is what produces both the supernova explosion and the heavy elements in its ejecta. The departure from the standard account is therefore twofold: the heavy elements are made by fission rather than by fusion or rapid neutron capture during the collapse, and the black hole's confinement of light is attributed not to escape velocity but to a depleted "energy continuum" that cannot carry radiation.

The argument

The structure of a black hole

Gulko opens with an observational objection. Accepted theory has black holes forming from collapsed cores of at least 1.4 solar masses, yet every black hole found has a mass of at least about five solar masses. Since stars become more numerous as they become less massive, the absence of black holes near the supposed minimum "suggests the theory is wrong." He adds that the Crab Nebula pulsar carries about 1.4 solar masses in an object "slightly smaller than the District of Columbia" and is perfectly visible.

From this he infers that the hole is not a singularity. Its darkness must then come from something other than an escape velocity exceeding light speed. His proposal is that the great mass of a body of collapsed matter "reduces the pressure and density of the energy continuum filling space" so severely that radiation cannot propagate through it. He stresses the consequence: this is not a one-way membrane. Particles can still leave if something propels them, exactly as a bullet crosses an evacuated gap between two plates that sound cannot cross.

Why the jets are a problem

The jets are twin, oppositely directed, near-light-speed, and stay narrow over enormous distances despite being made of mutually repelling ions. They are gamma-ray active, as are the double-lobed regions they eventually inflate — regions so like supernova remnants that, Gulko notes, they were long mistaken for them. He presses four objections against the standard friction-and-heat account: friction cannot reverse the motion of matter falling inward; a singularity has no polar regions to eject from, yet the geometry plainly says the object has poles and spins; accretion-disk material is not gamma-ray active before it arrives; and laboratory acceleration of stable particles to near light speed does not make them radioactive. He cites SS 433, whose jets were found to contain large amounts of un-ionized hydrogen — impossible, he says, at the temperature the jet speed implies.

Why the supernova is a problem

The implosion, he grants, is an established fact without a satisfactory explanation. Core hydrogen depletion should give slow contraction, since contraction liberates gravitational energy that offsets the falling fusion output — not a runaway collapse. The subsequent explosion is worse: the same collapse is asked both to require enormous energy and to supply it. And the nucleosynthesis does not work either. Violent nuclear impacts in the laboratory shatter nuclei rather than fusing them; fusion beyond the light elements is endothermic, so it cannot power an explosion; and an implosion lasting seconds offers no time to capture the many excess neutrons the ejected heavy elements actually carry. That physics needed "about 20 years to assemble a mathematical model in which implosion was followed by explosion" he takes as evidence the model is contrived.

The common mechanism

Gulko's replacement runs as follows. As core hydrogen is spent, progressively heavier nuclei form; the fusions become progressively less exothermic and finally endothermic, so the core cools at an accelerating rate, while Neutron capture — exothermic — proceeds slowly and unhurriedly, which is where the high neutron content of the heavy elements is acquired. Fusing many nuclei into few also reduces the mutual electrostatic repulsion holding the core open, so the core shrinks. Rapid cooling plus rapid shrinkage together give the implosion a physical cause.

The infalling outer layers then strike this collapsed core carrying gravitational energy inward. That energy restores what the endothermic fusions removed and fragments the collapsed matter at the core's surface. Fragmentation multiplies the number of nuclei and so expands the volume enormously, releasing energy as fission does — and it is this expansion plus energy release, not a rebounding shock, that constitutes the supernova explosion. The heavy elements in the ejecta are the fragments.

In a black hole the same process is channelled. The spinning collapsed body is oblate, so gravity is strongest at the poles; infalling material concentrates there, fragments the surface, and excavates axial holes. Later arrivals fall into these holes, where the expansion and energy release are confined and directed — the ejecta leave "like bullets from a rifle" as a narrow, fast jet. In a supernova the infall covers the whole surface at once, no barrel forms, and the ejecta go out in all directions at moderate speed.

Two further consequences are drawn. Fragments that are only incompletely expanded continue to break up long afterwards, which supplies gamma-ray activity to a jet long after it left the hole. And such fragments absorb energy from the surrounding continuum, creating a local low-pressure region — an "artificial gravity" — whose pressure gradient pushes jet particles toward the axis and keeps the jet narrow. The same absorption, varying from place to place, accounts for the clumping visible in ordinary nova shells.

Assessment

The paper's real strength is its inventory of anomalies. Gulko is right that jet collimation over megaparsec scales, the reversal of infalling material into outflow, and the presence of neutral hydrogen in the SS 433 jets are genuinely hard problems, and he is right that they are usually discussed in isolation from supernova physics. His central physical idea — that neutron-rich collapsed matter decompressed out of a gravitational well will fragment into heavy nuclei and release energy doing so — is not crankish at all. It is very close to the decompression of neutron-star matter that is now the mainstream account of r-process nucleosynthesis in neutron-star mergers, confirmed observationally by the kilonova AT2017gfo following GW170817. His instinct that a fission-like route to the heavy elements is energetically favourable is sound in that restricted setting.

The difficulties are equally clear. Two of the opening arguments do not survive checking. He writes that "an extremely tiny size is necessary for a mass to provide a gravitational acceleration which equals light speed" — acceleration and speed do not share dimensions, and the correct statement is about escape velocity; the argument is stated in a form that cannot be evaluated. And 1.4 solar masses is the Chandrasekhar limit for white-dwarf collapse, not the minimum black hole mass; the standard minimum is the Tolman–Oppenheimer–Volkoff limit near 2–3 solar masses, which is why the observed X-ray-binary black holes start around five. The "mass gap" he treats as fatal has also since narrowed: LIGO's GW190814 secondary at about 2.6 solar masses sits squarely inside it. His premise is thus weaker than he takes it to be.

The gamma-ray objection also assumes what it needs to prove. Jets radiate gamma rays by synchrotron and inverse-Compton scattering of relativistic electrons — no nuclear decay is required — and the diffuse Galactic gamma-ray background is standardly explained by cosmic rays colliding with interstellar gas to make pions. Gulko says there is "no possible source" of this radiation without pausing to rule these out. Likewise the SS 433 case is weaker as evidence than presented: those jets move at about 0.26c, not near light speed, and the cool clumps within them are an accepted, if intricate, feature of that system rather than an impossibility.

The load-bearing steps of the positive theory are asserted rather than derived. No number is given for the energy released by fragmenting collapsed matter, for the mass of collapsed matter a jet would have to consume, or for the depth of the "axial holes" needed to reach the observed jet Lorentz factors — so the rifle analogy carries the whole burden of explaining the velocity. The "energy continuum" whose pressure gradients supply gravity and whose depletion blocks radiation is likewise never characterised well enough to be tested; as used here it is a single adjustable notion doing several unrelated jobs. Most seriously, a black hole with a real surface that can be excavated is directly contradicted by the shadow-and-photon-ring images of M87* and Sgr A* from the Event Horizon Telescope, and by the absence of the surface-impact thermal emission that infalling matter onto a hard surface would produce. The paper contains no equations and makes no quantitative prediction that could be checked against these observations, which limits it to what it is: a well-observed list of puzzles joined to a qualitative story.

See also

• Arnold G Gulko
• Black Hole
• Supernova
• Gravity
• Nucleus
• Neutron