The wave island on The Broken-Born program

The gated condensation rate Γ_self

Mon, 01 Jan 0001 00:00:00 +0000

Γ_self is the rate at which the gated attraction of conjugate matter makes a wave-like dark-matter halo condense: the rate at which the halo’s waves, scattering off one another, move their power into a narrow range of low relative momenta. It applies on the wave island, the range of very light χ masses in which each quantum state of the halo holds so many quanta that the halo is a classical wave field rather than a gas of particles. There every scattering rate is multiplied by that number of quanta. Levkov, Panin and Tkachev (LPT) worked out this kind of condensation for gravity; the gated attraction adds a second channel to it. When the halo’s velocity spread is wider than the gate, the rate falls as the fourth power of their ratio, a power law rather than the exponential cutoff that particles show, and that difference became a test of whether dark matter is made of particles or waves. Debt 3 compared the rate with the gravitational channel and with the stirring of the halo by its own orbits. Its form is derived; its numerical coefficient is a heuristic estimate that has not been calibrated.

Obituary: Scenario A and the ultra-faint-dwarf endpoint

Mon, 01 Jan 0001 00:00:00 +0000

Scenario A was the assumption that, on the wave island, the gated attraction that condenses wave-like dark matter is also what gives ordinary dwarf galaxies their smooth, constant-density cores. Fitting those cores fixes the strength of the coupling, and with the coupling fixed, condensation is forced to happen, across the whole halo, in the ultra-faint dwarf galaxies, the faintest, densest and oldest galaxies known. Because the attraction makes a condensate collapse whenever it passes a critical mass, throwing off fast waves that escape the galaxy, these galaxies would by now have lost much of their dark matter. Instead they are among the most dark-matter-dominated systems observed: Segue 1 holds a dense, intact halo around stars about 13 billion years old. A much lighter mass, which would avoid the collapse, is excluded by other observations, and no other change of parameters rescues the scenario. Scenario A is dead.

Scenario B: tunable streams (quarantined)

Mon, 01 Jan 0001 00:00:00 +0000

Scenario B is the alternative to Scenario A on the wave island. In it, the smooth cores of dwarf galaxies are made by something other than conjugate matter’s gated attraction, such as the quantum pressure of extremely light wave dark matter or the feedback of ordinary matter, so nothing fixes the strength of that attraction. With the coupling free, it can be set anywhere in a window about ten orders of magnitude wide in which velocity streams form, or outside the window, where they do not. Streams are then possible but never required. That makes them an option the program can accommodate rather than a prediction it is committed to, which in Lakatos’s terms is a sign of a degenerating research programme. The checkpoint keeps the scenario alive but quarantined, among the program’s listed degeneration risks.

Relic abundance by misalignment on the wave island

Mon, 01 Jan 0001 00:00:00 +0000

Misalignment is a way for a very light field to acquire its relic density in the early universe: the field starts away from the minimum of its potential, stays there while the universe expands quickly, and later oscillates coherently about the minimum; the oscillation then behaves as cold dark matter. It is the standard production route for axions. Debt 3 noted that conjugate matter χ on the wave island, a field this light, coupled only through gravity and its own self-interaction, would be produced the same way. On the wave island only, that removes a difficulty the lab notebook had recorded: a light, strongly self-coupled sector connected to ordinary matter only through gravity cannot get its density by ordinary thermal freeze-out. It does not explain why dark matter outweighs ordinary matter by 5.4 to 1, a question that stays open for both remaining dark-matter candidates.