Radial stress in rotating ACKN/KSZ continuations of Einstein-cluster dark matter halos
Year: 2026
Type: article
Abstract: Einstein-cluster dark matter halos have zero radial pressure in the ideal static model. I test whether this property survives the exact finite-spin ACKN/KSZ rotating continuation, whose geodesic and scalar-wave equations are separable. Using the full metric, I require p r = 0 at every polar angle. The condition factorizes and leaves only flat or Schwarzschild seeds. Their rotating members are flat space or Kerr. Thus, a nonvacuum Einstein-cluster seed cannot remain radially pressureless in this class. If the same nonvacuum seed is kept, the rotating metric instead generates a negative radial principal stress, with leading behavior O ( a 2 ). For a relativistic Hernquist halo, I evaluate the ratio | p r |/ ρ h exactly at r = 10 M and a / M = 0.3 . The three published benchmarks give 2.36 × 10 − 3 , 2.27 × 10 − 2 , and 1.23 × 10 − 1 . The weak-halo estimate underpredicts the first two values by about 50%. Therefore, in the ACKN/KSZ class, preserving separability does not preserve the ideal Einstein-cluster matter source.
Source: Physics Letters B
Author: Mohsen Fathi
Institution: Universidad Central de Chile
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7222873372