Spiral Galaxy Rotation Curves Without Dark Matter or MOND -- Two Conjectures (1801.09304v1)

Abstract: Usual explanations of spiral galaxy rotation curves assume circular orbits of stars. The consequences of giving up this assumption are investigated here. In particular, hyperbolic stellar trajectories are found to be interesting. The two suggested models for the production of such trajectories will also explain the observed flat rotation curves without the postulation of dark matter or MOND. It is suggested that spiral galaxies may have started as compact objects with significant angular momenta and then disintegrated. The first model conjectures the existence of a spinning hot disk around a spherical galactic core. The disk is held together by local gravity and electromagnetic scattering forces. However, it disintegrates at the edge producing fragments that form stars. Once separated from the disk, the stars experience only the centrally directed gravitational force due to the massive core and remaining disk. A numerical simulation shows that a high enough angular velocity of the disk produces hyperbolic stellar trajectories that agree with the observed rotation curves. The second model conjectures a significant initial thermonuclear event that produces a dust plume along with large stars. This dust plume is made of ordinary matter. However, it acts like the postulated dark matter in producing initial circular trajectories. Unlike dark matter, the plume can be shown to escape the galaxy rapidly causing the star trajectories to evolve to hyperbolic shapes. This process can be seen to produce the observed rotation curves due to the initial circular orbits. Also, as the plume dissipates rapidly it does not obfuscate the stars from view. Both models have weaknesses as do the currently known models using dark matter or MOND.

• The paper presents two conjectural models explaining spiral galaxy rotation curves without requiring dark matter or Modified Newtonian Dynamics (MOND).
• The Spinner model proposes a rigid spinning disk ejecting stars on hyperbolic trajectories with significant tangential velocity.
• The Elvis model suggests a temporary dust plume from a core event mimics dark matter effects before rapidly dispersing, leaving stars on hyperbolic paths.

Spiral Galaxy Rotation Curves Without Dark Matter or MOND: An Analysis

The paper presents two conjectural models to explain spiral galaxy rotation curves without resorting to dark matter or Modified Newtonian Dynamics (MOND). This investigation challenges the conventional assumption that stars within galaxies follow circular orbits. Instead, the paper explores the implications of hyperbolic stellar trajectories, offering alternative explanations for the rotational behaviors observed in spiral galaxies.

Model 1: The Spinner Model

The spinner model hypothesizes the existence of a rigidly spinning disk surrounding the galactic core. In this scenario, the disk is composed of massive particles interacting through local gravitational and electromagnetic forces, leading to the outward fragmentation of stars at its boundary. As stars are released, they inherit significant tangential velocities from the disk, while their radial speeds initially remain zero. Over time, these radial speeds increase, resulting in hyperbolic trajectories.

This model's integrity relies on the assumption that the disk decreases in size consistently as material transforms into stars. Numerical simulations support the claim that such a mechanism could reproduce observed rotation curves. It demonstrates that the core mass influences these curves only marginally, whereas variations in disk mass density have little effect, indicating that the primary contribution to star speed originates from the disk's initial angular velocity.

Model 2: The Elvis Model

The second model posits a violent thermonuclear event initiating within a compact mass, forming an expansive dust plume comprised of ordinary matter that mimics the gravitational effects of dark matter. This plume briefly sustains the stars in circular orbits post-explosion. As the plume rapidly disperses, the stars' orbits transform from circular to hyperbolic. Importantly, while the plume obfuscates stellar visibility, it ultimately clears, allowing examination without the presence of additional non-baryonic matter.

This rapid dissipation of the dust plume causes stars to remain in positions dictated by their prior circular orbits, now moving in hyperbolic trajectories. The hypothesis suggests that various galactic forms may represent different evolutionary stages of similar intrinsic objects.

Critical Evaluation

Both models present innovative frameworks while eliminating the necessity for dark matter or MOND. They provide insight into observed galactic dynamics through conventional physics. However, these models introduce new challenges. For instance, the anticipated hyperbolic trajectories require additional observational support, particularly in identifying significant radial velocities at extended distances. The hypothesized local forces within the disk and the assumptions regarding thermal equilibrium in the plume must be substantiated through further theoretical and observational studies.

Implications and Future Directions

The proposed models have the potential to reshape our understanding of galactic rotation curves by aligning them with observable phenomena and gravitational principles without speculative matter. Future advancements might pivot upon these models, prompting the reassessment of galactic formation theories and dynamics. Further exploration might involve refined simulations incorporating comprehensive galactic interactions or observations aligning with the detailed process of stellar escape from galaxies. Such progress could offer definitive evidence or prompt the development of hybrid models that incorporate both traditional and novel explanations for galactic phenomena.