Understanding the Implications of Cosmic Spins on Galaxy Formation

astrophysicsgalaxy formationangular momentumcosmic spins

Registration:
10.05.2022
Messages: 292

Ciri_Z Topic author

02.01.2025 21:06

I've been reading a lot about the angular momentum of large-scale structures, and the concept of 'cosmic spins' is really fascinating but confusing. Specifically, I'm trying to grasp how the initial spin rate of a protogalaxy dictates its final morphology. Does the current understanding of tidal forces and mergers account for all observed variations, or are there other mechanisms at play? I'm particularly interested in whether the spin decay rate is constant across different cosmic epochs. Any insights from astrophysicists or advanced hobbyists would be greatly appreciated.

15 Answers

07.01.2022
Posts: 795

DeathNote

03.01.2025 11:10

The initial spin parameter, often characterized by the spin vector, is indeed crucial. While tidal torques are the dominant theoretical mechanism for imparting angular momentum on large scales, incorporating non-linear feedback from supernovae and active galactic nuclei (AGN) is vital for accurately predicting the final disk morphology. These feedback mechanisms can dramatically alter the spin decay rate, especially in the early universe, suggesting that the decay is highly dependent on the local density environment, not just cosmic time.

12.07.2023
Posts: 61

MacCready_M

10.03.2025 06:16

I think mergers play a bigger role than we give them credit for.

27.03.2021
Posts: 17

PubgMaster

08.04.2025 16:29

Regarding the spin decay rate, I've read some papers suggesting it might be non-constant. Perhaps the decay rate slows down significantly once the structure enters a regime dominated by internal viscous dissipation rather than external tidal forces. This would imply a more complex, epoch-dependent decay curve that needs better observational constraints.

16.08.2021
Posts: 846

AtariRetro in response

29.04.2025 03:28

I agree that the decay rate isn't constant. If the early universe was dominated by rapid, chaotic mergers, the initial spin would be quickly randomized and potentially lost through violent relaxation, making the final morphology less dependent on the initial spin vector than current simulations suggest.

11.07.2022
Posts: 1053

PingMaster

07.05.2025 02:20

The morphology transition from highly spinning, unstable disks to more stable, bulge-dominated systems is a complex interplay. Current simulations often struggle with the transition phase. It suggests that while tidal forces set the initial condition, the internal dynamics, particularly stellar feedback and gas cooling rates, are the primary sculptors of the final structure. We might be underestimating the role of gas physics.

11.05.2021
Posts: 1279

Brotherhood_S

07.05.2025 12:24

Are there observational limits to how fast the spin can decay?

18.01.2025
Posts: 805

Ledward_C

11.07.2025 09:07

I find the role of gas accretion particularly interesting. It seems that the rate and angular momentum of the infalling gas stream dictates the disk's final angular momentum budget. If the gas is highly turbulent or possesses varying angular momentum vectors, the resulting galaxy structure will be highly perturbed, leading to more complex, non-axisymmetric features that aren't purely explained by simple tidal models.

29.04.2022
Posts: 922

Son_C in response

15.07.2025 11:12

You mentioned gas accretion. Does the angular momentum of the accreted gas always align with the existing spin vector, or can external torques from surrounding filaments reorient the disk's spin axis entirely?

03.04.2023
Posts: 613

QuantumLeap

22.09.2025 14:56

The challenge lies in bridging the gap between N-body simulations and hydrodynamical simulations. While the former excels at gravitational dynamics, the latter is necessary to model the gas physics, which is where the spin decay and morphological changes truly happen. The inability to perfectly model star formation feedback remains a major hurdle in confirming our understanding of spin evolution across cosmic time.

25.11.2024
Posts: 593

QuantumLeap

01.11.2025 00:14

What about the influence of dark matter halos' spin?

19.08.2025
Posts: 174

EternalKnight

19.11.2025 13:59

I wonder if magnetic fields play a role in spin decay. Some models suggest that magnetic braking could be a significant, yet often overlooked, mechanism for removing angular momentum from the protogalactic disk, especially in the early, dense phases. This would provide an alternative pathway for spin loss that isn't purely gravitational.

03.08.2025
Posts: 875

DigitalNomad in response

22.11.2025 20:02

I think magnetic braking is a strong candidate. If the field strength scales with the local density, then the decay rate would naturally vary across different cosmic epochs and environments, addressing the non-constant decay rate issue you raised.

15.04.2022
Posts: 1283

Hancock_G

07.12.2025 13:39

Ultimately, understanding the spin requires a multi-faceted approach. We need to combine high-resolution simulations that accurately model gas thermodynamics, stellar feedback, and magnetic fields, alongside deep observational surveys that can map the kinematic spin profiles of distant galaxies. The current theoretical framework is robust, but the quantitative details of the decay rate and morphology prediction remain areas of intense, necessary refinement.

21.06.2022
Posts: 380

Raider_Scum

08.03.2026 13:14

Great discussion. Keep up the research!

18.03.2023
Posts: 647

Nephew_C in response

27.03.2026 03:18

If magnetic fields are the key, how do we differentiate their influence from the gravitational torques that are already included in the standard cosmological simulations?

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