Cosmic Shear from Galaxy Spins

Area of Science:

• Cosmology
• Astrophysics
• Galactic Dynamics

Background:

• The origin of galactic angular momentum and the distribution of galaxy spins are fundamental questions in cosmology.
• Galaxy spin axes are hypothesized to correlate with the intermediate principal axis of the gravitational shear tensor.

Purpose of the Study:

• To explore the relationship between galactic angular momentum and the gravitational shear field.
• To develop a method for reconstructing the gravitational potential from observed galaxy spin fields.

Main Methods:

• Utilizing the direction of the angular momentum vector, independent of its magnitude.
• Measuring the position angle and inclination of disk galaxies.
• Implementing a maximum likelihood shear inversion procedure with constrained linear minimization.
• Testing the theory against numerical simulations.

Main Results:

• Demonstrated the correlation between nonlinear structures and the initial shear field.
• Showed that accurate large-scale density reconstructions are achievable at expected noise levels.
• Validated the shear inversion technique through numerical simulations.

Conclusions:

• The observed galaxy spin fields can be used to reconstruct the gravitational shear field and the full gravitational potential.
• The maximum likelihood shear inversion procedure is a viable method for cosmological studies.
• This technique offers a new way to probe large-scale structures and cosmic evolution.