Evidence for a Preferred Handedness of Spiral Galaxies
In this article I study the distribution of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a preferred handedness. The SDSS data show a strong signal for such an asymmetry with a probability <0.2%. The asymmetry axis is at (RA,δ) ~(202°,25°) with an uncertainty ~15°. The axis appears to be correlated with that of the quadrupole and octopole moments in the WMAP microwave sky survey, an unlikely alignment that has been dubbed "the axis of evil". Our Galaxy is aligned with its spin axis along the same direction as the majority of the spirals...
...The Wilkinson Microwave Anisotropy Probe (WMAP) studied the cosmic microwave background (CMB) radiation (G. Hinshaw et al. 2006). Their results for the angular power spectra have been analyzed by Schwarz et al. (2004) and many others. Schwarz et al. show that: (1) the quadrupole plane and the three octopole planes are aligned, (2) three of these are orthogonal to the ecliptic, (3) the normals to these planes are aligned with the direction of the cosmological dipole and with the equinoxes. The respective probabilities that these alignments could happen by chance are 0.1%, 0.9%, and 0.4%. This alignment is considered to be so bizarre that it has been referred to as "the axis of evil" (AE) by K. Land and J. Magueijo (2005). Their nominal AE is at (l, b) ≈ (–100°, 60°), corresponding to (RA, δ) = (173°, 4°). The alignment with the ecliptic and equinoxes is especially problematic because this would suggest a serious bias in the WMAP data that is related to the direction of the Earth's spin axis, which is highly unlikely. Resolving this quandary requires data from another source with different systematics than WMAP...
We also see that the spin asymmetry is well aligned with the North Galactic Pole of our Galaxy (NGP in Fig. 3) at (193°,27°). This is due to the fact that our Galaxy also has its axis along the spin alignment with a handedness like that of the majority of the spiral galaxies. The probability that the axis of our Galaxy is aligned within 15° with the preferred spin axis by chance is 1.7%. Since most astronomical surveys, including the SDSS, tend to make observations toward the NGP and SGP to avoid the obscuration due to the Milky Way, the spin alignment axis is accidentally aligned with the SDSS coverage. ...
... The approximate agreement of the spin alignment axis with the WMAP quadrupole/ octopole axes reinforces the finding of an asymmetry in spiral galaxy handedness and suggests that this special axis spans the universe. The fact that the spin asymmetry appears to be independent of redshift suggests that it is not connected to local structure. On the other hand, the spiral galaxy handedness represents a unique and completely independent confirmation that the AE is not an artifact in the WMAP data due to foreground contamination.
Handedness, or chirality, in spiral galaxies refers to the direction in which the spiral arms wrap around the galactic center. It is significant because it provides evidence for the existence of a preferred direction or handedness in the universe.
Scientists use a variety of techniques, such as studying the rotation direction of stars and gas in the galaxy, analyzing the polarization of light, and measuring the orientation of dust particles, to determine the handedness of a spiral galaxy. These methods provide consistent results and allow for a more accurate determination of handedness.
No, handedness in spiral galaxies can vary. While most spiral galaxies have a preferred direction of handedness, there are some that exhibit the opposite direction or have a mix of both directions. This variation can provide important insights into the formation and evolution of galaxies.
The exact cause of handedness in spiral galaxies is still unknown, but it is believed to be a result of the initial conditions of the galaxy's formation. Some theories suggest that the spin of the galaxy's central black hole or the influence of neighboring galaxies could play a role in determining the handedness of a spiral galaxy.
Studying the handedness of spiral galaxies can provide important insights into the larger structure and dynamics of the universe. It can help us understand the overall distribution of matter and energy, as well as the effects of cosmic forces, such as dark matter and dark energy, on the formation and evolution of galaxies.