Since matter-action gravitons are biphotons, which are entangled photons, there is not only scalar gravity due to static matter graviton shadows, but also a radiant vector gravity due to radiant matter. In other words, the radiation of stars entangles their motions with other stars and this entanglement results in radiant vector gravity.
Here is a diagram that shows scalar gravity shadows that results from the matter body bonds to the universe along with the radiant vector gravity that transfers momentum from inner to outer stars. Radiant vector gravity transfers momentum from stars inside the CofM to stars outside the CofM. This radiant momentum transfer is what keeps spiral galaxies rotating at constant velocity instead of at their Keplerian velocities.
The plot below shows the velocity profile of the Milky Way along with the observed Sun as opposed to the Keplerian Sun. The actual Sun velocity is about 29% greater than the Keplerian Sun velocity reported by Sofue et al, 251 vs. 194 km/s. The Keplerian gravity force at the Sun at 8.0 kpc is 8.4e14 kg m/s^2, which is consistent with a Sun velocity of 194 km/s as opposed to the actual Earth velocity of 251 km/s.
However, there is a radiant vector gravity force in matter action that couples star motions and transfers momentum from inner to outer stars. The Sun radiance is 4.2e9 kg/s and results in a radiant vector force of 4.2e9 kg/s x 2.51e5 m/s / 2 = 5.5e14 kg m/s^2. Thus the scalar plus vector gravity of the Sun is actually 1.4e15 kg m/s^2, which is now consistent with the 29% increase in Sun velocity as sqrt(1.4e15/8.4e14) = 1.29. Radiant vector gravity now completes the virial energy theorem for galaxies without any need for dark matter.
Thus, radiant vector gravity is completely consistent with the momentum transfer that occurs from stars inside to outside the CofM for constant galaxy rotation. Radiant vector gravity completely explains galaxy rotation without any dark matter at all.
The figure above shows the biphoton shadows of scalar gravity along with the radiant vector gravity momentum transfers from inner to outer stars. Since the Sun is quite a bit more luminous than the average MW star, the Sun rotates faster than the galaxy average. The MW average rotation velocity is 204 km/s at r = 8 kpc while the Sun rotation is 251 km/s, which suggests that the Sun is 251 / 204 = 23% greater than the average stellar MW luminosity.
Since the average stellar luminosity is 2.1e10 Lsun / Nstars, this result further suggests that the number of MW stars is 91 billion as Nstars = 2.1e10 / 0.23, which assumes that MW stars at r = 8.0 kpc are representative of the whole MW. This MW 91 billion star estimate is at the lower end of the typical 100-400 billion star number estimate often cited.
Radiant vector gravity is also consistent with the Bullet Cluster 1E 0657-56 galaxy collision that displaced large gas clouds that were 10-15% of galaxy matter from the two galaxies shown. Despite the matter displacement of 10-15%, the weak-lensing contours of each of the two galaxies still align to the galaxy's radiant stars. These results show clearly that vector radiant gravity as well as static scalar gravity are both lensing the Bullet cluster.