An accurate linear model for redshift space distortions in the void-galaxy correlation function

Understand

Redshift space distortions within voids provide a unique method to test for environmental dependence of the growth rate of structures in low density regions, where effects of modified gravity theories might be important.

• We derive a linear theory model for the redshift space void-galaxy correlation that is valid at all pair separations, including deep within the void, and use this to obtain expressions for the monopole $\xi^s_0$ and quadrupole $\xi^s_2$ contributions.
• Our derivation highlights terms that have previously been neglected but are important within the void interior.
• As a result our model differs from previous works and predicts new physical effects, including a change in the sign of the quadrupole term within the void radius.