The Stability of the BAO Linear Point under Modified Gravity

Baryon Acoustic Oscillations (BAOs) are crucial in cosmological analysis, providing a standard ruler, as well as constraints on dark energy. In General Relativity models, the BAO Linear Point - the midpoint between the dip and the peak in the correlation function - has been shown to be rather robust to evolution and redshift space distortions. We show that this remains true even when the gravity model is not General Relativity, at least for $f(R)$ and DGP gravity models which have the same expansion history as the standard $\Lambda$CDM. For the Linear Point to be able to distinguish between modified gravity (MG) and $\Lambda$CDM, survey volumes of order tens of cubic Gpc are required.