Speaker
Description
A distinctive feature of relativistic effects in the cosmological probes is the presence of terms that scale with negative powers of $k$ relative to the matter density fluctuations. Perturbative calculations in $\Lambda$CDM have shown that the infrared divergences that these terms could in principle cause are cancelled out, in agreement with the equivalence principle.
In this talk, I will show that it is possible to derive a simple set of general conditions that control the infrared sensitivity of cosmological probes by working at linear order in relativistic perturbation theory and without assuming any gravity theory. Given the simplicity of our general conditions, I will show that it is possible to recover the $\Lambda$CDM cancellations mentioned above without performing any calculations. Finally, I will comment on the possibility of applying these conditions to gravity theories other than general relativity.
The importance of this work lies in the clear identification of the physical reasons that underlie the infrared sensitivity of the cosmological probes.
