Curbing PBHs with PTAs

Understand

Sizeable primordial curvature perturbations needed to seed a population of primordial black holes (PBHs) will be accompanied by a scalar-induced gravitational wave signal that can be detectable by pulsar timing arrays (PTA).

• We derive conservative bounds on the amplitude of the scalar power spectrum at the PTA frequencies and estimate the implied constraints on the PBH abundance.
• We show that only a small fraction of dark matter can consist of stellar mass PBHs.
• The strength and the shape of the constraint depend on the shape of the power spectrum and the nature of the non-Gaussianities.