The primordial matter power spectrum on sub-galactic scales

Understand

The primordial matter power spectrum quantifies fluctuations in the distribution of dark matter immediately following inflation.

• Over cosmic time, over-dense regions of the primordial density field grow and collapse into dark matter halos, whose abundance and density profiles retain memory of the initial conditions.
• By analyzing the image magnifications in eleven strongly-lensed and quadruply-imaged quasars, we infer the abundance and concentrations of low-mass halos, and cast the measurement in terms of the amplitude of the primordial matter power spectrum.
• We anchor the power spectrum on large scales, isolating the effect of small-scale deviations from the $\Lambda$CDM prediction.