Measuring the power spectrum of dark matter substructure using strong gravitational lensing

Yashar Hezaveh, Neal Dalal, Gilbert Holder, Theodore Kisner, Michael Kuhlen, Laurence Perreault Levasseur

Research output: Contribution to journalArticlepeer-review


In recent years, it has become possible to detect individual dark matter subhalos near images of strongly lensed extended background galaxies. Typically, only the most massive subhalos in the strong lensing region may be detected this way. In this work, we show that strong lenses may also be used to constrain the much more numerous population of lower mass subhalos that are too small to be detected individually. In particular, we show that the power spectrum of projected density fluctuations in galaxy halos can be measured using strong gravitational lensing. We develop the mathematical framework of power spectrum estimation, and test our method on mock observations. We use our results to determine the types of observations required to measure the substructure power spectrum with high significance. We predict that deep observations (∼10 hours on a single target) with current facilities can measure this power spectrum at the 3σ level, with no apparent degeneracy with unknown clumpiness in the background source structure or fluctuations from detector noise. Upcoming ALMA measurements of strong lenses are capable of placing strong constraints on the abundance of dark matter subhalos and the underlying particle nature of dark matter.

Original languageEnglish (US)
Article number048
JournalJournal of Cosmology and Astroparticle Physics
Issue number11
StatePublished - Nov 22 2016


  • dark matter simulations
  • dwarfs galaxies
  • gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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