Investigating dark matter substructure with pulsar timing – I. Constraints on ultracompact minihaloes

Abstract

Small-scale dark matter structure within the Milky Way is expected to affect pulsar timing. The change in gravitational potential induced by a dark matter halo passing near the line of sight to a pulsar would produce a varying delay in the light travel time of photons from the pulsar. Individual transits produce an effect that would either be too rare or too weak to be detected in 30-year pulsar observations. However, a population of dark matter subhalos would be expected to produce a detectable effect on the measured properties of pulsars if the subhalos constitute a significant fraction of the total halo mass. The effect is to increase the dispersion of measured period derivatives across the pulsar population. By statistical analysis of the ATNF pulsar catalogue, we place an upper limit on this dispersion of log σṖ ≤ −17.05. We use this to place strong upper limits on the number density of ultracompact minihalos within the Milky Way. These limits are completely independent of the particle nature of dark matter.The present-day mass of a UCMH or PBH may be directly mapped to the wavenumber of the primordial fluctua-

DarkSUSY 6: an advanced tool to compute dark matter properties numerically

“…• The core library contains a new set of functionalities to compute limits [29,30] on DM models from the formation of ultracompact minihalos [31][32][33]. 2 Apart from these additions included in the released version 6 of the code, there currently exist several publicly available packages to be used with DarkSUSY.…”

Primordial black holes from polynomial potentials in single field inflation

“…If the main component of dark matter is a weakly interacting massive particle (WIMP), the annihilation in an UCMH can produce highly luminous gamma-ray or neutrino sources. 1 The constraints on these fluxes also give severe upper bounds on the power spectrum, though they depend sensitively on the details 1 UCMHs lead to a time delay in pulsar timing by the Shapiro effect and the PTA experiments put an upper bound on the amplitude of power spectrum [27,28] (see also Refs. [29,30]).…”

“…However, in Ref. [27] they claimed that they used an optimistic value for the sensitivity of pulser timing experiment. The constraint is absent when we use a realistic value, so that we do not consider it in this paper.…”

The 21-cm signals from ultracompact minihaloes as a probe of primordial small-scale fluctuations

“…The Thomson scattering optical depth for the CMB photons also provides the UCMH abundance because the annihilation gamma-ray from UCMHs can contribute to the photon budget for cosmic reionization (Zhang 2011;Yang et al 2011;Yang 2016;Clark et al 2017). Observations of gravitational lensing by UCMHs also constraints the UCMH abundance (Li et al 2012;Clark et al 2016).…”

“…If the dark matter is weakly interacting massive particle (WIMP) (Steigman & Turner 1985;Jungman et al 1996;Kolb et al 1999), UCMHs can become cosmological gamma-ray sources because the signal of the annihilation of WIMPs is enhanced in the dense region at the center of UCMHs. Currently the non-detection of the gamma-ray emission from the WIMP annihilation provides the constraint on the UCMH abundance and the stringent constraints on the small-scale curvature power spectrum, A ζ < 10 −7 for 10 Mpc −1 < k < 10 8 Mpc −1 (Josan & Green 2010;Scott & Sivertsson 2010;Bringmann et al 2012;Clark et al 2016;Nakama et al 2018;Delos et al 2018a,b). The nondetection of neutrino from the WIMPs also provides a similar constraint (Yang et al 2013;Nakama et al 2018).…”