We show that the assumed scaling relations generically fail for dark matter-nucleus cross sections σχA∼10−32–10−27 cm2, significantly below the geometric sizes of nuclei and well within the regime probed by underground detectors. Here we calculate where model independence ends, i.e., where the cross section becomes so large that it violates its defining assumptions. For pointlike spin-independent scattering, the assumed scaling relation is σχA∝A2μA2σχN∝A4σχN, where the A2 comes from coherence and the μA2≃A2mN2 from kinematics for mχ≫mA. The results are typically assumed to be model independent, meaning that the form of the potential need not be specified and that the cross sections on different nuclear targets can be simply related to the cross section on nucleons. This indicates various reionization models have little influence (≲ 2.5%) on constraining parameters of dark matter decay or annihilation.Ĭritical probes of dark matter come from tests of its elastic scattering with nuclei. and the upper limit of ϵ 0 f d is 2.8468 × 10 ⁻²⁴ at 95%C.L. By comparison, we also constrain dark matter annihilation in the instantaneous reionization model from the same data combination except the Q HII constraints and star formation rate density. and the upper limit of ϵ 0 f d reads 2.7765 × 10 ⁻²⁴ at 95%C.L. Combining the latest Planck data, BAO data, SNIa measurement, Q HII constraints from observations of quasars, as well as the star formation rate density from UV and IR data, the optical depth is τ = 0.0571 +0.0005 -0.0006 at 68%C.L. We consider the ionization history including both dark matter annihilation and star formation, then put constraints on DM annihilation. In this paper, we take dark matter annihilation as an example and investigate whether different reionization models influence the constraints on dark matter annihilation. Therefore, they could modify the thermal and ionization history of our universe, then leave footprints on the cosmic microwave background power spectra.
If dark matter decay or annihilate, a large amount of energy and particles would be released into the cosmic plasma. This talk is intended for a broad astronomy audience. Observational work might be used to pin down the nature of dark matter once andįor all. Identification to astronomy, and show what kinds of theoretical and Given the absence of detections in thoseĮxperiments, I will advocate a return of the problem of dark-matter
Recent experimental astroparticle- and particle-physics results that constrain
Introduction to possible particle candidates for dark matter and highlight Status of the search for the nature of dark matter. Of determining the identity of dark matter has largely shifted to the fields ofĪstroparticle and particle physics. Identify the particle specie(s) that make up dark matter. However, this information is not enough to Of the mass budget of the Universe, clusters strongly to form the load-bearingįrame of structure for galaxy formation, and hardly interacts with ordinary From astronomical observations, we know that dark matter exists, makes up 23%