Constraints on the basic parameters of dark matter using the Planck data

Abstract

Dark Matter annihilation or decay can affect the anisotropy of the cosmic microwave background (CMB). Therefore the CMB data can be used to constrain the properties of dark matter particle. In this work, we use the new CMB data obtained by the Planck satellite to investigate the limits on the basic parameters of dark matter particle. The parameters are the dark matter mass (mχ) and the thermally averaged cross section ( σv ) for dark matter annihilation and the decay rate (Γ) (or life time τ = 1/Γ) for dark matter decay. For dark matter annihilation we also consider the impact of the structure formation process which is neglected by the recent work. We found that for DM annihilation the constraints on the parameters are fann = σv /mχ < 0.16 × 10 −26 cm 3 s −1 GeV −1 (or fann < 0.89 × 10 −6 m 3 s −1 kg −1 , 95% CL). For DM decay the constraints on the decay rate are Γ < 0.28 × 10 −25 s −1 (95% CL).

Constraints on primordial black holes and curvature perturbations from the global 21-cm signal

“…[34]. The interactions, between the high energy photons emitted from accreting PBHs and the particles exist in the universe, lead to the changes of the degree of inoization and the thermal history of the IGM through heating, ionization and excitation [9,11,37,[48][49][50][51]. The changes of the degree of ionization (x e ) and the temperature of the IGM (T k ) with redshift are governed by the following equations [37,[48][49][50]:…”

“…where R s (z) and I s (z) are the recombination and ionization rate from the standard sources, respectively. The ionization rate (I PBH ) and heating rate (K PBH ) caused by accreting PBHs can be written as follows [11,37,[48][49][50],…”

“…The changes of the temperature of the IGM, T k , with redshift can be obtained by solving the differential equations ( 14)- (17). Specifically, we have modified the public code RECFAST in CAMB 1 , including the effects from accreting PBHs, to solve the differential equations numerically [11,37,[48][49][50]58]. It should be noticed that the fudge factors are used in RECFAST module to calibrate for the standard cosmology, and more accurate calculations can be found from CosmoRec [59] and HyRec [60] modules.…”

Dark matter as a weakly coupled dark baryon

“…Bounds on radioactive DM can be inferred by rescaling bounds on decaying DM. An excessive reionization of CMB is roughly obtained for t CMB τ < 1.1 10 9 Gyr×∆E B /M B [60], where t CMB ≈ 380 kyr is the Universe age at photon decoupling and M B is the DM mass. If DM is still γ-radioactive today, one must have τ > 10 11 Gyr×∆E B /M B , for 0.1 MeV < ∼ ∆E B < ∼ 10 GeV [61].…”

Contributions of dark matter annihilation to the global 21 cm spectrum observed by the EDGES experiment

“…In Ref. [54], the authors have got the constraints on the dark matter parameters as M DM > ∼ 20 GeV for σv = 3 × 10 −26 cm −3 s −1 . Therefore, the parameters of the dark matter used here are within the current allowed parameter space.…”