Fractional Dark Matter decay: cosmological imprints and observational constraints

• Published in: Journal of cosmology and astroparticle physics 2020-01, Vol.2020 (1), p.45-45
• Main Authors: Xiao, Linfeng, Zhang, Le, An, Rui, Feng, Chang, Wang, Bin
• Format: Article
• Language: English
• Subjects: Dark matter; Decay; Decay rate; Distortion; Mathematical analysis; Particle decay; Radiation; Red shift
• ISSN: 1475-7516; 1475-7516
• DOI: 10.1088/1475-7516/2020/01/045

If a fraction fdcdm of the Dark Matter decays into invisible and massless particles (so-called “dark radiation”) with the decay rate (or inverse lifetime) Γdcdm, such decay will leave distinctive imprints on cosmological observables. With a full consideration of the Boltzmann hierarchy, we calculate the decay-induced impacts not only on the CMB but also on the redshift distortion and the kinetic Sunyaev-Zel'dovich effect, while providing detailed physical interpretations based on evaluating the evolution of gravitational potential. By using the current cosmological data with a combination of Planck 2015, Baryon Acoustic Oscillation and redshift distortion measurements which can improve the constraints, we update the 1σ bound on the fraction of decaying DM from fdcdm≲5.26% to fdcdm≲2.73% for the short-lived DM (assuming Γdcdm/H0≳104). However, no constraints are improved from RSD data (fdcdm≲0.94%) for the long-lived DM (i.e., Γdcdm/H0≲104). We also find the fractional DM decay can only slightly reduce the H0 and σ8 tensions, which is consistent with other previous works. Furthermore, our calculations show that the kSZ effect in future would provide a further constraining power on the decaying DM.