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WIMP/FIMP dark matter and primordial black holes with memory burden effect

Teruyuki Kitabayashi, Amane Takeshita

TL;DR

This work investigates dark matter comprising thermally produced WIMPs or FIMPs, DM from PBH Hawking radiation, and memory-burden-survived PBHs, under the regime where thermal production dominates PBH particle emission. It develops a memory-burden–aware PBH evaporation framework, deriving a modified mass-loss rate and an effective evaporation time that depends on the backreaction parameter $k$ and the end-point factor $q$, thereby extending PBH lifetimes. The study analyzes constraints from BBN, CMB, GWs, and warm DM, showing that memory burden lowers the DM warm bound and shifts allowed regions, with the effect being more pronounced for FIMPs than WIMPs. In the WIMP case, the relic density is roughly $\Omega_{\rm DM}h^2 \approx \Omega_{\rm FO}h^2+\Omega_{\rm PBH}h^2$ when thermal production dominates Hawking emission, while for FIMPs, $\Omega_{\rm DM}h^2\approx \Omega_{\rm FI}h^2+\Omega_{\rm PBH}h^2+\Omega_{\rm ev}h^2$; the WDM constraint then favors lower DM masses in the presence of memory burden, shaping the viable DM parameter space in non-dominant PBH scenarios.

Abstract

The lifetime of primordial black holes (PBHs), which formed in the early universe, can be extended by the memory burden effect. Light PBHs may exist today and be candidates for dark matter (DM). We assume that DM is made of thermally produced weakly interacting massive particles (WIMPs), WIMPs produced via the Hawking radiation of PBHs, and PBHs that survived Hawking evaporation via the memory burden effect. Feebly interacting massive particles (FIMPs) are alternatives to WIMPs. This paper shows that a small memory burden is preferable if the thermal production of WIMPs or FIMPs is much larger than the effect of PBH particle production via Hawking radiation. In addition, we show that the lower limit of the DM mass, called the warm DM (WDM) constraint, decreases with the memory burden effect of PBHs. Results suggest that the WDM constraint is more effective for FIMPs than for WIMPs.

WIMP/FIMP dark matter and primordial black holes with memory burden effect

TL;DR

This work investigates dark matter comprising thermally produced WIMPs or FIMPs, DM from PBH Hawking radiation, and memory-burden-survived PBHs, under the regime where thermal production dominates PBH particle emission. It develops a memory-burden–aware PBH evaporation framework, deriving a modified mass-loss rate and an effective evaporation time that depends on the backreaction parameter and the end-point factor , thereby extending PBH lifetimes. The study analyzes constraints from BBN, CMB, GWs, and warm DM, showing that memory burden lowers the DM warm bound and shifts allowed regions, with the effect being more pronounced for FIMPs than WIMPs. In the WIMP case, the relic density is roughly when thermal production dominates Hawking emission, while for FIMPs, ; the WDM constraint then favors lower DM masses in the presence of memory burden, shaping the viable DM parameter space in non-dominant PBH scenarios.

Abstract

The lifetime of primordial black holes (PBHs), which formed in the early universe, can be extended by the memory burden effect. Light PBHs may exist today and be candidates for dark matter (DM). We assume that DM is made of thermally produced weakly interacting massive particles (WIMPs), WIMPs produced via the Hawking radiation of PBHs, and PBHs that survived Hawking evaporation via the memory burden effect. Feebly interacting massive particles (FIMPs) are alternatives to WIMPs. This paper shows that a small memory burden is preferable if the thermal production of WIMPs or FIMPs is much larger than the effect of PBH particle production via Hawking radiation. In addition, we show that the lower limit of the DM mass, called the warm DM (WDM) constraint, decreases with the memory burden effect of PBHs. Results suggest that the WDM constraint is more effective for FIMPs than for WIMPs.

Paper Structure

This paper contains 15 sections, 44 equations, 4 figures.

Table of Contents

  1. Introduction
  2. PBH with memory burden effect
  3. Time evolution
  4. Initial density
  5. Survived PBH density
  6. Particle production
  7. Constraints
  8. BBN
  9. CMB
  10. GWs
  11. WDM
  12. WIMP/FIMP DM and PBHs
  13. WIMPs and PBHs
  14. FIMPs and PBHs
  15. Summary

Figures (4)

  • Figure 1: WDM constraint with memory burden effect of PBHs. Left panel: lower limit of WDM mass vs. initial mass of PBH. The left (right) gray region is excluded from the CMB (BBN) constraint. Right panel: $q$ dependence on lower limit of $m_\chi$.
  • Figure 2: Relic abundance of DM considering WIMPs and PBHs. Left: relic abundance of WIMPs due to Hawking radiation from PBHs, $\Omega_{\rm ev}h^2$. Right: total relic abundance of DM, $\Omega_{\rm DM}h^2$, according to initial PBH mass, $M_{\rm in}$. The left (right) gray region is excluded from the CMB (BBN) constraint.
  • Figure 3: Constraints on initial PBH density, $\beta$, considering WIMPs and PBHs. Top: $\beta$ vs. $M_{\rm in}$ at various $q$. The left (right) gray region is excluded from the CMB (BBN) constraint. Bottom left: $\beta$ v.s, $m_\chi$. Bottom right: $\beta$ vs. $\alpha_{\rm WIMP}$.
  • Figure 4: Relic abundance of DM and constraint on initial PBH density for FIMPs and PBHs. Only figures that differ from the case considering WIMPs are shown. Top: relic abundance of FIMPs owing to Hawking radiation from PBHs, $\Omega_{\rm ev}h^2$, according to initial PBH mass, $M_{\rm in}$. The left (right) gray region is excluded from the CMB (BBN) constraint. Bottom left: $\beta$ according to FIMP mass, $m_\chi$. Bottom right: $\beta$ according to FIMP coupling, $\alpha_{\rm FIMP}$.