Gravitational capture of magnetic monopoles by primordial black holes in the early universe

Zhang, Chen; Zhang, Xin

doi:10.1007/jhep10(2023)037

Cited by 5 publications

(1 citation statement)

References 102 publications

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“…In that case, the planet to solar mass window has direct connections to the recent Pulsar Timing Arrays (PTAs) results on a possible GW background [112][113][114][115][116][117][118][119][120][121], if interpreted as the induced GW signal (see also Refs. [160][161][162] for the merger of supermassive PBHs).…”

Section: Introductionmentioning

confidence: 99%

Gravitational wave constraints on the primordial black hole dominated early universe

Domènech

Lin

Sasaki

2021

J. Cosmol. Astropart. Phys.

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We calculate the gravitational waves (GWs) induced by the density fluctuations due to the inhomogeneous distribution of primordial black holes (PBHs) in the case where PBHs eventually dominate and reheat the universe by Hawking evaporation. The initial PBH density fluctuations are isocurvature in nature. We find that most of the induced GWs are generated right after evaporation, when the universe transits from the PBH dominated era to the radiation dominated era and the curvature perturbation starts to oscillate wildly. The strongest constraint on the amount of the produced GWs comes from the big bang nucleosynthesis (BBN). We improve previous constraints on the PBH fraction and find that it cannot exceed 10-4. Furthermore, this maximum fraction decreases as the mass increases and reaches 10-12 for MPBH∼ 5×108 g, which is the largest mass allowed by the BBN constraint on the reheating temperature. Considering that PBH may cluster above a given clustering scale, we also derive a lower bound on the scale of clustering. Interestingly, the GW spectrum for MPBH∼ 104 -108 g enters the observational window of LIGO and DECIGO and could be tested in the future. Although we focus on the PBH dominated early universe in this paper, our methodology is applicable to any model with early isocurvature perturbation.

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Section: Introductionmentioning

confidence: 99%

Gravitational wave constraints on the primordial black hole dominated early universe

Domènech

Lin

Sasaki

2021

J. Cosmol. Astropart. Phys.

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On the cosmological abundance of magnetic monopoles

Zhang,

et al. 2024

J. High Energ. Phys.

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We demonstrate that Debye shielding cannot be employed to constrain the cosmological abundance of magnetic monopoles, contrary to what is stated in the previous literature. Current model-independent bounds on the monopole abundance are then revisited for unit Dirac magnetic charge. We find that the Andromeda Parker bound can be employed to set an upper limit on the monopole flux at the level of FM ≲ 5.3 × 10−19cm−2s−1sr−1 for a monopole mass 1013 GeV/c2 ≲ m ≲ 1016 GeV/c2, which is more stringent than the MACRO direct search limit by two orders of magnitude. This translates into stringent constraints on the monopole density parameter ΩM at the level of 10−7˘10−4 depending on the mass. For larger monopole masses the scenarios in which magnetic monopoles account for all or the majority of dark matter are disfavored.

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Linear stability of vector Horndeski black holes

Chen,

Felice,

Tsujikawa

2024

J. Cosmol. Astropart. Phys.

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Horndeski's vector-tensor (HVT) gravity is described by a Lagrangian in which the field strength fμν = ∂μAν-∂νAμ of a vector field Aμ interacts with a double dual Riemann tensor Lμναβ in the form βLμναβ Fμν Fαβ , where β is a constant. In Einstein-Maxwell-HVT theory, there are static and spherically symmetric black hole (BH) solutions with electric or magnetic charges, whose metric components are modified from those in the Reissner-Nordström geometry. The electric-magnetic duality of solutions is broken even at the background level by the nonvanishing coupling constant β. We compute a second-order action of BH perturbations containing both the odd- and even-parity modes and show that there are four dynamical perturbations arising from the gravitational and vector-field sectors. We derive all the linear stability conditions associated with the absence of ghosts and radial/angular Laplacian instabilities for both the electric and magnetic BHs. These conditions exhibit the difference between the electrically and magnetically charged cases by reflecting the breaking of electric-magnetic duality at the level of perturbations. In particular, the four angular propagation speeds in the large-multipole limit are different from each other for both the electric and magnetic BHs. This suggests the breaking of eikonal correspondence between the peak position of at least one of the potentials of dynamical perturbations and the radius of photon sphere. For the electrically and magnetically charged cases, we elucidate parameter spaces of the HVT coupling and the BH charge in which the BHs without naked singularities are linearly stable.

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Gravitational capture of magnetic monopoles by primordial black holes in the early universe

Cited by 5 publications

References 102 publications

Gravitational wave constraints on the primordial black hole dominated early universe

Gravitational wave constraints on the primordial black hole dominated early universe

On the cosmological abundance of magnetic monopoles

Linear stability of vector Horndeski black holes

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