Constraints on small-scale primordial power by annihilation signals from extragalactic dark matter minihalos

Nakama, Tomohiro; Suyama, Teruaki; Kohri, Kazunori; Hiroshima, Nagisa

doi:10.1103/physrevd.97.023539

Cited by 43 publications

(60 citation statements)

References 93 publications

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“…3, we find that, for SKA curves, both results based on Eqs. (10) and (12) are almost the same, which means the weak-signal limit is a good approximation. This is mainly because the large number of pulsars increases the signal-to-noise ratio sufficiently so that ρ = 1 is reached in the weak-signal regime.…”

Section: Constraints On Curvature Perturbationsmentioning

confidence: 77%

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Gravitational waves induced by scalar perturbations as probes of the small-scale primordial spectrum

2019

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Compared to primordial perturbations on large scales, roughly larger than 1 megaparsec, those on smaller scales are not severely constrained. We revisit the issue of probing small-scale primordial perturbations using gravitational waves (GWs), based on the fact that, when large-amplitude primordial perturbations on small scales exist, GWs with relatively large amplitudes are induced at second order in scalar perturbations, and these induced GWs can be probed by both existing and planned gravitational-wave projects. We use accurate methods to calculate these induced GWs and take into account sensitivities of different experiments to induced GWs carefully, to report existing and expected limits on the small-scale primordial spectrum.

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Section: Constraints On Curvature Perturbationsmentioning

confidence: 77%

“…To take into account the frequency dependence of the induced GWs and sensitivity curves correctly, we have calculated the signal-tonoise ratio, defined in Eq. (10) or Eq. (12).…”

Section: Discussionmentioning

confidence: 99%

Gravitational waves induced by scalar perturbations as probes of the small-scale primordial spectrum

2019

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“…It has been claimed that ultracompact mini halos already rule out the power spectrum growing so large on scales of 10 6 Mpc −1[71]. However, these constraints are too strong because realistic halo formation is not as isolated as previously assumed leading to less steep density profiles[72,73] -see also[74].…”

mentioning

confidence: 95%

Primordial black holes with an accurate QCD equation of state

Byrnes

Hindmarsh

Young

et al. 2018

J. Cosmol. Astropart. Phys.

198

173

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Making use of definitive new lattice computations of the Standard Model thermodynamics during the quantum chromodynamic (QCD) phase transition, we calculate the enhancement in the mass distribution of primordial black holes (PBHs) due to the softening of the equation of state. We find that the enhancement peaks at approximately 0.7M⊙, with the formation rate increasing by at least two orders of magnitude due to the softening of the equation of state at this time, with a range of approximately 0.3M⊙ < M < 1.4M⊙ at full width half-maximum. PBH formation is increased by a smaller amount for PBHs with masses spanning a large range, 10 −3 M⊙ < MPBH < 10 3 M⊙, which includes the masses of the BHs that LIGO detected. The most significant source of uncertainty in the number of PBHs formed is now due to unknowns in the formation process, rather than from the phase transition. A near scale-invariant density power spectrum tuned to generate a population with mass and merger rate consistent with that detected by LIGO should also produce a much larger energy density of PBHs with solar mass. The existence of BHs below the Chandresekhar mass limit would be a smoking gun for a primordial origin and they could arguably constitute a significant fraction of the cold dark matter density. They also pose a challenge to inflationary model building which seek to produce the LIGO BHs without overproducing lighter PBHs. * C.Byrnes@sussex.ac.uk † m.b.hindmarsh@sussex.ac.uk ‡ S.M.Young@sussex.ac.uk

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“…If the dark matter is weakly interacting massive particle (WIMP) (Steigman & Turner 1985;Jungman et al 1996;Kolb et al 1999), UCMHs can become cosmological gamma-ray sources because the signal of the annihilation of WIMPs is enhanced in the dense region at the center of UCMHs. Currently the non-detection of the gamma-ray emission from the WIMP annihilation provides the constraint on the UCMH abundance and the stringent constraints on the small-scale curvature power spectrum, A ζ < 10 −7 for 10 Mpc −1 < k < 10 8 Mpc −1 (Josan & Green 2010;Scott & Sivertsson 2010;Bringmann et al 2012;Clark et al 2016;Nakama et al 2018;Delos et al 2018a,b). The nondetection of neutrino from the WIMPs also provides a similar constraint (Yang et al 2013;Nakama et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Currently the non-detection of the gamma-ray emission from the WIMP annihilation provides the constraint on the UCMH abundance and the stringent constraints on the small-scale curvature power spectrum, A ζ < 10 −7 for 10 Mpc −1 < k < 10 8 Mpc −1 (Josan & Green 2010;Scott & Sivertsson 2010;Bringmann et al 2012;Clark et al 2016;Nakama et al 2018;Delos et al 2018a,b). The nondetection of neutrino from the WIMPs also provides a similar constraint (Yang et al 2013;Nakama et al 2018). The Thomson scattering optical depth for the CMB photons also provides the UCMH abundance because the annihilation gamma-ray from UCMHs can contribute to the photon budget for cosmic reionization (Zhang 2011;Yang et al 2011;Yang 2016;Clark et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The 21-cm signals from ultracompact minihaloes as a probe of primordial small-scale fluctuations

Furugori

Abe

Tanaka

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Ultracompact minihalos (UCMHs) can form after the epoch of matter-radiation equality, if the density fluctuations of dark matter have significantly large amplitude on small scales. The constraint on the UCMH abundance allows us to access such small-scale fluctuations. In this paper, we present that, through the measurement of 21-cm fluctuations before the epoch of reionization, we can obtain a constraint on the UCMH abundance. We calculate the 21-cm signal from UCMHs and show that UCMHs provide the enhancement of the 21-cm fluctuations. We also investigate the constraint on the UCMH abundance and small-scale curvature perturbations. Our results indicate that the upcoming 21-cm observation, the Square Kilometre Array (SKA), provides the constraint on amplitude of primordial curvature power spectrum, A ζ 10 −6 on 100 Mpc −1 k 1000 Mpc −1 . Although it is not stronger than the one from the non-detection of gamma rays induced by dark matter annihilation in UCMHs, the constraint by the SKA will be important because this constraint is independent of the dark matter particle model.

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Constraints on small-scale primordial power by annihilation signals from extragalactic dark matter minihalos

Cited by 43 publications

References 93 publications

Gravitational waves induced by scalar perturbations as probes of the small-scale primordial spectrum

Gravitational waves induced by scalar perturbations as probes of the small-scale primordial spectrum

Primordial black holes with an accurate QCD equation of state

The 21-cm signals from ultracompact minihaloes as a probe of primordial small-scale fluctuations

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