Density perturbations in braneworld cosmology and primordial black holes

Bugaev, É. V.; Klimai, Peter

doi:10.1103/physrevd.83.023516

Cited by 20 publications

(27 citation statements)

References 55 publications

(90 reference statements)

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“…In this case, the power spectrum can be in agreement with the CMB data [12,16]. The fast waterfall phase itself has been the object of recent attention, especially to determine the contribution of iso-curvature perturbations [17][18][19][20][21][22] as well as the level of non-Gaussianities [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 66%

Slow roll during the waterfall regime: The small coupling window for supersymmetric hybrid inflation

Clesse¹,

Garbrecht

2012

Phys. Rev. D

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It has recently been pointed out that a substantial amount of e-folds can occur during the waterfall regime of hybrid inflation. Moreover, Kodama et.al. have derived analytic approximations for the trajectories of the inflaton and of the waterfall fields. Based on these, we derive here the consequences for F -and D-term SUSY hybrid inflation: A substantial amount of e-folds may occur in the waterfall regime, provided κ ≪ M 2 /M 2 P , where κ is the superpotential coupling, M the scale of symmetry breaking and MP the reduced Planck mass. When this condition is amply fulfilled, a number of e-folds much larger than Ne ≈ 60 can occur in the waterfall regime and the scalar spectral index is then given by the expression found by Kodama et.al. ns = 1−4/Ne. This value may be increased up to unity, if only about Ne e-folds occur during the waterfall regime, such that the largest observable scale leaves the horizon close to the critical point of hybrid inflation, what can be achieved for κ ≈ 10 −13 and M ≈ 5 × 10 12 GeV in F -term inflation. Imposing the normalization of the power spectrum leads to a lower bound on the scale of symmetry breaking.

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Section: Introductionmentioning

confidence: 66%

Slow roll during the waterfall regime: The small coupling window for supersymmetric hybrid inflation

Clesse¹,

Garbrecht

2012

Phys. Rev. D

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“…We have verified that the ellipticities become unobservably small by the time the inspiral enters the LIGO band, but they may be detectable in future experiments [42]. Mutiply-lensed quasars [43,44], pulsar timing arrays [45], and FRB lensing searches [46] may also allow probes of the ∼ 30 M PBH mass range.…”

Section: Gpcmentioning

confidence: 99%

Did LIGO Detect Dark Matter?

et al. 2016

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We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses 20 M M bh 100 M where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to emission of gravitational radiation and ultimately merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the 2 − 53 Gpc −3 yr −1 rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have no optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next generation experiments will be invaluable in performing these tests.The nature of the dark matter (DM) is one of the most longstanding and puzzling questions in physics. Cosmological measurements have now determined with exquisite precision the abundance of DM [1, 2], and from both observations and numerical simulations we know quite a bit about its distribution in Galactic halos. Still, the nature of the DM remains a mystery. Given the efficacy with which weakly-interacting massive particlesfor many years the favored particle-theory explanationhave eluded detection, it may be warranted to consider other possibilities for DM. Primordial black holes (PBHs) are one such possibility [3-6].Here we consider whether the two ∼ 30 M black holes detected by LIGO [7] could plausibly be PBHs. There is a window for PBHs to be DM if the BH mass is in the range 20 M M 100 M [8,9]. Lower masses are excluded by microlensing surveys [10][11][12]. Higher masses would disrupt wide binaries [9,13,14]. It has been argued that PBHs in this mass range are excluded by CMB constraints [15,16]. However, these constraints require modeling of several complex physical processes, including the accretion of gas onto a moving BH, the conversion of the accreted mass to a luminosity, the self-consistent feedback of the BH radiation on the accretion process, and the deposition of the radiated energy as heat in the photon-baryon plasma. A significant (and difficult to quantify) uncertainty should therefore be associated with this upper limit [17], and it seems worthwhile to examine whether PBHs in this mass range could have other observational consequences.In this Letter, we show that if DM consists of ∼ 30 M BHs, then the rate for mergers of such PBHs falls within the merger rate inferred from GW150914. In any galactic halo, there is a chance two BHs will undergo a hard scatter, lose energy to a s...

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“…[3], we suggested that if ∼ 30 M primordial black holes (PBH) make up the dark matter [17][18][19], then the rate for the merger of such events is consistent with the range inferred from the first LIGO events. PBHs in the mass range 20−100 M remain viable DM candidates [20,21]-lower masses are ruled out by null microlensing searches [22][23][24][25][26] and pulsar-timing-array searches [27], and higher masses by the dynamics of wide stellar binaries [21,28,29]. Ref.…”

Section: Introductionmentioning

confidence: 99%

Orbital eccentricities in primordial black hole binaries

et al. 2016

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It was recently suggested that the merger of ∼ 30 M primordial black holes (PBHs) may provide a significant number of events in gravitational-wave observatories over the next decade, if they make up an appreciable fraction of the dark matter. Here we show that measurement of the eccentricities of the inspiralling binary black holes can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH binaries are formed on highly eccentric orbits and can then merge on timescales that in some cases are years or less, retaining some eccentricity in the last seconds before the merger. This is to be contrasted with massive-stellar-binary, globular-cluster, or other astrophysical origins for binary black holes (BBHs) in which the orbits have very effectively circularized by the time the BBH enters the observable LIGO window. Here we discuss the features of the gravitational-wave signals that indicate this eccentricity and forecast the sensitivity of LIGO and the Einstein Telescope to such effects. We show that if PBHs make up the dark matter, then roughly one event should have a detectable eccentricity given LIGO's expected sensitivity and observing time of six years. The Einstein Telescope should see O(10) such events after ten years.

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Density perturbations in braneworld cosmology and primordial black holes

Cited by 20 publications

References 55 publications

Slow roll during the waterfall regime: The small coupling window for supersymmetric hybrid inflation

Slow roll during the waterfall regime: The small coupling window for supersymmetric hybrid inflation

Did LIGO Detect Dark Matter?

Orbital eccentricities in primordial black hole binaries

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