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In all inflationary scenarios of primordial black hole (PBH) formation, amplified scalar perturbations inevitably accompany an induced stochastic gravitational wave background (ISGWB) at smaller scales. In this paper, we study the ISGWB originating from the inflationary model, introduced in our previous paper [N. Bhaumik and R. K. Jain, Primordial black holes dark matter from inflection point models of inflation and the effects of reheating, J. Cosmol. Astropart. Phys. 01 (2020) 037] wherein PBHs can be produced with a nearly monochromatic mass fraction in the asteroid mass window accounting for the total dark matter in the universe. We numerically calculate the ISGWB in our scenario for frequencies ranging from nano-Hz to kHz that covers the observational scales corresponding to future space-based gravitational wave (GW) observatories such as IPTA, LISA, DECIGO, and Einstein Telescope. Interestingly, we find that ultralight PBHs (MPBH∼10-20 M⊙), which shall completely evaporate by today with an exceedingly small contribution to dark matter, would still generate an ISGWB that may be detected by a future design of the ground-based Advanced LIGO detector. Using a model-independent approach, we obtain a stringent lower mass limit for ultralight PBHs which would be valid for a large class of ultra slow roll inflationary models. Further, we extend our formalism to study the imprints of a reheating epoch on both the ISGWB and the derived lower mass bound. We find that any noninstantaneous reheating leads to an even stronger lower bound on the PBH mass and an epoch of a prolonged matter-dominated reheating shifts the ISGWB spectrum to smaller frequencies. In particular, we show that an epoch of an early matter-dominated phase leads to a secondary amplification of the ISGWB at a much smaller scale corresponding to the smallest comoving scale leaving the horizon during inflation or the end of the inflation scale. Finally, we discuss the prospects of the ISGWB detection by the proposed and upcoming GW observatories. [ABSTRACT FROM AUTHOR]

Recently, Brown et al. [Phys. Rev. D 98, 041301 (2018)] analyzed the spectral properties of the globular cluster 47 Tucanae (47 Tuc) using nine years of Fermi-LAT data. Their paper argues that the emission from 47 Tuc cannot be explained by millisecond pulsars (MSPs) alone because of a significant discrepancy between the MSP spectral properties and those of 47 Tuc. It is argued that there is a significant (greater than 5σ) preference for a two-source scenario. The second component could be from the annihilation of dark matter in a density spike surrounding the intermediate-mass black hole candidate in 47 Tuc. In this paper, we argue that the claimed discrepancy arises because their paper uses a stacked MSP spectrum to model the emission from MSPs in 47 Tuc, which is insufficient to account for the uncertainties in the spectrum of the MSPs in 47 Tuc. Contrary to their claims, we show that the significance of an additional dark matter component is ≲2σ when sample variance in the spectrum of a population of MSPs is accounted for. The spectrum of 47 Tuc is compatible with that of a population of MSPs similar to the disk population. [ABSTRACT FROM AUTHOR]

The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to 1.25M☉ rules out primordial black holes with masses ∼1019-1020 gm as a dominant constituent of the local dark matter density. Black holes with masses as large as 1024 gm will be excluded if recent observations by the NuStar Collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range 1020-1022 gm are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large spacetime volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass. [ABSTRACT FROM AUTHOR]

In this paper we present a new scenario where massive primordial black holes (PBHs) are produced from the collapse of large curvature perturbations generated during a mild-waterfall phase of hybrid inflation. We determine the values of the inflaton potential parameters leading to a PBH mass spectrum peaking on planetary like masses at matter-radiation equality and producing abundances comparable to those of dark matter today, while the matter power spectrum on scales probed by cosmic microwave background (CMB) anisotropics agrees with Planck data. These PBHs could have acquired large stellar masses today, via merging, and the model passes both the constraints from CMB distortions and microlensing. This scenario is supported by Chandra observations of numerous BH candidates in the central region of Andromeda. Moreover, the tail of the PBH mass distribution could be responsible for the seeds of supermassive black holes at the center of galaxies, as well as for ultraluminous x-ray sources. We find that our effective hybrid potential can originate e.g. from D-term inflation with a Fayet-Iliopoulos term of the order of the Planck scale but sub-Planckian values of the inflaton field. Finally, we discuss the implications of quantum diffusion at the instability point of the potential, able to generate a Swiss-cheese-like structure of the Universe, eventually leading to apparent accelerated cosmic expansion. [ABSTRACT FROM AUTHOR]

The direct detection of sub-GeV dark matter interacting with nucleons is hampered by the low recoil energies induced by scatterings in the detectors. This experimental difficulty is avoided in the scenario of boosted dark matter where a component of dark matter particles is endowed with large kinetic energies. In this paper, we point out that the current evaporation of primordial black holes with a mass from 1014 to 1016g is a source of boosted light dark matter with energies of tens to hundreds of MeV. Focusing on the XENON1T experiment, we show that these relativistic dark matter particles could give rise to a signal orders of magnitude larger than the present upper bounds. Therefore, we are able to significantly constrain the combined parameter space of primordial black holes and sub-GeV dark matter. In the presence of primordial black holes with masses of 1015 g and abundances compatible with present bounds, the limits on a dark matter-nucleon cross section are improved by four orders of magnitude. [ABSTRACT FROM AUTHOR]

Hawking evaporation of black holes in the early Universe is expected to copiously produce all kinds of particles, regardless of their charges under the Standard Model gauge group. For this reason, any fundamental particle, known or otherwise, could be produced during the black hole lifetime. This certainly includes dark matter (DM) particles. This paper improves upon previous calculations of DM production from primordial black holes (PBH) by consistently including the greybody factors, and by meticulously tracking a system of coupled Boltzmann equations. We show that the initial PBH densities required to produce the observed relic abundance depend strongly on the DM spin, varying in about ∼2 orders of magnitude between a spin-2 and a scalar DM in the case of nonrotating PBHs. For Kerr PBHs, we have found that the expected enhancement in the production of bosons reduces the initial fraction needed to explain the measurements. We further consider indirect production of DM by assuming the existence of additional and unstable degrees of freedom emitted by the evaporation, which later decay into the DM. For a minimal setup where there is only one heavy particle, we find that the final relic abundance can be increased by at most a factor of ∼4 for a scalar heavy state and a Schwarzschild PBH, or by a factor of ∼4.3 for a spin-2 particle in the case of a Kerr PBH. [ABSTRACT FROM AUTHOR]

Gravitational waves emitted by distorted black holes, such as those arising from the coalescence of binary black holes, or a falling compact star into a supermassive black hole, carry not only information about the corresponding spacetime but also the information about the environment surrounding the black holes. In this paper, we study the effects of the dark matter halos with three different density profiles on the gravitational axial perturbations of a Schwarzschild-like black hole. For this purpose, we first consider modified Schwarzschild black holes with three different dark matter profiles and derive the equation of motion of the axial perturbations of the modified Schwarzschild metric. It is shown that by ignoring the dark matter perturbations, a Regge-Wheeler-like master equation with a modified potential for the axial perturbation can be obtained explicitly. Then, we calculate the complex frequencies of the quasinormal modes of the Schwarzschild-like black hole in the dark matter halos by applying the sixth-order WKB method. The corresponding gravitational wave spectra with the effects of the dark matter halos have also been discussed. [ABSTRACT FROM AUTHOR]

Primordial black holes (PBHs) have been proposed to explain at least a portion of dark matter. Observations have put strong constraints on PBHs in terms of the fraction of dark matter which they can represent, fPBH, across a wide mass range--apart from the stellar-mass range of 20 M⊙ ≲ M PBH ≲ 100 M⊙. In this paper, we explore the possibility that such PBHs could serve as point-mass lenses capable of altering the gravitational-wave (GW) signals observed from binary black hole (BBH) mergers along their line-of-sight. We find that careful GW data analysis could verify the existence of such PBHs based on the fitting factor and odds ratio analyses. When such a lensed GW signal is detected, we expect to be able to measure the redshifted mass of the lens with a relative error ΔMPBH/MPBH ≲ 0.3. If no such lensed GW events were detected despite the operation of sensitive GW detectors accumulating large numbers of BBH mergers, it would translate into a stringent constraint of fPBH ≲ 10-2 - 10-5 for PBHs with a mass larger than ~ 10 M⊙ by the Einstein Telescope after one year of running, and fPBH ≲ 0.2 for PBHs with mass greater than ~ 50 M⊙ for advanced LIGO after ten years of running. [ABSTRACT FROM AUTHOR]

In this paper we present a class of potentials derived by no-scale supergravity in order to explain the production of primordial black holes (PBHs) in the Universe. By breaking the SU (2, 1) / SU (2) × U (1) symmetry we fix one of the two chiral fields and we derive effective scalar potentials which are capable of generating PBHs. Specifically, we modify well-known superpotentials, which reduce to Starobinsky-like effective scalar potentials. Thus, we derive scalar potentials which, on the one hand, explain the production of PBHs and, on the other hand, they conserve the transformation laws, which yield from the parametrization of the coset SU (2, 1) / SU (2) × U (1). Moreover, we generate PBHs by modifying the kinetic term of the Langrangian (or the Kähler potential) and we keep the superpotentials unmodified. In all cases we evaluate the fractional abundances of PBHs by comparing Press-Schechter approach and peak theory, while focusing on explaining the dark matter in the Universe. All models are in complete consistence with Planck constraints. [ABSTRACT FROM AUTHOR]

As an attractive candidate for dark matter, the primordial black holes (PBHs) in the mass range (8×1014∼1016) g could be detected via their Hawking radiation, including neutrinos and antineutrinos of three flavors. In this paper, we investigate the possibility to constrain the PBHs as dark matter by measuring (anti)neutrino signals at the large liquid-scintillator detector of Jiangmen Underground Neutrino Observatory (JUNO). Among six available detection channels, the inverse beta decay ¯νe+p→e++n is shown to be most sensitive to the fraction fPBH of PBHs contributing to the dark matter abundance. Given the PBH mass MPBH=1015 g, we find that JUNO will be able to place an upper bound fPBH≲3×10-5, which is 20 times better than the current best limit fPBH≲6×10-4 from Super-Kamiokande. For heavier PBHs with a lower Hawking temperature, the (anti)neutrinos become less energetic, leading to a relatively weaker bound. [ABSTRACT FROM AUTHOR]

Systems of enhanced memory capacity are subjected to a universal effect of memory burden, which suppresses their decay. In this paper, we study a prototype model to show that memory burden can be overcome by rewriting stored quantum information from one set of degrees of freedom to another one. However, due to a suppressed rate of rewriting, the evolution becomes extremely slow compared to the initial stage. Applied to black holes, this predicts a metamorphosis, including a drastic deviation from Hawking evaporation, at the latest after losing half of the mass. This raises a tantalizing question about the fate of a black hole. As two likely options, it can either become extremely long lived or decay via a new classical instability into gravitational lumps. The first option would open up a new window for small primordial black holes as viable dark matter candidates. [ABSTRACT FROM AUTHOR]

Gravitational waves may be one of the few direct observables produced by ultralight bosons, conjectured dark matter candidates that could be the key to several problems in particle theory, high-energy physics and cosmology. These axionlike particles could spontaneously form "clouds" around astrophysical black holes, leading to potent emission of continuous gravitational waves that could be detected by instruments on the ground and in space. Although this scenario has been thoroughly studied, it has not been yet appreciated that both types of detector may be used in tandem (a practice known as "multibanding"). In this paper, we show that future gravitational-wave detectors on the ground and in space will be able to work together to detect ultralight bosons with masses 25≲µ/(10-15 eV)≲500. In detecting binary-black-hole inspirals, the LISA space mission will provide crucial information enabling future ground-based detectors, like Cosmic Explorer or Einstein Telescope, to search for signals from boson clouds around the individual black holes in the observed binaries. We lay out the detection strategy and, focusing on scalar bosons, chart the suitable parameter space. We study the impact of ignorance about the system's history, including cloud age and black hole spin. We also consider the tidal resonances that may destroy the boson cloud before its gravitational signal becomes detectable by a ground-based follow-up. Finally, we show how to take all of these factors into account, together with uncertainties in the LISA measurement, to obtain boson mass constraints from the ground-based observation facilitated by LISA. [ABSTRACT FROM AUTHOR]

For primordial black holes (PBHs) to form a considerable fraction of cold dark matter, the required amplitude of primordial scalar perturbations is quite large (Pζ(k)~10-2) if PBH is formed in radiation epoch. In alternate cosmological histories, where additional epoch of arbitrary equation of state precede radiation epoch, the dynamics of PBH formation and relevant mass ranges can be different leading to lower requirement of primordial power at smaller scales of inflation. Moreover, this alternate history can modify the predictions for the gravitational wave (GW) spectrum, which can be probed by upcoming GW observations. In this paper we show that an early kination epoch can lead to percent level abundance of PBH for a lower amplitude of Pζ(k) as compared to PBH formation in a standard radiation epoch. Moreover, we calculate the effect of early kination epoch on the GW spectrum for first and second orders in perturbation theory which show enhancement in the amplitude of the GW spectrum in a kination epoch with respect to that in a standard radiation epoch. [ABSTRACT FROM AUTHOR]

Primordial black holes that survive until the present have been considered as a dark matter candidate. In this paper we argue that primordial 2-2-hole remnants provide a more promising and testable alternative. 2-2-holes arise in quadratic gravity as a new family of classical solutions for ultracompact matter distributions and they possess the black hole exterior without an event horizon. They may serve as the endpoint of gravitational collapse, providing a resolution for the information loss problem. Intriguing thermodynamic behavior is found for these objects when sourced by a thermal gas. A large 2-2-hole radiates with a Hawking-like temperature and exhibits an entropy-area law. At a late stage, the evaporation slows down and essentially stops as the mass asymptotically approaches a minimal value. This remnant mass is determined by a fundamental scale in quadratic gravity. We study the cosmological and astrophysical implications of having these remnants as dark matter and derive the corresponding constraints. A distinctive phenomenon associated with remnant mergers occurs, predicting fluxes of high-energy astrophysical particles due to the spectacular evaporation of the merger product. Measurements of high-energy photon and neutrino fluxes could possibly bound the remnant mass to be not far above the Planck mass. Early universe physics, on the other hand, requires that 2-2-holes quickly evolve into the remnant state after formation, putting an upper bound on the formation mass. [ABSTRACT FROM AUTHOR]

Primordial black holes (PBHs), as dark matter candidates, have attracted more and more attention as they could be possible progenitors of the heavy binary black holes (BBHs) observed by LIGO/Virgo. Accurately estimating the merger rate of PBH binaries will be crucial to reconstruct the mass distribution of PBHs. It was pointed out the merger history of PBHs may shift the merger rate distribution depending on the mass function of PBHs. In this paper, we use 10 BBH events from LIGO/Virgo O1 and O2 observing runs to constrain the merger rate distribution of PBHs by taking into account the effect of merger history. We perform the analysis by explicitly considering two commonly used PBH mass functions: the power-law and the log-normal ones, respectively. It is found that the second merger process makes a subdominant contribution to the total merger rate, and hence the merger history effect can be safely neglected. We also confirm that the main components of dark matter should not be made of stellar-mass PBHs. [ABSTRACT FROM AUTHOR]

We study the core mass-halo mass relation of bosonic dark matter halos, in the form of self-gravitating Bose-Einstein condensates, harboring a supermassive black hole. We use the "velocity dispersion tracing" relation according to which the velocity dispersion in the core vc²~GMc/Rc is of the same order as the velocity dispersion in the halo vh²~GMh/rh (this relation can be justified from thermodynamical arguments) and the approximate analytical mass-radius relation of the quantum core in the presence of a central black hole obtained in our previous paper [P.H. Chavanis, Eur. Phys. J. Plus 134, 352 (2019)]. For a given minimum halo mass (Mh)min~108 M⊙ determined by the observations, the only free parameter of our model is the scattering length as of the bosons (their mass m is then determined in order to match the characteristics of the minimum halo). For noninteracting bosons and for bosons with a repulsive self-interaction, we find that the core mass Mc increases with the halo mass Mh and achieves a maximum value (Mc)max at some halo mass (Mh)∗ before decreasing. The whole series of equilibria is stable. For bosons with an attractive self-interaction, we find that the core mass achieves a maximum value (Mc)max at some halo mass (Mh)∗ before decreasing. The series of equilibria becomes unstable above a maximum halo mass (Mh)max≥(Mh)∗. In the absence of black hole (Mh)max=(Mh)∗. At that point, the quantum core (similar to a dilute axion star) collapses. We perform a similar study for fermionic dark matter halos. We find that they behave similarly to bosonic dark matter halos with a repulsive self-interaction, the Pauli exclusion principle for fermions playing the role of the repulsive self-interaction for bosons. [ABSTRACT FROM AUTHOR]

The recently proposed trans-Planckian censorship conjecture (TCC) imposes a strong constraint on the inflationary Hubble scale, of which the upper bound could be largely relaxed by considering a noninstantaneous reheating history. In this paper we will show that, if the primordial black holes (PBHs) are formed at reentry in the radiation-dominated era from the enhanced curvature perturbations at small scales, the TCC would impose a lower bound on the PBH mass MPBH>γ(Hend/109 GeV)² M⊙ regardless of the details for reheating history, where γ is the collapse efficiency factor and Hend is the Hubble scale at the end of inflation. In particular, the current open window for PBHs to make up all the cold dark matter could be totally ruled out if the inflationary Hubble scale is larger than 10 TeV. For the case of PBHs formed in an early matter-dominated era, an upper mass bound is obtained. [ABSTRACT FROM AUTHOR]

In this paper, we argue that one can calculate the weak deflection angle of light in the background of an Einstein-Maxwell-Dilaton-axion black hole using the Gauss-Bonnet theorem. To support this, the optical geometry of the black hole and the Gibbons-Werner method is used to obtain the deflection angle of light in the weak-field limits. Moreover, we investigate the effect of a plasma medium on the deflection of light for a given black hole. Because the dilaton and axion are candidates for dark matter, this can give us a hint about the observation of the dark matter that is supported by the black hole. Hence, we demonstrate the observational viability by showing the effect of dark matter on the weak deflection angle of light. [ABSTRACT FROM AUTHOR]

Analyzing nine years of Fermi-LAT observations, we recently studied the spectral properties of the prominent globular cluster [Phys. Rev. 98, 041301 (2018)]. In particular, we investigated several models to explain the observed gamma-ray emission, ranging from millisecond pulsars (MSPs) to dark matter (DM), with the motivation for the latter model driven by recent evidence that 47 Tuc harbors an intermediate-mass black hole [B. Kiziltan et al., Nature (London) 542, 203 (2017)]. This investigation found evidence that the observed gamma-ray emission from 47 Tuc is due to two source populations of MSPs and DM. In preceding Comment [Phys. Rev. D 100, 068301 (2019)], Bartels and Edwards comment that this evidence is an artifact of the MSP spectra used in our paper. Here, we reply to this comment and argue that (i) Bartels and Edwards do not give due consideration to a very important implication of their result and (ii) there is tension between our MSP fit and their MSP fit when taking uncertainties into consideration. As such, we still conclude there is evidence for a DM component which motivates a deeper radio study of the prominent globular cluster 47 Tuc. [ABSTRACT FROM AUTHOR]

In this paper we present a new black hole solution surrounded by dark matter (DM) halo in the galactic center using the mass model of M87 and that coming from the universal rotation curve (URC) dark matter profile representing family of spiral galaxies. In both cases the DM halo density is cored with a size r0 and a central density ρ0: ρ(r)=ρ0/(1+r/r0)(1+(r/r0)2). Since r0ρ0=120 M⊙/pc² [Mon. Not. R. Astron. Soc. 397, 1169 (2009)], then by varying the central density one can reproduce the DM profile in any spiral. Using the Newman-Jains method we extend our solution to obtain a rotating black hole surrounded by dark matter halo. We find that the apparent shape of the shadow beside the black hole spin a, it also depends on the central density of the surrounded dark matter ρ0. As a specific example we consider the galaxy M87, with a central density ρ0=6.9×106 M⊙/kpc³ and a core radius r0=91.2 kpc. In the case of M87, our analyses show that the effect of dark matter on the size of the black hole shadow is almost negligible compared to the shadow size of the Kerr vacuum solution hence the angular diameter 42 μas remains almost unaltered when the dark matter is considered. For a small totally dark matter dominated spiral such as UGC 7232, we find similar effect of dark matter on the shadow images compared to the M87. However, in specific conditions having a core radius comparable to the black hole mass and dark matter with very high density, we show that the shadow images decreases compared to the Kerr vacuum black hole. The effect of dark matter on the apparent shadow shape can shed some light in future observations as an indirect way to detect dark matter using the shadow images. [ABSTRACT FROM AUTHOR]

Dark matter (DM) which sufficiently heats a local region in a white dwarf will trigger runaway fusion, igniting a type Ia supernova (SN). In a companion paper [P. W. Graham et al., Phys. Rev. D 98, 115027 (2018)], this instability was used to constrain DM heavier than 1016 GeV which ignites SN through the violent interaction of one or two individual DM particles with the stellar medium. Here we study the ignition of supernovae by the formation and self-gravitational collapse of a DM core containing many DM particles. For nonannihilating DM, such a core collapse may lead to a mini black hole that can ignite SN through the emission of Hawking radiation, or possibly as a by-product of accretion. For annihilating DM, core collapse leads to an increasing annihilation rate and can ignite SN through a large number of rapid annihilations. These processes extend the previously derived constraints on DM to masses as low as 105 GeV. [ABSTRACT FROM AUTHOR]

Primordial black holes (PBHs) with a mass from 10-16 to 10-11 M⊙ may comprise 100% of dark matter. Due to a combination of wave and finite source size effects, the traditional microlensing of stars does not probe this mass range. In this paper, we point out that x-ray pulsars with higher photon energies and smaller source sizes are good candidate sources for microlensing for this mass window. Among the existing x-ray pulsars, the Small Magellanic Cloud (SMC) X-1 source is found to be the best candidate because of its apparent brightness and long distance from Earth. We have analyzed the existing observation data of SMC X-1 by the RXTE telescope (around 10 days) and found that PBH as 100% of dark matter is close to but not yet excluded. Future longer observation of this source by x-ray telescopes with larger effective areas such as AstroSat, Athena, Lynx, and eXTP can potentially close the last mass window where PBHs can make up all of dark matter. [ABSTRACT FROM AUTHOR]

For a variety of ongoing and planned gravitational-wave (GW) experiments, we study expected constraints on the fraction (fPBH) of primordial black holes (PBHs) in dark matter by evaluating the energy-density spectra of two kinds of stochastic GW backgrounds. The first one is produced from an incoherent superposition of GWs emitted from coalescences of all of the binary PBHs. The second one is induced through nonlinear mode couplings of large primordial curvature perturbations inevitably associated with the generation of PBHs in the early Universe. In this paper, we focus on PBHs with masses 10-8 M⊙≤MPBH<1 M⊙, since they are not expected to be of stellar origin. In almost all mass ranges, we show that the experiments are sensitive enough to constrain the fraction for 10-5≲fPBH≲1 by considering the GWs from coalescing events and 10-10≲fPBH≲1 by considering the GWs from curvature perturbations. Exceptionally, the fraction cannot be constrained for fPBH≲3×10-3 by these two GW backgrounds only in the narrow mass range 2×10-5 M⊙≲MPBH≲4×10-5 M⊙. [ABSTRACT FROM AUTHOR]

Recently the Experiment to Detect the Global Epoch of Reionization Signature reported the detection of a 21 cm absorption signal stronger than astrophysical expectations. In this paper we study the impact of radiation from dark matter (DM) decay and primordial black holes (PBHs) on the 21 cm radiation temperature in the reionization epoch, and impose a constraint on the decaying dark matter and PBH energy injection in the intergalactic medium, which can heat up neutral hydrogen gas and weaken the 21 cm absorption signal. We assume a strong coupling limit in the Lyman-α background and consider decay channels DM→e+e-,γγ, μ+μ-, τ+τ-, bb and the 1015-17 g mass range for primordial black holes, and require that the heating of the neutral hydrogen does not negate the 21 cm absorption signal. For e+e-, γγ final states and PBH cases we find strong 21 cm bounds that can be more stringent than the current extragalactic diffuse photon bounds. For the DM→e+e- channel, the lifetime bound is τDM>1027 s for sub-GeV dark matter. The bound is τDM≥1026 s for the sub-GeV DM→γγ channel and reaches 1027 s for MeV DM. For bb and μ+μ-cases, the 21 cm constraint is better than all the existing constraints for mDM<30 GeV where the bound on τDM≥1026 s. For both DM decay and primordial black hole cases, the 21 cm bounds significantly improve over the cosmic microwave background damping limits from Planck data. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel scenario which simultaneously explains O(10)M⊙ primordial black holes (PBHs) and dark matter in the minimally supersymmetric standard model. Gravitational waves (GWs) events detected by LIGO-Virgo collaboration suggest an existence of black holes as heavy as ∼30M⊙. In our scenario, as seeds of the PBHs, we make use of the baryon number perturbations which are induced by the special type of Affleck-Dine mechanism. Furthermore, the scenario does not suffer from the stringent constraints from CMB μ-distortion due to the Silk damping and pulsar timing. We find the scenario can explain not only the current GWs events consistently, but also dark matter abundance by the nontopological solitons formed after Affleck-Dine mechanism, called Q-balls. [ABSTRACT FROM AUTHOR]

A primordial black hole (PBH) is one of the leading nonparticle candidates for dark matter (DM). Although several observations severely constrain the amount of PBHs, it was recently pointed out that there is an uncertainty on the microlensing constraints below ~ 10-10 M⊙, which was ignored originally but may weaken the constraints significantly. In this paper, facing this uncertainty, we investigate the possibility that PBHs can make up all DM in a broad mass spectrum. Moreover, we propose a concrete inflation model that can simultaneously produce PBHs for all DM in a broad mass spectrum around O (10-13) M⊙ and PBHs for LIGO events in a sharp mass spectrum at O(10)M⊙. [ABSTRACT FROM AUTHOR]

Primordial black holes (PBHs) have long been a candidate for the elusive dark matter (DM), and remain poorly constrained in the ∼20-100 M⊙ mass range. PBH binaries were recently suggested as the possible source of LIGO's first detections. In this paper, we thoroughly revisit existing estimates of the merger rate of PBH binaries. We compute the probability distribution of orbital parameters for PBH binaries formed in the early Universe, accounting for tidal torquing by all other PBHs, as well as standard large-scale adiabatic perturbations. We then check whether the orbital parameters of PBH binaries formed in the early Universe can be significantly affected between formation and merger. Our analytic estimates indicate that the tidal field of halos and interactions with other PBHs, as well as dynamical friction by unbound standard DM particles, do not do significant work on nor torque PBH binaries. We estimate the torque due to baryon accretion to be much weaker than previous calculations, albeit possibly large enough to significantly affect the eccentricity of typical PBH binaries. We also revisit the PBH-binary merger rate resulting from gravitational capture in present-day halos, accounting for Poisson fluctuations. If binaries formed in the early Universe survive to the present time, as suggested by our analytic estimates, they dominate the total PBH merger rate. Moreover, this merger rate would be orders of magnitude larger than LIGO's current upper limits if PBHs make a significant fraction of the dark matter. As a consequence, LIGO would constrain ∼10-300 M⊙ PBHs to constitute no more than ∼1% of the dark matter. To make this conclusion fully robust, though, numerical study of several complex astrophysical processes--such as the formation of the first PBH halos and how they may affect PBH binaries, as well as the accretion of gas onto an extremely eccentric binary--is needed. [ABSTRACT FROM AUTHOR]

LIGO-Virgo collaboration has found black holes as heavy as M∼30M⊙ through the detections of the gravitational waves emitted during their mergers. Primordial black holes (PBHs) produced by inflation could be an origin of such BHs. While it is tempting to presume that these PBHs constitute all dark matter (DM), there exist a number of constraints for PBHs with Ϭ(10)M⊙ which contradict with the idea of PBHs as all DM. Also, it is known that weakly interacting massive particle (WIMP) that is a common DM candidate is almost impossible to coexist with PBHs. These observations motivate us to pursue another candidate of DM. In this paper, we assume that the string axion solving the strong CP problem makes up all DM, and discuss the coexistence of string axion DM and inflationary PBHs for LIGO events. [ABSTRACT FROM AUTHOR]