Primordial Black Holes (PBHs) might have formed in the early Universe due to the collapse of density fluctuations. PBHs may act as the sources for some of the gravitational waves recently observed. We explored the formation scenarios of PBHs of stellar mass, taking into account the possible influence of the QCD phase transition, for which we considered three different models: Crossover Model (CM), Bag Model (BM), and Lattice Fit Model (LFM). For the fluctuations, we considered a running-tilt power-law spectrum; when these cross the $\sim 10^{-9}$-$10^{-1}\mathrm{~s}$ Universe horizon they originate 0.05-500~M$_{\odot}$ PBHs which could: i) provide a population of stellar mass PBHs similar to the ones present on the binaries associated with all known gravitational wave sources; ii) constitute a broad mass spectrum accounting for $\sim 76\%$ of all Cold Dark Matter (CDM) in the Universe.
The nature of dark matter (DM) is unknown. One compelling possibility is DM being composed of primordial black holes (PBHs), given the tight limits on some types of elementary particles as DM. There is only one remaining window of masses available for PBHs to constitute the entire DM density, $10^{17} - 10^{23} \mathrm{\; g}$. Here, we show that the kernel population in the cold Kuiper belt rules out this window, arguing in favor of a particle nature for DM.
Primordial nucleosynthesis is rightly hailed as one of the great successes of the standard cosmological model. Here we consider the initial forging of elements in the recently proposed Rh = ct universe, a cosmology that demands linear evolution of the scale factor. Such a universe cools extremely slowly compared to standard cosmologies, considerably depleting the available neutrons during nucleosynthesis; this has significant implications for the resultant primordial abundances of elements, predicting a minuscule quantity of helium which is profoundly at odds with observations. The production …
Trapped inflation has been proposed to provide a successful inflation with a steep potential. We discuss the formation of primordial black holes in the trapped inflationary scenario. We show that primordial black holes are naturally produced during inflation with a steep trapping potential. In particular, we have given a recipe for an inflaton potential with which particle production can induce large non-Gaussian curvature perturbation that leads to the formation of high stellar-mass primordial black holes. These primordial black holes could be dark matter observed by the LIGO detectors throug…
The possibility that primordial black hole binary mergers of stellar mass can explain the signals detected by the gravitational-wave interferometers has attracted much attention. In this scenario, primordial black holes can comprise only part of the entire dark matter, say, of order 0.1 %. This implies that most of the dark matter is accounted for by a different component, such as Weakly Interacting Massive Particles. We point out that in this situation, very compact dark matter minihalos, composed of the dominant component of the dark matter, are likely to be formed abundantly in the early Un…
In this Paper we consider a problem of formation and evolution of orbital parameters of a binary primordial black hole (PBH) due to gravitational interaction with clustering cold dark matter (CDM). Mass and initial separation have values, which are appropriate for the problem of explanation of the LIGO/Virgo events by coalescing binary PBHs. We consider both radiation dominated and CDM dominated stages of the evolution using numerical and semi-analytical means. We show that at the end time of our numerical simulations binary's semimajor axis decreases by approximately one hundred times, while …
We performed a series of high-resolution $N$-body simulations to examine whether dark matter candidates in the form of primordial black holes (PBHs) can solve the cusp-core problem in low-mass dwarf galaxies. If some fraction of the dark matter in low-mass dwarf galaxies consists of PBHs and the rest is cold dark matter, dynamical heating of the cold dark matter by the PBHs induces a cusp-to-core transition in the total dark matter profile. The mechanism works for PBHs in the 25-100 M$_{\sun}$ mass window, consistent with the LIGO detections, but requires a lower limit on the PBH mass fraction…
We show that primordial black holes can be produced from the collapse of large isocurvature perturbations of the cold dark matter. We develop a novel procedure to compute the resulting black hole abundance by studying matched perturbations of matter-only universes, and we use our procedure to translate observational constraints on black hole abundances into model-independent constraints on cold dark matter isocurvature perturbations over a wide range of scales. The constraint on the typical amplitude of the primordial perturbations weakens slightly slower than linearly on small scales.
Dark matter coupled solely gravitationally can be produced through the decay of primordial black holes in the early universe. If the dark matter is lighter than the initial black hole temperature, it could be warm enough to be subject to structure formation constraints. In this paper we perform a more precise determination of these constraints. We first evaluate the dark matter phase-space distribution, without relying on the instantaneous decay approximation. We then interface this phase-space distribution with the Boltzmann code CLASS to extract the corresponding matter power spectrum, which…
In this paper we show that to explain the observed distribution of amplitudes in a large sample of quasar lightcurves, a significant contribution from microlensing is required. This implies the existence of a cosmologically distributed population of stellar mass compact bodies making up a large fraction of the dark matter. Our analysis is based on the lightcurves of a sample of over 1000 quasars, photometrically monitored over a period of 26 years. The intrinsic variations in quasar luminosity are derived from luminous quasars where the quasar accretion disc is too large to be microlensed by s…
We study the effects of cold dark matter on the propagation of gravitational waves of astrophysical and primordial origin. We show that the dominant effect of cold dark matter on gravitational waves from astrophysical sources is a small frequency dependent modification of the propagation speed of gravitational waves. However, the magnitude of the effect is too small to be detected in the near future. We furthermore show that the spectrum of primordial gravitational waves in principle contains detailed information about the properties of dark matter. However, depending on the wavelength, the ef…
Non-Cold Dark Matter from Memory-Burdened Primordial Black Holes
Universitäts-Sternwarte, Ludwig-Maximilians-Universität München（慕尼黑大学天文台）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Excellence Cluster ORIGINS（ORIGINS卓越集群）；Theoretische Natuurkunde & The International Solvay Institutes, Vrije Universiteit Brussel（布鲁塞尔自由大学理论物理与国际索尔维研究所）；Max-Planck-Institut für Physik（马克斯·普朗克物理研究所）；Arnold Sommerfeld Center, Ludwig-Maximilians-Universität（慕尼黑大学阿诺德·索末菲中心）；Fakultät Physik, Technische Universität Dortmund（多特蒙德工业大学物理学院）
We study prospects of constraining the primordial magnetic field (PMF) and its evolution during the dark ages and cosmic dawn in light of EDGES 21-cm signal. Our analysis has been carried out on a `colder IGM' background which is one of the promising avenues to interpret the EDGES signal. We consider the dark matter-baryon interactions for the excess cooling. We find that the colder IGM suppresses both the residual free electron fraction and the coupling coefficient between the ionised and neutral components. The Compton heating also gets affected in colder IGM background. Consequently, the IG…
We put forward a novel class of exotic celestial objects that can be produced through phase transitions occurred in the primordial Universe. These objects appear as bubbles of stellar sizes and can be dominated by primordial black holes (PBHs). We report that, due to the processes of Hawking radiation and binary evolution of PBHs inside these stellar bubbles, both electromagnetic and gravitational radiations can be emitted that are featured on the gamma-ray spectra and stochastic gravitational waves (GWs). Our results reveal that, depending on the mass distribution, the exotic stellar bubbles …
Primordial black holes (PBHs) could provide the dark matter but a variety of constraints restrict the possible mass windows to $10^{16} - 10^{17}$g, $10^{20} - 10^{24}$g and $10 - 10^3M_{\odot}$. The last possibility is of special interest in view of the recent detection of black-hole mergers by LIGO. PBHs larger than $10^3 M_{\odot}$ might have important cosmological consequences even if they have only a small fraction of the dark matter density. In particular, they could generate cosmological structures either individually through the "seed" effect or collectively through the "Poisson" effec…
Primordial black holes in the asteroid-mass window ($\sim 10^{-16}$ to $10^{-11} \rm M_{\odot}$), which might constitute all the dark matter, can be captured by stars when they traverse them at low enough velocity. After being placed on a bound orbit during star formation, they can repeatedly cross the star if the orbit happens to be highly eccentric, slow down by dynamical friction and end up in the stellar core. The rate of these captures is highest in halos of high dark matter density and low velocity dispersion, when the first stars form at redshift $z \sim 20$. We compute this capture rat…
There has recently been interest in multi-Solar mass Primordial Black Holes (PBHs) as a dark matter (DM) candidate. There are various microlensing, dynamical and accretion constraints on the abundance of PBHs in this mass range. Taken at face value these constraints exclude multi-Solar mass PBHs making up all of the DM for both delta-function and extended mass functions. However the stellar microlensing event rate depends on the density and velocity distribution of the compact objects along the line of sight to the Magellanic Clouds. We study the dependence of the constraints on the local dark…
We investigate the formation and growth of massive black hole (BH) seeds in dusty star-forming galaxies, relying and extending the framework proposed by Boco et al. 2020. Specifically, the latter envisages the migration of stellar compact remnants (neutron stars and stellar-mass black holes) via gaseous dynamical friction towards the galaxy nuclear region, and their subsequent merging to grow a massive central BH seed. In this paper we add two relevant ingredients: (i) we include primordial BHs, that could constitute a fraction $f_{\rm pBH}$ of the dark matter, as an additional component parti…
Two gravitational wave events, i.e. GW200105 and GW200115, were observed by the Advanced LIGO and Virgo detectors recently. In this work, we show that they can be explained by a scenario of primordial black hole binaries that are formed in the early Universe. The merger rate predicted by such a scenario could be consistent with the one estimated from LIGO and Virgo, even if primordial black holes constitute a fraction of cold dark matter. The required abundance of primordial black holes is compatible with the existing upper limits from microlensing, caustic crossing and cosmic microwave backgr…
Combining constraints from microlensing and Lyman-$α$ forest, we provide a simple argument to show that large spatial clustering of stellar-mass primordial black holes at the time of formation, such as the one induced by the presence of large non-Gaussianities, is ruled out. Therefore, it is not possible to evade existing constraints preventing stellar-mass primordial black holes to be a dominant constituent of the dark matter by boosting their initial clustering.
The possible existence of primordial black holes in the stellar mass window has received considerable attention because their mergers may contribute to current and future gravitational-wave detections. Primordial black hole mergers, together with mergers of black holes originating from Population~III stars, are expected to dominate at high redshifts ($z\gtrsim 10$). However the primordial black hole merger rate density is expected to rise monotonically with redshift, while Population~III mergers can only occur after the birth of the first stars. Next-generation gravitational-wave detectors suc…
We adapted the Appleby-Battye-Starobinsky model of $F(R)$ gravity towards describing double cosmological inflation and formation of primordial black holes with masses up to $10^{19}$ g in the single-field model. We found that it is possible to get an enhancement of the power spectrum of scalar curvature perturbations to the level beyond the Hawking (black hole evaporation) limit of $10^{15}$ g, so that the primordial black holes resulting from gravitational collapse of those large primordial perturbations can survive in the present universe and form part of cold dark matter. Our results agree …
We recently showed that postulated ultracompact minihalos with a steep density profile do not form in realistic simulations with enhanced initial perturbations. In this paper we assume that a small fraction of the dark matter consists of primordial black holes (PBHs) and simulate the formation of structures around them. We find that in this scenario halos with steep density profiles do form, consistent with theoretical predictions. If the rest of the dark matter consists of weakly interacting massive particles (WIMPs), we also show that WIMPs in the dense innermost part of these halos would an…
We discuss early structure formation of small scales sourced by primordial black holes (PBHs) which constitute a small part of present cold dark matter component. We calculate the mass function and power spectrum of haloes originated from the Poisson fluctuations of PBH number and show that the number of small haloes is significantly modified in the presence of PBHs even if their fraction accounts for only $10^{-4}$--$10^{-3}$ of total dark matter abundance. We then compute the subsequent 21cm signature from those haloes. We find that PBHs can provide major contributions at high redshifts with…
We explore the warm inflation scenario theoretical predictions looking at two different dissipative regimes for several representative primordial potentials. As it is well known, the warm inflation is able to decrease the tensor-to-scalar ratio value, rehabilitating several primordial potential ruled out in the cold inflation context by the recent cosmic microwave background data. Here we show that it is also able to produce a running of the running $n_s"$ positive and within the Planck data limits. This is very remarkable since the standard cold inflation model is unable to justify the curren…
Testing primordial non-Gaussianities on galactic scales at high redshift
原始非高斯性提供了暴胀模型的一个重要检验。虽然普朗克宇宙微波背景实验对星系团尺度上的非高斯性产生了很强的限制，但在星系尺度上仍有相当大的非高斯性空间。我们已经测试了本地的非高斯高红移星系人口的影响，运行5个宇宙学N体模拟到z=6.5。对于这些模拟，我们采用相同的初始相位，以及高斯或尺度相关的非高斯原始波动，所有这些都与普朗克对集群尺度的约束一致。然后，我们使用Behroozi et al.（2013）的晕-恒星质量经验关系为每个晕分配恒星质量。我们的模拟与非高斯初始条件产生晕质量函数，显示出明显的偏离从类似的模拟与高斯初始条件在z>~10。我们观察到一个>0.3 dex的增强低端的晕质量函数，这导致了类似的影响星系恒星质量函数，这应该是测试未来的星系调查在z>10。由于宇宙再电离被认为是由高红移的矮星系驱动的，我们的发现可能对宇宙的再电离历史有影响。
As one of the prime contributors to the interstellar medium energy budget, magnetic fields naturally play a part in shaping the evolution of galaxies. Galactic magnetic fields can originate from strong primordial magnetic fields provided these latter remain below current observational upper limits. To understand how such magnetic fields would affect the global morphological and dynamical properties of galaxies, we use a suite of high-resolution constrained transport magneto-hydrodynamic cosmological zoom simulations where we vary the initial magnetic field strength and configuration along with…
We propose an extension of the scalaron-Higgs model by a non-minimal coupling of the Standard Model Higgs boson to the quadratic Ricci scalar resulting in a Higgs-dependent scalaron mass. The model predicts a successful stage of effective single-field Starobinsky inflation. It features a multi-field amplification mechanism leading to a peak in the inflationary power spectrum at small wavelengths which enhances the production of primordial black holes. The extended scalaron-Higgs model unifies inflationary cosmology with elementary particle physics and explains the origin of cold dark matter in…
