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David Wands19/05/2025, 09:20
Stochastic inflation offers a non-perturbative framework with which to calculate the distribution of density perturbations and in particular large, but rare fluctuations in the non-Gaussian tail of the distribution that could give rise to primordial black holes. Strongly enhanced density perturbations from single-field inflation require deviations from slow roll, and there are a number of...
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Alejandro Perez Rodriguez (Universidad Autonoma de Madrid)19/05/2025, 09:50
The probability of large primordial scalar perturbations (leading to primordial black hole formation and the concurrent GW backgrounds) is sensitive to the tail of the PDF of primordial curvature perturbations. We analyse such tails in inflationary models featuring an ultra slow-roll phase, known to enhance both the amplitude and non-Gaussianity of curvature perturbations at small scales. We...
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Syksy Räsänen19/05/2025, 10:10
I will discuss how to calculate the PBH abundance and mass distribution starting from the inflationary potential, taking into account stochastic effects and using the compaction function. We determine the radial profiles directly from stochastic calculation, and do not assume Gaussianity. I will outline progress and how to address the remaining open issues.
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Dr Laura Iacconi (Queen Mary University of London)19/05/2025, 11:00
Both single- and multi-field models of inflation might lead to enhanced scalar fluctuations on scales much smaller than those seeding the large-scale structure formation. In these scenarios, it is possible that the spike of power at high wavenumber might induce large corrections to the scalar power spectrum, e.g. in the form of loop corrections, potentially endangering the perturbativity of...
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Angelo Caravano19/05/2025, 11:20
Violating the slow-roll regime in the final stages of inflation can significantly enhance curvature perturbations, a scenario often invoked in models producing primordial black holes and small-scale scalar-induced gravitational waves. In this regime, tree-level computations may become insufficient, and nonlinear corrections can play a crucial role. In this talk, I will discuss how lattice...
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Eemeli Tomberg (UCLouvain)19/05/2025, 11:40
Inflationary models with an inflection point potential may produce a significant abundance of primordial black holes. I show that in typical models, inflation is eternal near the inflection point, that is, the volume of the inflating region diverges at late times. The inflating space then has a fractal structure, with eternal inflation taking place inside type II black holes. I discuss the...
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Parth Bhargava (ICG, Portsmouth)19/05/2025, 12:00
Quantum fluctuations during inflation in the very early universe inevitably generate inhomogeneities and anisotropies across all observable scales and beyond. In the stochastic approach to modeling inflationary dynamics, these quantum fluctuations are incorporated as stochastic noise. We employ the formalism of stochastic inflation to examine the role of quantum diffusion during inflation....
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Jacopo Fumagalli (ICCUB - Barcelona)19/05/2025, 14:00
We show that a broad power spectrum—modeled as a plateau between infrared and ultraviolet scales—results in a bimodal mass function, with the dominant peak corresponding to heavy PBHs associated with the infrared scale.
This result, based on compaction function statistics, significantly impacts overproduction bounds on the power spectrum amplitude, underscores the need for further...
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Andrea Costantini (Queen Mary University of London)19/05/2025, 14:20
Accurate predictions of correlators of the primordial curvature perturbation are critical for connecting inflationary models to cosmological observations. Numerical methods employing differential equations, such as the transport approach, have been extensively used to compute the evolution of these correlators.
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In this talk, I will present a novel numerical implementation of the transport... -
Xavier Pritchard (University of Sussex)19/05/2025, 14:40
In this talk I will discuss scalar fields in cosmology. Specifically, the impact they can have on early universe thermodynamics and primordial black holes.
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Luis Enrique Padilla Albores (Queen Mary University of London)19/05/2025, 15:00
In scalar field dark matter models, virialized halos form condensed central cores known as solitons. We extend this idea to the reheating phase of the early universe, a critical period that sets the stage for the emergence of structure after inflation. We study the formation of primordial black holes (PBHs) from the gravitational collapse of virialized configurations arising during this era....
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Ethan Milligan (QMUL)19/05/2025, 15:50
We present a numerical code that solves the Misner-Sharp system for a spherically symmetric cosmological model containing both a scalar field and a perfect fluid. While the code is capable of exploring general scenarios involving an minimally coupled scalar field and perfect fluid, we focus on the regime where the scalar field dominates the dynamics, particularly in the post-inflationary...
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Melissa Diamond19/05/2025, 16:10
I present a novel mechanism for creating primordial black holes. A heavy dissipative dark sector can come to dominate the universe, creating an early matter dominated era prior to Big Bang Nucleosynthesis (BBN). At this time the dark matter can form halos which persist after the phase transition back to radiation domination, and slowly collapse at late times. This leads to the late time...
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Chiara Animali (UCLouvain)19/05/2025, 16:30
I will present a novel framework for implementing stochastic inflation on stochastic trees, modelling the inflationary expansion as a branching process. The statistical properties of the curvature perturbation and other cosmological fields are encoded within the tree structure in a manner that fully captures quantum diffusion and its non-perturbative backreaction during inflation. Stochastic...
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Anish Ghoshal (University of Warsaw, Poland)19/05/2025, 16:50
We study the formation of primordial black holes (PBHs) from density fluctuations due to supercooled phase transitions (PTs) triggered in an axion-like particle (ALP) model. We find that the mass of the PBHs is inversely correlated with the ALP decay constant fa. For instance, for fa varying from (100 MeV) to (1012 GeV), the PBH mass varies between (103−10−24)M⊙. We then identify the ALP...
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19/05/2025, 17:10
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Florian Kühnel20/05/2025, 09:20
In the first part of my talk, I will discuss how recent advances in our understanding of quantum effects in black holes impact PBHs. On the one hand, this concerns deviations from Hawking radiation in the form of the memory-burden effect. On the other hand, I will discuss vorticity, which we recently conjectured to be a new characteristic of (near-extremally rotating) black holes. In the...
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Mr Nayan Das (Indian Institute of Technology Guwahati)20/05/2025, 09:40
We discuss the possibility of producing the observed baryon asymmetry of the Universe (BAU) and dark matter (DM) from evaporating primordial black holes (PBH) incorporating semi-classical and memory burden regime. In the simplest scenario of baryogenesis via vanilla leptogenesis with hierarchical right handed neutrino (RHN), it is possible to generate the observed BAU with PBH being sole...
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Andrea Boccia (Scuola Superiore Meridionale)20/05/2025, 10:00
In this talk I will address how “memory-burdened” primordial black holes (PBHs) of low mass, evaporating today, could in principle be detected via their neutrino emission.
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Using the latest IceCube data, we place novel constraints on the combined parameter space of PBH masses and memory burden effects. Additionally, we explore whether the ultra-high-energy neutrino event recently detected by... -
Sebastian Zell (LMU Munich)20/05/2025, 10:20
Mounting theoretical evidence suggests that the information stored in black holes suppresses their decay rate. This effect of memory burden opens up a new window for small primordial black holes (PBHs) below $10^{15}\,{\rm g}$ as dark matter candidates. In this talk, I show that the smooth transition from semi-classical evaporation to the memory-burdened phase strongly impacts observational...
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Marco Chianese (Scuola Superiore Meridionale)20/05/2025, 11:10
We explore the impact of the back-reaction of evaporation on the quantum state of Primordial Black Holes (PBHs), known as “memory burden”, on the baryon asymmetry production in the Universe through high-scale leptogenesis. Focusing on PBH masses ranging from 1 to 1000 grams, we investigate the interplay between the non-thermal production of heavy sterile neutrinos and the entropy injection...
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Dr Marco Calza (University of Trento)20/05/2025, 11:30
We introduce and describe $\tt GrayHawk$, a publicly available Mathematica-based tool designed for the efficient computation of gray-body factors for spherically symmetric and asymptotically flat black holes. This program provides users with a rapid and reliable means to compute gray-body factors for massless fields with spin (s = 0, 1/2, 1, 2) in modes specified by the angular quantum...
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Lucien Heurtier (King's College London)20/05/2025, 11:50
In this talk, I will give a general overview of how the thermal plasma behaves around evaporating, light, primordial black holes, and the effect this evolution can have on the Hawking radiation emitted by such black holes. In particular, I will present several particle physics frameworks in which the presence of a temperature gradient around evaporating black holes can have important...
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Clelia Altomonte (King's College London)20/05/2025, 12:10
Upon their evaporation via Hawking radiation, primordial black holes (PBHs) may deposit energy in the ambient plasma on scales smaller than the typical distance between two black holes, leading to the formation of hot spots around them.
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In this talk (based on the recent work https://arxiv.org/pdf/2501.05531), I will consider how the corresponding rise of the local temperature during the... -
Michael Hawkins (University of Edinburgh)20/05/2025, 14:00
In the last few years the case that primordial black holes make up a significant fraction of the dark matter has received steadily increasing support from a wide variety of observations. If indeed this is the case then there are a number of observational consequences to be expected. In this talk I shall describe situations where such a population of compact bodies should betray their...
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Francesca Scarcella (IFCA)20/05/2025, 14:20
Understanding the evolution of primordial black hole (PBH) populations across cosmic history is critical for reconciling observational data with theoretical formation models. Previous studies showed that gas accretion can significantly alter the mass and spin distributions of PBH binaries from their formation time to the low-redshift universe where gravitational wave signals are observed....
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Dominic Agius (IFIC, University of Valencia)20/05/2025, 14:40
The 21cm signal, soon to be probed by upcoming experiments, is a powerful late-time cosmological tool for constraining Primordial Black Holes (PBHs). Some of the most stringent limits on PBH abundance in the solar mass range are derived using 21cm forecasts. In this talk, I will critically re-examine these forecasts, highlighting the impact of astrophysical uncertainties on the derived...
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Mr Nicolas Esser20/05/2025, 15:00
Primordial black holes (PBHs) in the asteroid-mass range remain a viable and until now unconstrained dark matter (DM) candidate. If
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such PBHs exist, they could be captured by stars in DM-dominated environments with low velocity dispersion such as ultra-faint dwarf
galaxies (UFDs). The capture probability increases with the stellar mass, and captured PBHs would rapidly destroy their host... -
Valentin Thoss (Ludwig-Maximilians-Universität München)20/05/2025, 15:50
If primordial black holes (PBHs) of asteroidal mass make up the entire dark matter, they could be detectable through their gravitational influence in the solar system. In this work, we study the perturbations that PBHs induce on the orbits of planets. Detailed numerical simulations of the solar system, embedded in a halo of PBHs, are performed. We find that the gravitational effect of the PBHs...
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Lorenzo Stefanuto (University of Turin)20/05/2025, 16:10
In this talk, we present our study of the cosmic antiproton and antideuteron fluxes produced by the evaporation of galactic primordial black holes (PBHs) with lognormal initial mass distributions. The antimatter production spectra were obtained using our modified version of the BlackHawk code, which incorporates the new CosmiXs hadronization spectra and a state‐of‐the‐art Wigner function...
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Davide Perrone (Universite de Geneve (CH))20/05/2025, 16:30
Quasi-normal modes are a crucial feature of black holes and their study is fundamental to understanding these objects. These excitations are not only linear but it has been shown to have a relevant non-linear counterpart, in general difficult to calculate.
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The Penrose limit connects a plane wave geometry to the photon ring of a black hole, where the quasi-normal modes are located in the... -
Quim Iguaz Juan (UMass Amherst)20/05/2025, 16:50
Observation of an exploding black hole would provide the first direct evidence of primordial black holes, of Hawking radiation, and provide definitive information on the particle spectrum of nature. However, indirect constraints suggest that direct observation of an exploding Schwarzschild black hole is implausible. We introduce a dark-QED toy model consisting of a dark photon and a heavy...
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20/05/2025, 17:10
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Bernard Carr (Queen Mary University of London)21/05/2025, 09:00
If most of the dark matter comprises primordial black holes (PBHs), then numerous constraints imply that they must be in either the asteroidal or solar mass range. Although the first possibility arises naturally if the PBHs formed at the QCD transition, it is sometimes claimed that this possibility is excluded by microlensing surveys and the frequency of gravitational-wave events. However,...
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Theodoros Papanikolaou21/05/2025, 09:30
In this talk, we propose a novel and natural mechanism of cosmic acceleration driven by primordial black holes (PBHs) with repulsive-like interiors. Using a new ``Swiss Cheese'' cosmological approach we show that this cosmic acceleration is quite general by examining three regular black hole spacetimes, namely the Hayward, the Bardeen and the Dymnikova ones as well as the de...
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Daniele Perri (Warsaw University)21/05/2025, 09:50
Very little is known about the universe’s history from after the end of inflation until the Big Bang nucleosynthesis (BBN), which spans more than $10^{39}$ orders of magnitude in time scales. In this work, we show that if there was a long period of matter domination in this unknown period, and if the particle causing the matter domination has moderate self-interactions, the matter particles...
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Joao Rosa (University of Coimbra)21/05/2025, 10:10
I discuss the production of bosonic dark matter by light primordial black holes via superradiance, alongside Hawking emission. In particular, I will show that the resulting dark matter clouds may, under certain conditions, survive as self-gravitating (microscopic) boson stars after the black holes evaporate completely (before BBN). I will also discuss some of the potential implications of this...
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Houri Ziaeepour21/05/2025, 11:00
SU(∞)-QGR is a recently developed foundationally quantum model of
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cosmology and gravity (reviewed in arXiv:2409.08932). It treats the Universe as an isolated quantum system having an infinite number of mutually commuting observables. Quantum fluctuations locally fragment the SU(∞) group representing Hilbert space of the Universe to approximately isolated subsystems representing G x SU(∞),... -
Samuel Young (University of Sussex)21/05/2025, 11:20
Primordial black holes (PBHs) are a compelling dark matter candidate, with their gravitational interactions shaping the evolution of cosmic structure from the earliest times. In this talk, I will present results from our recent fully-collisional simulations of PBH structure formation and binary evolution. We find that the dynamic interactions between PBHs introduce significant feedback...
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Baptiste Blachier (UCLouvain (CURL) and LPENS)21/05/2025, 11:40
By extending the so-called excursion-set formalism - often used in the context of Dark Matter halos formation - to two-point statistics, we revisit the initial spatial clustering of Primordial Black Holes (PBHs) originating from the Hubble reentry of large Gaussian density fluctuations in the early Universe. Our work propose a way to correlate the formation of pairs of PBHs, revealing features...
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Marco Manno (University of Salento)21/05/2025, 12:00
Light Primordial Black Holes (LPBHs) with masses in the range $10$ g $\leq M_{\rm BH} \leq 10^9$ g, although they evaporate before Big Bang Nucleosynthesis, can play a significant role in the production of both Dark Matter and Dark Radiation. In particular, LPBHs can evaporate into light axions or axion-like particles (ALPs) with masses $m_a \lesssim$ MeV, contributing to the effective number...
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Itziar Aldecoa Tamayo (Sussex University)21/05/2025, 12:20
Motivated by many interesting features present in braneworld cosmology and higher-dimensional gravity, we have reexamined foundational concepts and processes that have previously been studied, such as gravitational collapse, black hole accretion and Hawking emission. In this talk we delve into the phenomenological signatures characteristic of this framework and consider the possibility of the...
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Juan Garcia-Bellido21/05/2025, 14:00
I will review the formation of PBH clusters due to large exponential tails in the curvature perturbation distribution and study the strong non-linear dynamics of PBH in clusters, which produce PBH binaries that could have been detected via their GW emission in LVK.
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Antonio Junior Iovino (New York University Abu Dhabi)21/05/2025, 14:30
Primordial Black Holes (PBHs) are fascinating astrophysical objects that could provide valuable insights into the early universe, cosmology, and gravitational physics.
The standard formation scenario assumes that PBHs originate from the gravitational collapse of large curvature fluctuations generated during inflation. These same large scalar fluctuations, which can lead to PBH formation...
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Andrew Miller21/05/2025, 14:50
Gravitational waves from sub-solar mass inspiraling compact objects would provide almost smoking-gun evidence for primordial black holes (PBHs). We perform the first search for inspiraling planetary-mass compact objects in equal-mass and highly asymmetric mass-ratio binaries using data from the first half of the LIGO-Virgo-KAGRA third observing run. Though we do not find any significant...
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Andrea Ianniccari (University of Geneva)21/05/2025, 15:10
The physics of Primordial Black Holes has garnered significant interest in recent years, largely due to the numerous detections of gravitational
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waves originating from BH binary mergers and the hypothesis that some of
these may be of primordial origin.
We show that in realistic models where primordial black holes are formed due to the collapse of sizeable inflationary perturbations, their... -
Anjali Abirami Kugarajh (Gran Sasso Science Institute)21/05/2025, 16:00
The detection of gravitational waves (GWs) from binary black hole mergers has opened an exciting new avenue for cosmological research. Because GWs interact very weakly with matter, there is potential to observe primordial GWs among the signals captured by current and future detectors. This provides a unique opportunity to probe the early universe physics. Primordial GWs are typically generated...
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Benjamin Gladwyn (University of Oxford (GB))21/05/2025, 16:20
Mounting evidence suggests that the semi-classical description of a black hole breaks down at the latest after losing an~$O(1)$ fraction of its mass. As a result, effects such as memory burden can slow down evaporation so that small primordial black holes (PBHs), in particular those in the mass range~$10^{6}\, \text{g}$ to~$10^{9}\, \text{g}$, become viable dark matter candidates. I will...
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21/05/2025, 16:40
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Mrs Gabriele Franciolini22/05/2025, 09:00
Primordial black holes (PBHs) can form in the early universe and represent an intriguing dark matter candidate as well as a unique probe of the physics governing the early universe. Focusing on subsolar mass PBHs, we will discuss avenues to constrain their abundance with gravitational waves (GWs). These include i) direct searches for mergers using LIGO/Virgo/Kagra detectors; and ii) indirect...
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Ameek Malhotra22/05/2025, 09:30
The formation of primordial black holes (PBHs) from amplified density fluctuations in the early universe may also generate scalar-induced gravitational waves (GW), carrying vital information about the primordial power spectrum and the universe's expansion history. We present a Bayesian approach to reconstruct both the scalar power spectrum and the equation of state from GW observations, using...
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Simon Biot (ULB)22/05/2025, 09:50
The dynamics of early primordial black hole (PBH) binaries with an extended mass distribution are investigated. Specifically, we examine the perturbations and disruptions from the low-mass background population induced by such mass functions. Using dedicated Monte-Carlo simulations, new calculations of the so-called merger rate suppression factors are presented. Our results suggest that the...
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Frans van Die (Technion)22/05/2025, 10:10
The discovery of subsolar mass black holes would provide compelling evidence
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for the primordial origin of these objects. In this talk, I explore
how gravitational wave (GW) signals from a Galactic population of (sub)solar
mass primordial black hole (PBH) binaries could be identified by LISA (arXiv:
2410.04522). By modeling the formation and evolution of PBH binaries that
end up in the... -
Jan Tränkle (ITP Leibniz University Hanover)22/05/2025, 11:00
Although there is substantial observational evidence for an
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early period of exponential expansion of the Universe, known as
inflation, followed by a subsequent era of radiation domination, the
intermediate period connecting these two epochs, referred to as
reheating, remains challenging to constrain. In this talk, I will
present the primordial black hole (PBH) reheating scenario,... -
Ao Wang (Institute of Theoretical Physics，Chinese Academy of Sciences; Institute for Theoretical Physics, Leibniz University Hannover)22/05/2025, 11:20
Primordial black holes (PBHs) serve as a compelling candidate for dark matter and a potential probe of early universe physics. One promising avenue for constraining their abundance is through the stochastic gravitational wave background (SGWB) induced by primordial curvature perturbations. In this talk, I will present how current and future gravitational wave observatories—including Pulsar...
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22/05/2025, 11:40
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Satyabrata Datta (Nanjing Normal University)
Blue-tilted Gravitational Waves (BGWs) have emerged as a promising candidate for explaining the cosmic gravitational wave signals observed by Pulsar Timing Arrays (PTA). Within the standard cosmological model, the frequency range of BGWs is restricted by the Big Bang Nucleosynthesis (BBN) limit on gravitational wave amplitude, which prevents their detection at interferometer scales. However,...
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Federico De Lillo (Universiteit Antwerpen)
Primordial black holes (PBHs) are possible sources of a gravitational-wave background (GWB), detectable with LISA and the next observing runs of LIGO--Virgo--KAGRA. In case of a detection, it will be crucial to distinguish the possible sources of this GWB. One possibility is to exploit the duty cycle that quantifies the number of sources present in the time domain signal, which can be very...
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Ilia Musco
We have investigated primordial black holes formation within a model of the early Universe dominated by a massless scalar field, developing a numerical spherically symmetric code dedicated to this problem. Imposing initial conditions on super horizon scales using the gradient expansion approach, we show that a massless scalar filed is equivalent to a perfect fluid, where the pressure is equal...
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