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15/06/2026, 09:00
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Stefano Profumo15/06/2026, 09:15
Primordial black holes, if produced in the early Universe, may not evaporate completely but instead leave behind stable or long-lived Planck-mass remnants, or "Planck-tons". I review theoretical arguments for such relics from quantum gravity frameworks, including generalized uncertainty principles, loop quantum gravity, and string-theoretic corrections, which suggest a breakdown of...
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Gia Dvali15/06/2026, 10:00
We discuss the Memory Burden Effect in black holes and its observational implications. The essence of this universal phenomenon is that the information load carried by a black hole influences its macroscopic dynamics. This influence is quantified by a new macroscopic characteristics of a black hole in form of the memory burden parameter which measures the ``weight" of its information load....
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Giuseppe Filiberto Vitale15/06/2026, 11:30
We study the coupled cosmological evolution of primordial black holes (PBHs) and radiation in the Arkani-Hamed-Dimopoulos-Dvali (ADD) framework with $n$ large extra dimensions and a fundamental gravity scale $M_\star$ at the TeV scale. For PBHs with horizon radius smaller than the compactification scale, the higher-dimensional geometry implies a larger horizon size at fixed mass and therefore...
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Paola Simone15/06/2026, 11:45
Hawking radiation from primordial black holes provides a unique link between particle physics and black hole physics. In this work, we investigate the phenomenology of black hole evaporation, focusing on photon and neutrino signals produced through secondary emission processes. Particular attention is given to potential signatures arising in Beyond Standard Model scenarios, such as...
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Jae Hyeok Chang (Seoul National University)15/06/2026, 12:00
The Hawking radiation of photons from primordial black holes can be detected in future gamma-ray telescopes if PBHs constitute even a small fraction of dark matter. PBHs can likewise radiate new particles, which is particularly interesting when these particles are largely secluded from the Standard Model sector and would otherwise be difficult to access. In this talk, I will describe how such...
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yeji park (IBS-CTPU-PTC)15/06/2026, 12:15
Primordial black holes (PBHs) have been emitting particles through Hawking radiation since the early universe, and the resulting spectra encode the imprint of their mass distribution. Because realistic PBH formation naturally yields extended mass functions, we develop a learned mapping between the mass function and the photon spectrum in both directions. The conventional forward chain is slow,...
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Kazunori Kohri15/06/2026, 14:00
I am going to provide a comprehensive overview of
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observational constraints on primordial black holes. If time permits,
I will discuss the following hot topics; PBHs as seeds of SMBHs, the BBN
bound, MeV gamma-rays, formations in the early matter-dominated era,
cosmological accretions, hot spot formations, and the Poltergeist
mechanism. -
Jinn-Ouk Gong (Asia Pacific Centerfor Theoretical Physics)15/06/2026, 14:45
We formulate reheating as a constrained variational problem in the space of equation-of-state histories, rather than attempting to describe it through microscopic models. We introduce a regularized functional framework that identifies reheating histories which extremize a given cosmological observable under minimal physical assumptions. As illustrative applications, we consider prompt...
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Cheng Cheng (Center for Physical Sciences and Technology (FTMC))15/06/2026, 16:15
The early universe may have experienced a kination epoch - a phase where a scalar field's kinetic energy dominates the expansion. In this talk, I will outline how scalar-field inhomogeneities during this era can trigger strong non-linear dynamics, and how these can collapse to form primordial black holes(PBHs). Based on numerical relativity simulations, I will show the conditions under which...
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Luis Padilla (Rikkyo University)15/06/2026, 16:30
In this talk, I will discuss how primordial black holes can form in non-standard stages of the early Universe dominated by scalar fields. I will focus on three representative scenarios: slow reheating with a quadratic potential, a quartic scalar field, and a massless scalar field.
The main goal is to understand when scalar fields can be effectively described as perfect fluids during...
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HAYAMI IIZUKA (Rikkyo University)15/06/2026, 16:45
We develop a formulation of nonlinear cosmological perturbations on superhorizon scales in multi-fluid systems. It is based on the Arnowitt–Deser–Misner formalism combined with a spatial gradient expansion, characterized by a small parameter $\epsilon \equiv k/(a^{(b)}H)$, where $a(t)$ is the scale factor of the flat Friedmann-Lemaître-Robertson-Walker spacetime, ${}^{(b)}H(t)$ is the...
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Laia Montellà (ICCUB)15/06/2026, 17:00
We show that the threshold to form a black hole, in an asymptotically flat and radiation-dominated Friedman-Robertson-Walker (FRW) Universe, is not solely (mainly) determined by the behaviour of the compaction function at its extrema, as earlier thought, but also by the Ricci scalar of the spatial geometry at smaller (but super-horizon) scales, which we call "the core". We introduce three...
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Przemek Mróz16/06/2026, 09:15
The field of gravitational microlensing has been closely linked, since its inception, to the search for compact objects (including primordial black holes) as candidates for dark matter. The seminal idea by Bohdan Paczyński to use microlensing as a probe of dark matter launched a field that continues to deliver cutting-edge scientific results.
Microlensing is particularly sensitive to...
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Dr Boyuan Liu (Center for Astronomy of Heidelberg University)16/06/2026, 10:00
Primordial black holes (PBHs) have long been considered a promising candidate for or an important component of dark matter. Recent gravitational wave observations of binary black hole (BH) mergers and discoveries at the high-redshift Universe made by JWST have triggered renewed interest in PBHs in the stellar-mass ($\sim10-100\ \rm M_\odot$) and supermassive regimes ($\sim 10^6 − 10^{11}\rm...
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Prof. João Rafael Lucio dos Santos (UFCG, Leibniz University and University of Heidelberg)16/06/2026, 11:30
The Fast Radio Bursts (FRBs) are some of the most intriguing radio phenomena measured in radio astronomy \cite{lorimer}. These energetic bursts have extremely high radio luminosities, corresponding to $\sim 10^{36} \,–\, 10^{44}$ $\mathrm{erg \,s}^{-1}$, which is not far from gamma ray bursts. Since their discovery in 2007, several investigations have been proposed to model their sources and...
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Théo Paré (LUPM)16/06/2026, 11:45
We explore the gravitational heating of exoplanetary systems by dark matter substructures of different kinds (primordial black holes -- PBHs, ultra-compact -- UCMHs, or classical subhalos). In this context, the scales of the dark objects probed are of the same order as the orbital radii of planets of interest. Distant exoplanets are quite sensitive to heating processes because less bound to...
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Agnese Tolino (IFIC (CSIC-UV))16/06/2026, 12:00
Density spikes are steep enhancements in the dark matter (DM) distribution that arise from gravitational infall onto a central compact object. In the standard scenario where DM consists of particles, such spikes may form around a sub-dominant population of massive primordial black holes (PBHs), potentially leading to large enhancements of the DM density in their vicinity.
The situation can...
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Francescopaolo Lopez16/06/2026, 12:15
Very little is known about the reheating phase after inflation, which is only constrained to end before Big Bang Nucleosynthesis, at a temperature higher than O(1) MeV. We show that this effectively matter dominated phase can be long enough that structures, such as halos, can form, inflaton stars can condense inside the halos and eventually grow to collapse into PBH. By employing PBH...
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Chulmoon Yoo16/06/2026, 14:00
In this talk, we will begin by briefly reviewing the research conducted so far on the formation of primordial black holes during the matter-dominated era. Then we introduce more details of the analytical investigation on the formation dynamics, particularly focusing on the effect of inhomogeneity and ellipticity. Finally, we will report recent results obtained from the attempts on numerical...
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Eemeli Tomberg (UCLouvain)16/06/2026, 14:45
Stochastic inflation allows us to study large inflationary perturbations that may collapse into primordial black holes. I discuss the spectral decomposition of the perturbation distribution in stochastic inflation near a local maximum of the inflaton potential, relevant for primordial black hole production from inflection point models. I compare the stochastic computation with results from...
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Yoann Launay16/06/2026, 15:00
In this talk, I will review our recent work and its attempt to extend the scope and predictive power of the stochastic formalism for inflation. After briefly introducing the specificity of our stochastic coarse-graining procedure, I will discuss our formulation of stochastic dynamics in full General Relativity, including all metric and scalar matter degrees of freedom, as well as gradient...
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Alejandro Perez Rodriguez (University of Washington)16/06/2026, 15:15
Computing the abundance of primordial black holes from inflation requires dealing with large, non-Gaussian primordial quantum fluctuations. Recently, progress has been made in computing the statistics of such perturbations using classical or semiclassical techniques, like lattice calculations. One may question, however, the reliability of these methods to capture the underlying quantum...
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Benjamin Charles Gladwyn (University of Oxford (GB))16/06/2026, 15:30
Large inflationary perturbations are a leading mechanism for primordial black hole (PBH) formation. Lattice simulations have been proposed as a route beyond perturbation theory, but their reliability has not been systematically established. In this talk, we demonstrate that certain implementations can produce significantly incorrect PBH abundances and identify the key sources of these...
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Baptiste Blachier16/06/2026, 15:45
In the excursion-set formalism, various quantities are derived
from the first-passage time of a random walk describing the density contrast as the coarse-graining scale varies. In the context of Primordial Black Holes (PBHs) formation, I will show that different choices of hypersurfaces for the sampling of the theory affect the nature of the random walk.Using a synchronous sampling, the...
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Alba Romero Rodríguez17/06/2026, 09:15
The formation of primordial black holes from large-amplitude primordial curvature perturbations is expected to be accompanied by a stochastic background of scalar-induced gravitational waves. In this talk, I will present the latest constraints on the integrated power of the curvature power spectrum peak associated with such a background, derived using data from the O4a observing run of the...
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Sokratis Trifinopoulos (University of Zurich (CH))17/06/2026, 10:00
Primordial black holes (PBHs) offer a particularly rich window onto the early Universe: the same large primordial curvature perturbations that collapse to form PBHs also generate a stochastic background of scalar-induced gravitational waves (SIGWs), while the PBHs themselves can later form binaries and merge, producing gravitational-wave signals in complementary frequency bands. In this talk,...
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Simon Biot (ULB)17/06/2026, 11:30
This talk focuses on the dynamics of early primordial black hole binaries with a broad mass distribution. We highlight the subtleties that arise when calculating merger rates for these distributions and propose a framework to account for some of them. While the quest for a definitive rate remains ongoing, we provide critical insights into how mass-function variance impacts theoretical...
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Xinpeng Wang (Kavli IPMU, University of Tokyo)17/06/2026, 11:45
Dark matter fermions interacting through an attractive force mediated by a light scalar can form bound structures already in the very early universe. We show that binaries composed of such dark matter halos can generate gravitational wave (GW) signals observable today, even when the individual halos are extremely light. Because the dark Yukawa interaction, which is much stronger than gravity,...
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Jan Tränkle17/06/2026, 12:00
In the standard formation picture, primordial black holes (PBHs) form in the radiation-dominated early Universe from the collapse of enhanced curvature perturbations. However, the reheating period connecting inflation to the radiation epoch is poorly constrained, as is the inflaton potential below CMB scales. Observational constraints are therefore consistent with the Universe having undergone...
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Nicholas Leister17/06/2026, 12:15
We investigate the scalar-induced gravitational wave (SIGW) signal originating from the evaporation of primordial black holes (PBHs). In the idealized monochromatic mass scenario, a pronounced SIGW signal arises via the so-called poltergeist mechanism, triggered by a sharp transition from matter to radiation domination. However, more realistic extended mass distributions—such as those...
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Christian Byrnes (University of Sussex)17/06/2026, 14:00
While black holes can be the remnants of stellar collapse, some may have formed in the early universe - making them primordial black holes (PBHs). These would form a relic from the early universe, preserving a memory of the initial conditions of the universe at early times and on small scales. PBHs do not require the introduction of new fundamental physics, making them a special dark matter...
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Marco Calza (University of Trento)17/06/2026, 16:15
We enlarged the capabilities of the publicly available Mathematica-based tool $\tt GrayHawk$. This second version enlarges the spectrum of metrics that can be considered in two distinct and disjoined directions. First, it allows a fully numeric computation of tortoise coordinates integral, allowing the user to take into account many metrics for which the analytic computation was impractical....
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Prof. Bum-Hoon Lee (Sogang University)17/06/2026, 16:30
Primordial black hole (PBH) formation is a manifestation of critical phenomena in gravitational collapse, where near the threshold the black hole mass exhibits a universal scaling behavior. The Einstein–Dilaton–Gauss–Bonnet (EdGB) gravity is the simplest extension of the Einstein Gravity with the higher curvature by introducing the Gauss-Bonnet term without any ghost states. The...
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Suruj Jyoti Das (Institute for Basic Science, CTPU)17/06/2026, 16:45
We study the cosmological implications of stable hairy black hole solutions by spontaneous symmetry breaking (SSB) in Einstein-scalar-Gauss-Bonnet theory. For such solutions and the SSB potential to be consistent with the cosmological history, we find that the compact objects that develop scalar hair might be in the primordial black hole mass range. We estimate the evolution of such PBH in the...
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Joao Rosa (University of Coimbra)17/06/2026, 17:00
We show that a late period of warm inflation, denoted as lukewarm inflation and sustaining a slowly-varying temperature parametrically below the GUT scale, naturally leads to an enhanced and nearly scale-invariant curvature perturbation power spectrum at small scales. We compute the resulting spectrum of primordial black holes and scalar-induced gravitational waves, which depend on the...
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Ms Wenzer Qin (New York University)18/06/2026, 09:15
In this talk, I will discuss a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead to collapsed dark matter halos at very early times. For halos forming prior to 1+z ~ 200, the Cosmic Microwave Background (CMB) is...
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Parth Bhargava (Institute of Cosmology and Gravitation (ICG), Portsmouth)18/06/2026, 10:00
Quantum fluctuations during cosmic inflation inevitably generate inhomogeneities and anisotropies on all observable scales and beyond. The $\delta N$ formalism provides a powerful framework to describe the nonlinear curvature perturbation in terms of fluctuations in the duration of inflation, $N$. In its standard implementation, $\delta N$ is calculated using the classical trajectory to find...
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Koki Tokeshi18/06/2026, 10:15
The excursion-set formalism enables us to infer the mass distribution of collapsed objects, such as primordial black holes (PBHs), by the language of stochastic processes. Within the framework, it is investigated how the resulting PBH mass function is affected by a smooth coarse-graining procedure, for which the stochastic noise becomes fully correlated across scales. It is found that these...
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Marco de Cesare (Scuola Superiore Meridionale)18/06/2026, 10:30
I will discuss the scattering problem for a massless scalar field in a Schwarzschild-de Sitter black hole background and its possible implications for primordial black holes. A rigorous application of the method of matched asymptotic expansions allows us to solve analytically the low-frequency s-wave dynamics, and connect the scalar’s evolution in the proximity of the black-hole horizon with...
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Piotr Toczek (University of Warsaw)18/06/2026, 11:30
Black holes in the asteroid-mass range, $10^{15}$ - $10^{20}$ kg, provide a compelling candidate for dark matter. This window remains largely unconstrained observationally, while the low masses provide an interesting challenge in explaining their possible origin. In this talk, I will discuss a particular formation scenario of such objects, where curvature perturbations responsible for...
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Philipp Schicho (University of Geneva)18/06/2026, 11:45
Strongly supercooled first-order phase transitions have been proposed as a primordial black hole (PBH) production mechanism, but existing estimates rely on simplified thermodynamics. Reliable PBH predictions require precise nucleation dynamics within realistic, classically conformal extensions of the Standard Model.
In this talk, I employ high-temperature dimensional reduction and one-loop...
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Michael Zantedeschi18/06/2026, 12:00
The memory burden effect describes how an object's stored information resists its own decay. I will show how this mechanism can halt Hawking evaporation and dynamically stabilize black holes against complete decay. Importantly, the phenomenon is not exclusive to gravity: it can arise in generic quantum many-body systems and renormalizable field theories, underscoring its broader theoretical...
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Dr Sten Delos (Carnegie Observatories)18/06/2026, 14:00
Primordial black holes (PBHs) reshape how cosmic structure forms. I will trace how a PBH population's discreteness, dynamics, and formation history each leave their mark. Being discrete and massive, PBHs carry Poisson fluctuations that seed excess small-scale power and accelerate early structure growth. But PBHs also interact gravitationally with one another, and I will present the first...
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Prof. Theodoros Papanikolaou (University of Patras, Greece)18/06/2026, 14:45
We show that Schwarzschild primordial black holes (PBHs) formed in the radiation-dominated era can grow extremely rapidly through \textit{radiative absorption} governed by the full Stefan--Boltzmann law. Notably, we find that whenever the temperature of the PBH environment is larger than the PBH horizon temperature, PBHs generically gain mass. In particular, by accounting for radiative...
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Philip Lu (KIAS)18/06/2026, 15:00
I will present the PBH reformation mechanism, wherein light PBHs can recollapse into heavier and more stable PBHs. Given a moderate initial abundance, light PBHs can initiate an early matter-dominated era before evaporating and reheating the radiation plasma. Structure formation is enabled during matter-domination, leading to clouds of PBHs growing and collapsing into heavier PBHs. Compared to...
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Mr Jingxu Wu (M.V.Lomonosov Moscow State University)18/06/2026, 15:15
Primordial black holes (PBHs) serve as a compelling and natural dark-matter candidate, originating from the nonlinear collapse of overdense regions in the early Universe without requiring extensions to the Standard Model. During their cosmic evolution, PBH binaries are expected to accrete surrounding dark matter, forming extremely dense minihalos or ``spikes.'' These environments exert...
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Dr Mohammed Riajul Haque (Tsung Dao Lee Institute, Shanghai Jiao Tong University)18/06/2026, 15:30
The Hubble parameter, $H_0$, remains a cornerstone of modern cosmology, yet its precise determination continues to be challenged by the persistent tension between early- and late-Universe measurements. In this talk, I investigate the potential of multi-band gravitational-wave (GW) observations to provide an independent and complementary probe of $H_0$ using primordial black holes (PBHs) as...
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Yann GOUTTENOIRE (Institute of Astrophysics of Paris)19/06/2026, 09:15
I will present the 13 channels of gravitational wave production which are at play when the universe is reheated from the evaporation of a population of primordial black holes dominating the energy density of the universe
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Jitumani Kalita (Indian Institute of Technology, Guwahati)19/06/2026, 10:00
We investigate the impact of a finite temperature environment on the Hawking radiation from black holes (BHs), immersed in a cosmological thermal bath. The emitted particles from BHs interact with the thermal background and thermalize, leading to a modification in the Hawking radiation spectrum. By employing the methods of Thermofield Dynamics (TFD), a real time formalism of thermal quantum...
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Dr Jong-Hyun Yoon (Chungnam National University)19/06/2026, 10:15
Evaporating primordial black holes heat the surrounding plasma via Hawking radiation, forming localized hotspots whose temperature may far exceed that of the cosmological background. Previous studies of hotspot formation and cooling have treated the subsequent energy transport in flat spacetime, thereby neglecting the expansion of the Universe. We formulate the diffusion equation governing the...
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Andrea Boccia (Scuola Superiore Meridionale)19/06/2026, 10:30
We investigate how the formation of primordial black holes (PBHs) in the early Universe can be enhanced by a temporary softening of the equation of state, caused by heavy particles becoming non-relativistic. As a concrete example, we consider the Minimal Supersymmetric Standard Model (MSSM) and compute the resulting equation of state for different realizations of its mass spectrum.
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Assuming a... -
Ahmad Elsayed Moursy (Cairo University)19/06/2026, 10:45
Stochastic Gravitational Wave Backgrounds (SGWBs) can arise from a variety of cosmological and astrophysical sources. In this work, we explore several well-motivated scenarios within Grand Unified Theories (GUTs) that can generate a SGWB, where an inflationary phase is required to ensure consistency with current observational constraints. The resulting gravitational wave signals can explain...
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19/06/2026, 12:30
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Charchit Kumar Sethi (International Center for Theoretical Physics, Asia Pacific (ICTP-AP))
Primordial black holes (PBHs) are compelling dark matter (DM) candidates; however, current observational constraints indicate that they cannot account for the entirety of the DM abundance. This motivates scenarios in which additional DM components coexist with PBHs and form dense structures, often referred to as ``dark dresses,'' around them. Such environments induce dynamical friction,...
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Chulmoon Yoo
In this talk, we will begin by briefly reviewing the research conducted so far on the formation of primordial black holes during the matter-dominated era. Then we introduce more details of the analytical investigation on the formation dynamics, particularly focusing on the effect of inhomogeneity and ellipticity. Finally, we will report recent results obtained from the attempts on numerical...
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Mr Ashu Kushwaha
The abundance and mass function of primordial black holes (PBHs) are often estimated using the Press-Schechter (PS) formalism. In the case of halo formation, the PS formalism suffers from the miscounting of regions collapsing into halos, known as the cloud-in-cloud problem, which is usually corrected by introducing a multiplicative `fudge factor 2'. By analogy, this factor has sometimes been...
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Wenzer Qin (New York University)
In this talk, I will discuss a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead to collapsed dark matter halos at very early times. For halos forming prior to 1+z ~ 200, the Cosmic Microwave Background (CMB) is...
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Anne Green
Primordial Black Holes (PBHs), black holes formed from over-densities in the early Universe, have become a popular dark matter candidate. I will overview the current status of i) mechanisms for their formation in the early Universe, and ii) observational probes of their abundance.
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Nilanjandev Baumik (International Center for Theoretical Physics Asia-Pacific, Beijing)
Primordial black holes (PBHs) serve as key probes of the early Universe and cosmic evolution. In this study, we explore the formation of PBHs near the QCD phase transition, driven by a broadly peaked inflationary scalar power spectrum. This mechanism naturally results in an extended PBH mass distribution. Consequently, it generates two distinct stochastic gravitational wave backgrounds...
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