NEHOP'25 - New Horizons in Primordial Black Hole Physics

Session

PBHs from inflation & other formation scenarios

19 May 2025, 14:00

Brussels

35. The unexpected shape of the primordial black hole mass function

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...

41. Primordial correlators from Multi-point propagators

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.
In this talk, I will present a novel numerical implementation of the transport...

45. Scalar fields and primordial black holes

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.

49. Primordial black hole formation in a slow-reheating scenario

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....

56. Primordial Black Hole Formation in a Scalar Field Dominated Universe

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...

57. Making PBHs in a Early Matter Dominated Era

Melissa Diamond

19/05/2025, 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...

48. Harvesting primordial black holes from stochastic trees

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...

59. Slaying Axion-Like Particles via Gravitational Waves and Primordial Black Holes from Supercooled Phase Transition

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...

96. Discussion

19/05/2025, 17:10

61. Primordial black hole formation from a massless scalar field

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...