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Dark matter and black holes

1–5 Dec 2025
Kavli IPMU
Asia/Tokyo timezone

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Contribution List

36 / 36
204. Conservative Thoughts on Black Holes
Surjeet Rajendran
01/12/2025, 10:00
205. The Origin of Supermassive Black Holes from Pop III.1 Seeds and Implications for Particle Physics and Cosmology
Jonathan Tan
01/12/2025, 10:30

The origin of supermassive black holes (SMBHs) is a key open question for contemporary astrophysics and cosmology. Here we discuss the predictions of a model of SMBH formation from Pop III.1 protostars, i.e., metal-free stars forming in locally isolated dark matter minihalos, where dark matter annihilation has a chance to alter the structure of the star allowing growth to supermassive scales...
206. Searches for dark sector particles at Belle and Belle II
Sourav Dey
01/12/2025, 11:20

I will give an update on important and recent results on dark sector particle searches at Belle and Belle II
207. Finding Macroscopic Dark Matter
Zachary Picker
01/12/2025, 11:40
208. Fermionic freeze-in from flavon portal
Nandini Das
01/12/2025, 12:00

We investigate the phenomenology of a non-thermal dark matter (DM) candidate in the context of flavor models that explain the hierarchy in the masses and mixings of quarks and leptons via the Froggatt-Nielsen (FN) mechanism. A flavor-dependent U(1)FN symmetry explains the fermion mass and mixing hierarchy, and also provides a mechanism for suppressed interactions of the DM, assumed to be a...
210. Verifying primordial black holes as dark matter by mergers, evaporation, and occasionally the memory burden effect
Kazunori Kohri
01/12/2025, 14:30

I will discuss methods for verifying primordial black holes to be dark
matter in terms of mergers, evaporation, and occasionally the memory
burden effect
211. Bosonic dark matter dynamics in neutron stars
Deep Ghosh
01/12/2025, 15:30

Excessive dark matter (DM) capture in neutron star (NS) via DM-nucleon scattering, leads to transmutation of NS into solar mass black hole. The formation of such black hole depends on the thermal properties of captured DM particles, particularly if DM particles are bosons. In this work, we study the capture of bosonic particle and subsequent dynamics inside the star, taking the NS temperature...
212. A Dark Matter Probe in Accreting Pulsar–Black Hole Binaries
Ali Akil
01/12/2025, 15:50

The accretion of dark matter (DM) into astrophysical black holes slowly increases their mass. The rate of this mass accretion depends on the DM model and the model parameters. If this mass accretion effect can be measured accurately enough, it is possible to rule out some DM models, and, with the sufficient technology and the help of other DM constraints, possibly confirm one model. We propose...
213. Dark matter spikes with strongly self-interacting particles
Takashi Toma
01/12/2025, 16:10

An unavoidable prediction of scenarios with Dark Matter (DM) self-interactions is the existence of number changing processes that convert $n$ initial DM particles into $m$ final ones ($n\to m$ processes), possibly accompanied by Standard Model particles. We argue that the $n\rightarrow m$ processes could be probed in DM spikes at the center of galaxies, where the high density may allow sizable...
214. Supermassive Stars: evading (temporarily!) the inevitable with Dark Matter
George Fuller
02/12/2025, 10:00
215. Dark Matter and the Formation of Direct Collapse Supermassive Black Holes
Yifan Lu
02/12/2025, 10:30

The surprising abundance and properties of supermassive black holes (SMBHs) observed at high redshifts have opened a new window into the interplay between cosmology and dark matter physics. While explaining how SMBHs are assembled within the first few hundred million years after the Big Bang remains a major challenge, an attractive route is the direct collapse of pristine, metal-free gas...
216. 20 GeV halo-like gamma-ray excess: dark matter annihilation?
Tomonori Totani
02/12/2025, 11:20

Fifteen years of the Fermi Large Area Telescope (LAT) data in the halo region of the Milky Way (MW) are analyzed to search for gamma rays from dark matter annihilation. Gamma-ray maps within the region of interest (|l| < 60 deg, 10 < |b| < 60 deg) are modeled using point sources, the GALPROP models of cosmic-ray interactions, isotropic background, and templates of Loop I and the Fermi bubbles,...
218. Vacuum relics in ultra-slow-roll inflation
Albert Escrivà
02/12/2025, 11:50

We study the formation of vacuum bubbles in ultra-slow-roll inflation. Our results show that these bubbles play a significant role in the dynamics of the system and provide an important contribution to the primordial black hole population, potentially accounting for a substantial fraction of dark matter.
219. LVK O4a Constraints on Primordial Black Holes
Sachiko Kuroyanagi
02/12/2025, 14:00

I will review various methods for constraining primordial black holes through gravitational wave observations and discuss the latest results from the O4a run of the LIGO-Virgo-KAGRA collaboration.
220. Planck relics as dark matter
Stefano Profumo
02/12/2025, 14:30

I will survey scenarios that produce Planck-mass relics and assess whether they can stably carry electric, magnetic, or dark charge. I’ll examine charge retention and neutralization in the late Universe (including Schwinger discharge and plasma capture), and highlight quantum-gravity effects near extremality—especially for magnetically charged and near-extremal black holes. Finally, I’ll...
221. Exotic defect dynamics in axion cosmology
Yu Komiya
02/12/2025, 15:30

We investigate an early history in which topological defects are dynamical within an axion cosmology post-inflation, motivated by the increasing popularity of models predicting primordial black holes formed of defects contributing to present-day dark matter content. We highlight the capabilities of the axionic context, and identify unique features pertaining to the interactions between defects...
222. PBHs and Dark Matter Regurgitation from First Order Phase Transitions
Philip Lu
02/12/2025, 15:50

First order phase transitions can create a large mass gap between the false and true vacua for dark sector particles, effectively trapping them in false vacuum pockets. After an initial contraction phase, these particles coalesce into semi-stable compact objects, thermal balls and Fermi balls. Further cooling of these objects leads to a final collapse into primordial black holes. We show how...
223. BSM-enhanced PBH Dark Matter
Xavier Pritchard
02/12/2025, 16:10

In this talk I will give an overview of several beyond Standard model theories predicting a large number of additional degrees of freedom. The corresponding softening in equations of state can be significant. I will show that, within these models, it is then possible to achieve a large enhancement in PBH abundance on scales relevant for PBHDM; namely, the asteroid mass and memory burden windows.
224. The role of dark matter in the origin and dynamical evolution of massive black binaries towards the LISA band
Lucio Mayer
04/12/2025, 10:00

The typical binaries of massive black holes that the LISA gravitational wave detector will observe
are in the range 10^4-10^6 solar masses. In the low redshift Universe, observations of active
galactic nuclei and other types of sources suggest that such black holes preferentially reside
in dwarf galaxies. Dwarf galaxies are notoriously dark matter dominated down to their cores. I...
225. TBA
John Silverman
04/12/2025, 10:30
226. Primordial Black Hole formation from power spectrum with finite width
Jianing Wang
04/12/2025, 11:20

Primordial black holes (PBHs) can form from gravitational collapse of large over-
densities in the early Universe, giving rise to rich phenomena in astrophysics and cosmology. We develop a novel, general, and systematic method based on theory of density contrast peaks to calculate the abundance of PBHs for a broad power spectrum of curvature perturbations with Gaussian statistics. We...
227. When Tiny Halos Stir Spacetime: Gravitational Waves from the Fifth Forces
Xinpeng Wang
04/12/2025, 11:40

Dark matter fermions interacting via attractive fifth forces mediated by a light mediator can form dark matter halos in the very early Universe. Motivated by the scenario, we discovered that the bound systems composed of such halos, even very light, are capable of generating Gravitational Wave (GW) signals detectable today.
Due to the additional strong force that contributes to the...
228. Exploring Ultra-Slow-Roll Inflation in Composite Pseudo-Nambu–Goldstone Boson Models: Implications for Primordial Black Holes and Gravitational Waves
Marco Merchand Medina
04/12/2025, 12:00

We study inflation driven by a scalar potential arising from composite-sector dynamics, inspired by generalized composite Higgs models. The introduction of a non-minimal coupling, possessing the same functional form as the potential, induces a flattening at large field values that enables successful inflation. We analyze the conditions for ultra-slow-roll inflation, which leads to enhanced...
229. Evaporating black holes: how the burden of their memory stabilizes them
Michael Zantedeschi
04/12/2025, 14:00

The memory burden effect describes how an object's stored information resists its own decay. This mechanism is especially pronounced in saturons—systems that saturate unitarity bounds on entropy—with black holes providing the prime example. I will show how memory burden can halt Hawking evaporation and dynamically stabilize black holes against complete decay. Crucially, this phenomenon is not...
230. Seeding Supermassive Black Holes from the Dark Sector
Haibo Yu
04/12/2025, 14:30

I will present a novel mechanism for forming supermassive black holes through dark matter dynamics. In the self-interacting dark matter framework, halos can undergo gravothermal collapse, producing black hole seeds that subsequently grow via baryonic Eddington and dark Bondi accretion. This process can naturally account for the massive black holes observed at high redshift, including the JWST...
232. Primordial black holes from inflation and their observational imprints (online)
Rajeev Kumar Jain
04/12/2025, 15:30

Primordial black holes (PBH) have recently emerged as a very interesting candidate for the cold dark matter in the universe. We study their generation in a single field inflationary model with an inflection point potential and found that PBHs can be produced in our scenario in the asteroid-mass window with a nearly monochromatic mass fraction, accounting for the total dark matter in the...
231. The trichotomy of PBH initial conditions
Laia Montellà
04/12/2025, 15:50

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 maximum, as earlier thought, but also by the three-dimensional curvature at smaller (but super-horizon) scales, which we call "the core". We find three classes of initial...
233. Primordial black hole formation from the merger of oscillons
Naoya Kitajima
04/12/2025, 16:10

We show that the merger of oscillons results in a broad spectrum of the oscillon mass. A huge number of oscillon samples obtained from numerical lattice simulations reveal that the oscillon mass distribution has an exponential tail in a heavy-mass region. This enables us to infer the fractional abundance of heavy oscillons. Using the criterion for the primordial black hole (PBH) formation from...
234. Observational search of PBH
Masahiro Takada, Sunao Sugiyama
05/12/2025, 10:00

Gravitational microlensing is a powerful probe of PBHs, and I will give a review of the microlensing searches for PBHs.Gravitational microlensing is a powerful probe of PBHs, and I will give a review on the microlensing search of PBH
235. Discovery of a Little Red Dot candidate at z ~ 10
Takumi Tanaka
05/12/2025, 11:20

Deep IR observations by JWST have discovered a new population of high-redshift compact objects known as "little red dots" (LRDs) with a characteristic V-shape SED. Based on the detection of broad Balmer emission lines, previous studies suggested that LRDs are low-luminosity AGNs, possibly linked to super-Eddington accretion shortly after seed BH formation. In this study, we propose a new color...
236. Neutrino signals from Dark Stars seeding SMBHs
Thomas Schwemberger
05/12/2025, 11:40

Dark Stars (DS), powered by dark matter annihilation may form in the place of Pop. III stars. They can grow to $\gtrsim 10^5~M_\odot$ and collapse to black holes making them excellent candidates to seed supermassive black holes. We establish first constraints on DSs as SMBH progenitors based on DM annihilations using data from Super-Kamiokande and IceCube neutrino experiments, while remaining...
237. Revisiting the merger rate of primordial black holes
Shunsuke Neda
05/12/2025, 12:00

The merger rate of binary black holes inferred by the LIGO-Virgo-KAGRA (LVK) collaboration is potentially compatible with primordial black holes (PBHs). Reexamining the latest merger rate calculations for Poisson-distributed PBHs, we find that they did not fully implement the binary formation conditions required for PBH pairs to decouple from the Hubble flow. Once these conditions are properly...
238. Sub-GeV dark matter detection around SMBH.
Shigeki Matsumoto
05/12/2025, 14:00
239. TBA
Shunsaku Horiuchi
05/12/2025, 14:30
217. Microlensing of Black Hole shadow
Priyanka Sarmah
209. TBA
George Fuller
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