Stochastic Tsunamis: Diffuse Scalar Background from Black Hole Formation ✛ ✦
Context
Ultralight scalar fields are promising candidates for dark matter, the search for which began after the observations of Vera Rubin. However, their detection faces challenges: local density may be low, or the field may be clumped in distant structures. If the field exists but makes up only a small fraction of dark matter, background methods based on accumulating signals from many astrophysical events become a key alternative search channel. Unlike individual transient signals, the diffuse background does not require a rare 'lucky' event near Earth and avoids wave-packet dispersion thanks to the expansion of the universe.
Methods
The researchers modeled the energy spectrum of radiation from a single collapse using two types of initial field profiles: Yukawa (long-range) and compact (confined within the source up to 20 Schwarzschild radii). The field evolution was described by the Klein–Gordon equation in flat spacetime with corrections for the remnant's gravity. Then, using Edwin Hubble's discovery and the Hubble law within Friedmann cosmology, the contribution from all core-collapse supernovae over cosmic history was integrated, accounting for redshift of frequencies. The star formation rate, initial mass function, and stellar evolution models were taken from modern data, while uncertainties from progenitor metallicity were accounted for through systematic variation.
Results
The main result is the predicted stochastic background, peaking in the acoustic frequency range of 1–1000 Hz. For the Yukawa profile, the signal could be detected by future atom interferometers like MAGIS-km and AEDGE, at coupling levels already permitted by the MICROSCOPE experiment. Detector sensitivity was assessed by translating constraints on dark matter: the broadband signal yields a signal-to-noise advantage due to simultaneous analysis of many frequency bins, equivalent to a sensitivity reduction of only √Q times (~1000) compared to a monochromatic search. The background appears nearly independent of the field mass up to m_ϕ ~ $10^{-13}$ eV, surpassing the masses accessible by single-transient searches by 10 orders of magnitude.
Implications
The proposed mechanism opens a new window for searching for ultralight scalar fields, especially in scenarios where they do not dominate dark matter. It also marks the first use of a stochastic background generated by astrophysical collapses in late epochs, akin to stochastic backgrounds of gravitational waves and neutrinos. The result bridges methods from particle physics and astrophysics.
Future development
The next step is to extend the analysis to larger scalar masses, where dispersion and radiation suppression by the black hole horizon must be considered. At redshifts down to non-relativistic energies, the background may concentrate into a narrow peak near the rest frequency, paving the way for direct dark matter detection experiments.
Impact
The result will influence the planning of future experiments with atom interferometers and gravitational-wave observatories, broadening their scientific scope. It also stimulates theoretical studies of nonlinear field configurations near compact objects.
Next steps
Full simulations accounting for relativistic corrections and accretion effects are needed, along with the development of optimal broadband signal processing strategies for various detectors.
Key open problems
The work is directly connected to the nature of dark matter and the existence of light fundamental fields predicted by extensions of the Standard Model. It also touches on unresolved questions of backreaction of gravity on radiation during dynamic collapse.
The knowledge machine's view
This section is addressed to the author of the paper and their colleagues. Neighbouring works were found by meaning-based search across our archive, not by word overlap. We do not review: we show the field around the work.
What the work does
The paper examines the diffuse scalar background from stellar collapses into black holes. The authors modeled the emission from a single event with different field profiles and then integrated the contribution from all core-collapse supernovae over cosmic history, obtaining a background peak in the acoustic range of 1–1000 Hz.
Where its strength is
The strength of the work lies in its first prediction of a stochastic background of ultralight scalars produced by astrophysical collapses in late epochs, and in demonstrating its detectability by future atomic interferometers across a wide range of masses.
Where it could go next
- It might be interesting to see how the predicted background relates to direct searches for scalar dark matter, for example, via atomic interferometry—in our archive, there is a nearby paper that details the sensitivity of such experiments to ultralight fields and possible systematics.based on: Hearing the Silence: The Hunt for Scalar Dark Matter arXiv:2607.12144
- Another direction could be to account for the contribution from collapses in the early Universe, including hypothetical dark stars that could form supermassive black holes—this would extend the model to high redshifts and possibly change the shape of the background.based on: Dark Stars: Cradle of Giant Black Holes arXiv:2511.08578
Worth trying
- Test a joint analysis method for scalar and gravitational-wave backgrounds to separate contributions from different collapse populations.
- Use star formation rate data from recent surveys to refine the uncertainty related to progenitor metallicity.
Why this may matter
If the background is detected, it would open a new window into the physics of ultralight scalars, especially in scenarios where they do not dominate dark matter, and would allow testing models of stellar evolution and collapse.
Nearby works in our archive
- The Invisible Spring Around a Black Holesimilarity 0.68
- Dark Stars: Cradle of Giant Black Holessimilarity 0.65
- Cosmic Clocks and the Whisper of Gravitysimilarity 0.64
- Black Hole Lens Catches Light from Distant Nebulaesimilarity 0.64
- Dark Matter Waves Stir Stars in Dwarf Galaxiessimilarity 0.64
- Tiny Black Holes: A New Key to Dark Mattersimilarity 0.64
- Hearing the Silence: The Hunt for Scalar Dark Mattersimilarity 0.64
The closest work in the archive sits at 0.68 by meaning — the usual level for our corpus.
Original abstract
as written by the authors arXiv:2607.12013
Massive astrophysical objects can source huge static configurations of a scalar field. When such an object ends up forming a black hole, for instance, via a core-collapse supernova, the scalar field loses its source abruptly; then the static configuration becomes dynamical and propagates away in a burst, a "scalar tsunami". These bursts accumulate over cosmological history, forming a relic stochastic diffuse scalar background peaked in the $$1-10^3~\text{Hz}$$ range. We propose this as a novel mechanism for the generation of such a background, compute its spectrum, and compare it with the sensitivity of future experiments. We show how this extends the experimental sensitivity to scalar masses $$m_\phi\lesssim 10^{-13}~\text{eV}$$, ten orders of magnitude larger than those accessible via individual transient events previously considered.
The signal peak lies in the audible frequency range of 1–1000 Hz. If our ears could detect scalar perturbations, we would hear a constant hum from thousands of distant supernovae collapsing every second across the universe — a kind of 'sound of cosmic tsunamis'.
Key numbers
- peak signal frequency: 1–1000 Hz
- scalar field mass: m_ϕ ≲ 10-13 eV
- fraction of field energy relative to source mass: 10%
- core-collapse supernova rate: ≈ 105 events per Gpc^3 per year
- MICROSCOPE sensitivity to coupling constant d_e: 2.3×10-4