Searching for stochastic gravitational waves below a nanohertz

Supermassive black hole binaries source gravitational waves measured by Pulsar Timing Arrays. The frequency spectrum of this stochastic background is predicted more precisely than its amplitude. We argue that Dark Matter friction can suppress the spectrum around nHz frequencies, where it is measured, allowing to derive robust and significant bounds on the Dark Matter density, which, in turn, controls indirect detection signals from galactic centers. A precise spectrum of gravitational waves would translate in a tomography of the DM density profile, potentially probing DM particle-physics effects that induce a characteristic DM density profile, such as DM annihilations or de Broglie wavelength.

Section: Dark Matter Influence On Gravitational Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Probing the Dark Matter density with gravitational waves from super-massive binary black holes

Ghoshal,

Strumia

2024

“…Because the PTA experiments such as NANOGrav continue to prefer a positive slope of the GW spectrum, GW with tensor blue tilt are one of the most favorable candidates [44][45][46][47][48]. Additionally, such GW not only exhibit testable characteristic spectral features at high frequencies but even for GW detection below nano-Hz frequencies [49,50], they are among only a few candidates with strong amplitude. This paper is organised as follows.…”

Section: Jcap03(2024)031mentioning

confidence: 99%

Imprint of inflationary gravitational waves and WIMP dark matter in pulsar timing array data

Borah,

Das,

Samanta

2024

Motivated by the recent release of new results from five different pulsar timing array (PTA) experiments claiming to have found compelling evidence for primordial gravitational waves (GW) at nano-Hz frequencies, we consider the prospects of generating such a signal from inflationary blue-tilted tensor power spectrum in a specific dark matter (DM) scenario dubbed as Miracle-less WIMP. While Miracle-less WIMP, due to insufficient interaction rate with the Standard Model (SM) bath gets thermally overproduced, inflationary blue-tilted gravitational waves (BGW) in compliance with PTA data, conflict cosmological observations if reheat temperature after inflation is sufficiently high. Both these issues are circumvented with late entropy dilution, bringing DM abundance within observational limits and creating a doubly-peaked feature in the BGW spectrum consistent with cosmological observations. The blue-tilted tail of the low-frequency peak can fit NANOGrav 15 yr data, while other parts of the spectrum are within reach of present and future GW experiments.

Probing the origin of primordial black holes through novel gravitational wave spectrum

Banerjee

Dey

2023

In this article we investigate the cumulative stochastic gravitational wave spectra as a tool to gain insight on the creation mechanism of primordial black holes. We consider gravitational waves from the production mechanism of primordial black holes and from the gravitational interactions of those primordial black holes among themselves and other astrophysical black holes. We specifically focus on asynchronous bubble nucleation during a first order phase transition as the creation mechanism. We have used two benchmark phase transitions through which the primordial black holes and the primary gravitational wave spectra have been generated. We have considered binary systems and close hyperbolic interactions of primordial black holes with other primordial and astrophysical black holes as the source of the secondary part of the spectra. We have shown that this unique cumulative spectra have features which directly and indirectly depend on the specifics of the production mechanism.