LIGO/Virgo BH spins limit dark matter

[notFritzArgelander]

https://phys.org/news/2021-04-fast-spin ... -dark.html

[AntennaGuy]

Interesting. But it looks like it only excludes a very narrow range of possible masses. "The black holes' existence rules out the existence of ultralight bosons with masses between 1.3x10^-13 electronvolts and 2.7x10^-13 electronvolts."

[notFritzArgelander]

Interesting. But it looks like it only excludes a very narrow range of possible masses. "The black holes' existence rules out the existence of ultralight bosons with masses between 1.3x10^-13 electronvolts and 2.7x10^-13 electronvolts."

Quite true and the paper abstract is much more modest than the article:

https://arxiv.org/abs/1908.02312

Ultralight bosons can form clouds around rotating black holes if their Compton wavelength is comparable to the black hole size. The boson cloud spins down the black hole through a process called superradiance, lowering the black hole spin to a characteristic value. It has been suggested that spin measurements of the black holes detected by ground-based gravitational-wave detectors can be used to constrain the mass of ultralight bosons. Unfortunately, a measurement of the individual black hole spins is often uncertain, resulting in inconclusive results. Instead, we use hierarchical Bayesian inference to combine information from multiple gravitational-wave sources and obtain stronger constraints. We show that hundreds of high signal-to-noise ratio gravitational-wave detections are enough to exclude (confirm) the existence of non-interacting bosons in the mass range [10−13,3×10−12] eV ([10−13,10−12] eV). The precise number depends on the distribution of black hole spins at formation and the mass of the boson. From the few uninformative spin measurements of binary black hole mergers detected by LIGO and Virgo in their first two observing runs, we cannot draw statistically significant conclusions.

The bold emphasis is mine.

The problem with this method is that the Compton wavelength needs to be of the order of the event horizon. Since the masses of merging BHs are in a small range only a small range can be excluded. As an antenna person, you know how that works, the relationship between simple antennas and wavelength....

PS How's the VMC working out?

[AntennaGuy]

Re: "PS How's the VMC working out?"
Believe it or not, I still haven't actually set it up to use it yet! Hoping to get some time & opportunity sooner rather than later.