How large are neutron-star mountains, given no continuous gravitational waves? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
How large are neutron-star mountains, given no continuous gravitational waves?
Plain
A spinning neutron star with a tiny bump on its crust would emit a steady gravitational-wave hum. None has been detected, and it is not known how large a bump the crust can support or how large real bumps are.
Precise · changed · core
Revision 1: Searches for continuous gravitational waves from known pulsars set upper limits on ellipticity $\epsilon$ of order $1e-8\ \text{to}\ 1e-9$ for some nearby millisecond pulsars. Determine the maximum ellipticity a realistic crust can sustain (estimates range from about $1e-9\ \text{to}\ 1e-6$ depending on how the mountain is built) and whether a floor near $\epsilon \sim 1e-9$ exists, as suggested by millisecond-pulsar spin-down.
Revision 2: Searches for continuous gravitational waves from known pulsars set upper limits on ellipticity $\epsilon$ of order $10^{-8}\ \text{to}\ 10^{-9}$ for some nearby millisecond pulsars. Determine the maximum ellipticity a realistic crust can sustain (estimates range from about $10^{-9}\ \text{to}\ 10^{-6}$ depending on how the mountain is built) and whether a floor near $\epsilon \sim 10^{-9}$ exists, as suggested by millisecond-pulsar spin-down.
Settled by · changed · core
Revision 1: A detection of continuous gravitational waves, or a crust-elasticity calculation with a self-consistent formation history giving $\epsilon_{\mathrm{max}}$ below current limits.
Revision 2: A detection of continuous gravitational waves, or a crust-elasticity calculation with a self-consistent formation history giving $\epsilon_{\max}$ below current limits.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
open
Status note
Searches of LIGO-Virgo-KAGRA fourth observing run data were in progress in 2026 with no reported detection.
Posed since
(empty)

Decisions