IQUIST Master Calendar

Back to Listing

Medium and High Energy Physics Seminar: Cecilia Chirenti (University of Maryland) "The r-mode puzzle"

Event Type
Room 464
Feb 7, 2022   1:00 pm   3:00 pm
Cecilia Chirenti (University of Maryland)
Brandy Koebbe
Originating Calendar
Physics - High Energy Seminar

Stellar-mass black holes observed in X-rays are spun up by accretion from a companion and many seem to spin close to or at the physically allowed limit imposed by the Kerr metric. The same does appear to be true for neutron stars, with a maximum reported spin of 716 Hz for PSR J1748-2446ad, which is less than half of the estimated breakup rotational frequency for a typical neutron star. R-modes (also called Rossby waves) have been proposed as a possible mechanism for limiting the spins of accreting neutron stars. The r-mode instability mechanism can also potentially make a rotating neutron star into a strong source of gravitational waves, but the shape of the instability window depends on details of the neutron star equation of state and viscosity. I will briefly review the theory of CFS instabilities and discuss some tantalizing hints of r-modes, possibly observed as modulations in the emission of millisecond pulsar XTE J1751-305 and 4U 1636-536, some puzzles (such as LMXBs which seem to sit in the middle of the instability window) and current upper limits on continuous gravitational wave detections by LIGO.

link for robots only