Millisecond Pulsars and Black Holes in Globular Clusters
Shi Ye
Abstract--Over a hundred millisecond radio pulsars (MSPs) have been observed in globular clusters (GCs), motivating theoretical studies of the formation and evolution of these sources through stellar evolution coupled to stellar dynamics. Here we study MSPs in GCs using realistic N-body simulations with our Cluster Monte Carlo code. We show that neutron stars (NSs) formed in electron-capture supernovae (including both accretion-induced and merger-induced collapse of white dwarfs) can be spun up through mass transfer to form MSPs. Both NS formation and spin-up through accretion are greatly enhanced through dynamical interaction processes. We find that our models for average GCs at the present day with masses ≈ 2 × 10^5 solar mass
can produce up to 10 − 20 MSPs, while a very massive GC model with mass ≈ 10^6 solar mass
can produce close to 100. We show that the number of MSPs is anti-correlated with the total number of stellar-mass black holes (BHs) retained in the host cluster. The radial distributions are also affected: MSPs are more concentrated towards the center in a host cluster with a smaller number of retained BHs. As a result, the number of MSPs in a GC could be used to place constraints on its BH population. Interestingly, our models also demonstrate the possibility of dynamically forming NS–NS and NS–BH binaries in GCs, although the predicted numbers are very small.
Room temperature optomechanical squeezing
Nancy Aggarwal, PhD
Quantum fluctuations of light impose a fundamental limit precision optical measurements, laser interferometric detection of gravitational waves (GWs), for example. Current generation GW detectors are limited by quantum noise and plan to improve their sensitivity by injecting squeezed states of light generated by non-linear optical materials. We present an alternative technology for producing squeeze states of light using the radiation pressure interaction of light with a mechanical oscillator. Such optomechanical (OM) squeezed light sources would be widely applicable for future precision measurements because their non-linearity is independent of the laser wavelength. Previously, OM squeezers were limited to cryogenic temperatures. I will present our recent measurement of squeezed light from an OM system at room temperature [1]. Operation of a quantum OM system at room temperature not only makes its integration into complex interferometers more feasible, it also provides a resource for exploring quantum light-matter interactions in a human-perceivable environment.
Bud Robinson
(847) 491-3644
Email