Measurement of theHg+1995d96s2 D5/22Electric Quadrupole Moment and a Constraint on the Quadrupole Shift

The I-Love-Q relations are approximate equation-of-state independent relations that connect the moment of inertia, the spin-induced quadrupole moment, and the tidal deformability of neutron stars. In this paper, we study the I-Love-Q relations for superfluid neutron stars for a general relativistic two-fluid model: one fluid being the neutron superfluid and the other a conglomerate of all charged components. We study to what extent the two-fluid dynamics might affect the robustness of the I-Love-Q relations by using a simple two-component polytropic model and a relativistic mean field model with entrainment for the equation-of-state. Our results depend crucially on the spin ratio Ωn/Ωp between the angular velocities of the neutron superfluid and the normal component. We find that the I-Love-Q relations can still be satisfied to high accuracy for superfluid neutron stars as long as the two fluids are nearly co-rotating Ωn/Ωp≈1. However, the deviations from the I-Love-Q relations increase as the spin ratio deviates from unity. In particular, the deviation of the Q-Love relation can be as large as O(10%) if Ωn/Ωp differ from unity by a few tens of percent. As Ωn/Ωp≈1 is expected for realistic neutron stars, our results suggest that the two-fluid dynamics should not affect the accuracy of any gravitational waveform models for neutron star binaries that employ the relation to connect the spin-induced quadrupole moment and the tidal deformability.

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Collision Induced Microwave Absorption in N2, CH4, and N2–Ar, N2–CH4 Mixtures at 1.1 and 2.3 cm−1

Canadian Journal of Physics ◽

10.1139/p74-112 ◽

1974 ◽

Vol 52 (9) ◽

pp. 821-829 ◽

Cited By ~ 8

Author(s):

I. R. Dagg ◽

G. E. Reesor ◽

J. L. Urbaniak

Keyword(s):

Microwave Absorption ◽

Quadrupole Moment ◽

Linear Dependence ◽

Relaxation Times ◽

High Sensitivity ◽

Higher Order ◽

Induced Absorption ◽

High Q ◽

Order Dependence

Collision induced microwave absorption is reported in pure N2, N2–Ar, N2–CH4, mixtures, and in pure CH4 in the 35 and 70 GHz regions (1.1 and 2.3 cm−1) at a temperature of 22 °C. The measurements are accomplished using overmoded high Q cavities capable of pressurization of up to 5000 p.s.i.g. The apparatus and method are described. With the high sensitivity attained, the results in pure N2 from 30 → 250 amagat reveal terms in the square and cube of the density from which the relaxation times are calculated. The linear dependence on frequency of the collision induced absorption up to 2.3 cm−1 is established. Higher order dependence on the density is observed in the N2–Ar and N2–CH4 mixtures. Various estimates of the quadrupole moment of N2 are given, making use of earlier results in other frequency regions.

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