Binary systems as resonance detectors for gravitational waves

Abstract

Gravitational waves at suitable frequencies can resonantly interact with a binary system, inducing changes to its orbit. A stochastic gravitational-wave background causes the orbital elements of the binary to execute a classic random walk, with the variance of orbital elements growing with time.The lack of such a random walk in binaries that have been monitored with high precision over long time-scales can thus be used to place an upper bound on the gravitational-wave background. Using periastron time data from the Hulse-Taylor binary pulsar spanning ∼ 30 years, we obtain a bound of hc < 7.9 × 10 −14 at ∼ 10 −4 Hz, where hc is the strain amplitude per logarithmic frequency interval. Our constraint complements those from pulsar timing arrays, which probe much lower frequencies, and ground-based gravitational-wave observations, which probe much higher frequencies. Interesting sources in our frequency band, which overlaps the lower sensitive frequencies of proposed spacebased observatories, include white-dwarf/supermassive black-hole binaries in the early/late stages of inspiral, and TeV scale preheating or phase transitions. The bound improves as (time span) −2 and (sampling rate) −1/2 . The Hulse-Taylor constraint can be improved to ∼ 3.8 × 10 −15 with a suitable observational campaign over the next decade. Our approach can also be applied to other binaries, including (with suitable care) the Earth-Moon system, to obtain constraints at different frequencies. The observation of additional binary pulsars with the SKA could reach a sensitivity of hc ∼ 3 × 10 −17 .

Blue-tilted tensor spectrum and thermal history of the Universe

“…The spectral index of the primordial GW spectrum can change at some frequency. Therefore, #1 There are more ways to obtain upper bounds on the amount of the stochastic GWs, such as dark radiation constraints from the CMB [28,29], CMB µ distortion [30,31], helioseismology [32], precision Doppler tracking from the Cassini spacecraft [33], orbital monitoring of binary systems [34], torsion-bar antennas [35], seismic spectrum from the Earth [36], synchronous recycling interferometers [37], crosscorrelation measurement between the Explorer and Nautilus cryogenic resonant bar detectors [38], and Global Positioning System (GPS) satellite [39].…”

Strong lensing interferometry for compact binaries

“…The binary-resonance effect can provide an upper bound on the stochastic gravitational wave background at the orbital frequency of a binary [4]. Such an upper bound is roughly given by…”

“…The post-Keplerian orbital changes provided excellent confirmation of gravitational wave emission [1][2][3]. More recently, it was pointed out that the same data can be used to bound the stochastic gravitational wave background at an orbital frequency ∼10 −4 Hz, and such a bound can be lowered to the interesting range if the timing precision can be improved by a few orders of magnitude [4].…”

“…We then calculate the projected precision and discuss some practical issues to show that a pulsar binary can indeed reach it. Finally, we discuss the improvement this might bring to the upper bound of a stochastic gravitational wave provided by the binary-resonance detector [4] and the possibility to determine the spin of the companion neutron star or black hole.…”

Complementarity plus backreaction is enough

“…This is equivalent to an interference effect between their emissions. In certain cases the original emission greatly amplifies the influence of the incoming radiation and serves as a good detector [21]. accordingly modified.…”