Arm cavity resonant sideband control for laser interferometric gravitational wave detectors

We present a new optical control scheme for a laser interferometric gravitational wave detector that has a high degree of tolerance to interferometer spatial distortions and noise on the input light. The scheme involves resonating the rf sidebands in an interferometer arm cavity.     

Physics of interferometric gravitational wave detectors

The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave detector like LIGO is a complex, non-linear, coupled, dynamic system. This article summarizes various interesting design characteristics of these detectors and techniques that were implemented in order to reach and maintain its operating condition. Specifically, the following topics are discussed: (i) length sensing and control, (ii) alignment sensing and control and (iii) thermal lensing which changes the performance and operating point of the interferometer as the input power to LIGO is increased.     

Enhanced sensitivity of a gravitational wave detector

We calculate the change in energy absorbed and the power spectrum in a coherently driven antenna induced by interaction with gravitational radiation. The coherent driving field prepares the antenna in a correlated state which enhances the sensitivity of the detector as proposed in a recent paper by Weber.     

Signal processing in a Dulkyn gravitational wave detector

We consider a system for stabilization of the phase, correlation self-compensation of noise, and optimal processing of the response signal in a Dulkyn laser pentagonal gravitational-wave detector, providing noise detection and optimal processing of the PSR J1537 + 1155 response signal in the laser pentagonal detector. Kazan State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 22–28, February, 1998.     

Earth-orbiting low-frequency gravitational wave detector

We propose a new method of gravitational wave detection in the 10^–1÷ 10^–2Hz band for a space laboratory based on the use of the Kozorez effect in the magnetic interaction of superconducting solenoids.     

Underground spherical gravitational wave detector

Recently significant advancements have been made towards the realization of a large spherical gravitational wave detector. Research and development activities have already begun in several countries. We present here the main features and capabilities of a spherical gravitational wave detector. In particular, we discuss the interaction between a spherical antenna and cosmic rays that may require a large detector to be placed underground.     

Remark on a toroidal detector of a gravitational wave

The object of this paper is to review the detector of a gravitational wave that was proposed by Braginsky and Mensky (1971). The derivation of the sensitivity is based on the same assumption as they proposed. It is concluded that the phase difference is linear in time and that the sensitivity of this detector is different from the result claimed by Braginsky and Mensky. The foundation to obtain the phase difference, i.e., the sensitivity, in this paper is not the frequency as they used but rather the movement of the wave front in the detector.     

Excess noise in the steel suspension wires for the laser gravitational wave detector

Progress in the research in mechanical excess noise is reported. An improved technique for wire oscillation measurement has been applied to the investigation of the suspension of a test mass for a GW detector. The dependence of the excess noise intensity in the fundamental violin mode of the steel wires on the stress value is obtained.     

Sensitivity of the heterodyne gravitational wave detector

In order to explore the actual astrophysical possibilities of the heterodyne gravitational wave detector we study its main limitation, due to the motion around the Earth and the Sun. This places an intrinsic limit to the time during which the detector stays tuned to the source and prevents us from taking full advantage of the very large quality factor of sources like pulsars. We study the ratio of signal to thermal noise and find, for a wave of given amplitude, that it is proportional to ^4/3 Q ^1/2, where is the frequency of the source andQ the mechanical quality factor. Consideration of possible astrophysical sources shows the difficulty of detection and points to the need for a tunable heterodyne system.     

Nanohertz gravitational wave searches with interferometric pulsar timing experiments

We estimate the sensitivity to nano-Hertz gravitational waves of pulsar timing experiments in which two highly stable millisecond pulsars are tracked simultaneously with two neighboring radio telescopes that are referenced to the same timekeeping subsystem (i.e., "the clock"). By taking the difference of the two time-of-arrival residual data streams we can exactly cancel the clock noise in the combined data set, thereby enhancing the sensitivity to gravitational waves. We estimate that, in the band (10(-9)-10(-8)) Hz, this "interferometric" pulsar timing technique can potentially improve the sensitivity to gravitational radiation by almost 2 orders of magnitude over that of single-telescopes. Interferometric pulsar timing experiments could be performed with neighboring pairs of antennas of the NASA's Deep Space Network and the forthcoming large arraying projects.     

Investigation of Brownian coating noise in laser interferometric gravitational antennas

We report the results of a detailed study of the Brownian noise of an interferometric coating, which is the principal factor that limits the sensitivity of laser gravitational antennas. It is established that the noise level is lower than previously anticipated due to the influence of interference that takes place inside the coating. Optimizing a coating with the goal of decreasing the Brownian noise is attempted.     

On the response of a gravitational radiation detector to magnetic field fluctuations

An attempt was made to measure the sensitivity of the Maryland gravitational radiation detector to fluctuating magnetic fields with frequencies of 0.1 to 30 Hertz. No response was found for fields along the cylinder axis and normal to it. For some of the tests, the weakest intensity to which any part of the cylinder was exposed exceeded 100 times the intensity of fluctuations of the earth's magnetic field at these frequencies.     

Propagation effect of gravitational wave on detector response

正Dear Editors,The detection of gravitational waves(GW)in the event GW150914 by the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory(LIGO)[1]opens a new era for the direct detection of GW[2],searching black hole coalescence[3]and‘heavy’black holes with more than25 solar mass[4],test of general relativity[5],understanding the astrophysical environment of black hole formation[6],etc.In one words,the era of multi-messenger astronomy has     

Sources and technology for an atomic gravitational wave interferometric sensor

We study the use of atom interferometers as detectors for gravitational waves in the mHz–Hz frequency band, which is complementary to planned optical interferometers, such as laser interferometer gravitational wave observatories (LIGOs) and the Laser Interferometer Space Antenna (LISA). We describe an optimized atomic gravitational wave interferometric sensor (AGIS), whose sensitivity is proportional to the baseline length to power of 5/2, as opposed to the linear scaling of a more conservative design. Technical challenges are briefly discussed, as is a table-top demonstrator AGIS that is presently under construction at Berkeley. We study a range of potential sources of gravitational waves visible to AGIS, including galactic and extra-galactic binaries. Based on the predicted shot noise limited performance, AGIS should be capable of detecting type Ia supernovae precursors within 500 pc, up to 200 years beforehand. An optimized detector may be capable of detecting waves from RX J0806.3+1527.     

Radiation pressure induced instabilities in laser interferometric detectors of gravitational waves

The large scale interferometric gravitational wave detectors consist of Fabry-Perot cavities operating at very high powers ranging from tens of kW to MW for next generations. The high powers may result in several nonlinear effects which would affect the performance of the detector. In this paper, we investigate the effects of radiation pressure, which tend to displace the mirrors from their resonant position resulting in the detuning of the cavity. We observe a remarkable effect, namely, that the freely hanging mirrors gain energy continuously and swing with increasing amplitude. It is found that the “time delay”, that is, the time taken for the field to adjust to its instantaneous equilibrium value, when the mirrors are in motion, is responsible for this effect. This effect is likely to be important in the optimal operation of the full-scale interferometers such as VIRGO and LIGO. Received 12 July 1999