The GEO 600 laser-interferometric gravitational wave detector near Hannover, Germany, is one of s... more The GEO 600 laser-interferometric gravitational wave detector near Hannover, Germany, is one of six such interferometers now close to operation worldwide. The UK/German GEO collaboration uses advanced technologies, including monolithic silica suspensions and signal recycling, to deliver a sensitivity comparable with much larger detectors in their initial configurations. Here we review the design and performance of GEO 600 and consider the prospects for a direct detection of continuous gravitational waves from spinning neutron stars.
Rapidly rotating neutron stars are the most likely sources of persistent gravitational radiation ... more Rapidly rotating neutron stars are the most likely sources of persistent gravitational radiation in the frequency band 100 Hz–1 kHz. These objects may generate continuous gravitational waves (GW) through a variety of mechanisms, including nonaxisymmetric distortions of the star [1–5], velocity perturbations in the star's fluid [1, 6, 7], and free precession [8, 9]. Regardless of the specific mechanism, the emitted signal is a quasiperiodic wave whose frequency changes slowly during the observation time due to energy loss through ...
We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsa... more We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10ÿ24. These ...
This work presents methods to search for periodic gravitational waves generated by known pulsars,... more This work presents methods to search for periodic gravitational waves generated by known pulsars, using data collected by interferometric gravitational wave detectors. To illustrate these methods, upper limits are placed on the strength of waves emitted by pulsar J19392134 at its expected 1284 Hz emission frequency during S1 1. S1 is the first observational science run of the Laser Interferometer Gravitational Wave Observatory LIGO 2, 3 and GEO 4, 5 detectors and it took place during 17 days between 23 August and 9 ...
We have performed a search for bursts of gravitational waves associated with the very bright gamm... more We have performed a search for bursts of gravitational waves associated with the very bright gamma ray burst GRB030329, using the two detectors at the LIGO Hanford Observatory. Our search covered the most sensitive frequency range of the LIGO detectors (approximately ...
We report on a search for gravitational wave bursts using data from the first science run of the ... more We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6
We report on a search for gravitational waves from coalescing compact binary systems in the Milky... more We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of R < 1.7 × 10 2 per year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the coalescence rate of binary systems in which each component has a mass in the range 1-3 M⊙.
For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave dete... more For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.
Space-based interferometric gravitational wave instruments such as the ESA/NASA Laser Interferome... more Space-based interferometric gravitational wave instruments such as the ESA/NASA Laser Interferometer Space Antenna (LISA) observe gravitational waves by measuring changes in the light travel time between widely separated spacecraft. One potential noise source for these instruments is interaction with the solar wind, in particular the free electrons in the interplanetary plasma. Variations in the integrated column density of free electrons along the laser links will lead to time-of-flight delays which directly compete with signals produced by gravitational waves. In this paper we present a simplified model of the solar plasma relevant for this problem, anchor key parameters of our model using data from the NASA Wind/solar wind experiment instrument, and derive estimates for the effect in the LISA measurement. We find that under normal solar conditions, the gravitational wave sensitivity limit from the free-electron effect is smaller than other noise sources that are expected to limit LISA's sensitivity.
Analysis of the accuracy of actuation electronics in the laser interferometer space antenna pathf... more Analysis of the accuracy of actuation electronics in the laser interferometer space antenna pathfinder. Review of Scientific Instruments, 91(4), 045003. There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.
The zodiacal dust complex, a population of dust and small particles that pervades the solar syste... more The zodiacal dust complex, a population of dust and small particles that pervades the solar system, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. We present a new set of data obtained from direct measurements of momentum transfer to a spacecraft from individual particle
LISA Pathfinder (LPF) was a European Space Agency mission with the aim to test key technologies f... more LISA Pathfinder (LPF) was a European Space Agency mission with the aim to test key technologies for future space-borne gravitational-wave observatories like LISA. The main scientific goal of LPF was to demonstrate measurements of differential acceleration between free-falling test masses at the sub-femto-g level, and to understand the residual acceleration in terms of a physical model of stray forces, and displacement readout noise. A key step towards reaching the LPF goals was the correct calibration of the dynamics of LPF, which was a three-body system composed by two testmasses enclosed in a single spacecraft, and subject to control laws for system stability. In this work, we report on the calibration procedures adopted to calculate the residual differential stray force per unit mass acting on the two test-masses in their nominal positions. The physical parameters of the adopted dynamical model are presented, together with their role on LPF performance. The analysis and results of these experiments show that the dynamics of the system was accurately modeled and the dynamical parameters were stationary throughout the mission. Finally, the impact and importance of calibrating system dynamics for future space-based gravitational wave observatories is discussed.
Non-recurrent short term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n −1 were ... more Non-recurrent short term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n −1 were observed between 2016 February 18 and 2017 July 3 aboard the European Space Agency LISA Pathfinder (LPF) mission orbiting around the Lagrange point L1 at 1.5×10 6 km from Earth. The energy dependence of three Forbush decreases (FDs) is studied and reported here. A comparison of these observations with others carried out in space down to the energy of a few tens of MeV n −1 shows that the same GCR flux parameterization applies to events of different intensity during the main phase. FD observations in L1 with LPF and geomagnetic storm occurrence is also presented. Finally, the characteristics of GCR flux non-recurrent variations (peaks and depressions) of duration < 2 days and their association with interplanetary structures are investigated. It is found that, most likely, plasma compression regions between subsequent corotating high-speed streams cause peaks, while heliospheric current sheet crossing cause the majority of the depressions.
Test mass charging caused by cosmic rays will be a significant source of acceleration noise for s... more Test mass charging caused by cosmic rays will be a significant source of acceleration noise for spacebased gravitational wave detectors like LISA. Operating between December 2015 and July 2017, the technology demonstration mission LISA Pathfinder included a bespoke monitor to help characterise the relationship between test mass charging and the local radiation environment. The radiation monitor made in situ measurements of the cosmic ray flux while also providing information about its energy spectrum. We describe the monitor and present measurements which show a gradual 40% increase in count rate coinciding with the declining phase of the solar cycle. Modulations of up to 10% were also observed with periods of 13 and 26 days that are associated with co-rotating interaction regions and heliospheric current sheet crossings. These variations in the flux above the monitor detection threshold (≈ 70 MeV) are shown to be coherent with measurements made by the IREM monitor on-board the Earth orbiting INTEGRAL spacecraft. Finally we use the measured deposited energy spectra, in combination with a GEANT4 model, to estimate the galactic cosmic ray differential energy spectrum over the course of the mission.
We report on the performance of the capacitive gap-sensing system of the Gravitational Reference ... more We report on the performance of the capacitive gap-sensing system of the Gravitational Reference Sensor (GRS) onboard the LISA Pathfinder (LPF) spacecraft. From in-flight measurements, the system has demonstrated a performance, down to 1 mHz, that is ranging between 0.7 aF Hz −1/2 and 1.8 aF Hz −1/2. That translates into a sensing noise of the test mass motion within 1.2 nm Hz −1/2 and 2.4 nm Hz −1/2 in displacement and within 83 nrad Hz −1/2 and 170 nrad Hz −1/2 in rotation. This matches the performance goals for LPF and it allows the successful implementation of the gravitational waves observatory LISA. A 1/f tail has been observed for frequencies below 1 mHz, the tail has been investigated in detail with dedicated in-flight measurements and a model is presented in the paper. A projection of such noise to frequencies below 0.1 mHz shows that an improvement of performance at those frequencies is desirable for the next generation of GRS sensors for space-borne gravitational waves observation.
The joint ESA-NASA mission Laser Interferometer Space Antenna LISA consists of a triangular forma... more The joint ESA-NASA mission Laser Interferometer Space Antenna LISA consists of a triangular formation of three satellites LISA will directly measure gravitational waves generated by compact binaries within our Galaxy and black hole binaries and mergers throughout the Universe The gravitational waves are detected by measuring the stretching of space-time between the satellites with laser interferometry The satellite formation is a general circular solution of the Hill-Clohessy-Wiltshire equations This means that in linearised approximation the satellites will describe a circle around a reference point maintaining a fixed position with respect to each other The reference point the centre of the triangle orbits the Sun in a circular orbit trailing the Earth at twenty degrees When evaluating the complete equations of motion of the satellites the distance between the satellites will vary about one to two percent The angle between the arms from one satellite to the others will vary about ...
The GEO 600 laser-interferometric gravitational wave detector near Hannover, Germany, is one of s... more The GEO 600 laser-interferometric gravitational wave detector near Hannover, Germany, is one of six such interferometers now close to operation worldwide. The UK/German GEO collaboration uses advanced technologies, including monolithic silica suspensions and signal recycling, to deliver a sensitivity comparable with much larger detectors in their initial configurations. Here we review the design and performance of GEO 600 and consider the prospects for a direct detection of continuous gravitational waves from spinning neutron stars.
Rapidly rotating neutron stars are the most likely sources of persistent gravitational radiation ... more Rapidly rotating neutron stars are the most likely sources of persistent gravitational radiation in the frequency band 100 Hz–1 kHz. These objects may generate continuous gravitational waves (GW) through a variety of mechanisms, including nonaxisymmetric distortions of the star [1–5], velocity perturbations in the star's fluid [1, 6, 7], and free precession [8, 9]. Regardless of the specific mechanism, the emitted signal is a quasiperiodic wave whose frequency changes slowly during the observation time due to energy loss through ...
We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsa... more We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10ÿ24. These ...
This work presents methods to search for periodic gravitational waves generated by known pulsars,... more This work presents methods to search for periodic gravitational waves generated by known pulsars, using data collected by interferometric gravitational wave detectors. To illustrate these methods, upper limits are placed on the strength of waves emitted by pulsar J19392134 at its expected 1284 Hz emission frequency during S1 1. S1 is the first observational science run of the Laser Interferometer Gravitational Wave Observatory LIGO 2, 3 and GEO 4, 5 detectors and it took place during 17 days between 23 August and 9 ...
We have performed a search for bursts of gravitational waves associated with the very bright gamm... more We have performed a search for bursts of gravitational waves associated with the very bright gamma ray burst GRB030329, using the two detectors at the LIGO Hanford Observatory. Our search covered the most sensitive frequency range of the LIGO detectors (approximately ...
We report on a search for gravitational wave bursts using data from the first science run of the ... more We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6
We report on a search for gravitational waves from coalescing compact binary systems in the Milky... more We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of R < 1.7 × 10 2 per year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the coalescence rate of binary systems in which each component has a mass in the range 1-3 M⊙.
For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave dete... more For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.
Space-based interferometric gravitational wave instruments such as the ESA/NASA Laser Interferome... more Space-based interferometric gravitational wave instruments such as the ESA/NASA Laser Interferometer Space Antenna (LISA) observe gravitational waves by measuring changes in the light travel time between widely separated spacecraft. One potential noise source for these instruments is interaction with the solar wind, in particular the free electrons in the interplanetary plasma. Variations in the integrated column density of free electrons along the laser links will lead to time-of-flight delays which directly compete with signals produced by gravitational waves. In this paper we present a simplified model of the solar plasma relevant for this problem, anchor key parameters of our model using data from the NASA Wind/solar wind experiment instrument, and derive estimates for the effect in the LISA measurement. We find that under normal solar conditions, the gravitational wave sensitivity limit from the free-electron effect is smaller than other noise sources that are expected to limit LISA's sensitivity.
Analysis of the accuracy of actuation electronics in the laser interferometer space antenna pathf... more Analysis of the accuracy of actuation electronics in the laser interferometer space antenna pathfinder. Review of Scientific Instruments, 91(4), 045003. There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.
The zodiacal dust complex, a population of dust and small particles that pervades the solar syste... more The zodiacal dust complex, a population of dust and small particles that pervades the solar system, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. We present a new set of data obtained from direct measurements of momentum transfer to a spacecraft from individual particle
LISA Pathfinder (LPF) was a European Space Agency mission with the aim to test key technologies f... more LISA Pathfinder (LPF) was a European Space Agency mission with the aim to test key technologies for future space-borne gravitational-wave observatories like LISA. The main scientific goal of LPF was to demonstrate measurements of differential acceleration between free-falling test masses at the sub-femto-g level, and to understand the residual acceleration in terms of a physical model of stray forces, and displacement readout noise. A key step towards reaching the LPF goals was the correct calibration of the dynamics of LPF, which was a three-body system composed by two testmasses enclosed in a single spacecraft, and subject to control laws for system stability. In this work, we report on the calibration procedures adopted to calculate the residual differential stray force per unit mass acting on the two test-masses in their nominal positions. The physical parameters of the adopted dynamical model are presented, together with their role on LPF performance. The analysis and results of these experiments show that the dynamics of the system was accurately modeled and the dynamical parameters were stationary throughout the mission. Finally, the impact and importance of calibrating system dynamics for future space-based gravitational wave observatories is discussed.
Non-recurrent short term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n −1 were ... more Non-recurrent short term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n −1 were observed between 2016 February 18 and 2017 July 3 aboard the European Space Agency LISA Pathfinder (LPF) mission orbiting around the Lagrange point L1 at 1.5×10 6 km from Earth. The energy dependence of three Forbush decreases (FDs) is studied and reported here. A comparison of these observations with others carried out in space down to the energy of a few tens of MeV n −1 shows that the same GCR flux parameterization applies to events of different intensity during the main phase. FD observations in L1 with LPF and geomagnetic storm occurrence is also presented. Finally, the characteristics of GCR flux non-recurrent variations (peaks and depressions) of duration < 2 days and their association with interplanetary structures are investigated. It is found that, most likely, plasma compression regions between subsequent corotating high-speed streams cause peaks, while heliospheric current sheet crossing cause the majority of the depressions.
Test mass charging caused by cosmic rays will be a significant source of acceleration noise for s... more Test mass charging caused by cosmic rays will be a significant source of acceleration noise for spacebased gravitational wave detectors like LISA. Operating between December 2015 and July 2017, the technology demonstration mission LISA Pathfinder included a bespoke monitor to help characterise the relationship between test mass charging and the local radiation environment. The radiation monitor made in situ measurements of the cosmic ray flux while also providing information about its energy spectrum. We describe the monitor and present measurements which show a gradual 40% increase in count rate coinciding with the declining phase of the solar cycle. Modulations of up to 10% were also observed with periods of 13 and 26 days that are associated with co-rotating interaction regions and heliospheric current sheet crossings. These variations in the flux above the monitor detection threshold (≈ 70 MeV) are shown to be coherent with measurements made by the IREM monitor on-board the Earth orbiting INTEGRAL spacecraft. Finally we use the measured deposited energy spectra, in combination with a GEANT4 model, to estimate the galactic cosmic ray differential energy spectrum over the course of the mission.
We report on the performance of the capacitive gap-sensing system of the Gravitational Reference ... more We report on the performance of the capacitive gap-sensing system of the Gravitational Reference Sensor (GRS) onboard the LISA Pathfinder (LPF) spacecraft. From in-flight measurements, the system has demonstrated a performance, down to 1 mHz, that is ranging between 0.7 aF Hz −1/2 and 1.8 aF Hz −1/2. That translates into a sensing noise of the test mass motion within 1.2 nm Hz −1/2 and 2.4 nm Hz −1/2 in displacement and within 83 nrad Hz −1/2 and 170 nrad Hz −1/2 in rotation. This matches the performance goals for LPF and it allows the successful implementation of the gravitational waves observatory LISA. A 1/f tail has been observed for frequencies below 1 mHz, the tail has been investigated in detail with dedicated in-flight measurements and a model is presented in the paper. A projection of such noise to frequencies below 0.1 mHz shows that an improvement of performance at those frequencies is desirable for the next generation of GRS sensors for space-borne gravitational waves observation.
The joint ESA-NASA mission Laser Interferometer Space Antenna LISA consists of a triangular forma... more The joint ESA-NASA mission Laser Interferometer Space Antenna LISA consists of a triangular formation of three satellites LISA will directly measure gravitational waves generated by compact binaries within our Galaxy and black hole binaries and mergers throughout the Universe The gravitational waves are detected by measuring the stretching of space-time between the satellites with laser interferometry The satellite formation is a general circular solution of the Hill-Clohessy-Wiltshire equations This means that in linearised approximation the satellites will describe a circle around a reference point maintaining a fixed position with respect to each other The reference point the centre of the triangle orbits the Sun in a circular orbit trailing the Earth at twenty degrees When evaluating the complete equations of motion of the satellites the distance between the satellites will vary about one to two percent The angle between the arms from one satellite to the others will vary about ...
Uploads
Papers by O. Jennrich