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  • 1
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    Time Domain Simulations of Arm Locking in LISA (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Arm locking is a technique that has been proposed for reducing laser frequency fluctuations in the Laser Interferometer Space Antenna (LISA). a gravitational-wave observatory sensitive' in the milliHertz frequency band. Arm locking takes advantage of the geometric stability of the triangular constellation of three spacecraft that comprise LISA to provide a frequency reference with a stability in the LISA measurement band that exceeds that available from a standard reference such as an optical cavity or molecular absorption line. We have implemented a time-domain simulation of arm locking including the expected limiting noise sources (shot noise, clock noise. spacecraft jitter noise. and residual laser frequency noise). The effect of imperfect a priori knowledge of the LISA heterodyne frequencies and associated "pulling" of an arm locked laser is included. We find that our implementation meets requirements both on the noise and dynamic range of the laser frequency.
    Keywords: Astrophysics
    Format: application/pdf
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  • 2
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    Observing Mergers of Nonspinning Black Hole Binaries with LISA (2008)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: Recent advances in the field of numerical relativity now make it possible to calculate the final, most powerful merger phase of binary black hole coalescence. We present the application of nonspinning numerical relativity waveforms to the search for and precision measurement of black hole binary coalescences using LISA. In particular, we focus on the advances made in moving beyond the equal mass, nonspinning case into other regions of parameter space, focusing on the case of nonspinning holes with ever-increasing mass ratios. We analyze the available unequal mass merger waveforms from numerical relativity, and compare them to two models, both of which use an effective one body treatment of the inspiral, but which use fundamentally different approaches to the treatment of the merger-ringdown. We confirm the expected mass ratio scaling of the merger, and investigate the changes in waveform behavior and their observational impact with changing mass ratio. Finally, we investigate the potential contribution from the merger portion of the waveform to measurement uncertainties of the binary's parameters for the unequal mass case.
    Keywords: Astrophysics
    Type: 7th International LISA Symposium/Space Science Institute of Catalonia (IEEC); Jun 14, 2008 - Jun 20, 2008; Barcelona; Spain
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  • 3
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    New Concepts for Space-Based Gravitational Wave Missions (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The most astrophysically interesting sources in the gravitational wave spectrum lie in the low-frequency band (0.0001 - 1 Hz), which is only accessible from space. For two decades, the LISA concept has been the leading contender for a detector in this band. Despite a strong recommendation from Astro2010, there is strong motivation to find a less expensive concept, even at the loss of some science. We are searching for a lower cost mission concept by examining alternate orbits, less-capable measurement concepts, radically different implementations of the measurement concept and other cost-saving ideas. We report the results of our searches to date, and summarize the analyses behind them.
    Keywords: Astrophysics
    Type: GSFC.ABS.4428.2011
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  • 4
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    Micrometeoroid Events in LISA Pathfinder (2019)
    In:  Other Sources
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    Publication Date: 2019-11-30
    Description: 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 impacts. This technique is made possible by the extreme precision of the instruments flown on the LISA Pathfinder spacecraft, a technology demonstrator for a future space-based gravitational wave observatory. Pathfinder employed a technique known as drag-free control that achieved rejection of external disturbances, including particle impacts, using a micropropulsion system. Using a simple model of the impacts and knowledge of the control system, we show that it is possible to detect impacts and measure properties such as the transferred momentum, direction of travel, and location of impact on the spacecraft. In this paper, we present the results of a systematic search for impacts during 4348 hr of Pathfinder data. We report a total of 54 candidates with transferred momenta ranging from 0.2 to 230 Ns. We furthermore make a comparison of these candidates with models of micrometeoroid populations in the inner solar system, including those resulting from Jupiter-family comets (JFCs), Oort Cloud comets, Halley-type comets, and asteroids. We find that our measured population is consistent with a population dominated by JFCs, with some evidence for a smaller contribution from Halley-type comets, in agreement with consensus models of the zodiacal dust complex in the momentum range sampled by LISA Pathfinder.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN75583 , Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 883; 1; 53
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  • 5
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    Constraints on LISA Pathfinder's Self-Gravity: Design Requirements, Estimates and Testing Procedures (2016)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: LISA Pathfinder satellite was launched on 3 December 2015 toward the Sun Earth first Lagrangian point (L1) where the LISA Technology Package (LTP), which is the main science payload, will be tested. LTP achieves measurements of differential acceleration of free-falling test masses (TMs) with sensitivity below 3 x 10(exp -14) m s(exp -2) Hz(exp - 1/2) within the 130 mHz frequency band in one dimension. The spacecraft itself is responsible for the dominant differential gravitational field acting on the two TMs. Such a force interaction could contribute a significant amount of noise and thus threaten the achievement of the targeted free-fall level. We prevented this by balancing the gravitational forces to the sub nm s(exp -2) level, guided by a protocol based on measurements of the position and the mass of all parts that constitute the satellite, via finite element calculation tool estimates. In this paper, we will introduce the gravitational balance requirements and design, and then discuss our predictions for the balance that will be achieved in flight.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN41786 , Classical and Quantum Gravity (ISSN 0264-9381) (e-ISSN 1361-6382); 33; 23; 235015
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  • 6
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    Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 +/- 0.1 fm s(exp -2)/square root of Hz, or (0.54 +/- 0.01) x 10(exp -15) g/square root of Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 +/- 0.3) fm square root of Hz, about 2 orders of magnitude better than requirements. At f less than or equal to 0.5 mHz we observe a low-frequency tail that stays below 12 fm s(exp -2)/square root of Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN41716 , Physical Review Letters (ISSN 0031-9007) (e-ISSN 1079-7114); 116; 23; 231101
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