Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X17: LISA Instrumentation and Data AnalysisLive
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Sponsoring Units: DGRAV Chair: Ada Uminska, Univ. of Florida |
Tuesday, April 20, 2021 10:45AM - 10:57AM Live |
X17.00001: The Development of the Telescope Test Structure for LISA Telescope Stability Measurements Soham Kulkarni, Ada Uminska, Jose Sanjuan, Joseph Gleason, Paul Fulda, Guido Mueller The LISA telescope is a critical part of the science interferometer and is subject to the 1pm/$\mathrm{\sqrt{Hz}}$ in-band length stability requirement and the long term length stability requirement of 1 um over mission durations. These tests will be conducted by building an ultra-stable optical cavity, the Telescope Test Structure (TTS), around it. The TTS design must be accommodating of the $\sim$84 cm long telescope, the internal and external alignment tolerances with the telescope and the manufacturing limitations while meeting the stringent requirements. Here we report the stability of scaled down, ULE based design for the TTS that meets the LISA requirement with a comfortable margin. Additionally, we also report stability results for a metal-ULE hybrid design which has more adaptability and allows faster turn-around times for design changes while meeting the LISA requirement. [Preview Abstract] |
Tuesday, April 20, 2021 10:57AM - 11:09AM Live |
X17.00002: Design and Fabrication of an Optical Truss Interferometer for the LISA Telescope Kylan Jersey, Yanqi Zhang, Ian Harley-Trochimczyk, Felipe Guzman The LISA telescope is a bidirectional component that is used to expand a laser beam that is transmitted to the far spacecraft and compress a large incoming beam that is received to a diameter of a few mm at the optical bench. Since the telescope is directly in the path of the LISA long-arm interferometer, it must have a very high structural stability in the pm/$\surd $Hz level at mHz frequencies. One way to measure the stability of the LISA telescope structure is by using compact optical truss interferometers (OTI). The OTI setup consists of three Fabry-Perot cavities mounted around the mirrors of the telescope to monitor structural distortions over time, which are operated with a common laser source. Each cavity is to be equipped with acousto-optic and electro-optical modulators to shift the nominal laser frequency for each cavity as well as to modulate the laser phase for Pound-Drever-Hall locking. Changes in each cavity's length will translate to changes in their corresponding laser frequency, which can be measured against a reference laser that is locked to an external ultra-stable cavity. We have created a design and initiated the fabrication of prototypes of the OTI and will present on our design process and prototype testing. [Preview Abstract] |
Tuesday, April 20, 2021 11:09AM - 11:21AM Live |
X17.00003: LISA Optical Truss Readout Paul Edwards, Paul Fulda In LISA, the optical truss is a subsystem proposed to track pathlength variations in the telescope and ensure the telescope structure meets the required picometer stability. The optical truss is located at the telescope and comprises three separate Fabry-Perot cavities in a triangular configuration, with cavity input mirrors embedded in the telescope primary mirror assembly (M1) and cavity end mirrors around the telescope secondary mirror (M2). If the telescope is not picometer stable, cavity length measurements serve as a potential witness channel for length noise. A simple method of cavity length measurements would involve three separate lasers, each locked to their respective cavities. However, one alternative, which uses only a single laser source, is to lock pairs of sidebands to each of the three cavities. Via this sideband locking, the frequencies of sidebands are tuned to track resonance. An implementation of this locking scheme for the optical truss was performed. An electro-optic modulator (EOM) was used to phase modulate the beam, and the cavity locking error signal was applied to a voltage controlled oscillator (VCO) to tune the EOM and lock sidebands to a single cavity. We report early demonstrations of this scheme and plans for its characterization and optimization. [Preview Abstract] |
Tuesday, April 20, 2021 11:21AM - 11:33AM Live |
X17.00004: Fiber-based Two-wavelength Heterodyne Laser Interferometer Yanqi Zhang, Ki-Nam Joo, Felipe Guzman Precision displacement laser interferometry is crucial in gravitational wave observatories, for instance, in the direct measurement of the test mass dynamics, and for ancillary instrumentation regarding the low-noise operation of the observatories. We are currently developing a fiber-based heterodyne laser interferometer that features compact size and low noise floor. Two wavelengths are utilized to construct a reference and a measurement interferometer with only one optical setup. The highly common optical paths between the two interferometers provide a high common-mode rejection ratio to typical noise sources. In this paper, the interferometer design will be stated, along with a mathematical model describing noise effects expected from various fiber components in the system. A benchtop prototype has already shown sub-nanometer-level displacement sensitivities in air at frequencies above 100 mHz in our lab. We will present the progress and measurement results on the performance of the proposed interferometer, including initial results in vacuum. [Preview Abstract] |
Tuesday, April 20, 2021 11:33AM - 11:45AM Live |
X17.00005: Arm locking performance for the new LISA design Sourath Ghosh, Josep Sanjuan, Guido Mueller LISA is a future space-based gravitational wave (GW) detector which will detect GW in the low frequency regime (0.1 mHz to 1 Hz). The sources in this regime are: supermassive binary black hole mergers, extreme mass ratio binary inspirals and galactic compact binaries.LISA's interferometer signals will be dominated by laser frequency noise which has to be cancelled by about 7 orders of magnitude using an algorithm called time delay interferometry (TDI). TDI has been expanded to also subtract differential clock noise between the ultra-stable oscillators on each spacecraft. It is currently being studied if apparent length changes caused by spacecraft jitter also have to be subtracted via TDI. For the classical LISA mission, arm locking had been proposed to reduce the laser frequency noise by a few orders of magnitude to reduce the potential risks associated with TDI and its expansion. McKenzie et al. 2009 calculated the expected performance of arm locking for the original LISA mission with 5 Gm arm length taking into account clock noise, residual spacecraft motion and shot noise. We updated this calculation and will present the expected residual laser frequency noise for the new LISA mission with 2.5Gm arm lengths, the currently assumed clock noise, spacecraft motion and shot noise. [Preview Abstract] |
Tuesday, April 20, 2021 11:45AM - 11:57AM Live |
X17.00006: Time-Frequency Analysis for LISA Black Hole Binaries Matthew Digman, Neil Cornish Future space-based gravitational-wave interferometers such as LISA will offer rich opportunities to study novel gravitational-wave sources that are not observable from ground-based detectors. They will also facilitate detailed multi-wavelength studies of the inspiral phase of stellar origin black hole binaries whose merger is later observable from the ground. Extracting the maximum possible scientific yield from these sources in LISA data presents multiple novel data analysis challenges. This talk will examine the utility of applying wavelet-based time-frequency analysis to the study of stellar origin black hole binaries in LISA data. [Preview Abstract] |
Tuesday, April 20, 2021 11:57AM - 12:09PM Live |
X17.00007: Archival Searches for Stellar-Mass Binary Black Holes in LISA Data Rebecca Ewing, Surabhi Sachdev, Ssohrab Borhanian, B.S. Sathyaprakash Stellar-mass binary black holes will sweep through the frequency band of the Laser Interferometer Space Antenna (LISA) for months to years before appearing in the audio-band of ground-based gravitational-wave detectors. One can expect several tens of these events up to a distance of 500 Mpc each year. The LISA signal-to-noise ratio for such sources even at these close distances will be too small for a blind search to confidently detect them. However, next generation ground-based gravitational-wave detectors, expected to be operational at the time of LISA, will observe them with signal-to-noise ratios of several thousands and measure their parameters very accurately. We show that such high-fidelity observations of these sources by ground-based detectors help in archival searches to dig tens of signals out of LISA data each year. [Preview Abstract] |
Tuesday, April 20, 2021 12:09PM - 12:21PM Live |
X17.00008: Redshift factor from numerical relativity in the high mass ratio limit. Sergi Navarro Albalat, Aaron Zimmerman The redshift factor helps us model high mass ratio inspirals by: providing a benchmark to different approximation schemes, connecting the first order redshift to second order binding energy and angular momentum, and playing a direct role in the hamiltonian formulation of EMRI dynamics. In this work we use numerical relativity simulations to extract the redshift factor in the high mass ratio limit. We compare it to the predicted value from first order gravitational self-force as well as giving a prediction of the second order contribution. [Preview Abstract] |
Tuesday, April 20, 2021 12:21PM - 12:33PM Live |
X17.00009: A frequency-domain description for bound orbits of spinning bodies in curved spacetime Lisa Drummond, Scott Hughes Very large mass ratio binary black hole systems are of interest as a clean limit of the two-body problem in general relativity, as well as their importance as sources for the Laser Interferometer Space Antenna (LISA). To leading order, the motion of the smaller body in such systems is a geodesic of the larger black hole’s spacetime. Accurate models of such systems require post-geodesic corrections to this motion. Post-geodesic effects that drive the small body away from the geodesic include gravitational self-force effects, and spin-curvature force, which arises from coupling of the small body's spin to the black hole's spacetime curvature. In this talk, we discuss new calculations of the impact of the spin-curvature force. Using the fact that the small body’s motion is “close to” a geodesic (in a sense that can be made precise) plus recent closed-form results (van de Meent 2019) describing precession of the small body's spin along black hole orbits, we develop a frequency-domain formulation of the motion which allows us to compute the spin-curvature correction to geodesic orbits. As an illustration of our results, we show how this correction yields high-precision shifts to the frequencies of orbital motion, which will importantly affect waveform models for LISA. [Preview Abstract] |
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