Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Sensitivity Studies for Third-Generation Gravitational Wave Observatories

S. Hild, M. Abernathy, F. Acernese, P. Amaro-Seoane, N. Andersson, K. Arun, F. Barone, B. Barr, M. Barsuglia, M. Beker, N. Beveridge, S. Birindelli, S. Bose, L. Bosi, S. Braccini, C. Bradaschia, T. Bulik, E. Calloni, G. Cella, E. Chassande Mottin, S. Chelkowski, A. Chincarini, J. Clark, E. Coccia, C. Colacino, J. Colas, A. Cumming, L. Cunningham, E. Cuoco, S. Danilishin, K. Danzmann, R. De Salvo, T. Dent, R. De Rosa, L. Di Fiore, A. Di Virgilio, M. Doets, V. Fafone, P. Falferi, R. Flaminio, J. Franc, F. Frasconi, A. Freise, D. Friedrich, P. Fulda, J. Gair, G. Gemme, E. Genin, A. Gennai, A. Giazotto, K. Glampedakis, C. Gräf, M. Granata, H. Grote, G. Guidi, A. Gurkovsky, G. Hammond, M. Hannam, J. Harms, D. Heinert, M. Hendry, I. Heng, E. Hennes, J. Hough, S. Husa, S. Huttner, G. Jones, F. Khalili, K. Kokeyama, K. Kokkotas, B. Krishnan, T. G. F. Li, M. Lorenzini, H. Lück, E. Majorana, I. Mandel, V. Mandic, M. Mantovani, I. Martin, C. Michel, Y. Minenkov, N. Morgado, S. Mosca, B Mours, H. Müller-Ebhardt, P. Murray, R. Nawrodt, J. Nelson, R. Oshaughnessy, C. D. Ott, C. Palomba, A. Paoli, G. Parguez, A. Pasqualetti, R. Passaquieti, D. Passuello, L. Pinard, W. Plastino, R. Poggiani1, P. Popolizio, M. Prato, M. Punturo, P. Puppo, D. Rabeling, P. Rapagnani, J. Read, T. Regimbau, H. Rehbein, S. Reid, F. Ricci, F. Richard, A. Rocchi, S. Rowan, A. Rüdiger, L. Santamaría, B. Sassolas, B. Sathyaprakash, R. Schnabel, C. Schwarz, P. Seidel, A. Sintes, K. Somiya, F. Speirits, K. Strain, S Strigin, P. Sutton, S. Tarabrin, A. Thüring, J. van den Brand, M. van Veggel, C. van den Broeck, A. Vecchio, J. Veitch, F. Vetrano, A. Vicere, S. Vyatchanin, B. Willke, G. Woan, K. Yamamoto

TL;DR

The paper develops the ET-D sensitivity model for a third-generation gravitational-wave observatory, incorporating seismic isolation, gravity-gradient noise, quantum-noise shaping with frequency-dependent squeezing, and cryogenic thermal-noise budgets for silicon test masses. It shows that sub-10 Hz sensitivity is dominated by seismic and gravity-gradient noise, while higher frequencies are limited primarily by quantum noise and mirror thermal noise, with a crossover around 35 Hz between the low- and high-frequency interferometers. The study also details the design implications of a triangular multi-detector network and quantifies how detector orientation affects the effective sensitivity. The ET-D model provides a more realistic baseline for planning a full 3-detector GW observatory and identifies key future work to include additional optical and laser-noise contributions.

Abstract

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.

Sensitivity Studies for Third-Generation Gravitational Wave Observatories

TL;DR

The paper develops the ET-D sensitivity model for a third-generation gravitational-wave observatory, incorporating seismic isolation, gravity-gradient noise, quantum-noise shaping with frequency-dependent squeezing, and cryogenic thermal-noise budgets for silicon test masses. It shows that sub-10 Hz sensitivity is dominated by seismic and gravity-gradient noise, while higher frequencies are limited primarily by quantum noise and mirror thermal noise, with a crossover around 35 Hz between the low- and high-frequency interferometers. The study also details the design implications of a triangular multi-detector network and quantifies how detector orientation affects the effective sensitivity. The ET-D model provides a more realistic baseline for planning a full 3-detector GW observatory and identifies key future work to include additional optical and laser-noise contributions.

Abstract

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.

Paper Structure

This paper contains 7 sections, 4 equations, 7 figures, 1 table.

Table of Contents

  1. Introduction
  2. Seismic Isolation and Gravity Gradient Noise
  3. Shaping of Quantum Noise
  4. Thermal noise contributions
  5. Overall sensitivity of the Einstein Telescope
  6. Building a Full Third-Generation Observatory
  7. Summary and Future Plans

Figures (7)

  • Figure 1: Seismic noise spectrum from an underground location in the Black Forest, Germany (left hand panel). Transfer function of a superattenuator consisting of 6 stages with an overall height of 17 m (center panel). The right hand panel shows the resulting seismic noise contribution for the 17 m superattenuator for the seismic excitation at the Black Forest site (green dashed line). For comparison also ET-B and ET-C are plotted. Their seismic noise contribution is based on the assumption of a generic 5-stage 50 m suspension.
  • Figure 2: Left panel: Gravity gradient noise contribution to ET, for various $\beta$ values, assuming the BFO spectrum shown in Figure 1 as seismic excitation level. Right panel: Suspension thermal noise of the low frequency interferometer of ET as described in Ricci10
  • Figure 3: Left panel: Simplified schematic of an ET interferometer. Quantum noise suppression is achieved by the injection of squeezed light states with frequency dependent squeezing angle. The frequency dependent rotation of the squeezing angle can be realised by using the dispersion of filter cavities, on which the squeezed light is reflected. Each ET low-frequency interferometer will require two filter cavities, while each high-frequency interferometer only requires a single filter cavity. Right hand panel: Quantum noise contribution of the ET low-frequency interferometer, as described in Hild10 (dashed line) and with squeezing losses from filter cavities taken into account (solid line) ET-0104A-10.
  • Figure 4: Left: Quantum noise contribution for a low-frequency ET interferometer with different signal recycling options. For ET-D we assumed detuned signal recycling with SRM reflectivity of 80 %. Also plotted are a tuned signal recycling configuration using a 30 % reflectivity SRM and quantum noise without any signal recycling. In brackets the number of required filter cavities is stated. Right: Quantum noise and mirror thermal noise contributions for different mirror diameters. The aspect ratio is kept constant for all scenarios. Reducing the mirror size (and thus their weight) only slightly increases the mirror thermal noise contributions, but significantly decreases the sensitivity at low frequencies, due to increased radiation pressure noise.
  • Figure 5: Noise budgets for the ET-D low and high-frequency interferometers, using the parameters given in Table \ref{['tab:summary']}.
  • ...and 2 more figures