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REVIEW 2 major objections 6 minor 265 references

LIGO A$^\sharp$: Detector Design and Science Prospects Beyond A+

T0 review · 2 major / 6 minor · reviewed 2026-08-16 · deepseek-v4-flash

Pith's one-line read The LIGO A♯ upgrade would roughly double gravitational-wave sensitivity beyond A+ and multiply compact-binary detection rates by four to eight, while adding minutes of neutron-star early warning.

desk verdict A thorough, transparent A# design study whose headline science is conditional on coating-thermal-noise R&D the paper itself flags as undemonstrated; worth serious refereeing despite that. read the letter →

arxiv 2608.11673 v1 pith:SNZRNMDX submitted 2026-08-12 astro-ph.IM astro-ph.HEgr-qc

L. Sun , K. Kuns , B. J. J. Slagmolen , P. Fritschel , P. Schmidt , B. T. Lantz , S. S. Y. Chua , Divyajyoti
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S. W. Ballmer M. A. Barton A. V. Cumming K. L. Dooley J. C. Driggers A. Effler M. Evans B. Farr G. González N. Lu D. J. Ottaway C. Palomba O. J. Piccinni G. Pratten S. Raja A. P. Subhash P. J. Sutton K. Toland R. L. Ward A. G. Abac I. Abouelfettouh K. Ackley A. Adam S. Adhicary D. Adhikari R. X. Adhikari V. K. Adkins S. Afroz M. Agathos N. Aggarwal S. Aggarwal O. D. Aguiar P. Ajith L. Albers S. Al-Kershi S. Al-Shammari J. A. Alvarez S. Alvarez-Lopez O. Amarasinghe A. Amato S. An A. B. Anand C. Anand A. Ananyeva S. B. Anderson W. G. Anderson F. Andrade-Oliveira M. Andrés-Carcasona J. L. Andrey T. Andric J. Anglin J. Anna J. M. Antelis L. V. da Conceição T. Aoki E. Z. Appavuravther E. A. Appelt S. Appert S. K. Apple K. Arai M. C. Araya J. S. Areeda M. Ramos Arevalo S. Armstrong M. Arogeti S. M. Aronson K. G. Arun G. Ashton S. M. Aston K. AultONeal G. Avallone E. A. Avila C. Badger S. Bae K. A. Baker T. Baker M. Ball S. Banagiri D. Bankar T. M. Baptiste P. Baral J. C. Barayoga K. 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Thomas P. Thomas J. E. Thompson S. R. Thondapu E. Thrane A. Tiwari P. Tiwari S. Tiwari V. Tiwari M. R. Todd A. M. Toivonen V. Tommasini H. Tong C. I. Torrie G. Traylor L. Traylor M. Trevor A. Tripathee R. J. Trudeau T. Tsang K. Tsuji L. Tsukada A. Tuci A. S. Ubhi R. P. Udall V. Undheim V. Upadhyaya L. E. Uronen H. Vahlbruch G. Vajente J. Valencia M. Valentini J. van Dongen K. Vandra M. VanDyke J. Vanier J. Vanosky A. F. Vargas V. Varma A. Vecchio J. Veitch P. J. Veitch B. Verma Y. Verma S. M. Vermeulen F. A. Ramis Vidal S. Vidyant A. D. Viets A. Vijaykumar A. Vilkha F. Llamas Villarreal E. T. Vincent S. Vitale N. Vithanachchi A. Vives L. Vizmeg B. Vizzone D. Voigt E. R. G. von Reis J. S. A. von Wrangel W. E. Vossius L. Vujeva S. P. Vyatchanin J. Wack L. E. Wade M. Wade A. Wade K. J. Wagner L. Wallace W. H. Wang Y. F. Wang Z. Wang P. Wang J. Warner N. Y. Washington B. Weaver S. A. Webster N. L. Weickhardt M. Weinert A. J. Weinstein O. Weisenberger R. Weiss L. Wen K. Wette C. Wheeler J. T. Whelan B. F. Whiting E. G. Wickens D. Wilken B. M. Williams D. Williams M. J. Williams N. S. Williams J. L. Willis B. Willke C. W. Winborn A. Wingfield J. Winterflood C. C. Wipf G. Woan N. E. Wolfe H. T. Wong J. L. Wright B. Wu D. S. Wu K. Wu E. Wuchner D. M. Wysocki Y. Xia V. A. Xu Y. Xu M. Ben Yaala H. Yamamoto T. Yan H. Yang K. Z. Yang Z. Yarbrough A. B. Yelikar X. Yin M. Yoshihara S. Yuan M. Zanolin M. Zeeshan M. Zevin H. Zhang L. Zhang N. Zhang R. Zhang T. Zhang C. Zhao Y. Zhao L.-M. Zheng Y. Zheng H. Zhong H. Zhou H. O. Zhu Z. Zhu D. Z. Zieba A. B. Zimmerman M. E. Zucker R. Arès J. J. Carter S. J. Madden K. McKenzie E. R. Rees B. Shapiro
This is my paper · ORCID
classification astro-ph.IMastro-ph.HEgr-qc PACS 04.80.Nn95.55.Ym
keywords LIGOA♯gravitational-wavedetectorupgradecoatingthermalnoisefrequency-dependentsqueezingtest-masssuspensioncompactbinarydetectionratesneutronstarearlywarningnext-generationobservatorypathfinder
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper argues that a room-temperature upgrade of the existing LIGO detectors, named A♯, can roughly double broadband strain sensitivity relative to the A+ design and raise compact-binary detection rates by a factor of four to eight. The projected gains come from heavier 105 kg test masses, a redesigned suspension and seismic isolation, higher arm-cavity power of 1.5 MW, 10 dB of observed frequency-dependent squeezing, and mirror coatings with half (baseline) or a quarter (optimistic) of today's thermal noise. If the sensitivity curves hold, A♯ would give thousands of black-hole merger detections per year, tens to hundreds of neutron-star events, about six to seven minutes of early warning for a nearby binary neutron star, and ensure detection of the merger-created stochastic background if it is still missing after O5. The paper also positions A♯ as a technology pathfinder for next-generation ground-based observatories, since its core upgrades overlap with designs such as Cosmic Explorer.

What carries the argument

The load-bearing object is the A♯ noise budget, a frequency-separated budget of strain noise in which each band is assigned a specific engineering fix. Below 50 Hz the fix is a heavier 105 kg test mass, higher-stress fused-silica suspension fibers, lower-noise local interferometric sensors, upgraded seismic isolation, and a factor-of-two suppression of Rayleigh-wave Newtonian noise; from 50 to 300 Hz the fix is lower coating thermal noise, with a baseline target of half the Advanced LIGO level and an optimistic target of a quarter; above 300 Hz the fix is 1.5 MW arm power, 10 dB observed squeezing, and reduced optical loss. The wideband variant changes the signal-recycling mirror to broaden the high-frequency bandwidth to 3.4 kHz at the cost of mid-band sensitivity, and all projections are evaluated through this strain-noise-versus-frequency machinery plus population models that convert sensitivity into detection rates.

What would settle it

Run a direct measurement campaign on full-scale optics: take a 300 mm GaAs/AlGaAs coating through bonding onto a 105 kg fused-silica test mass and measure its mechanical loss and optical absorption at 1064 nm; if the loss is not low enough to reach the assumed factor-of-four reduction, or if the titania-germania coating cannot deliver the factor-of-two on both input and end masses, then the mid-band sensitivity curves and all forecasts resting on them must be revised downward.

Watch

Extended reading notes

Core claim

The central claim, stated on the paper's own terms, is that the A♯ design—an upgrade package built around the existing 4 km facilities and room-temperature fused-silica technology—would approximately double the broadband strain sensitivity of LIGO relative to the projected A+ performance. Using the merger rates inferred from the first part of the fourth observing run, the paper projects that annual detection rates for binary mergers increase by roughly a factor of four to eight over A+, with the exact factor depending on the upgrade scenario. The paper further claims that the improved low-frequency sensitivity is what enables the headline multi-messenger gains: a 1.4+1.4 solar-mass binary neutron star at about 130 Mpc would be detectable roughly six to seven minutes before merger, compared with about 1.6 minutes for A+, and the number of neutron-star events localized to better than 100 square degrees would roughly double or triple. Because the gain is broadband, the same upgrade simultaneously improves measurements of black-hole populations, higher-order modes, intermediate-mass black holes, ringdowns, the neutron-star equation of state, continuous waves, and the stochastic background.

Load-bearing premise

The projections rest on the assumption that the mirror coatings can be made much quieter—half today's coating-induced thermal noise in the baseline design and a quarter in the optimistic design—even though no demonstrated path exists for the baseline amorphous coatings beyond the half level, and the quarter level requires 300 mm crystalline coatings that have not yet been made at that size.

Editorial extensions

If this is right

  • Compact-binary catalogs grow by a factor of four to eight, yielding roughly 2,800 black-hole, 120 neutron-star–black-hole, and 69 binary-neutron-star detections per year in the baseline configuration, with the optimistic configuration reaching about 6,600 black-hole and 210 binary-neutron-star events per year.
  • Low-frequency improvements move binary-neutron-star early warning from about 1.6 minutes (A+) to about 6–7 minutes for a 1.4+1.4 solar-mass system at z=0.03, and raise the number of events localized to better than 100 square degrees from roughly 14 to 26–43 per year.
  • The A♯ network can measure the peak of the black-hole merger-rate redshift distribution, for example a peak near z=1.5, and roughly triple the annual number of detections with higher-order-mode SNR above 8 relative to A+ when the optimistic coatings are used.
  • A♯ baseline yields a ringdown SNR of about 12 for a 20 solar-mass binary at 400 Mpc, enough for informative pure-ringdown measurements with an overtone, whereas O4 and A+ give SNRs of 3.8 and 6.0 and are largely uninformative.
  • Any of the A♯ configurations provides enough sensitivity to ensure detection of the astrophysical stochastic background from compact binary mergers if it remains undetected after O5.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If coating thermal noise stalls at the currently demonstrated 40% reduction rather than the assumed 50%, mid-band sensitivity and the equation-of-state, higher-order-mode, and detection-rate forecasts that depend on it would degrade, while the low-frequency early-warning and massive-black-hole gains would largely survive.
  • The factor-of-four-to-eight rate increase is a volume-scaling projection built on O4a merger rates; if future catalogs revise local rates, the absolute event counts shift, but the relative improvement across A♯ configurations should remain close to the projected factor.
  • The wideband-versus-baseline trade-off suggests a natural division of labor in a two-detector network, with one detector optimized for broadband reach and the other for kHz sensitivity, though the paper only notes the downtime cost of switching optics.
  • The A♯ technology list—heavy test masses, low-loss or crystalline coatings, high power, advanced squeezing—is a de facto risk-reduction program for next-generation observatories, so even partial success on the coating front would leave a useful pathfinder role.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

2 major / 6 minor

Summary. The paper presents the LIGO A♯ detector concept, a post-O5 upgrade of the LIGO observatories that retains room-temperature fused-silica technology and 1064 nm laser light. It proposes low-frequency upgrades (105 kg test masses, redesigned suspensions, improved seismic and angular sensors, factor-of-two Newtonian-noise suppression), mid-frequency coating scenarios (baseline reduction of coating thermal noise to 50% of the Advanced LIGO level, and an optimistic reduction to 25%), and high-frequency upgrades (1.5 MW arm power, 10 dB observed squeezing, and an optional wideband signal-recycling configuration). On the basis of these projected sensitivity curves, the paper forecasts a factor-of-four-to-eight increase in compact-binary detection rates relative to A+, improved BNS early warning and localization, better BBH population inference, higher-order-mode and ringdown measurements, EOS constraints, continuous-wave and stochastic-background prospects, and sensitivity to ultralight dark matter. The astrophysical forecasts are computed with standard tools (GWFish, Bilby, gwpopulation, NRSur7dq4) and are explicitly presented as conditional on the assumed sensitivity curves.

Significance. If the projected sensitivity is realized, A♯ would be a substantial scientific stepping stone between A+ and next-generation observatories, roughly doubling broadband strain sensitivity and enabling a wide range of compact-binary and multimessenger science. The paper's main strengths are its transparency and its use of standard, reproducible analysis tools: the scenarios are clearly labeled, the optimistic coating case is described as a limiting case, and the paper itself flags cases where the projected signal-to-noise ratios are marginal, notably the BNS post-merger signals in §3.3.2. The forecasts are conditional on the assumed noise curves and do not feed back into the design, so there is no circularity in the central argument. The significance is real but contingent on technology development that is unevenly mature across the three frequency bands: the low-frequency suspension and Newtonian-noise targets are backed by an engineering design, whereas the mid-frequency coating assumptions, especially the optimistic GaAs/AlGaAs scenario, are explicitly acknowledged as not yet demonstrated at the required scale.

major comments (2)
  1. [§2.2.1, §2.2.2, Tables 3–4, Fig. 17] The central science projections are computed from sensitivity curves in which the baseline coating thermal noise is set to 50% of the Advanced LIGO level and the optimistic scenario to 25%. However, §2.2.1 states that there is no clearly defined pathway to a significant further reduction with amorphous metal-oxide materials, and §2.2.2 lists unresolved items for the 300 mm GaAs/AlGaAs route, including diameter scale-up, sub-ppm absorption and scatter, birefringence noise, and generation-recombination noise. Because coating noise enters the total strain noise in quadrature in the 50–300 Hz band, a partial realization of the assumed reduction directly reduces the surveyed volume for BNS and low-mass BBH systems and weakens the EOS constraints that support the headline factor-of-four-to-eight rate increase. I request a sensitivity scan in which the coating-thermal-noise reduction is varied, for example 0%, 25%, 40%, and 50% relative to Advanced LIGO, with the resulting BNS and BBH ranges, annual detection counts, and tidal-deformability constraints reported for each case. Without this, the reader cannot tell how much of the advertised science is contingent on a single unproven technology.
  2. [§1, Table 4] The abstract and introduction state that detection rates increase by approximately a factor of four to eight relative to A+, depending on the upgrade scenario. Reduced to the median numbers in Table 4, the ratios are about 3.5 to 4 for the baseline configuration across classes and about 8 to 12 for the optimistic configuration, and the 90% credible intervals of the underlying rate estimates overlap substantially, for example the A+ BNS range of 3–61 per year versus the A♯ baseline range of 18–229 per year. The headline factor should be restated as a class- and scenario-dependent median ratio, with the rate-uncertainty caveat carried into the abstract, rather than as a single factor interval that suggests a precision the current rate measurements do not support.
minor comments (6)
  1. [§2.1 bullet list and §2.2.1] The A+ design is described in Section 2 as incorporating a 30% reduction in coating thermal noise, while §2.2.1 says the A+ target is now based on a 40% reduction for the end test masses and a 12% reduction for the input test masses; please reconcile these statements so the baseline A♯ improvement is unambiguously defined.
  2. [§3.2.2] The sentence stating that A♯ optimistic gives 'a factor-of-a-few increase in the fraction of events with detectable higher-order modes relative to the A+ or A♯ configurations without major improvements to the coating thermal noise' is ambiguous; please state explicitly which configuration is the reference and report the conditional fractions consistently for all four configurations.
  3. [§3.3.1] The EOS forecasts use zero-noise Bilby injections; the paper should state this assumption prominently and note that single-noise-realization credible intervals from zero-noise runs can be narrower than those obtained with realistic noise, which is relevant to the quoted 'approximately 40% improvement' in tidal-deformability constraints.
  4. [Table 3] The column header 'BBHz max' should be written as 'BBH z_max' for clarity.
  5. [§3.1.4 and §3.2.1] The simulated BNS and BBH populations both use the Madau–Dickinson star-formation model with an inverse-time-delay distribution, but the two sections quote different local rate densities (130 Gpc^-3 yr^-1 for the BNS full population and 19 Gpc^-3 yr^-1 for BBHs); please add a sentence explaining how these choices relate to the GWTC-4 rate constraints quoted in Table 4.
  6. [§3.3.2] The post-merger SNR analysis is a good example of honest reporting: the conclusion that A♯ baseline is unlikely to enable regular post-merger detections is clearly stated, and the wideband configuration is recommended only for exceptionally nearby events.

Circularity Check

0 steps flagged · score 1.0 of 10

No significant circularity: the science forecasts are explicit conditionals on clearly labeled sensitivity assumptions, with independent population inputs and external benchmarks.

full rationale

The paper's derivation chain is: (1) fix a set of detector parameters; (2) build strain-noise curves from physics-based component models; (3) compute detection ranges, rates, and parameter-estimation forecasts; (4) compare with A+ and O4. Each link is explicit and conditional. The coating-thermal-noise reductions are assumptions, not fitted values: Section 2.2.1 states 'we assume that the 50% reduction for titania-germania coatings suggested in Ref. [71] can be realized with further development and applied to both input and end test masses,' and Section 2.2.2 labels the optimistic case an 'optimistic limiting case' involving 300 mm GaAs/AlGaAs coatings with open items including birefringence noise and generation-recombination noise. The rate and EOS projections therefore inherit the coating assumption, but this is a documented sensitivity and risk, not a circular reduction of a prediction to its input. Population inputs come from external GWTC-4 analyses, and the paper's own injection-recovery exercises (e.g., figure 11 and figure 17) are self-consistency demonstrations rather than predictions of injected values as independent facts. Self-citations exist, notably the post-O5 study group report [13] defining the A# design, the wideband tuning reference [23], and the population-inference procedure [151], but they are contextual and corroborative; the central claims are supported by the paper's own modeling and by external benchmarks such as the A+ design curve and O4 data. No step reduces to its own input by construction.

Assumptions & free parameters 5 free parameters · 4 assumptions · 0 invented entities

The projections rest on several adjustable design targets (coating noise, squeezing, power, Newtonian noise suppression) that are chosen by hand and are not yet demonstrated. These are not fitted to the science outcomes, so the circularity burden is low, but they are load-bearing for the forecast. The population and waveform models are inputs from prior independent analyses.

free parameters (5)
  • Baseline coating thermal noise reduction = 50% relative to Advanced LIGO
    Assumed achievable with titania-germania coatings; central to mid-frequency sensitivity.
  • Optimistic coating thermal noise reduction = 75% relative to Advanced LIGO
    Assumed achievable with GaAs/AlGaAs crystalline coatings; a scenario.
  • Observed squeezing level = 10 dB
    Target for frequency-dependent squeezing, affecting high-frequency sensitivity.
  • Arm cavity power = 1.5 MW
    Target circulating power, up from 550 kW in A+.
  • Newtonian noise suppression = 6 dB (factor 2)
    Assumed suppression from seismometer arrays and tilt sensors.
assumptions (4)
  • domain assumption GWTC-4 merger rates and population models are correct
    Detection rate forecasts use rates from Ref [5].
  • domain assumption IMRPhenomXPHM and NRSur7dq4 waveform models are accurate for the simulated signals
    Used for higher-order modes and IMBH studies.
  • standard math Flat Lambda-CDM cosmology with H0=67.9 km/s/Mpc and Omega_m=0.3065
    Used for horizon redshift calculations.
  • domain assumption The design noise curves can be achieved
    All projections are conditional on the assumed PSDs.

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Cite this review

Pith. "Pith review of LIGO A$^\sharp$: Detector Design and Science Prospects Beyond A+." pith.science (2026). https://pith.science/paper/SNZRNMDX

@misc{pith2026260811673,
  author       = {Pith},
  title        = {Pith review of: LIGO A$^\sharp$: Detector Design and Science Prospects Beyond A+},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/SNZRNMDX}},
  note         = {Machine review of arXiv:2608.11673}
}
abstract

We present the LIGO A$^\sharp$ detector concept, an upgrade for the LIGO observatories based on room-temperature interferometers beyond the fifth observing run (O5). Building on the A+ sensitivity, A$^\sharp$ targets broadband sensitivity improvements through heavier test masses, improved suspensions and seismic isolation, increased arm-cavity power, enhanced frequency-dependent squeezing, reduced coating thermal noise considering two scenarios, and improved control of mechanical motion and optical modes. We describe the principal design choices, projected noise performance, and corresponding astrophysical prospects. LIGO A$^\sharp$ substantially increases compact-binary detection rates, strengthens population inference, and improves both early-warning times and localization for binary neutron star mergers. The improved sensitivity enables more detailed studies of compact-binary coalescences, including higher-order multipoles, intermediate-mass black holes, remnant black hole ringdown, and the neutron star equation of state. It also broadens the discovery potential for new gravitational-wave sources such as continuous waves and bursts, should enable detection of the stochastic background from compact binary mergers if it remains undetected after O5, and strengthens the role of gravitational-wave detectors as probes of fundamental physics. We discuss key technical challenges and the role of A$^\sharp$ as both a major scientific upgrade for the 2030s and a technology pathfinder for next-generation gravitational-wave observatories, such as Cosmic Explorer.

Figures

Figures reproduced from arXiv: 2608.11673 by the authors.

Figure 1
Figure 1. Design strain noise spectra for the LIGO A [PITH_FULL_IMAGE:figures/full_fig_p016_1.png] view at source ↗
Figure 2
Figure 2. Horizon redshifts for representative compact binary coalescences and [PITH_FULL_IMAGE:figures/full_fig_p017_2.png] view at source ↗
Figure 3
Figure 3. Noise budget for the A♯ baseline target design sensitivity. The total coating thermal noise, the sum of both Brownian and thermo-optic noise, corresponds to a factor-of-two reduction from the Advanced LIGO level. For the noise budgets of the A♯ optimistic and A♯ wideband configurations, see figures 5 and 7, respectively. 2.1. Low-frequency upgrades Significant research efforts have led to continuous improvements in … view at source ↗
Figures from the paper (19 more)
Figure 4
Figure 4. Figure 4: Advanced LIGO and A+ suspension (left) for the input test mass, and a [PITH_FULL_IMAGE:figures/full_fig_p022_4.png]
Figure 5
Figure 5. Figure 5: A♯ optimistic noise budget. The total coating thermal noise, the sum of both Brownian and thermo-optic noise, corresponds to a factor-of-four reduction from the Advanced LIGO level. One coating technology that could potentially reach this lower-noise target is crystall…
Figure 6
Figure 6. Figure 6: Conceptual optical layout of the A♯ upgrades, building on A+ [11], as discussed in section 2.3. The design includes 105 kg test masses, increased arm￾cavity power of 1.5 MW, an observed squeezing level of 10 dB, advanced test-mass thermal-deformation control and spatia…
Figure 7
Figure 7. Figure 7: A♯ wideband noise budget. Compared to the A♯ baseline design, the signal recycling mirror (SRM) transmission is reduced to 5% (from 32.5%), and the filter cavity finesse and detuning is re-optimized. Relative to the A♯ baseline configuration, there are several trade-of…
Figure 8
Figure 8. Figure 8: Horizon redshifts corresponding to an SNR of 8 for face-on, optimally [PITH_FULL_IMAGE:figures/full_fig_p037_8.png]
Figure 9
Figure 9. Figure 9: Cumulative numbers of BNS events as a function of localization area (left) [PITH_FULL_IMAGE:figures/full_fig_p041_9.png]
Figure 10
Figure 10. Figure 10: Input population used for population inference. The grey histogram [PITH_FULL_IMAGE:figures/full_fig_p042_10.png]
Figure 11
Figure 11. Figure 11: Population-inference results for the A [PITH_FULL_IMAGE:figures/full_fig_p043_11.png]
Figure 12
Figure 12. Figure 12: Expected distribution of the SNR in the higher-order modes ( [PITH_FULL_IMAGE:figures/full_fig_p046_12.png]
Figure 13
Figure 13. Figure 13: One-dimensional posterior probability distribution of the source-frame [PITH_FULL_IMAGE:figures/full_fig_p048_13.png]
Figure 14
Figure 14. Figure 14: Left: One-dimensional posterior distribution of the effective precession [PITH_FULL_IMAGE:figures/full_fig_p049_14.png]
Figure 15
Figure 15. Figure 15: Strain amplitude spectral density of a numerical-relativity waveform for [PITH_FULL_IMAGE:figures/full_fig_p051_15.png]
Figure 16
Figure 16. Figure 16: Pure-ringdown constraints (90% credible regions) on the remnant BH [PITH_FULL_IMAGE:figures/full_fig_p052_16.png]
Figure 17
Figure 17. Figure 17: One-dimensional posterior probability density of the binary tidal [PITH_FULL_IMAGE:figures/full_fig_p053_17.png]
Figure 18
Figure 18. Figure 18: Mass-radius constraints for a simulated GW170817-like BNS event at a [PITH_FULL_IMAGE:figures/full_fig_p053_18.png]
Figure 19
Figure 19. Figure 19: Sensitivity reach for all-sky CW searches (95% confidence level). The [PITH_FULL_IMAGE:figures/full_fig_p058_19.png]
Figure 20
Figure 20. Figure 20: Forecast of the astrophysical GW background from compact [PITH_FULL_IMAGE:figures/full_fig_p059_20.png]
Figure 21
Figure 21. Figure 21: Horizon distance (colored contours) as a function of remnant BH mass and [PITH_FULL_IMAGE:figures/full_fig_p060_21.png]
Figure 22
Figure 22. Figure 22: Projected sensitivity to ultralight dark matter for the detector [PITH_FULL_IMAGE:figures/full_fig_p061_22.png]

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