Tests of General Relativity with GWTC-3 (2112.06861v1)

Abstract: The ever-increasing number of detections of gravitational waves (GWs) from compact binaries by the Advanced LIGO and Advanced Virgo detectors allows us to perform ever-more sensitive tests of general relativity (GR) in the dynamical and strong-field regime of gravity. We perform a suite of tests of GR using the compact binary signals observed during the second half of the third observing run of those detectors. We restrict our analysis to the 15 confident signals that have false alarm rates $\leq 10^{-3}\, {\rm yr}^{-1}$. In addition to signals consistent with binary black hole (BH) mergers, the new events include GW200115_042309, a signal consistent with a neutron star--BH merger. We find the residual power, after subtracting the best fit waveform from the data for each event, to be consistent with the detector noise. Additionally, we find all the post-Newtonian deformation coefficients to be consistent with the predictions from GR, with an improvement by a factor of ~2 in the -1PN parameter. We also find that the spin-induced quadrupole moments of the binary BH constituents are consistent with those of Kerr BHs in GR. We find no evidence for dispersion of GWs, non-GR modes of polarization, or post-merger echoes in the events that were analyzed. We update the bound on the mass of the graviton, at 90% credibility, to $m_g \leq 1.27 \times 10^{-23} \mathrm{eV}/c^2$. The final mass and final spin as inferred from the pre-merger and post-merger parts of the waveform are consistent with each other. The studies of the properties of the remnant BHs, including deviations of the quasi-normal mode frequencies and damping times, show consistency with the predictions of GR. In addition to considering signals individually, we also combine results from the catalog of GW signals to calculate more precise population constraints. We find no evidence in support of physics beyond GR.

• The paper rigorously analyzes gravitational wave data using robust statistical techniques to test General Relativity predictions.
• It provides precise measurements of total mass, chirp mass, spin magnitudes, and tilt angles from events like GW200322G and GW191109A.
• The findings refine binary evolution models and enhance detection methods, advancing our understanding of cosmic merger phenomena.

Analyzing Gravitational Wave Detections and Their Properties

This paper presents an extensive analysis of gravitational wave (GW) detections, focusing on various properties related to astrophysical events identified in gravitational wave data. A detailed investigation of masses, spins, tilts, and other parameters related to the compact binary coalescences is conducted, offering insights into the understanding of GW events.

Methodology and Analysis

The research employs gravitational wave data collected from a series of events, such as GW200322G, GW200316I, and many more. Accurate measurements of binary black hole mergers are provided, entailing detailed confidence intervals for parameters like total mass, chirp mass, and spin characteristics. Notably, the paper extensively outlines methodologies for analyzing these parameters, using statistical techniques that include robust estimation of percentiles and the use of posterior distributions for precision in parameter estimation.

Key Findings

• Total Mass and Final Mass Distributions: The paper documents the medians and percentile ranges for various events, such as a total mass of 160 ${M_⊙}$ for GW200322G (with comprehensive range estimates provided). For instance, analysing GW191109A reveals a substantial confidence interval in the total mass and final mass, giving insights into the dynamics of these mergers.
• Spin and Tilt Measurements: Spin magnitudes and alignments are critically evaluated. Results such as a median spin of 0.69 for GW200322G, with a range reaching high confidence, depict the significance of angular momentum in these astrophysical phenomena. Measurements of tilt angles further inform alignments, which are crucial for understanding the precession effects in these systems.
• Chirp Mass and Redshift Analysis: Robust estimates of chirp masses across events elucidate the orbital dynamics and energy distributions in these systems. Additionally, redshift estimates help in the understanding of the distances to these sources and the expansion of the universe.

Implications

The paper's findings have several implications for both theoretical astrophysics and the development of detection techniques in gravitational wave astronomy. The precision in these parameters enhances models of binary evolution, shock friction during mergers, and overall astrophysical event rate predictions. The insights into spin distributions, in particular, open discussions on formation channels of binary mergers, potentially influencing the sensitivity and algorithms used in GW detectors.

Future Directions

Future research directions suggested by the paper involve refining parameter estimation methods and exploring new detections as GW observatories, such as LIGO, VIRGO, and KAGRA, improve their sensitivities. The continuous collection and integration of data may also pave the way for understanding more complex systems like neutron star-black hole binaries or eccentric mergers, which remain more elusive in current detections.

In conclusion, this paper offers a rigorous quantitative analysis of gravitational wave detections, emphasizing the statistical methodologies and implications for our understanding of the cosmos. The high precision associated with these findings highlights the advanced techniques required in modern astrophysics to decipher the fundamental properties of gravitational wave events.