Binary Black Hole Mergers in the first Advanced LIGO Observing Run (1606.04856v4)

Abstract: The first observational run of the Advanced LIGO detectors, from September 12, 2015 to January 19, 2016, saw the first detections of gravitational waves from binary black hole mergers. In this paper we present full results from a search for binary black hole merger signals with total masses up to $100 M_\odot$ and detailed implications from our observations of these systems. Our search, based on general-relativistic models of gravitational wave signals from binary black hole systems, unambiguously identified two signals, GW150914 and GW151226, with a significance of greater than $5\sigma$ over the observing period. It also identified a third possible signal, LVT151012, with substantially lower significance, and with an 87% probability of being of astrophysical origin. We provide detailed estimates of the parameters of the observed systems. Both GW150914 and GW151226 provide an unprecedented opportunity to study the two-body motion of a compact-object binary in the large velocity, highly nonlinear regime. We do not observe any deviations from general relativity, and place improved empirical bounds on several high-order post-Newtonian coefficients. From our observations we infer stellar-mass binary black hole merger rates lying in the range $9-240 \mathrm{Gpc}^{-3} \mathrm{yr}^{-1}$. These observations are beginning to inform astrophysical predictions of binary black hole formation rates, and indicate that future observing runs of the Advanced detector network will yield many more gravitational wave detections.

• The paper achieves a breakthrough by reporting the first high-significance detection of gravitational waves from binary black hole mergers.
• Advanced LIGO's analysis using general-relativistic models enabled precise measurements of black hole masses and spins, including GW150914's 36.2-solar-mass primary.
• The inferred merger rates (9–240 Gpc³ yr⁻¹) and findings support future gravitational-wave detections and advance our understanding of astrophysical phenomena.

Overview of Binary Black Hole Mergers in the First Advanced LIGO Observing Run

This paper presents the results from the first observational run of the Advanced LIGO detectors that operated between September 12, 2015, and January 19, 2016. A significant milestone was achieved during this period as gravitational waves from binary black hole mergers were observed for the first time. The paper details the findings associated with binary black hole mergers, specifically the events GW150914, GW151226, and a less certain event, LVT151012.

The analysis of this run utilized general-relativistic models of gravitational-wave signals emanating from binary black hole systems. The paper remains critical as it unambiguously identified two gravitational-wave events with a high statistical significance greater than 5σ, underscoring the reliability of the results. Additionally, there is a discussion of a third potential signal, LVT151012, which presented a probability of 87% for being of astrophysical origin, despite lower statistical significance.

Numerical and Technical Highlights

Significant numerical results were presented:

• GW150914 and GW151226: These events were identified with high significance, demonstrating the capability of LIGO to observe gravitational waves from stellar-mass binary black holes.
• Black Hole Mass and Spin Measurements: The paper provides insights into the parameters of the observed systems, including component masses and spins for the binary black holes. GW150914's primary mass is reported as 36.2 solar masses, while GW151226's primary mass is 14.2 solar masses. Such observations are instrumental in understanding the mass distribution of black holes.
• Merger Rates: The inferred rates of stellar-mass binary black hole mergers range between 9–240 Gpc³ yr⁻¹. This range provides a basis for predicting future gravitational-wave detections with increasing rates in upcoming observational runs.

Implications and Theoretical Impact

The results confirm Einstein's theory of general relativity as none of the observed waveforms showed significant deviations from the theory's predictions. The precise estimation of high-order post-Newtonian coefficients enhances the understanding of two-body motion in the strong-field regime. These observations provide a wealth of information for astrophysics, particularly in shaping predictions related to the formation rates of binary black holes.

Future Developments

The paper accentuates that future observing runs by the Advanced LIGO and Virgo detectors will likely lead to many more gravitational-wave detections. It suggests that refining the observing technology will open pathways for studying the nonlinear dynamics of binary black holes, further expanding our understanding of these astrophysical phenomenons.

In conclusion, this pioneering run has set the stage for substantial theoretical and practical advancements in the field of astrophysics, remarkably showcasing the intersection of empirical observation and theoretical physics. The ability to observe and confirm the existence of gravitational waves sets a precedent for forthcoming astronomical studies and observational technologies, paving the way for novel insights into the universe’s most enigmatic phenomena.