GRANITE (GRAvitational-wave parameter iNference Integration Tool Environment) is a pipeline designed to perform rapid and reliable parameter estimation (PE) for gravitational-wave (GW) events, particularly in the context of low-latency multi-messenger astronomy. It provides an efficient alternative to computationally expensive Bayesian inference frameworks, enabling researchers to extract astrophysical information from GW detections within minutes to hours.
The motivation behind GRANITE is to support the growing need for fast PE tools that can inform electromagnetic (EM) follow-up efforts and real-time scientific interpretation. In many cases, the time scale for identifying optical, X-ray, or radio counterparts is limited to hours or days following a GW detection. Thus, a balance between speed and accuracy is essential.
Key Features:
- Rapid posterior estimation: GRANITE delivers probability distributions for key source parameters—such as masses, spins, luminosity distance, and inclination angle—on short timescales, allowing prompt astrophysical classification.
- Model selection capabilities: The pipeline can compare competing waveform models or source hypotheses, providing statistical evidence for or against specific scenarios (e.g., binary neutron star vs. neutron star–black hole).
- User-friendly interface: GRANITE is designed with accessibility in mind, targeting scientists with varying levels of GW analysis experience. It offers streamlined configuration, standardized outputs, and compatibility with popular data formats (e.g., HDF5, JSON).
- Low-latency integration: The pipeline can be connected to automated detection alerts from existing search pipelines (e.g., MBTA, cWB), making it suitable for triggering EM follow-up or feeding into broker systems.
- Resource-efficient: While full Bayesian samplers like Bilby or LALInference offer high-precision results, they can require hours to days of computing time. GRANITE achieves useful PE results with significantly lower computational cost, making it ideal for real-time applications.
Scientific Use:
GRANITE is suited for both compact binary coalescence (CBC) events and more general transient signals. In typical use cases, it helps characterize the nature of a detected signal—estimating component masses, determining whether the system includes neutron stars, and providing sky localization refinements in conjunction with other tools.
Its ability to produce rapid posterior samples allows observers to:
- Prioritize follow-up campaigns based on likely EM brightness (e.g., BNS vs BBH)
- Inform modelers on the physical parameters of potential kilonova progenitors
- Estimate source inclination, redshift, and chirp mass for cosmological interpretation
GRANITE complements more detailed, slower inference frameworks by providing a first-pass characterization, especially valuable in the early hours following a detection.
GRANITE fills a critical niche in the gravitational-wave data analysis ecosystem: providing fast, accessible, and informative parameter estimation to support time-sensitive multi-messenger science. Its integration into alert pipelines and usability by a broad community of scientists make it a valuable tool for maximizing the scientific return of the GW detector network.
Link: Public release pending