On June 1, 2017, the LIGO Scientific Collaboration and Virgo Collaboration announced the third confirmed observation of gravitational waves from colliding black holes. The gravitational wave signals were observed by the LIGO’s twin observatories on January 4, 2017.

Comparison of gravitational-wave signal templates from recent LIGO observations. This figure shows reconstructions of the three confident and one candidate (LVT151012) gravitational wave signals detected by LIGO to date, including the most recent detection GW170104. Each row shows the signal arriving at the Hanford detector as a function of time. The thickness of the curves indicates the 90% confidence interval on the model parameters. Only the portion of each signal that LIGO was sensitive to is shown here (the final seconds leading up to the black hole merger). [Credit: LIGO/B. Farr (U. Chicago)]

New Population of Binary Black Holes. LIGO has discovered a new population of black holes with masses that are larger than what had been seen before with X-ray studies alone (purple). The three confirmed detections by LIGO (GW150914, GW151226, GW170104), and one lower-confidence detection (LVT151012), point to a population of stellar-mass binary black holes that, once merged, are larger than 20 solar masses—larger than what was known before. [Image credit: LIGO/Caltech/Sonoma State (Aurore Simonnet)]

Animation of the inspiral and collision of two black holes consistent with the masses and spins of GW170104. The top part of the movie shows the black hole horizons (surfaces of “no return”). The initial two black holes orbit each other, until they merge and form one larger remnant black hole. The shown black holes are spinning, and angular momentum is exchanged among the two black holes and with the orbit. This results in a quite dramatic change in the orientation of the orbital plane, clearly visible in the movie. Furthermore, the spin-axes of the black holes change, as visible through the colored patch on each black hole horizon, which indicates the north pole.

The lower part of the movie shows the two distinct gravitational waves (called ‘polarizations’) that the merger is emitting into the direction of the camera. The modulations of the polarizations depend sensitively on the orientation of the orbital plane, and thus encode information about the orientation of the orbital plane and its change during the inspiral. Presently, LIGO can only measure one of the polarizations and therefore obtains only limited information about the orientation of the binary. This disadvantage will be remedied with the advent of additional gravitational wave detectors in Italy, Japan and India.

Finally, the slowed-down replay of the merger at the end of the movie makes it possible to observe the distortion of the newly formed remnant black hole, which decays quickly. Furthermore, the remnant black hole is “kicked” by the emitted gravitational waves, and moves upward. (Credit: A. Babul/H. Pfeiffer/CITA/SXS.)

Dancing Duo of Black Holes. Artist’s conception shows two merging black holes similar to those detected by LIGO. The black holes are spinning in a non-aligned fashion, which means they have different orientations relative to the overall orbital motion of the pair. LIGO found hints that at least one black hole in the system called GW170104 was non-aligned with its orbital motion before it merged with its partner. [Image credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)]

Before the Merge: Spiraling Black Holes. Artist’s conception shows two merging black holes similar to those detected by LIGO. The black holes—which will ultimately spiral together into one larger black hole—are illustrated to be orbiting one another in a plane. The black holes are spinning in a non-aligned fashion, which means they have different orientations relative to the overall orbital motion of the pair. There is a hint of this phenomenon found by LIGO in at least one black hole of the GW170104 system. [Image credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)]

Sky Map of LIGO’s Black-Hole Mergers. This three-dimensional projection of the Milky Way galaxy onto a transparent globe shows the probable locations of the three confirmed LIGO black-hole merger events—GW150914 (blue), GW151226 (orange), and the most recent detection GW170104 (magenta)—and a fourth possible detection, at lower significance (LVT151012, green). The outer contour for each represents the 90 percent confidence region; the innermost contour signifies the 10 percent confidence region. [Image credit: LIGO/Caltech/MIT/Leo Singer (Milky Way image: Axel Mellinger)]

Forecasting LIGO Detections in the Three-Detector Era. This map illustrates how the addition of the Virgo detector, scheduled to come online this summer, could improve the localization of sources of gravitational waves. The map shows the estimated locations of the four black-hole merger events detected by LIGO to date (including one event seen at lower significance), after including hypothetical Virgo data. Outer contours represent the 90 percent confidence region; innermost contours signify the 10 percent confidence region. [Image credit: LIGO/Caltech/MIT/Leo Singer (Milky Way image: Axel Mellinger)]

Numerical simulation of a binary black-hole coalescence with masses and spins consistent with the GW170104 observation. The strength of the gravitational wave is indicated by elevation as well as color, with blue indicating weak fields and yellow indicating strong fields. We rescale the amplitude of the gravitational wave during the simulation to show the signal during the entire animation not only close to merger, where it is strongest. The sizes of the black holes are increased by a factor of two to improve visibility. The bottom panel in the video shows the gravitational waveform starting at frequency of 25Hz. The fade in of the video corresponds to a frequency of about 30Hz.
[Credits: Numerical-relativistic simulation: S. Ossokine, A. Buonanno (Max Planck Institute for Gravitational Physics) and the Simulating eXtreme Spacetimes project; scientific visualization: T. Dietrich (Max Planck Institute for Gravitational Physics), R. Haas (NCSA)]

Comparison of the two events GW150914 (top) and GW170104 (bottom). The strength of the gravitational wave is indicated by elevation and color. We rescale the amplitude of the gravitational wave during the simulation to show the signal during the entire animation and not only close to merger, where it is strongest. The sizes of the black holes are increased by a factor of two to improve visibility. The two animations for GW150914 and GW170104 start at the same gravitational wave frequency of about 25Hz, but because of the different total mass of the binaries, GW150914 merges earlier and has a smaller number of orbits until merger. See this link for a left/right panel version.
[Credits: Numerical-relativistic simulation: S. Ossokine, A. Buonanno (Max Planck Institute for Gravitational Physics) and the Simulating eXtreme Spacetimes project; scientific visualization: T. Dietrich (Max Planck Institute for Gravitational Physics), R. Haas (NCSA)]