Wealth of Discoveries From Gravitational-Wave Data Leads to Most Detailed Black Hole “Family Portrait”

Black Hole Cluster

This illustration generated by a computer model shows multiple black holes found within the heart of a dense globular star cluster. Credit: Aaron M. Geller, Northwestern University/CIERA

New analysis of gravitational-wave data leads to wealth of discoveries.

An international research collaboration including Northwestern University astronomers has produced the most detailed family portrait of black holes to date, offering new clues as to how black holes form. An intense analysis of the most recent gravitational-wave data available led to the rich portrait as well as multiple tests of Einstein’s theory of general relativity. (The theory passed each test.)

The team of scientists who make up the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration is now sharing the full details of its discoveries. This includes new gravitational-wave detection candidates which held up to scrutiny — a whopping total of 39, representing a variety of black holes and neutron stars — and new discoveries as a result of combining all the observations. The 39 events averaged more than one per week of observing.

The observations could be a key piece in solving the many mysteries of exactly how binary stars interact. A better understanding of how binary stars evolve has consequences across astronomy, from exoplanets to galaxy formation.

Details are reported in a trio of related papers which were published in pre-print on October 28 at arxiv.org. The studies also are being submitted to peer-reviewed journals.

Gravity Waves Black Hole Merger

This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. Credit: LIGO/T. Pyle

The gravitational-wave signals on which the studies are based were detected during the first half of the third observing run, called O3a, of the National Science Foundation’s Laser Interferometry Gravitational-wave Observatory (LIGO), a pair of identical, 4-kilometer-long interferometers in the United States, and Virgo, a 3-kilometer-long detector in Italy. The instruments can detect gravitational-wave signals from many sources, including colliding black holes and colliding neutron stars.

“Gravitational-wave astronomy is revolutionary — revealing to us the hidden lives of black holes and neutron stars,” said Christopher Berry, an LSC member and author of the papers. “In just five years we have gone from not knowing that binary black holes exist to having a catalog of over 40. The third observing run has yielded more discoveries than ever before. Combining them with earlier discoveries paints a beautiful picture of the universe’s rich variety of binaries.”

Berry is the CIERA Board of Visitors Research Professor in Northwestern’s CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics) and a lecturer at the University of Glasgow. Other Northwestern authors include CIERA members Maya Fishbach and Chase Kimball. CIERA is home to a broad group of researchers in theory, simulation and observation who study black holes, neutron stars, white dwarfs and more.

Stellar Graveyard Masses

A collection of masses for a wide range of compact objects. The graphic shows black holes (blue), neutron stars (orange) and compact objects of uncertain nature (gray) detected through gravitational waves. Each compact binary merger corresponds to three compact objects: the two coalescing objects and the final merger remnant. Credit: Aaron M. Geller, Northwestern University and Frank Elavsky, LIGO-Virgo

As a member of the collaboration, Northwestern researchers analyzed data from the gravitational-wave detectors to infer the properties of detected black hole and neutron star binaries and to provide an astrophysical interpretation of these discoveries.

The papers are summarized as follows:

  • The “catalog paper” details the detections of black holes and neutron stars from the first half of O3a, bringing the total number of detection candidates for that period to 39. This number vastly exceeds detections from the first two observing runs. (The first run had three gravitational-wave detections, and the second had eight.) Previously announced detections from O3a include a mystery object in the mass gap (GW190814) and the first-of-its-kind intermediate mass black hole (GW190521).
  • In the “populations paper,” the researchers reconstructed the distribution of masses and spins of the black hole population and estimated the merger rate for binary neutron stars. The results will help scientists understand the detailed astrophysical processes which shape how these systems form. This improved understanding of the mass distribution of black holes and knowing that black hole spins can be misaligned suggests there could be multiple ways for binary black holes to form.
  • Using the set of detections reported in the catalog paper, the researchers conducted detailed analysis by combining everything together. In what they call the “testing general relativity paper,” the authors placed constraints on Einstein’s theory of general relativity. The theory passed with flying colors, and they updated their best measurements on potential modifications.

“So far, LIGO and Virgo’s third observing run has yielded many surprises,” said Fishbach, a NASA Einstein Postdoctoral Fellow and LSC member. “After the second observing run, I thought we’d seen the whole spectrum of binary black holes, but the landscape of black holes is much richer and more varied than I imagined. I’m excited to see what future observations will teach us.”

Fishbach coordinated writing of the populations paper which outlines what the collaboration has learned about the properties of the family of merging black holes and neutron stars.

Berry helped coordinate analysis as part of a global team to infer the properties of the detections, and he served as an LSC Editorial Board reviewer for the catalog and testing general relativity papers.

Graduate student Chase Kimball, an LSC member, contributed calculations of the rates of mergers to the populations paper. Kimball is co-advised by Berry and Vicky Kalogera, the principal investigator of Northwestern’s LSC group, director of CIERA and the Daniel I. Linzer Distinguished University Professor of Physics and Astronomy in the Weinberg College of Arts and Sciences.

The LIGO and Virgo detectors finished their latest observing run this past March. The data analyzed in these three papers were collected from April 1, 2019, to October 1, 2019. Researchers are in the process of analyzing data from the second half of the observing run, O3b.

The detectors are scheduled to resume observing next year after work is done to increase their detection range.

“Merging black hole and neutron star binaries are a unique laboratory,” Berry said. “We can use them to study both gravity — so far Einstein’s general relativity has passed every test —and the astrophysics of how massive stars live their lives. LIGO and Virgo have transformed our ability to observe these binaries, and, as our detectors improve, the rate of discovery is only going to accelerate.”

The populations paper is titled “Population properties of compact objects from the second LIGO–Virgo Gravitational-Wave Transient Catalog.”
arXiv: 2010.14533

The catalog paper is titled “GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run.”

The testing general relativity paper is titled “Tests of General Relativity with Binary Black Holes from the second LIGO–Virgo.”

This research was funded by the U.S. National Science Foundation.

9 Comments on "Wealth of Discoveries From Gravitational-Wave Data Leads to Most Detailed Black Hole “Family Portrait”"

  1. Warning Black Hole fans: beware of the Neutroid.

    Are Black holes are so massive that their gravity prevents HEAT and Light from escaping or is it just light.

    I think Black holes are simply the galaxy center funnel that we see in hurricanes, we see both a funnel hole and a neutroid in space galaxy photos I have been so I am neutral.

    This theory suggest each galaxy has a giant Neutroid at its center.


    The Steady State Galaxy Theory



    The Steady State Galaxy Theory
    An Alternative To
    The Big Bang Theory
    Work in progress: Check back for updates.
    Last revised May 10,2005.

    ” Basic Operation of Galaxies”

    ( the holds that galaxies do not decay but are recycled through process …I think galaxies can decay )

    ” At the center of each galaxy is a neutroid which acts to constantly recycle all the matter and energy in the galaxy. This neutroid is similar to a neutron star but is very much larger and has reached a size where the pressure and temperature at its surface are great enough to generate a nuclear fusion process. In the areas of the neutroid’s magnetic poles, the products of fusion are trapped by the magnetic field and are pushed out along the magnetic field by the pressure of the nuclear fusion process going on below. This results in a column of material composed of hydrogen, helium and other light elements being ejected at each of the neutroid’s two magnetic poles. This material moves out from the neutroid at essentially constant velocity until it reaches a point where the magnetic field is no longer strong enough to control it. Once free of the magnetic field the material then continues under it’s own momentum to travel to the outer edge of the galaxy before starting to fall back toward the neutroid. …..


    A fourth arguement which has been used to support the Big Bang theory is that it would account for the abundance of helium we find in the universe. The amount of helium present (24%) cannot be accounted for by star production and according to Gamow it was generated by the Big Bang.

    Under the Steady State Galaxy theory, the nuclear fusion process which is expelling the material from the neutroid would generate large amounts of helium as well as other light elements and is the source of the excess helium found in the universe.”

    If helium 4 can escape most gravitational fields – why couldn’t the composition of dark matter in the universe be helium 4 gravity particles? If this is the case the universe is much older than 60 Billion years .

    If you can verify that dark matter is helium 3 or 4 gravity then you’ll win a prize.

    • Torbjörn Larsson | November 22, 2020 at 10:41 am | Reply

      That is pseudoscience and links to pseudoscience sites.

      • Torbjörn Larsson | November 22, 2020 at 10:45 am | Reply

        E.g. we know from the cosmic background spectra that dark matter isn’t baryons (such as He atoms).

        “The first peak mostly shows the density of baryonic matter, while the third peak relates mostly to the density of dark matter, measuring the density of matter and the density of atoms.[59]” [“Dark matter” @ Wikipedia]

  2. Vivian Robinson | November 15, 2020 at 4:42 pm | Reply

    Black holes are said to originate from a mathematical solution to Einstein’s gravitational field equations. The following article on “The Physics of Einstein’s Gravity” shows that it requires flawed mathematics and no understanding of basic physical principles to derive an equation that suggests black holes are possible. Einstein never believed in them. This presentation shows why he as correct. Another metric equation shows that at distances greater than about 5 times the Schwarzschild radius, alpha, it is not possible to tell the difference between a black hole of a given mass and another object of a larger mass. It also predicts, complete with physical reason and mathematical equation, the structure observed by the Event Horizon Telescope collaboration.


    • Torbjörn Larsson | November 22, 2020 at 10:48 am | Reply

      That’s self promotion and is not a peer reviewed publication reference.

      The science behind the EHT black hole shadow image was amply described at the online press conference. And yes, it was confirming general relativity amply!

  3. MURPHY CHESNEY | November 15, 2020 at 9:56 pm | Reply

    It never fails to amaze me how, from day one, relativity has attracted doubters. How many successful tests of General Relativity do we need to accept the equations? For me the best argument is that the equations were derived by Hilbert simultaneously with Einstein. Hilbert was unquestionably the best mathematician of the 20th century and probably the last one who mastered the entire field of mathematics.

  4. A bullet proof vest will stop a bullet from penetrating its composition. But if you take the same bullet at an even less velocity and bring it to an infinite point in its geometry. It will punch right through the vest. Many basic kinetic operations are universal in their mechanics. Without necessarily being in a macro sense quantum mechanical.

  5. What is with the bizarre misunderstandings in some replies? Besides even trying to refute relativity with questionable references, even basic misunderstandings of what black holes are seem to be common… Why?

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