Nav: Home

Where in the universe can you find a black hole nursery?

August 07, 2019

Gravitational wave researchers at the University of Birmingham have developed a new model that could help astronomers track down the origin of heavy black hole systems in the Universe.

Black holes are formed following the collapse of stars and possibly supernova explosions. These colossally dense objects are measured in terms of solar masses (M?) - the mass of our sun.

Typically, stars will only form black holes with masses of up to 45 M?. These systems then pair and merge together, producing gravitational waves that are observed by the LIGO and Virgo detectors.

Stellar collapse, however, causes instabilities that prevent the formation of heavier black holes - so a new model is needed to explain the existence of binary black hole systems with masses larger than about 50 M?.

These objects are thought to be formed from binary black holes which have then gone on to merge with other black holes. Scientists believe that these 'next generation' black holes --made up of the merger of their 'parents' -- might be the heavier black holes observable by LIGO and Virgo.

In a new study, published in Physical Review D Rapid Communications, researchers from the University of Birmingham's Institute for Gravitational Wave Astronomy, suggest that future detections of multiple generations of black-hole mergers would allow us to figure out their birthplace. They have produced new calculations that could help astronomers better understand these mergers - and where to find them.

"Star clusters - groups of stars that are bound together by gravity - might act like black-hole 'nurseries', providing an ideal environment to grow generations of black holes, " explains Dr Davide Gerosa, lead author of the paper. "But in order to know what type of star clusters are most likely to be capable of producing these, we first need to know something about the physical conditions that would be needed."

The team believes they have found part of the solution to this puzzle by calculating the likely 'escape speed' a cluster needs to have to be able to host a black hole with a mass above 50 M?. The escape speed is the velocity at which an object would need to be travelling to escape gravitational pull. For instance, a rocket leaving earth would need to be travelling at 11km/s (25,000 mph) to get into orbit.

When they merge, black holes receive recoils or kick. Much like a gun recoils as a bullet is shot, black holes recoil as gravitational waves are emitted. The next generation of black holes can form only if their parents have not been 'kicked out' of the cluster, i.e. only if the escape speed of the cluster is large enough.

The team calculated that observing black holes with mass above 50 M? would suggest that the cluster where they lived had an escape speed larger than about 50km/s.

Co-author Professor Emanuele Berti from Johns Hopkins University, explains: "Gravitational wave observations provide an unprecedented opportunity to understand the astrophysical settings where black holes form and evolve. A very massive event would point towards a dense environment with large escape speed".

Where might you find these types of dense clusters? Many predictions for LIGO and Virgo so far concentrated on 'globular clusters' - spherical collections of about a million stars tightly bound together in the outskirts of galaxies. Their escape speed, however, is too low. This new study finds globular clusters are unlikely to host multiple generations of black holes. Astronomers will need to look further afield: nuclear star clusters, found towards the centre of some galaxies are dense enough and might provide the type of environment needed to produce these objects.

"Gravitational-wave astronomy is revolutionizing our understanding of the Universe," says Dr Gerosa. "We are all waiting for upcoming results from LIGO and Virgo to put these and other astrophysical predictions to the test".
-end-
For further information please contact Beck Lockwood, Press Office, University of Birmingham, tel 0121 414 2772: email: r.lockwood@bham.ac.uk

Notes to editor:

The University of Birmingham is ranked amongst the world's top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 6,500 international students from over 150 countries.

Gerosa et al (2019). 'Escape speed of stellar clusters from multiple-generation black-hole mergers in the upper mass gap'. Physical Review D - Rapid Communications.

University of Birmingham

Related Science Articles:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.
Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.
Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.
Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.
World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.
PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.
Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.
Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.
More Science News and Science Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#569 Facing Fear
What do you fear? I mean really fear? Well, ok, maybe right now that's tough. We're living in a new age and definition of fear. But what do we do about it? Eva Holland has faced her fears, including trauma and phobia. She lived to tell the tale and write a book: "Nerve: Adventures in the Science of Fear".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.