Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Monster galaxy may have been stirred up by black-hole mischief

26.10.2012
Astronomers using the NASA/ESA Hubble Space Telescope have obtained a remarkable new view of a whopper of an elliptical galaxy, with a core bigger than any seen before. There are two intriguing explanations for the puffed up core, both related to the action of one or more black holes, and the researchers have not yet been able to determine which is correct.
Spanning a little over one million light-years, the galaxy is about ten times the diameter of the Milky Way galaxy. The bloated galaxy is a member of an unusual class of galaxies with an unusually diffuse core filled without any a concentrated peak of light around a central black hole. Viewing the core is like seeing a city with no centre, just houses sprinkled across a vast landscape.

An international team of astronomers used Hubble's Advanced Camera for Surveys and Wide Field Camera 3 to measure the amount of starlight across the galaxy, catalogued as 2MASX J17222717+3207571 but more commonly called A2261-BCG (short for Abell 2261 Brightest Cluster Galaxy). Located three billion light-years away, the galaxy is the most massive and brightest galaxy in the Abell 2261 cluster.

The Hubble observations revealed that the galaxy's puffy core, measuring about 10 000 light-years, is the largest yet seen. A galaxy's core size is typically correlated with the dimensions of its host galaxy, but in this case, the central region is much larger than astronomers would expect for the galaxy's size. The bloated core is more than three times larger than the centre of other very luminous galaxies.

Astronomers have proposed two possibilities for the puffy core. One scenario is that a pair of merging black holes gravitationally stirred up and scattered the stars. Another idea is that the merging black holes were ejected from the core. Left without an anchor, the stars began spreading out even more, creating the puffy appearance of the core.

Previous Hubble observations have revealed that supermassive black holes, with masses millions or billions times more than the Sun, reside at the centres of nearly all galaxies and may play a role in shaping those central regions.

"Expecting to find a black hole in every galaxy is sort of like expecting to find a pit inside a peach," explains astronomer Tod Lauer of the National Optical Astronomy Observatory in Tucson, USA, a co-author of the Hubble study. "With this Hubble observation, we cut into the biggest peach and we can't find the pit. We don't know for sure that the black hole is not there, but Hubble shows that there's no concentration of stars in the core."

Team leader Marc Postman of the Space Telescope Science Institute in Baltimore, USA, said the galaxy stood out in the Hubble image. "When I first saw the image of this galaxy, I knew right away that it was unusual," Postman explained. "The core was very diffuse and very large. The challenge was then to make sense of all the data, given what we knew from previous Hubble observations, and come up with a plausible explanation for the intriguing nature of this particular galaxy."

The paper describing the results appeared in the 10 September issue of the Astrophysical Journal.

The astronomers expected to see a slight cusp of light in the galaxy's centre, marking the location of the black hole and attendant stars. Instead, the starlight's intensity remained fairly even across the galaxy.

One possibility for the puffy core may be due to two central black holes orbiting each other. These black holes collectively could have been as massive as several billion suns. One of the black holes would be native to the galaxy, while the second could have been added from a smaller galaxy that was gobbled up by the massive elliptical.

In this scenario, stars circling in the giant galaxy's centre came close to the twin black holes. The stars were then given a gravitational boot out of the core. Each gravitational slingshot robbed the black holes of momentum, moving the pair ever closer together, until finally they merged, forming one supermassive black hole that still resides in the galaxy's centre.

Another related possibility is that the black hole merger created gravity waves, which are ripples in the fabric of space. According to the theory of general relativity, a pair of merging black holes produces ripples of gravity that radiate away. If the black holes are of unequal mass, then some of the energy may radiate more strongly in one direction, providing the equivalent of a rocket thrust. The imbalance of forces would have ejected the merged black hole from the centre at speeds of millions of kilometres per hour, resulting in the rarity of a galaxy without a central black hole. "The black hole is the anchor for the stars," Lauer explains. "If you take it out, all of a sudden you have a lot less mass. The stars aren't held together very well and they move outwards, enlarging the core even more."

The team admits that the ejected black-hole scenario may sound far-fetched, "but that's what makes observing the Universe so intriguing — sometimes you find the unexpected," Postman says.

Lauer adds: "This is a system that's interesting enough that it pushes against a lot of questions. We have thought an awful lot about what black holes do. But we haven't been able to test our theories. This is an interesting place where a lot of the ideas we've had can come together and can be tested, fairly exotic ideas about how black holes may interact with each other dynamically and how they would affect the surrounding stellar population."

The team is now conducting follow-up observations with the Very Large Array radio telescope in New Mexico. The astronomers expect material falling onto a black hole to emit radio waves, among other types of radiation. They will compare the VLA data with the Hubble images to more precisely pin down the location of the black hole, if it indeed exists.

The Abell 2261 cluster is part of a multi-wavelength survey, led by Postman, called the Cluster Lensing And Supernova survey with Hubble (CLASH). The survey probes the distribution of dark matter in 25 massive galaxy clusters.

Notes
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

[1] The international team of astronomers in this study consists of Marc Postman (Space Telescope Science Institute, USA), Tod R. Lauer (National Optical Astronomy Observatory, USA), Megan Donahue (Michigan State University, USA), Genevieve Graves (University of California, Berkeley, USA), Dan Coe (Space Telescope Science Institute, USA), John Moustakas (University of California, La Jolla, USA and Siena College USA), Anton Koekemoer (Space Telescope Science Institute, USA), Larry Bradley (Space Telescope Science Institute, USA), Holland C. Ford (Johns Hopkins University, USA), Claudio Grillo (University of Copenhagen, Denmark), Adi Zitrin (University of Heidelberg, Germany), Doron Lemze (Johns Hopkins University, USA), Tom Broadhurst (University of the Basque Country, Spain and IKERBASQUE Basque Foundation for Science, Spain), Leonidas Moustakas (Jet Propulsion Laboratory, California Institute of Technology, USA), BegoñÞa Ascaso Instituto Astrofísico de Andalucía, Spain), Elinor Medezinski (Johns Hopkins University, USA) and Daniel Kelson (Observatories of the Carnegie Institution of Washington, USA).

The research is published in a paper entitled "A brightest cluster galaxy with an extremely flat core", which appears in the 10 September issue of the Astrophysical Journal.

Image credit: Credit: NASA, ESA, M. Postman (Space Telescope Science Institute, USA), T. Lauer (National Optical Astronomy Observatory, USA), and the CLASH team.
Contacts

Marc Postman
Space Telescope Science Institute
Baltimore, USA
Tel: +1-410-338-4340
Email: postman@stsci.edu

Adi Zitrin
Heidelberg University, Center for Astronomy, Institute for Theoretical Astrophysics
Heidelberg, Germany
Email: adizitrin@gmail.com

Tod Lauer
National Optical Astronomy Observatory
Tucson, USA
Tel: +1-520-318-8920
Email: lauer@noao.edu

Oli Usher
Hubble/ESA
Garching, Garching
Tel: +49-89-3200-6855
Email: ousher@eso.org

Ray Villard
Space Telescope Science Institute
Baltimore, USA
Tel: +1-410-338-4514
Email: villard@stsci.edu

Oli Usher | EurekAlert!
Further information:
http://www.eso.org
http://www.spacetelescope.org/news/heic1216/

More articles from Physics and Astronomy:

nachricht When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

nachricht Thermal Radiation from Tiny Particles
22.06.2018 | Universität Greifswald

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>