Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NASA's Hubble Spots a Relic from a Shredded Galaxy

21.02.2012
Astronomers using NASA's Hubble Space Telescope may have found evidence for a cluster of young, blue stars encircling one of the first intermediate-mass black holes ever discovered.

Astronomers believe the black hole may once have been at the core of a now-disintegrated unseen dwarf galaxy. The discovery of the black hole and the possible star cluster has important implications for understanding the evolution of supermassive black holes and galaxies.

Astronomers know how massive stars collapse to form black holes but it is not clear how supermassive black holes, which weigh billions of times the mass of our Sun, form in the cores of galaxies. One idea is that supermassive black holes may build up through the merger of smaller black holes.

Sean Farrell of the Sydney Institute for Astronomy in Australia discovered a middleweight black hole in 2009 using the European Space Agency's XMM-Newton X-ray space telescope. Known as HLX-1 (Hyper-Luminous X-ray source 1), the black hole has an estimated weight of about 20,000 solar masses. It lies towards the edge of the galaxy ESO 243-49, 290 million light-years from Earth.

Farrell then observed HLX-1 simultaneously with NASA's Swift observatory in X-ray and Hubble in near-infrared, optical, and ultraviolet wavelengths. The intensity and the color of the light may indicate the presence of a young, massive cluster of blue stars, 250 light-years across, encircling the black hole. Hubble can't resolve the stars individually because the suspected cluster is too far away. The brightness and color is consistent with other clusters of stars seen in other galaxies, but some of the light may be coming from the gaseous disk around the black hole.

"Before this latest discovery we suspected that intermediate-mass black holes could exist, but now we understand where they may have come from," Farrell said. "The fact that there seems to be a very young cluster of stars indicates that the intermediate-mass black hole may have originated as the central black hole in a very-low-mass dwarf galaxy. The dwarf galaxy might then have been swallowed by the more massive galaxy, just as happens in our Milky Way."

From the signature of the X-rays, Farrell's team knew there would be some blue light emitted from the high temperature of the hot gas in the disk swirling around the black hole. They couldn't account for the red light coming from the disk. It would have to be produced by a much cooler gas, and they concluded this would most likely come from stars. The next step was to build a model that added the glow from a population of stars. These models favor the presence of a young massive cluster of stars encircling the black hole, but this interpretation is not unique, so more observations are needed. In particular, the studies led by Roberto Soria of the Australian International Centre for Radio Astronomy Research, using data from Hubble and the ground-based Very Large Telescope, show variations in the brightness of the light that a star cluster couldn't cause. This indicates that irradiation of the disk itself might be the dominant source of visible light, rather than a massive star cluster.

"What we can definitely say with our Hubble data is that we require both emission from an accretion disk and emission from a stellar population to explain the colors we see," said Farrell.

Such young clusters of stars are commonly found inside galaxies like the host galaxy, but not outside the flattened starry disk, as found with HLX-1. One possible scenario is that the HLX-1 black hole was the central black hole in a dwarf galaxy. The larger host galaxy may then have captured the dwarf. In this conjecture, most of the dwarf's stars would have been stripped away through the collision between the galaxies. At the same time, new young stars would have formed in the encounter. The interaction that compressed the gas around the black hole would then have also triggered star formation.

Farrell theorizes that the possible star cluster may be less than 200 million years old. This means that the bulk of the stars formed following the dwarf's collision with the larger galaxy. The age of the stars tells how long ago the two galaxies crashed into each other.

Farrell proposed for more observations this year. The new findings are published in the February 15 issue of the Astrophysical Journal. Soria and his colleagues have published their alternative conclusions in the January 17 online issue of the Monthly Notices of the Royal Astronomical Society.

For images and more information about HLX-1 and Hubble, visit:

http://hubblesite.org/news/2012/11

http://www.nasa.gov/hubble

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

Ray Villard | Newswise Science News
Further information:
http://www.nasa.gov/hubble

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: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>