Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Spying on Black-Hole Eating Habits with LISA

14.01.2005


As big fish eat little fish in the Earth’s vast oceans, so too do supermassive black holes gorge on smaller black holes and neutron stars, making themselves more massive in the process. Using sophisticated computer modeling, Penn State scientists have calculated the rate of this black-hole snacking, called "extreme-mass-ratio inspirals." They expect to see several events per year with the Laser Interferometer Space Antennae (LISA), a joint NASA - European Space Agency mission now in development.



Steinn Sigurdsson, associate professor of astronomy and astrophysics at Penn State, discusses the inspiral rate today during a presentation at the American Astronomical Society meeting in San Diego. These events will be a major source of gravitational waves, which are ripples in spacetime. Sigurdsson said that this type of black hole inspiral provides one of the cleanest tests for assessing Einstein’s theory of general relativity.

"Most galaxies contain a supermassive black hole, and from time to time a smaller black hole or neutron star will fall in," said Sigurdsson. "Very little light, if any, is emitted. This is done in the dark. Our best chance of studying the process is through gravitational radiation."


Predicted by Einstein, gravitational radiation has not yet been detected directly. These waves travel at light speed. Yet, unlike light waves, the subtle gravitational waves hardly interact with matter. A passing wave causes all matter to bob, like buoys on the ocean. LISA works by setting out three spacecraft -- buoys in spacetime -- and measuring the change in their separation as they bob in response to passing gravitational waves. The three LISA spacecraft will be separated from each other by over 3 million miles, while the gravitational waves alter the distance between them by far less than the width of an atom.

These waves, Sigurdsson said, grow more intense in the weeks just before the larger black hole consumes the smaller object. That is when LISA could detect an imminent merger. Higher-mass objects falling into the black hole might produce detectable waves years in advance of the merger. Sigurdsson puts the inspiral rate at about 1 per million years per galaxy. Because there are millions of galaxies in the visible universe, LISA might detect several inspirals each year.

Extreme-mass-ratio inspirals involve what scientists call compact objects -- stellar-size black holes, neutron stars, or white dwarfs. Supermassive black holes also can swallow stars like our Sun. But these stars get ripped apart first, and they do not produce detectable gravitational waves.

Compact objects are dense. Neutron stars, for example, contain the densest material found in nature. As a result, they act like trace particles falling into a black hole, a perfect physics experiment. This is a clean merger without splintering. So, the mergers serve as very precise tests for Einstein’s theory of general relativity. Any discrepancy between observation and theory would point to a flaw in general relativity.

LISA’s lasers will measure tiny changes caused by passing waves in the motion of freely falling test masses in each spacecraft at a sub-nanometer accuracy. Technology to detect such subtle changes is now in development at several institutes, including Penn State. An ESA-led "LISA-Pathfinder" mission is expected to launch in 2008 to test formation flying and other technologies. LISA will launch a few years after this.

"The study of gravitational radiation is the newest frontier in astronomy," said Lee Samuel Finn, professor of astronomy and astrophysics and director of Penn State’s Center for Gravitational Wave Physics. "Scientists and engineers around the world are working together to make LISA a reality. Steinn’s work, one important piece among many, builds upon theories and models developed in recent years at Penn State and other institutes."

LISA will detect low-frequency waves, in the millihertz range. LIGO, the Laser Interferometer Gravitational Wave Observatory, will detect higher-frequency, kilohertz waves. The ground-based LIGO is funded by the National Science Foundation. Observations are being conducted at the two LIGO facilities, in Livingston, Louisiana, and Hanford, Washington.

LISA is a joint venture between NASA, the European Space Agency, and European national space agencies. In addition to leading the LISA Pathfinder mission, Europe will contribute much of the scientific instrumentation and the interplanetary propulsion systems to LISA. NASA’s Goddard Space Flight Center will manage the mission for NASA and will provide the spacecraft and final integration. NASA’s Jet Propulsion Laboratory will supply NASA’s test package on LISA Pathfinder and the scientific instrumentation and operations support for the main LISA mission.

Barbara K. Kennedy | EurekAlert!
Further information:
http://lisa.nasa.gov/.
http://www.psu.edu
http://www.science.psu.edu/alert/Sigurdsson1-2005.htm

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>