Un enorme agujero negro atraviesa el espacio a gran velocidad

Expulsado de su galaxia tras chocar y fusionarse con otro agujero, puede ser la primera prueba de que muchos de estos objetos vagan perdidos por el espacio intergaláctico sin haber sido detectados

The galaxy at the center of this image contains an X-ray source, CID-42, with exceptional properties. After combining data from several telescopes -- including NASA's Chandra X-ray Observatory -- researchers think that CID-42 contains a massive black hole being ejected from its host galaxy at several million miles per hour.

The main panel is a wide-field image of CID-42 and its surroundings taken by the Canada-French-Hawaii Telescope and the Hubble Space Telescope in optical light. The galaxy is located nearly four billion light years from Earth. The outlined box on the main panel represents the more localized view of CID-42 that is shown in the three separate boxes on the right-hand side of the graphic. At the top is an image from the Chandra X-ray Observatory. The X-ray emission is concentrated in a single source, corresponding to one of the two sources seen in deep observations by Hubble, which is shown in the middle inset box. The bottom inset shows how the X-rays align with the optical data in the two insets above.

The precise location of this source was recently obtained using Chandra's High Resolution Camera, giving an important clue in telling astronomers what is happening within this galaxy. Previous Chandra observations had detected a bright X-ray source likely caused by super-heated material around one or more supermassive black holes. However, they could not distinguish if the X-rays came from one or both of the optical sources because Chandra was not pointed directly at CID-42, giving an X-ray source that was less sharp than usual.

The new data help to clarify the situation. Researchers think that CID-42 is the byproduct of two galaxies that have collided, producing the distinctive tail seen in the upper part of the optical image inset. A simulation by co-author Laura Blecha shows more details of how this spectacular event was thought to unfold.

When this galaxy collision occurred, the supermassive black holes in the center of each galaxy also collided. The two black holes then merged to form a single black hole, that recoiled from gravitational waves produced by the collision, giving the newly merged black hole a sufficiently large kick for it to eventually escape from the galaxy. In this scenario, the source with the X-rays is the black hole being ejected from the galaxy. The other optical source is thought to be the bright star cluster that was left behind at the center of the galaxy.

With the higher resolution Chandra data a new feature was discovered in CID-42, a small extension to the lower right of the source. This could be a jet from the black hole or stars forming near it.

There are two other possible, but less likely, explanations for the optical data detected in CID-42. Both would involve the presence of a second supermassive black hole in CID-42, requiring X-ray emission from a second source to be heavily obscured.

Credits: X-ray: NASA/CXC/SAO/F.Civano et al; Optical: NASA/STScI; Optical (wide field): CFHT, NASA/STScI

http://www.nasa.gov/mission_pages/chandra/multimedia/cid42.html

La galaxia en el centro de la imagen contiene el sistema donde se encuentra el agujero negro expulsado

Resulta escalofriante, pero es real. Un equipo de astrónomos ha encontrado pruebas contundentes de que un agujero negro masivo está siendo expulsado de su galaxia anfitriona, situada a unos 4 millones de años luz de la Tierra, a una velocidad de millones de kilómetros por hora. Según nuevas observaciones del telescopio espacial Chandra de rayos X de la NASA, el agujero negro errante chocó violentamente con otro agujero y se fusionó, pero el gigante recién formado recibió una fuerte patada de retroceso de las ondas de radiación gravitacionales y salió disparado. La investigación, que aparecerá publicada en breve en The Astrophysical Journal, puede ser la primera prueba de que estos pozos cósmicos, aunque parezca increíble, pueden vagar perdidos por el espacio sin que los hayamos detectado.

«Es difícil de creer que un agujero negro supermasivo que pesa millones de veces la masa del Sol pueda moverse en absoluto, y mucho menos ser expulsado de una galaxia a una velocidad enorme», reconoce Francesca Civano, del Centro Harvard-Smithsoniano de Astrofísica (CfA ), responsable del estudio. «Pero estos nuevos datos apoyan la idea de que las ondas gravitatorias - ondulaciones en el tejido del espacio predichas por Albert Einstein, pero nunca detectadas directamente- pueden ejercer una fuerza muy poderosa»

El fenómeno tiene importantes implicaciones para la astronomía. Aunque la expulsión de un agujero negro supermasivo en una galaxia por la emisión de las ondas gravitacionales sea poco frecuente, puede significar que existan muchos agujeros negros gigantes que se mueven perdidos a través de los vastos espacios intergalácticos y que no han sido detectados. «Estos agujeros negros serían invisibles para nosotros -dice Laura Blecha, también del CfA- porque han consumido todo el gas que los rodea después de haber sido expulsado de su galaxia».

Patada cósmica
El equipo estudiaba un sistema conocido como CID-42, situado en el centro de una galaxia a unos 4 millones de años luz de distancia. Allí, el fantástico telescopio Hubble de la NASA había localizado dos fuentes distintas de luz óptica. Otras observaciones realizadas con telescopios terrestres, como el Magallanes y el Very Large Telescope en Chile comprobaron que los dos objetos se estaban separando a una velocidad de casi 5 millones de kilómetros por hora.

Los astrónomos sabían que allí ocurría algo especial, pero no estaban seguros de si se trataba de uno o de dos agujeros negros. Cuando la cámara de alta resolución del Chandra apuntó directamente a CID-42, el equipo descubrió qué había ocurrido. Los científicos creen que se produjo el choque de dos galaxias. Cuando esto sucedió, también colisionaron los dos agujeros negros supermasivos situados en su centro. Los dos pozos cósmicos se fusionaron para formar un único agujero, que retrocedió ante las ondas gravitacionales producidas por la colisión. El agujero negro recién fusionado recibió una patada lo suficientemente grande como para salir disparado de la galaxia.

Hay otras dos explicaciones posibles para lo que está sucediendo en CID-42. Una supondría un encuentro entre tres agujeros negros supermasivos, de forma que saliera expulsado el más ligero. Otra idea es que el sistema tenga dos agujeros negros supermasivos que se mueven en espiral el uno hacia el otro, en lugar de separarse, pero los científicos han descartado estas dos posibilidades.

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Astronomers have found strong evidence that a massive black hole is being ejected from its host galaxy at a speed of several million miles per hour. New observations from NASA's Chandra X-ray Observatory suggest that the black hole collided and merged with another black hole and received a powerful recoil kick from gravitational wave radiation.

"It's hard to believe that a supermassive black hole weighing millions of times the mass of the sun could be moved at all, let alone kicked out of a galaxy at enormous speed," said Francesca Civano of the Harvard-Smithsonian Center for Astrophysics (CfA), who led the new study. "But these new data support the idea that gravitational waves -- ripples in the fabric of space first predicted by Albert Einstein but never detected directly -- can exert an extremely powerful force."

Although the ejection of a supermassive black hole from a galaxy by recoil because more gravitational waves are being emitted in one direction than another is likely to be rare, it nevertheless could mean that there are many giant black holes roaming undetected out in the vast spaces between galaxies.

"These black holes would be invisible to us," said co-author Laura Blecha, also of CfA, "because they have consumed all of the gas surrounding them after being thrown out of their home galaxy."

Civano and her group have been studying a system known as CID-42, located in the middle of a galaxy about four billion light years away. They had previously spotted two distinct, compact sources of optical light in CID-42, using NASA's Hubble Space Telescope.

More optical data from the ground-based Magellan and Very Large Telescopes in Chile supplied a spectrum (that is, the distribution of optical light with energy) that suggested the two sources in CID-42 are moving apart at a speed of at least 3 million miles per hour.

Previous Chandra observations detected a bright X-ray source likely caused by super-heated material around one or more supermassive black holes. However, they could not distinguish whether the X-rays came from one or both of the optical sources because Chandra was not pointed directly at CID-42, giving an X-ray source that was less sharp than usual.

"The previous data told us that there was something special going on, but we couldn't tell if there were two black holes or just one," said another co-author Martin Elvis, also of CfA. "We needed new X-ray data to separate the sources."

When Chandra's sharp High Resolution Camera was pointed directly at CID-42, the resulting data showed that X-rays were coming only from one of the sources. The team thinks that when two galaxies collided, the supermassive black holes in the center of each galaxy also collided. The two black holes then merged to form a single black hole that recoiled from gravitational waves produced by the collision, which gave the newly merged black hole a sufficiently large kick for it to eventually escape from the galaxy.

The other optical source is thought to be the bright star cluster that was left behind. This picture is consistent with recent computer simulations of merging black holes, which show that merged black holes can receive powerful kicks from the emission of gravitational waves.

There are two other possible explanations for what is happening in CID-42. One would involve an encounter between three supermassive black holes, resulting in the lightest one being ejected. Another idea is that CID-42 contains two supermassive black holes spiraling toward one another, rather than one moving quickly away.

Both of these alternate explanations would require at least one of the supermassive black holes to be very obscured, since only one bright X-ray source is observed. Thus the Chandra data support the idea of a black hole recoiling because of gravitational waves.

These results will appear in the June 10 issue of The Astrophysical Journal.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra Program for the agency's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations.

For Chandra images, multimedia and related materials, visit:

http://www.nasa.gov/chandra

For an additional interactive image, podcast, and video on the finding, visit:

http://chandra.si.edu

 
 

J.D. Harrington, 202-358-0321
Headquarters, Washington
j.d.harringron@nasa.gov

Janet Anderson, 256-544-0034
Marshall Space Flight Center, Huntsville, Ala.
janet.l.anderson@nasa.gov

Megan Watzke 617-496-7998
Chandra X-ray Center, Cambridge, Mass.
m.watzke@cfa.harvard.edu

http://www.nasa.gov/mission_pages/chandra/news/H-12-182.html

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