Hola amigos : A VUELO DE UN QUINDE EL BLOG., hemos recibido de la Agencia Espacial NASA, que NASA’s Chandra Observatory ha detectado una lluvia cósmico a medio crecimiento de una Galaxia, es un descubrimiento que los astrónomos han descubierto que el crecimiento de las galaxias que contienen agujeros negros supermasivos puede ser frenado por un fenómeno que se conoce como precipitación cósmica.
Precipitación Cósmica no es un fenómeno meteorológico, ya que comúnmente asociamos la palabra - lluvia, aguanieve o nieve. Más bien, es un mecanismo que permite que el gas caliente para producir una lluvia de nubes frías de gas que caen en una galaxia. Los investigadores han analizado los rayos X de más de 200 cúmulos de galaxias, y creemos que esta precipitación gaseoso es clave para entender cómo los agujeros negros gigantes afectan el crecimiento de las galaxias.
More information......
A study of over 200 galaxy clusters, including
Abell 2597 shown here, with NASA’s Chandra X-ray Observatory has revealed how an
unusual form of cosmic precipitation stifles star formation.
Image Credit:
NASA/CXC/DSS/Magellan
Using NASA’s Chandra X-ray Observatory, astronomers have found that the
growth of galaxies containing supermassive black holes can be slowed down by a
phenomenon referred to as cosmic precipitation.
Cosmic precipitation is not a weather event, as we commonly associate the
word -- rain, sleet, or snow. Rather, it is a mechanism that allows hot gas to
produce showers of cool gas clouds that fall into a galaxy. Researchers have
analyzed X-rays from more than 200 galaxy clusters, and believe that this
gaseous precipitation is key to understanding how giant black holes affect the
growth of galaxies.
“We know that precipitation can slow us down on our way to work,” said Mark
Voit of Michigan State University (MSU) in East Lansing, lead author of the
paper that appears in the latest issue of Nature. “Now we have evidence that it
can also slow down star formation in galaxies with huge black holes.”
Astronomers have long pursued the quest to understand how supermassive black
holes, which can be millions or even billions of times the mass of the sun,
affect their host galaxies.
“We’ve known for quite some time that supermassive black holes influence the
growth of their host galaxies, but we haven’t yet figured out all of the
details,” said co-author Megan Donahue, also of MSU. “These results get us a
step closer.”
The study looked at some of the largest known galaxies lying in the middle of
galaxy clusters. These galaxies are embedded in enormous atmospheres of hot gas.
This hot gas should cool and many stars should then form. However, observations
show that something is hindering the star birth.
The answer appears to lie with the supermassive black holes at the centers of
the large galaxies. Under specific conditions, clumps of gas can radiate away
their energy and form cool clouds that mix with surrounding hot gas. Some of
these clouds form stars, but others rain onto the supermassive black hole,
triggering jets of energetic particles that push against the falling gas and
reheat it, preventing more stars from forming. This cycle of cooling and heating
creates a feedback loop that regulates the growth of the galaxies.
“We can say that a typical weather forecast for the center of a massive
galaxy is this: cloudy with a chance of heat from a huge black hole,” said
co-author Greg Bryan of Columbia University in New York.
Voit and his colleagues used Chandra data to estimate how long it should take
for the gas to cool at different distances from the black holes in the study.
Using that information, they were able to accurately predict the “weather”
around each of the black holes.
They found that the precipitation feedback loop driven by energy produced by
the black hole jets prevents the showers of cold clouds from getting too strong.
The Chandra data indicate the regulation of this precipitation has been going on
for the last 7 billion years or more.
“Without these black holes and their jets, the central galaxies of galaxy
clusters would have many more stars than they do today,” said co-author Michael
McDonald of the Massachusetts Institute of Technology in Cambridge.
While a rain of cool clouds appears to play a key role in regulating the
growth of some galaxies, the researchers have found other galaxies where the
cosmic precipitation had shut off. The intense heat in these central galaxies,
possibly from colliding with another galaxy cluster, likely “dried up” the
precipitation around the black hole.
Future studies will test whether this precipitation-black hole feedback
process also regulates star formation in smaller galaxies, including our own
Milky Way galaxy.
A pre-print of the Nature study is available online. The study builds on work
by Voit and Donahue that was published in the Jan. 20 issue of The Astrophysical
Journal Letters and also is available online.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the
Chandra program for the agency’s Science Mission Directorate in Washington. The
Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls
Chandra's science and flight operations.
An interactive image, podcast, and video about these findings are available
at:
For more Chandra images, multimedia and related materials, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
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