Estimad@s Clientes y/o amantes del LEAN:
Estos días ha aparecido
una de esas noticias que a mí me impactan, y además, es fruto de una observación
directa: la existencia de algunos agujeros negros supermasivos puede ser debido
al choque entre dos galaxias
Pero si ya de por sí
la noticia es impresionante, para mí lo es más el hecho de que esta conclusión
ha sido posible gracias a la observación en frecuencias de la luz, Rayos X e infrarrojos
Por otro lado, decir
que como resultado de este choque se deberían detectar ondas gravitatorias en
el LIGO, esa maravilla de la ciencia que acaba de empezar su vida
Ahí van los links
que más me han gustado sobre este tema tan apasionante
Científicos descubren relación entre el origen de las
galaxias y la creación de agujeros negros
La investigación resalta que el origen de cierta cantidad de
agujeros negros supermasivos estarían relacionados al choque de galaxias.
https://www.fayerwayer.com/2018/11/galaxias-agujeros-negros/
Sabemos que hay un
agujero negro supermasivo en el centro de la Vía Láctea. Además del
perturbador hecho de que está en nuestro vecindario espacial, no conocemos
mucho de cómo llegó ahí o cómo se creó. De hecho, es algo que todavía
guarda cierto misterio alrededor de esos agujeros negros de tal tamaño en
galaxias como la nuestra.
Un equipo científico internacional entre los que se incluyen
investigadores chilenos acaba de descubrir algo revelador sobre este
tema. Según el grupo, la existencia de los agujeros negros
supermasivos se debería a un fenómeno entre galaxias. Más
específicamente: el brutal choque entre dos de ellas.
El documento publicado en Nature lanzó
la conclusión después de tomar 20 años de observaciones de telescopios
como el Hubble o el Keck y el observatorio de rayos-X Neil Gehrels Swift.
El astrónomo del Instituto de Astrofísica de la
Universidad Católica, Ezequiel Treister, explicó en qué consiste el estudio:
Lo que descubrimos es que casi el 20% de los agujeros negros
en rápido crecimiento (conocidos como AGN) están asociados a las últimas etapas
del proceso de choque de galaxias. Es decir, un poco antes que se
fusionen y formen un solo y colosal agujero negro".
En otras palabras, se cree que cierta cantidad de
agujeros negros supermasivos debe su existencia al choque de dos galaxias.
Esto se daría al unirse los dos núcleos galácticos en un solo gran agujero
negro.
El proceso se daría como en la siguiente simulación hecha
por computadora. Durante tres mil millones de años, las dos galaxias se
acercarían y chocarían para unirse en un solo elemento. Mientras tanto, se
compara con una toma real del telescopio de rayos-x Swift-BAT.
¿Qué significa esto?
Treister resalta las grandes incógnitas que esta
investigación está tratando de resolver:
“Gracias a este trabajo hoy estamos más cerca de resolver
dos grandes enigmas de la astrofísica: cómo se formaron las galaxias y cómo
crecen los agujeros negros supermasivos que viven en el centro de las mismas, y
aún más importante… el por qué ambos procesos están conectados".
Este estudio es muy útil para reconocer qué ocurrirá en un
futuro para galaxias como la nuestra. Ya conocíamos que la Vía
Láctea chocará en un futuro con Andrómeda. Por lo tanto, podremos
esperar que se de el mismo proceso de la simulación que acabamos de ver.
La investigación concluye que los agujeros negros
oscurecidos, es decir, aquellos que están cubiertos de material como polvo y
gas producto de la fusión galáctica, tienen una mayor probabilidad de
participar de este tipo de dinámica. “El choque de galaxias es un
mecanismo clave para obscurecer estos procesos”, afirmó Claudio Ricci,
astrónomo del Núcleo de Astronomía de la Universidad Diego Portales y también
parte del equipo de trabajo.
Ahora el objetivo es lograr entender cómo es que se produce
la alimentación y crecimiento de estos agujeros negros durante el proceso de
choque de dos galaxias, y cómo se produce la interacción con las galaxias que
las hospedan.
Astronomers
Unveil Growing Black Holes in Colliding Galaxies
Peering
through thick walls of gas and dust surrounding the messy cores of merging
galaxies, astronomers are getting their best view yet of close pairs of
supermassive black holes as they march toward coalescence into mega black
holes.
A team of
researchers led by Michael Koss of Eureka Scientific Inc., in Kirkland,
Washington, performed the largest survey of the cores of nearby galaxies in
near-infrared light, using high-resolution images taken by NASA's Hubble Space
Telescope and the W. M. Keck Observatory in Hawaii.
The Hubble
observations represent over 20 years' worth of snapshots from its vast archive.
These
images reveal the final stage of a union between a pair of galactic nuclei in
the messy cores of colliding galaxies.
The image
at left, taken by Hubble's Wide Field Camera 3, shows the merging galaxy NGC 6240.
A close-up of the two brilliant cores of this galactic union is shown at right.
This view,
taken in infrared light, pierces the dense cloud of dust and gas encasing the
two colliding galaxies and uncovers the active cores. The hefty black holes in
these cores are growing quickly as they feast on gas kicked up by the galaxy
merger. The black holes' speedy growth occurs during the last 10 million to 20
million years of the merger.
Credits:
NASA, ESA, and M. Koss (Eureka Scientific, Inc.)
"Seeing
the pairs of merging galaxy nuclei associated with these huge black holes so
close together was pretty amazing," Koss said. "In our study, we see
two galaxy nuclei right when the images were taken. You can't argue with it;
it's a very 'clean' result, which doesn't rely on interpretation."
The images
also provide a close-up preview of a phenomenon that must have been more common
in the early universe, when galaxy mergers were more frequent. When galaxies
collide, their monster black holes can unleash powerful energy in the form of
gravitational waves, the kind of ripples in space-time that were just recently
detected by ground-breaking experiments.
The new
study also offers a preview of what will likely happen in our own cosmic
backyard, in several billion years, when our Milky Way combines with the
neighboring Andromeda galaxy and their respective central black holes smash
together.
"Computer
simulations of galaxy smashups show us that black holes grow fastest during the
final stages of mergers, near the time when the black holes interact, and
that's what we have found in our survey," said study team member Laura
Blecha of the University of Florida, in Gainesville. "The fact that black
holes grow faster and faster as mergers progress tells us galaxy encounters are
really important for our understanding of how these objects got to be so
monstrously big."
A galaxy
merger is a slow process lasting more than a billion years as two galaxies,
under the inexorable pull of gravity, dance toward each other before finally
joining together. Simulations reveal that galaxies kick up plenty of gas and
dust as they undergo this slow-motion train wreck.
Images of
four other colliding galaxies, along with close-up views of their coalescing
nuclei in the bright cores, are shown beneath the Hubble snapshots of NGC 6240.
The left image of each pair, showing the merging galaxies, was taken by the
Panoramic Survey Telescope and Rapid Response System (Pan-STARRS).
The right
image, showing the bright cores, was taken in near-infrared light by the W. M.
Keck Observatory in Hawaii, using adaptive optics to sharpen the view. The
nuclei in each of the Hubble and Keck Observatory infrared photos are only about
3,000 light-years apart — a near-embrace in cosmic terms.
If there
are pairs of black holes, they will likely merge within the next 10 million
years to form a more massive black hole. These observations are part of the
largest-ever survey of the cores of nearby galaxies using high-resolution
images in near-infrared light taken by the Hubble and Keck observatories. The
survey galaxies' average distance is 330 million light-years from Earth.
Credits:
NASA, ESA, and M. Koss (Eureka Scientific, Inc.); W. M. Keck Observatory;
Panoramic Survey Telescope and Rapid Response System (Pan-STARRS)
The ejected
material often forms a thick curtain around the centers of the coalescing
galaxies, shielding them from view in visible light. Some of the material also
falls onto the black holes at the cores of the merging galaxies. The black
holes grow at a fast clip as they engorge themselves with their cosmic food,
and, being messy eaters, they cause the infalling gas to blaze brightly. This
speedy growth occurs during the last 10 million to 20 million years of the
union. The Hubble and Keck Observatory images captured close-up views of this
final stage, when the bulked-up black holes are only about 3,000 light-years
apart — a near-embrace in cosmic terms.
It's not
easy to find galaxy nuclei so close together. Most prior observations of
colliding galaxies have caught the coalescing black holes at earlier stages
when they were about 10 times farther away. The late stage of the merger
process is so elusive because the interacting galaxies are encased in dense
dust and gas and require high-resolution observations in infrared light that
can see through the clouds and pinpoint the locations of the two merging
nuclei.
The team
first searched for visually obscured, active black holes by sifting through 10
years' worth of X-ray data from the Burst Alert Telescope (BAT) aboard NASA's
Neil Gehrels Swift Telescope, a high-energy space observatory. "Gas
falling onto the black holes emits X-rays, and the brightness of the X-rays
tells you how quickly the black hole is growing," Koss explained. "I
didn't know if we would find hidden mergers, but we suspected, based on
computer simulations, that they would be in heavily shrouded galaxies.Therefore
we tried to peer through the dust with the sharpest images possible, in hopes
of finding coalescing black holes."
The
researchers combed through the Hubble archive, identifying those merging
galaxies they spotted in the X-ray data. They then used the Keck Observatory's
super-sharp, near-infrared vision to observe a larger sample of the
X-ray-producing black holes not found in the Hubble archive.
"People
had conducted studies to look for these close interacting black holes before,
but what really enabled this particular study were the X-rays that can break
through the cocoon of dust," Koss said. "We also looked a bit farther
in the universe so that we could survey a larger volume of space, giving us a
greater chance of finding more luminous, rapidly growing black holes."
The team
targeted galaxies with an average distance of 330 million light-years from
Earth. Many of the galaxies are similar in size to the Milky Way and Andromeda
galaxies. The team analyzed 96 galaxies from the Keck Observatory and 385
galaxies from the Hubble archive found in 38 different Hubble observation
programs. The sample galaxies are representative of what astronomers would find
by conducting an all-sky survey.
To verify
their results, Koss's team compared the survey galaxies with 176 other galaxies
from the Hubble archive that lack actively growing black holes. The comparison
confirmed that the luminous cores found in the researchers' census of dusty
interacting galaxies are indeed a signature of rapidly growing black-hole pairs
headed for a collision.
When the
two supermassive black holes in each of these systems finally come together in
millions of years, their encounters will produce strong gravitational waves.
Gravitational waves produced by the collision of two stellar-mass black holes
have already been detected by the Laser Interferometer Gravitational-Wave
Observatory (LIGO). Observatories such as the planned NASA/ESA space-based
Laser Interferometer Space Antenna (LISA) will be able to detect the
lower-frequency gravitational waves from supermassive black-hole mergers, which
are a million times more massive than those detected by LIGO.
Future
infrared telescopes, such as NASA's planned James Webb Space Telescope and a
new generation of giant ground-based telescopes, will provide an even better
probe of dusty galaxy collisions by measuring the masses, growth rate, and
dynamics of close black-hole pairs. The Webb telescope may also be able to look
in mid-infrared light to uncover more galaxy interactions so encased in thick
gas and dust that even near-infrared light cannot penetrate them.
The Hubble
Space Telescope is a project of international cooperation between NASA and ESA
(European Space Agency). NASA's Goddard Space Flight Center in Greenbelt,
Maryland, manages the telescope. The Space Telescope Science Institute (STScI)
in Baltimore, Maryland, conducts Hubble science operations. STScI is operated
for NASA by the Association of Universities for Research in Astronomy in
Washington, D.C.
Donna
Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Last
Updated: Nov. 7, 2018
Editor: Karl
Hille
Por último, ahí van unos posts que he dedicado en mi blog
“Historias del LEAN” sobre este tema:
Mensajes amables de fin de semana: primera detección
triple de una onda gravitacional:
Las ondas gravitacionales detectadas por el LIGO y el
VIRGO podrían ser originadas por el choque de dos agujeros gusano, en vez del
de dos agujeros negros...!!!!todo depende del eco!!!!:
Como siempre, he incluido estas reflexiones en mi blog
“Historias del LEAN”:
Que disfrutéis cada hora del fin de semana
Un cordial saludo
Alvaro Ballesteros
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