July 14, 2017
The multiple images of the discovered galaxy
are indicated by white arrows
(bottom right shows the scale of the image in seconds of arc).
Credit: Hubble Space Telescope (HST)
Thanks to an amplified image produced by,
lens, and the Gran Telescopio CANARIAS (GTC)
a team of
scientists from the Polytechnic University of Cartagena
and the Instituto de Astrofísica de Canarias (IAC,
have discovered one of the brightest galaxies known from the epoch
when the universe had 20% of its present age.
According to Einstein’s theory of
General Relativity when a ray of
light passes close to a very massive object, the gravity of the
object attracts the photons and deviates them from their initial
This phenomenon, known as
gravitational lensing, is
comparable to that produced by lenses on light rays, and acts as a
sort of magnifier, changing the size and intensity of the apparent
image of the original object.
Using this effect, a team of scientists from the Instituto de
Astrofisica de Canarias (IAC) led by researcher Anastasio
Díaz-Sánches of the Polytechnic University of Cartagena (UPT)
has discovered a very distant galaxy, some 10 thousand million light
years away, about a thousand times brighter than the Milky Way.
It is the brightest of
the submillimetre galaxies, called this because of their very strong
emission in the far infrared. To measure it they used the Gran
Telescopio Canarias (GTC) at the Roque de los Muchachos
Observatory (Garafía, La Palma).
"Thanks to the
gravitational lens" notes Anastasio Díaz Sánchez, a researcher
at the UPCT and first author of the article "produced by a
cluster of galaxies between ourselves and the source, which acts
as if it was a telescope, the galaxy appears 11 times bigger and
brighter than it really is, and appears as several images on an
arc centered on the densest part of the cluster, which is known
as an 'Einstein Ring.'
The advantage of this
kind of amplification is that it does not distort the spectral
properties of the light, which can be studied for these very
distant objects as if they were much nearer".
To find this galaxies,
whose discovery was recently published in an article (Discovery
of a Lensed Ultrabright Submillimeter Galaxy at z = 2.0439)
in the Astrophysical Journal Letters, a search of the whole
sky was carried out, combining the data bases of the satellites,
...in order to identify
the brightest sub-millimeter galaxies.
Its light, amplified by a
much nearer galaxy cluster acting as a lens, forms an image which
appears much bigger than it should, and thanks to this effect they
could characterize its nature and properties spectroscopically using
at high velocity
The galaxy is notable for having a high rate of star formation.
It is forming stars at a
rate of 1000 solar masses per year, compared to the Milky Way which
is forming stars at a rate of some twice a solar mass per year.
an IAC astrophysicist and a co-author of the article, adds.
"This type of objects
harbor the most powerful star forming regions known in the
universe. The next step will be to study their molecular
The fact that the galaxy
is so bright, its light is gravitationally amplified, and has
multiple images allows us to look into its internal properties,
which would otherwise not be possible with such distant galaxies.
"In the future we
will be able to make more detailed studies of its star formation
using interferometers such as the Northern Extended Millimeter
Array (NOEMA/IRAM), in France, and the Atacama Large Millimeter
Array (ALMA), in Chile" concludes IAC researcher Helmut
Dannerbauer, who is another contributor to this discovery.