Astronomers discover one of the brightest galaxies known

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 a gravitational
lens, and the Gran Telescopio CANARIAS a team of scientists
from the Polytechnic University of Cartagena and the
Instituto de Astrofísica de Canarias have discovered one of
the brightest galaxies known from the epoch when the universe
had 20 percent 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
intial path. 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 , called this because of their very
strong emissionin 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 ” 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 centred 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 in the Astrophysical Journal Letters, a
search of the whole sky was carried out, combining the data
bases of the satellites WISE (NASA) and Planck (ESA) in order
to identify the brightest submillimetre 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 the GTC.

Forming stars at high velocity

The galaxy is notable for having a high rate of . It is forming stars at a rate of
1000 solar masses per year, compared to the Milky Way which is
forming at a rate of some twice a solar mass per
year. Susana Iglesias-Groth, an IAC astrophysicist and a
co-author of the article, adds. “This type of objects harbour
the most powerful star forming regions known in the universe.
The next step will be to study their molecular content”.

The fact that the galaxy is so bright, its is gravitationally amplifed, 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 ast 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.

Explore further:
New ‘Einstein
ring’ is discovered

More information: A. Díaz-Sánchez et al, Discovery of a
Lensed Ultrabright Submillimeter Galaxy at z = 2.0439, The
Astrophysical Journal
(2017). DOI: 10.3847/2041-8213/aa79ef

Journal reference: Astrophysical
Journal Letters
Astrophysical
Journal

Provided by: Instituto de Astrofísica de Canarias
(IAC)

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