Scientists have managed to do something previously thought impossible: capture a particular type of wireless signal from a galaxy that floats about 9 billion light years from Earththey announced Monday in a journal known as
of Monthly Notices of the Royal Astronomical Society.
We are talking about a kingdom with starspossibly planets, probably black holes – all the cosmic stuff – that existed when the universe was only about 5 billion years. It is extremely young, a time well
prior to the materialization of our solar system
and the appearance of life as we know it.
This is the first time anyone has picked up this type of radio signal, associated with a wavelength known as parting at 21 cmat such a considerable distance.
“It’s the equivalent of going back 8.8 billion years”has
said in a press release
Arnab Chakrabortya cosmologist in the Department of Physics at McGill University and co-author of a study on detection.
Why do we like the 21cm parting?
No matter where you are in the universe, you’ll probably end up around some kind ofhydrogen.
Number 1 in the periodic table and number 1 in our hearts (literally, because it is present in our blood), hydrogen is considered the most abundant element of our cosmos. You will find it in the water, in your body, in the air and in the sun. Hydrogen is everywhere. And it makes sense.
The different elements are in fact different combinations of protons and electrons, and hydrogen has exactly one of each. It’s simple, clean, the perfect item.
Alright, let’s stop talking about hydrogen now. Hydrogen being omnipresent in our universe, it is a
awesome way to figure out where everything is
and to understand the evolution of the cosmos. Just follow hydrogen, neutral hydrogen gas to be exact.
“The cold, atomic reservoir of neutral hydrogen provides the basic fuel for star formation in a galaxy”write the authors of the study.
“Understanding the evolution of galaxies over cosmic time requires knowing the cosmic evolution of this neutral gas”.
parting at 21 cm
is a radio wavelength emitted by a process carried out by none other than… hydrogen. In fact, when she was
officially invented in 1951she was literally called the hydrogen line.
That’s why astronomers point their radio telescopes skyward, pick up lots of signals from the 21cm line, and try to figure out where they’re coming from.
Thanks to the line at 21 cm, for example, we were able to admire
the amazing spiral structure
of the Milky Way, observe the ins and outs of our
Andromeda, and study the shimmering mists of the duo of
magellanic cloud. But what these three kingdoms have in common is that they are nearby. We live in one of them, and the other two are also very close – Andromeda is only about 2.5 million light years.
“A galaxy emits different types of radio signals. So far, it has only been possible to pick up this particular signal from a nearby galaxy, which limits our knowledge to the galaxies closest to Earth.”said Chakraborty.
However, the line at 21 cm sometimes made it possible to peek into the remotest corners of the universe. Previous record holders for this very special signal include radio waves from a
distance of some 5 billion years. But nothing compares to the team’s latest detection, which nearly doubles that distance.
Thanks to giant metric wave radio telescope located in India, Chakraborty and his fellow researchers picked up a radio signal ray at 21 cm from a galaxy located at almost 9 billion light years and carrying a complicated little robot name – SDSSJ0826+5630 – which allowed them to observe things like the composition of gas in this extraordinarily distant menagerie of stars.
This is an image of the radio signal from the distant galaxy. Don’t think about it too much. Just realize that this image represents something billions of light years from where you are sitting. (Credit: Chakraborty & Roy/NCRA-TIFR/GMRT)
In particular, they found that the atomic mass of the gas contained in this particular galaxy is equivalent to almost twice the mass of stars visible to us, which means it is much brighter than previously thought.
General relativity strikes again
“Thanks to a natural phenomenon called gravitational lenswe were able to pick up a weak signal at a record distance”said Chakraborty.
In a word, thegravitational lensing effect refers to how light (visible or not) emanating from stars or other space objects is distorted and distorted when it passes in front of an object with strong gravitational density. This is a consequence of the amazing general relativity theory of Einstein,
which you can read in more detail here.
In this case, the “light” which undergoes a gravitational lens is the signal of the line at 21 cm, and the hyperdense object is a whole galaxy which is located between the signal source and the observing team’s telescope.
“This has the effect of amplifying the signal by a factor of 30, which allows the telescope to pick it up”said in a statement Nirupam Royassociate professor in the department of physics at the Indian Institute of Science and co-author of the study.
Illustration showing the detection of the signal from a distant galaxy, subject to a gravitational lens. The redshift indicates the distance an object is from the Earth observation point. Higher redshift values mean something is farther away. This signal lies around the redshift z ~1.3. (credit: Swadha Pardesi)
That’s huge, because signals like this usually start to fade as they travel through the space vacuumwhich makes it rather difficult for scientists to capture them before they disappear…
“It will help us understand the composition of galaxies at much greater distances from Earth”said Chakraborty.
And for the future, according to the research team, these results demonstrate that the combination of gravitational lensing with radio astronomy could one day unveil a a host of secrets about the early universe. Perhaps it will reveal a tangle of cosmic trails that we did not know had to be followed.