A Mysterious Source Has Been Sending Radio Signals to Earth from Space for Decades
Radio signals from space are one of the most intriguing mysteries of modern astronomy. These signals, known as fast radio bursts (FRBs), are brief but intense flashes of radio waves that appear to come from distant galaxies. Scientists have detected dozens of FRBs since the first one was discovered in 2007, but they still don't know what causes them or what they mean.
Some FRBs are one-off events that never repeat, while others seem to recur at irregular intervals. However, one particular source has been sending radio signals to Earth for more than three decades, baffling astronomers with its unusual behavior.
The longest-running FRB mystery
The source, dubbed FRB 121102, was first detected in 2012 by the Arecibo Observatory in Puerto Rico. It was later found to be located in a dwarf galaxy about 3 billion light-years away from Earth. Unlike most FRBs, which last only a few milliseconds, FRB 121102 emits bursts that last up to several seconds. It also repeats sporadically, sometimes sending hundreds of bursts in a single day and then going silent for months or years.
In 2016, researchers discovered that FRB 121102 has a peculiar property: its bursts are highly polarized and twisted by a strong magnetic field. This suggests that the source is located in an extreme environment, such as near a supermassive black hole or a powerful neutron star. However, the exact nature and origin of FRB 121102 remain unknown.
A new clue from gravitational lensing
Recently, a team of astronomers used a cosmic trick to detect the most distant signal of its kind from another galaxy, which could shed some light on the mystery of FRB 121102. The signal was an emission line from neutral hydrogen, the most abundant element in the universe and the main ingredient of the primordial gas that filled the cosmos after the Big Bang.
Neutral hydrogen emits light at a characteristic wavelength of 21 centimeters, but this wavelength is stretched by the expansion of the universe as it travels across vast distances. Therefore, detecting neutral hydrogen signals from faraway galaxies is very challenging, as they are faint and easily obscured by other sources.
However, the researchers were able to overcome this obstacle by using an effect called gravitational lensing. This is when the gravity of a massive object bends and magnifies the light coming from behind it, acting like a natural telescope. In this case, the researchers used the GMRT in India to observe a galaxy cluster that acted as a gravitational lens for a more distant galaxy behind it.
The galaxy behind the cluster, named SDSSJ0826+5630, is located 8.8 billion light-years away from Earth, meaning that its light took that long to reach us. By using the gravitational lensing effect, the researchers were able to detect the neutral hydrogen signal from this galaxy for the first time.
Implications for understanding FRBs
What does this have to do with FRB 121102? Well, according to the researchers, SDSSJ0826+5630 is very similar to the host galaxy of FRB 121102 in terms of its size, mass and star formation rate. This means that both galaxies could have similar conditions for producing FRBs.
The detection of neutral hydrogen from SDSSJ0826+5630 also implies that this galaxy has not undergone much ionization by starlight or other sources. Ionization is when atoms lose their electrons due to energetic radiation. This process affects how neutral hydrogen emits and absorbs radio waves, and could also affect how FRBs propagate through space.
Therefore, by studying neutral hydrogen signals from distant galaxies like SDSSJ0826+5630, astronomers could learn more about how FRBs are generated and transmitted across the universe. This could help them solve the puzzle of FRB 121102 and other mysterious radio signals from space.
Conclusion
Radio signals from space are fascinating phenomena that offer glimpses into the hidden secrets of the cosmos. By using innovative techniques and instruments, astronomers are constantly expanding their horizons and discovering new clues about these signals and their sources. One day, they might be able to crack the code of FRBs and reveal their true nature and significance.
Source:
(1) Strange Radio Signals Detected From Spinning Mystery Object in Space. https://www.msn.com/en-us/news/technology/strange-radio-signals-detected-from-spinning-mystery-object-in-space/ar-AA1e7NFW.
(2) A mysterious source has been sending radio signals to Earth from space for decades. https://www.independent.co.uk/space/radio-signals-pulsar-universe-astrophysics-b2379361.html.
(3) Scientists baffled as weird radio signals sent to Earth from space for 35 years. https://www.express.co.uk/news/science/1792989/space-pulsars-mysterious-object-radio-signals.
(4) Signals from space: Five theories on what they are - BBC News. https://www.bbc.com/news/science-environment-46825450.
(5) Radio signal from 8 billion light-years away could reveal the secrets .... https://www.livescience.com/radio-signal-reveal-universe-dark-age.
(6) Mysterious radio signal from space is repeating every 16 days. https://www.cnn.com/2020/02/11/world/repeating-fast-radio-burst-pattern-scn-trnd/index.html.
