Repeating radio signals coming from a mystery source far beyond the Milky Way have been discovered by scientists. While one-off fast radio bursts (FRBs) have been detected in the past, this is the first time multiple signals have been detected coming from the same place in space.
FRBs are radio signals from deep space that last for just a few milliseconds. Since their discovery over a decade ago, scientists have been searching for more to try to understand their origin. At present, there are several theories as to what they could be, with most involving some cataclysmic event like a supernova or a neutron star collapsing into a black hole.
All of the events seen so far appear to have been one-offs, with subsequent observations failing to find follow-up bursts coming from the same position as the original. However, an international team of researchers has now discovered an additional 10 bursts coming from the same direction as FRB 121102, using the Arecibo radio telescope in Puerto Rico.
Publishing their findings in the journal Nature, the researchers report the subsequent bursts have the same dispersion measures and sky positions as the original FRB. This, they say, means the source must have survived whatever event caused the FRB to be produced in the first place – i.e. it cannot have been a cataclysmic one-off event. They also found the bursts differed in brightness from other FRBs, suggesting a different source.
Paul Scholz, from McGill University, was the first person to notice the repeating burst: “I knew immediately that the discovery would be extremely important in the study of FRBs.”
In the study, researchers suggest the repeating bursts are coming from a very young neutron star. “Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetised, extragalactic neutron star,” they wrote.
The team now hopes to identify the galaxy from which the repeating FRBs came from. “Once we have precisely localised the repeater’s position on the sky, we will be able to compare observations from optical and X-ray telescopes and see if there is a galaxy there,” said Jason Hessels, corresponding author on the study. “Finding the host galaxy of this source is critical to understanding its properties.”
Their study follows another paper on FRBs published earlier this month. Also appearing in Nature, researchers announced the discovery of the location and host galaxy of another FRB first discovered in April last year.
They found FRB 150418 had emanated from an elliptical galaxy six billion light years away. Unlike FRB 121102, this burst did not repeat, leading scientists to say it was probably produced by merger event, where two stars that are orbiting each other come together. In the paper, the team also said they believe there are at least two different sources of FRBs.
Original article: Mystery Signals from Space
Sit back and relax.
This is going to take a while.
But cheer up: she’s doing it as much for you as herself.
Does life exist beyond Earth? Not surprisingly, searches of the solar system yield no evidence because the only planet (or moon) located in the right place is Earth. However, the discovery of exoplanets (planets outside our solar system) boosted researchers’ enthusiasm for finding life beyond Earth. Thus far, our technology lacks the sensitivity to detect any signatures of life outside of our solar system, but scientists continue to make progress. While these advances reveal additional indicators that Earth may be rare (or unique) in its capacity to support life, they also provide a way to genuinely test the rare-earth hypothesis.
Using current telescope technology, scientists can measure only orbits, masses, and sizes of exoplanets. Over the next decade, advances will permit the detection of life signatures from stars in the neighborhood of the solar system, which will allow powerful tests of the rare-earth hypothesis. An article published in the journal Astrobiology highlights one of those tests.
Earth currently resides near the habitable zone’s inner edge. Yet, as the Sun’s luminosity increases (with age), the habitable zone will move farther and farther out, making Earth less habitable. As Earth’s surface temperature increases, the planet will go from supporting large-bodied, complex life (like humanity) to hosting only multicellular life and then only microbial life. Eventually it will be completely devoid of any life. The whole progression takes between 2 to 3 billion years. Although Earth provides an impractical venue for testing this idea, older exoplanets in the solar neighborhood serve as good places for the test.
As described in Astrobiology, researchers identified six Sun-like stars that could host Earth-like planets residing in the continuous habitable zone (CHZ). Each of these stars measures between 6 and 7 billion years old (as compared to the 4.6-billion-year age for the Sun and Earth). Applying biosphere evolution models to (hypothetical) planets orbiting the stars revealed that each planet was in a different stage of decline from Earth-like to almost extinct. Future measurements to find planets around these stars and characterize their biosignatures will yield constraints on the validity of the rare-earth hypothesis.1
Even though better testing is still a ways off, the current research does highlight one more criterion that habitable planets must meet. Not only must they start in the habitable zone, they must remain within a habitable zone that continually moves farther away from the host star. As the Astrobiology article states, “If the development of Earth-like biospheres is rare, requiring a sequence of low-probability events to occur, biosphere evolution models suggest they are rarer still, with only thousands being present in the Galaxy as a whole.” Research continues to point to a rare, finely designed Earth.
Original article: Search for New Earth Reveals Design