False color image of the radio signal from the galaxy’s atomic hydrogen.
Chakraborty and Roy/NCRA-TIFR/GMRT
Astronomers using a radio telescope in India have picked up the most distant radio signal from a galaxy ever, fueling hopes that the secrets of the early universe can be unlocked using existing telescope technology.
The signal comes from a galaxy called SDSSJ0826+5630, which exists 8.8 billion light-years away. This essentially means that it exists closer to the Big Bang (when an infinitely hot and dense single point inflated to form our ever-expanding universe) than any other galaxy previously discovered using radio astronomy.
They used a technique called gravitational lensing, a ripple in space-time that allows background objects to be extremely magnified by foreground objects.
Radio signals get weaker the farther a galaxy is from Earth, making it harder for current radio telescopes to pick up, but a new paper published this week in the Monthly Notices of the Royal Astronomical Society gives hope that the study of much larger galaxies distances from Earth may already be close.
Illustration showing the detection of a signal from a distant galaxy.
Swadha Pardesi
“A galaxy emits different kinds of radio signals,” said Arnab Chakraborty, a postdoctoral researcher who studies cosmology in the physics department at McGill University in Montreal, Canada. “Until now, it has only been possible to pick up this particular signal from a nearby galaxy, limiting our knowledge to those galaxies closer to Earth.”
The researchers – both from Montreal and India – used the Giant Metrewave Radio Telescope in Pune, India, to pick up the signal at a specific wavelength called the 21 cm line.
Gravitational lensing—sometimes called “nature’s magnifying glass”—occurs when the gravitational pull of a closer but aligned galaxy distorts and bends light from a distant star or galaxy, causing it to appear warped and magnified—in this case by a factor of 30 .
One of the dishes of the Giant Metrewave Radio Telescope (GMRT) near Pune, Maharashtra, India.
National Center for Radio Astrophysics
The signal from SDSSJ0826+5630 was emitted when the universe was only 4.9 billion years old, but as the universe is expanding, it took 8.8 billion years to reach the telescope.
This breakthrough proves that it is possible to observe distant galaxies using existing low-frequency radio telescopes. “This will help us understand the composition of galaxies at much greater distances from Earth,” Chakraborty said.
Radio astronomy is the study of the sky in radio frequencies. Stars, galaxies and other cosmic phenomena emit waves of light. Visible light is electromagnetic radiation, as are radio waves, gamma rays, X-rays, and infrared rays. So to get a full picture of what’s out there, astronomers must use radio telescopes to detect and amplify radio waves from space.
Wishing you clear skies and wide-open eyes.
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