Radio telescopes are the most sensitive radio receivers in the world, capable of detecting extremely weak bursts of radio emissions from celestial bodies in the farthest part of the universe.
Recently, a team of astronomers used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to use the help of nature to detect a distant galaxy, which is probably the weakest radio-emitting object discovered so far.
This discovery is part of a VLA Frontier Field Survey led by NRAO astronomer Eric Murphy, which uses distant clusters of galaxies as natural lenses to study further objects. Clusters of galaxies act as gravitational lenses, using the gravitational force of galaxies in the cluster to bend and amplify light and radio waves from more distant celestial bodies.
In this composite image, the VLA radio image is superimposed on the visible-light image of the Hubble Space Telescope. The prominent red-orange object is a radio remnant in the foreground galaxy cluster-possibly a large structure caused by shock waves. The galaxy cluster is called MACSJ0717.5+3745 and is more than 5 billion light-years away from Earth.
Detailed VLA observations show that many galaxies in this image emit radio waves in addition to visible light. VLA data shows that one of the galaxies is more than 8 billion light-years away from Earth. Its light waves and radio waves have been bent by the gravitational lensing effect of the middle star cluster.
Astronomers say that the radio image of this distant galaxy is called VLAHFF-J071736.66+374506.4, which is magnified more than 6 times by a gravitational lens. This magnification is why VLA can detect it.
by the gravitational lens, combined with the extremely sensitive VLA imaging, allows us to see the structure of a galaxy 300 times less massive than our Milky Way galaxy as never before, and the age of the universe was less than half of what it is now. Eric Jimenez of NRAO -Andrade said: “This gives us valuable insights into the star formation of such low-mass galaxies at the time and how they eventually assembled into larger-scale galaxies.
The scientists reported on their work in two papers in the Astrophysical Journal.