Cosmic lens detects faint radio galaxy over 8 billion light years from Earth

Radio telescopes are the most sensitive radio receivers in the world, and they are able to find extremely weak tufts of radio emissions from objects in the most remote regions of the universe. Recently, a team of astronomers used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) array to take advantage of nature’s helping hand to discover a distant galaxy that is possibly the weakest emitting object. nowadays.

The discovery was part of the VLA Frontier Fields Legacy Survey, led by NRAO astronomer Eric Murphy, who used distant galaxy clusters as natural lenses to study distant objects. The clusters functioned as gravitational lenses, using the gravitational forces of the galaxies within the clusters to bend and amplify light and radio waves from distant objects.

A VLA radio image superimposed on the Hubble Space Telescope image of the MACSJ0717.5 + 3745 galaxy cluster. Prominent orange-red objects are large structures called radio residues, and can be caused by shock waves within of the cluster. Credit: Heywood et al. Sofia Dagnello, NRAO / AUI / NSF; STScI.

In this compound, the VLA radio image is superimposed on the visible light image of The Hubble Space Telescope. The prominent red-orange objects are radio remnants – large structures possibly triggered by shock waves – within the foreground group of galaxies, called MACSJ0717.5 + 3745, which are over 5 billion years old – light of the Earth.

Detailed observations from the VLA have shown that many galaxies in this image emit radio waves in addition to visible light. VLA data revealed that one of these galaxies, shown in the recess, is over 8 billion light years away. Its light and radio waves have been distorted by the gravitational lensing effect of the interfering mass.

Astronomers have said that the radio image of this distant galaxy, called VLAHFF-J071736.66 + 374506.4, has been magnified more than 6 times by a gravitational lens. It is this magnification that allowed the VLA to discover it.

The distant galaxy, VLAHFF-J071736.66 + 374506.4, is more than 8 billion light years from Earth. Credit: Heywood et al. Sofia Dagnello, NRAO / AUI / NSF; STScI.

“It is possibly the weakest radio emission object ever to be discovered,” said Ian Heywood of the University of Oxford in the UK. “This is exactly why we want to use these galaxy clusters as powerful cosmic lenses to learn more about the things behind them.

“The magnification provided by the gravitational lens, combined with the highly sensitive VLA imaging, gave us an unprecedented look at the structure of a galaxy 300 times less massive than Milky Way At a time when the universe was less than half of its current age. This gives us valuable information about how stars formed in these low-mass galaxies at the time and how they eventually converged into more massive galaxies, NRAO’s Eric Jimenez-Andrade said.

Scientists report their work in two articles in The astrophysical journal.

Reference:

“VLA Border Field Scanning: High Resolution Deep Radiography of MACS Lens Clusters at 3 and 6 GHz” by I. Hywood, EJ Murphy, EF Jiménez-Andrade, L. Armus, WD Cotton, C. DeCoursey, M. Dickinson, TJW Lazio , E. Momjian, K. Penner, me. Smile and Om Smirnov, acceptable, The astrophysical journal.
arXiv: 2103.07806

“The VLA Frontier Field Survey: A comparison of the radio and UV / optical size of galaxies at 0.3 ≲z≲3 star-making galaxies” بقلم EF Jiménez-Andrade ، EJ Murphy ، I.Hywood ، I. Smail ، K. Penner ، E. Momjian ، M. Dickinson ، L. Armus and TJW Lazio ، Accepted ، The astrophysical journal.
arXiv: 2103.07807

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