Cosmic lens reveals faint radio galaxy more than 8 billion light-years from Earth – tech2.org

Cosmic lens reveals faint radio galaxy more than 8 billion light-years from Earth


Galaxy Cluster MACSJ0717.5 + 3745

Composite image of the galaxy cluster MACSJ0717.5 + 3745, with VLA radio image superimposed on visible light image from the Hubble Space Telescope. The extraction is a detail of the distant galaxy VLAHFF-J071736.66 + 374506.4, probably the weakest radio-emitting object found so far, revealed by the magnifying effect of the gravitational lensing. Credit: Heywood et al .; Sophia Dagnello, NRAO / AUI / NSF; STScI.

Radio telescopes are the world’s most sensitive radio receivers, capable of finding extremely faint wisps of radio emission from objects in the farthest reaches of the universe. Recently, a team of astronomers used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to harness the help of nature to detect a distant galaxy that is probably the weakest radio-emitting object ever found.

The discovery was part of the VLA Frontier Fields Legacy Survey, led by NRAO astronomer Eric Murphy, which used distant clusters of galaxies as natural lenses to study even more distant objects. The clusters served as gravitational lenses, using the gravitational pull of the galaxies in the clusters to bend and magnify the light and radio waves coming from more distant objects.

Galaxy Cluster MACSJ0717.5 + 3745 Composite

VLA radio image superimposed on a Hubble Space Telescope image of the galaxy cluster MACSJ0717.5 + 3745. The prominent orange-red objects are large structures called radio relics, possibly caused by shock waves within the cluster. Credit: Heywood et al .; Sophia Dagnello, NRAO / AUI / NSF; STScI.

In this composite, a VLA radio image is superimposed on a visible light image of the hubble space telescope. The prominent orange-red objects are radio relics (large structures possibly caused by shock waves) within the foreground galaxy cluster, called MACSJ0717.5 + 3745, which is more than 5 billion light-years from the Land.

Detailed observations from the VLA showed that many of the galaxies in this image emit radio waves in addition to visible light. The VLA data revealed that one of these galaxies, shown in the extraction, is more than 8 billion light-years away. Its light and radio waves have been bent by the gravitational lensing effect of the middle cluster.

The radio image of this distant galaxy, called VLAHFF-J071736.66 + 374506.4, has been magnified more than 6 times by gravitational lensing, the astronomers said. That increase is what allowed the VLA to detect it.

Galaxy VLAHFF-J071736.66 + 374506.4

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

“This is probably the weakest radio-emitting object ever detected,” 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 objects behind them.”

“The magnification provided by the gravitational lensing, combined with extremely sensitive VLA images, gave us an unprecedented look at the structure of a galaxy 300 times less massive than our own. Milky Way at a time when the universe was less than half its current age. This is giving us valuable information about the formation of stars in low-mass galaxies at that time and how they eventually assembled into more massive galaxies, ”said Eric Jimenez-Andrade of NRAO.

The scientists report their work in a couple of articles in the Astrophysical Journal.

References:

“The VLA Frontier Fields Survey: Deep, High-Resolution Radio Imaging of MACS Lens Clusters at 3 and 6 GHz” by I. Heywood, EJ Murphy, EF Jiménez-Andrade, L. Armus, WD Cotton, C. DeCoursey , M. Dickinson, TJW Lazio, E. Momjian, K. Penner, I. Smail and OM Smirnov, accepted, Astrophysical Journal.
arXiv: 2103.07806

“The VLA Boundary Field Study: A Radio and UV / Optical Size Comparison of 0.3≲z≲3 Star-Forming Galaxies” by EF Jiménez-Andrade, EJ Murphy, I. Heywood, I. Smail, K. Penner, E. Momjian, M. Dickinson, L. Armus and TJW Lazio, accepted, Astrophysical Journal.
arXiv: 2103.07807

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under a cooperative agreement by Associated Universities, Inc.



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