Since gravity affects everything with mass or energy, and photons of light have energy, gravity can bend the path of light as it moves through space. When just the right collection of objects pile together between us and some distant galaxy, the collected gravity can act like a lens to focus light in our direction, light that normally would have journeyed elsewhere. 

Using the Very Large Array of radio dishes in New Mexico, scientists have explored the region of sky around the galaxy cluster MACJ0717.5+3745 looking for distant systems magnified by gravity, and they found one. The impossibly named galaxy VLAHFF-J071736.66+374506.4 has been magnified six times by the cluster’s gravity, allowing astronomers to observe an ancient galaxy like nothing previously seen. 

According to Eric Jimenez-Andrade: The magnification provided by the gravitational lens, combined with extremely sensitive VLA imaging, gave us an unprecedented look at the structure of a galaxy 300 times less massive than our Milky Way at a time when the universe was less than half its current age. This is giving us valuable insights on star formation in such low-mass galaxies at that time and how they eventually assembled into more massive galaxies. 

This work is described in a pair of papers appearing in The Astrophysical Journal.

More Information

NRAO press release

“The VLA Frontier Fields Survey: Deep, High-resolution Radio Imaging of the MACS Lensing Clusters at 3 and 6 GHz,” I. Heywood et al., to be published in The Astrophysical Journal (preprint on arxiv.org)

“The VLA Frontier Field Survey: A Comparison of the Radio and UV/optical size of 0.3≲z≲3 star-forming galaxies,” E. F. Jiménez-Andrade et al., to be published in The Astrophysical Journal (preprint on arxiv.org)