A strange double object that appeared to be an exact reflection of the same galaxy and its oddball companion, which baffled scientists for years, has led to the discovery of an entirely new galaxy.
The three objects are actually distorted images of the same distant galaxy which is located 11 billion light-years from Earth. As well as allowing for the discovery of a new distant galaxy, the cosmic optical illusion has provided scientists with a rare example of an alignment of a galaxy with Earth so precise it causes three perfect copies of the same distant object.
The reflected images have been named Hamilton’s Object, after their discoverer Timothy Hamilton, an astronomer at Shawnee State University in Portsmouth, Ohio.
While analyzing the cores of active galaxies, known as quasars, NASA’s Hubble Space Telescope Hamilton stumbled across two bright images that appeared to be an exact reflection of each other.
The strange double object appeared to be two identical galactic bulges, the thick cluster of stars that exist towards the center of some galaxies. The bulges were accompanied by three parallel split streaks.
In addition to this strange reflection, a third odd image was located close by, in cosmic terms. The galactic bulge reflection and its oddball companion baffled researchers for years, with many theories suggested but failing to explain the arrangement.
“We were really stumped,” Hamilton said in a Hubble press release. “My first thought was that maybe they were interacting galaxies with tidally stretched-out arms. It didn’t really fit well, but I didn’t know what else to think.”
The team got to the bottom of the effect causing Hamilton’s Object by drafting in experts specializing in gravitational lensing.
Gravitational lensing is the effect of objects of great mass in the universe warping the very fabric of space itself, first predicted in Albert Einstein’s theory of general relativity.
One consequence of the warping of space is that when light passes it, the straight line in which it travels is curved. As well as creating some stunning cosmic optical illusions, the effect can be used to study objects that are too far to be visualized, even with the most powerful telescopes like Hubble.
“Think of the rippled surface of a swimming pool on a sunny day, showing patterns of bright light on the bottom of the pool,” University of Hawaii researcher Richard Griffiths, who led the investigation, explained. “These bright patterns on the bottom are caused by a similar kind of effect as gravitational lensing.
“The ripples on the surface act as partial lenses and focus sunlight into bright squiggly patterns on the bottom.”
A NASA graphic showing how gravitational lensing curves light and creates cosmic optical illusions. Researchers used the phenomenon to discover a weird object was actually the reflection of a distant galaxy. NASA
Griffiths and the team discovered that this ripple effect distorts the distant galaxy almost like a funhouse mirror, creating Hamilton’s Object. The effect is caused by dense amounts of dark matter, the mysterious substance that creates the gravitational effect that prevents galaxies from flying apart.
This dark matter belongs to a cluster of galaxies that lie 7 billion light-years away and in between Earth and the newly discovered galaxy, warping its light and making it appear in the night sky in three separate locations.
Despite this realization, the team still had to assess if all three of the reflected images were at the same distance. To solve this, they brought in University of Heidelberg gravitational lensing expert Jenny Wagner and University of Manchester scientist Nicolas Tessore.
The duo provided software that could interpret unusual lensing effects like those causing Hamilton’s Object. The software revealed that the image was created because the dark matter around the galaxy cluster is so smoothly distributed.
Thus, the findings, published in a paper in the Monthly Notices of the Royal Astronomical Society, may also give astronomers a method of cracking the mysteries of dark matter.
“We know it’s some form of matter, but we have no idea what the constituent particle is. So we don’t know how it behaves at all. We just know that it has mass and is subject to gravity,” Griffiths concludes. “The significance of the limits of size on the clumping or smoothness is that it gives us some clues as to what the particle might be.
“The smaller the dark matter clumps, the more massive the particles must be.”
A Hubble Space Telescope picture showing three magnified images of a distant galaxy embedded in a cluster of galaxies. The illusion is created by gravitational lensing and led to the discovery of a new galaxy. Richard E. Griffiths UH Hilo)/Jenny Wagner ZAH/ Joseph DePasquale (STScI/NASA/ESA