The results could fundamentally change our understanding of how most massive galaxies form and evolve.
Spiral galaxies have been known to exist for a long time — our Milky Way is one, after all! But recently, a new and strange kind of cosmological monster has been spotted in deep space. Named “super spirals,” these unexpected and unexplainable galaxies dwarf our Milky Way, and they compete in both size and brightness with the largest galaxies in the known universe.
According to a team from the Infrared Processing and Analysis Centre (IPAC) at the California Institute of Technology, these newly found super spirals are 8 to 14 times brighter than the Milky Way, have 10 times as much mass, and create 30 times more stars. And their size? They span an impressive 440,000 light-years in width, making our 100,000-light-year-wide galaxy look like a pipsqueak.
SEE ALSO: Our Sun Was Involved In “Cannibalism on Astronomical Scales”
Being so enormous, it is hard to imagine how the super spirals went unnoticed for so long. It turns out that they were hiding in plain sight by mimicking the appearance of regular spiral galaxies. Analyzing archived NASA data from the NASA/IPAC Extragalactic Database (NED) — an online database of over 100 million galaxies — the team revealed that these supposedly nearby objects were in fact distant, ginormous versions of typical spirals.
The team had set out to examine the brightest galaxies and thought that ellipticals — a type of massive galaxy that looks a lot like a football — would win hands down. So they were quite surprised to to see that of the 800,000 galaxies they studied, most of the brightest ones were spiral instead of elliptical.
“We have found a previously unrecognized class of spiral galaxies that are as luminous and massive as the biggest, brightest galaxies we know of,” Patrick Ogle, an astrophysicist at IPAC and lead author of a new paper, said in a press release. “It's as if we have just discovered a new land animal stomping around that is the size of an elephant but had shockingly gone unnoticed by zoologists.”
The discovery of these rare, super spiral galaxies opens a can of worms for researchers — it is a mystery as to how such giant objects could have formed.
According to established astrophysical theory, spiral galaxies should not be able to get this large because their size and star-making potential are limited by their own gravity. As spiral galaxies grow by gravitationally attracting gas from intergalactic space, their masses reach a tipping point where any newly captured gas will rush in too quickly. This gas is then heated up, preventing any new star formation by a process known as quenching. However, super spirals remain unquenched.
SEE ALSO: Are There Dark “Noodles” of Matter Hiding in Our Galaxy?
Luckily, astronomers are not completely in the dark. A crucial hint about the origin of super spirals may have been found in 4 of the 53 seen by Ogle and colleagues: They contain two galactic nuclei instead of the usual one.
Double nuclei, which look like two egg yolks in a frying pan, are a telltale sign of two galaxies having just merged together. Conventionally, the merger of two spiral galaxies are destined to become elliptical ones, but the team speculates that a special merger involving two, gas-rich spiral galaxies could in fact settle into a new, larger disk — a super spiral!
“Super spirals could fundamentally change our understanding of the formation and evolution of the most massive galaxies,” said Ogle. “We have much to learn from these newly identified, galactic leviathans.”
Facebook comments