Scientists have identified a group of miniature galaxies situated approximately 3 million light-years distant, which encompasses the tiniest and dimmest galaxy known to date.
This galaxy, named Andromeda XXXV, along with its companions circling around our neighboring galaxy, Andromeda, might alter our perceptions of cosmic evolution.
This is due to dwarf galaxies of such a tiny size typically being obliterated under the hotter and more dense environments. early universe And yet, for some reason, this small galaxy managed to survive without getting destroyed.
Despite their small scale—approximately one-millionth the size of our Milky Way—they function just as well as full-sized galaxies," explained team member and University of Michigan professor Eric Bell in a press release. "Imagine a person with all the capabilities intact, yet shrunk down to the size of a single grain of rice.
Meet Andromeda XXXV
Dwarf galaxies are not unfamiliar to scientists. Our home galaxy, the Milky Way , is orbited by many of these satellite galaxies trapped within the grasp of its larger galactic neighbors.
Nevertheless, many aspects of dwarf galaxies remain mysteries to scientists. Due to their smaller size, these galaxies emit less light compared to larger ones, which makes them more difficult to observe and investigate from far away.
Although astronomers have managed to pinpoint numerous dwarf galaxies revolving around the Milky Way, detecting similar small galaxies circling our luminous neighboring galaxies has proven extremely challenging. Thus, the small galaxies of the Milky Way Have served as our sole source of knowledge regarding tiny galactic entities.
This assignment is relatively easier when concerning the nearest large galaxy to the Milky Way, which is Andromeda. Dwarf galaxies have been observed near Andromeda. Previously, they were big and noticeable, merely reinforcing the data that astronomers had collected regarding dwarf galaxies orbiting the Milky Way.
To uncover these groundbreaking smaller and fainter dwarf galaxies, lead researcher Marcos Arias, an astronomer from the University of Michigan, along with his collaborators examined extensive astronomical databases. They were also granted observing time with major telescopes. Hubble Telescope to aid their search.
This discovery showed that Andromeda XXXV is not just a satellite galaxy, but its size is also significant enough to alter our understanding of galactic evolution theories.
I found this quite astonishing," Bell stated. "Given that it’s the dimmest object detected in the area, it presents an intriguing setup. However, multiple aspects about it were unforeseen.
A cosmic murder mystery
A crucial element of galactic evolution revolves around the duration of their star-forming periods This appeared to be the primary distinction between the Milky Way's dwarf galaxies and the less massive satellite galaxies orbiting Andromeda.
Arias noted that most of the Milky Way’s satellite galaxies possess extremely old stellar communities, ceasing star formation roughly 10 billion years back. In contrast, she pointed out that some analogous satellites orbiting Andromeda were still producing stars until approximately 6 billion years ago,
Stellar creation depends on a continuous supply of gas and dust to collapse and form new stars. Once this fuel runs out, star formation stops, effectively causing the galaxy to “die.”
Therefore, Bell characterized the circumstances surrounding these tiny galaxies as a "cold case" puzzle. Was star formation halted within the dwarf galaxies? gas supplies petered out On their own, or when these gases were stripped away by gravitational forces from a massive galactic host?
For the Milky Way, it seems that the supply of gas needed for star formation naturally dwindled over time. In contrast, for the smaller galaxies surrounding Andromeda, it looks like they were essentially “destroyed” by their larger host galaxy.
The lighting is somewhat dim, but it seems these galaxies either fell or were shoved out of place. It appears they were pushed," Bell stated. "This has taught us something fundamentally new regarding how galaxies form.
What is particularly intriguing is the prolonged duration of star formation observed in Andromeda XXXV. To grasp this phenomenon, we must look back to the era when the very first galaxies were formed.
Why doesn’t Andromeda XXXV qualify as a ‘deep-fried’ galaxy?
The initial era of the cosmos was characterized by extremely high temperatures and densities. This inflationary era was initiated by the Big Bang Continuing on, as the universe expanded and cooled, the initial atoms of hydrogen formed, leading to the creation of the first stars that clustered together. first galaxies.
These stars and galaxies emitted energy just like the earliest feeding black holes, which also helped reheat the universe. This event marked the demise of tiny galaxies, with experts suggesting that this heat essentially boiled away the gas required for star formation within these stellar clusters.
Nevertheless, against all odds, Andromeda XXXV endured!
Bell stated, "Initially we believed everything would essentially turn into ash since the whole cosmos transformed into a cauldron of searing hot liquid, resembling boiling oil. We anticipated that it would entirely exhaust its supply of gas; however, that seems not to be the case. This entity has an estimated mass of around 20,000 times that of our sun and continued to form stars without issue for several additional billions of years."
Exactly why Andromeda XXXV managed to avoid being destroyed remains an enigma.
“I don’t have a solution,” Bell stated. “The fact remains that the universe did experience warming; however, we’re now realizing the outcomes are far more complex than previously understood.”
NASA Other agencies are preparing missions that might uncover additional dwarf galaxies orbiting larger galaxies, which could shed light on this enigma. However, it’s likely that these discoveries may raise new queries similar to how the finding of Andromeda XXXV did.
Arias noted, 'We still have much to uncover.' There are numerous aspects we must continue to study — particularly concerning our immediate surroundings when it comes to galactic development, transformation, and organization — before we can deconstruct the chronology of the universe’s past and grasp how we arrived at this point.'
The team's study was released on Tuesday (March 11) in The Astrophysical Journal Letters.
