Scientists have discovered a bow and arrow galaxy sitting roughly 2 billion light-years from Earth, and it is, by all accounts, absolutely enormous, deeply strange, and completely unlike anything radio astronomers have clapped eyes on in the past quarter-century. Which, frankly, is the kind of sentence you do not get to type very often, and should be savoured accordingly.
What on Earth (or Off It) Is a Bow and Arrow Galaxy?
The galaxy in question has been given the magnificently unwieldy name RAD-Bow-And-Arrow Radio Galaxy, or RAD-BAARG if you are in a hurry, which astronomers apparently are not. Radio galaxies are typically powered by supermassive black holes doing what supermassive black holes do best: consuming everything in sight and firing colossal jets of charged particles in opposite directions like the universe’s most destructive sprinkler system. Normally, this results in a pleasingly symmetrical pair of glowing plasma lobes — like two cosmic balloons tied either side of a birthday cake made of doom. RAD-BAARG, however, has decided symmetry is for lesser galaxies.
On one side, a jet is ploughing headlong into a wall of compressed gas — a so-called bow shock — and has been bent into the shape of a drawn bow, stretching an almost incomprehensible 1.8 million light-years across. On the other side, the second jet twists into a distorted S-shape before fading into a faint tail, forming the arrow. The overall structure measures about 2.3 million light-years in length. For context, our own Milky Way is roughly 100,000 light-years across. RAD-BAARG makes it look like a postage stamp.
A Citizen Scientist Walks Into a Galaxy
Here is where the story gets genuinely heartwarming, in a nerdy sort of way. RAD-BAARG was not spotted by a room full of PhDs sipping lukewarm coffee and arguing about dark matter. It was first noticed by Pranim Limbo, a citizen scientist working through India’s RAD@home Astronomy Collaboratory, a rather brilliant initiative that lets enthusiastic amateurs poke through genuinely cutting-edge radio telescope data. Limbo was inspecting images from the LOFAR Two-metre Sky Survey — one of the most sensitive radio surveys ever conducted — when he spotted something that had no business existing.
Ananda Hota, the principal investigator of RAD@home, put it with admirable understatement: the structure of this source is unlike that of any radio galaxy seen in the last 25 years. Furthermore, Hota has presumably seen quite a lot of radio galaxies, so this is not a sentiment to be dismissed lightly.
Why Is the Bow and Arrow Galaxy Such a Big Deal?
Astronomers have long predicted that galaxies falling into larger clusters should create bow shocks as they plunge through the hot, thin gas filling the space between galaxies — the so-called intracluster medium. However, actually catching one in the act has been, until now, extraordinarily difficult. The gas is too diffuse and faint to detect easily. Consequently, RAD-BAARG is not just a peculiar shape; it is a direct, detailed window into a phenomenon that has largely remained theoretical.
The discovery has been published in the Monthly Notices of the Royal Astronomical Society, which is, despite its name, published more than once a month and contains considerably more excitement than its title suggests. Meanwhile, the combined image — stitched together from LOFAR radio data and optical imaging from the Beijing-Arizona Sky Survey — is absolutely gorgeous. Red tendrils of plasma curve through the cosmos like something a very ambitious artist might produce after an unusually inspiring evening.
The Universe: Still Showing Off
There is something quietly magnificent about the fact that the universe, some 13.8 billion years into its existence, is still producing structures nobody has ever seen before. The bow and arrow galaxy joins a growing catalogue of cosmic objects that seem almost deliberately designed to make humans feel simultaneously tiny and electrified with wonder — alongside the Cat’s Eye Nebula, the Crab Nebula, and whatever a cosmic hamburger is, which we are absolutely going to look up immediately after filing this piece. As bullseyes go, this one is 1.8 million light-years wide. Not bad for a Tuesday.
Read the original story at LiveScience – Weird News.
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