Milky Way-Like Galaxy From 12 Billion Years Ago Discovered by Indian Scientists

Indian astronomers have made a groundbreaking discovery that challenges our understanding of early galaxy formation. Scientists Rashi Jain and Yogesh Wadadekar spotted a fully-formed spiral galaxy from when the Universe was only 1.5 billion years old, approximately 12 billion years ago.

The finding is significant because galaxies from this early cosmic period were believed to be mostly irregular and chaotic in structure, not the sophisticated spiral formations observed in this discovery.

James Webb Telescope Reveals Ancient Cosmic Pinwheel

Using the James Webb Space Telescope (JWST), the researchers identified what Prof Wadadekar describes as a “massive, beautifully structured cosmic pinwheel” that bears remarkable similarity to our own Milky Way galaxy.

“The galaxy looks remarkably similar to our own Milky Way, despite being present when the universe was only 10% of its current age,” said Prof Wadadekar. The team has named the galaxy Alaknanda after a Himalayan river.

The research was published in Astronomy and Astrophysics, a leading European journal, in November.

PhD Researcher Makes Rare Discovery

Ms Jain, a PhD researcher at the Pune-based National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research (NCRA-TIFR), spotted the galaxy earlier this year while analyzing data from the $10 billion telescope launched jointly by the US, European and Canadian space agencies in 2021.

“I had been looking at details of 70,000 objects and there was only one there that was a grand design spiral galaxy, spanning approximately 30,000 light-years in diameter,” she says.

Key Features of the Ancient Galaxy

The newly discovered galaxy exhibits several distinctive characteristics:

• Two symmetrical spiral arms emanating from a central disc
• A bright central bulge at its core
• “Beads-on-a-string” pattern showing star clusters along spiral arms
• Approximately one-third the size of the Milky Way
• Contains 10 billion solar masses of stars

Rapid Formation Challenges Cosmic Understanding

The discovery has left scientists astonished by the galaxy’s rapid development in cosmic terms.

“This galaxy had to assemble 10 billion solar masses of stars and simultaneously form a large disc with spiral arms in just a few hundred million years. That’s incredibly rapid by cosmic standards,” Prof Wadadekar told the BBC.

The galaxy is forming new stars at a rate roughly 20 to 30 times faster than the Milky Way’s current star formation rate.

Early Universe More Mature Than Previously Thought

According to NASA, there are an estimated hundred billion galaxies, many of which began forming within millions of years of the Big Bang. Astronomers have long believed the Universe during cosmic dawn was very chaotic, with galaxies being small and low in mass.

“But this galaxy is a different beast,” says Prof Wadadekar. “It’s massive, it’s one-third of the Milky Way in size, and has 10 billion stars.”

Growing Evidence of Sophisticated Early Structures

Since James Webb began operations, astronomers have been discovering newer, more distant galaxies. While initial images showed many galaxies as red blobs or faint smudges, recent years have revealed more sophisticated structures, including spiral galaxies.

“Finding such a well-formed spiral galaxy so far back in time is a rare exception, but such exceptions challenge our understanding of the universe’s early past and how galaxies formed and evolved,” Ms Jain says.

Looking Into the Cosmic Past

The information about Alaknanda is from 12 billion years ago, as the galaxy’s light has traveled that distance to reach Earth. When the Universe is 13.8 billion years old, this means scientists are observing the galaxy when the cosmos was only one-tenth of its current age.

“We can see into the past because the light has reached us. A galaxy’s lifetime is so big that we can’t see it from start to finish, so we do statistical studies,” says Ms Jain.

When asked about the galaxy’s current state, Prof Wadadekar offers a cosmic perspective: “When people ask me about where it is at present, I tell them wait for 12 billion years to see where it is now.”

Next Steps in Research

The researchers plan to apply for follow-up observations with James Webb or the Alma observatory in Chile to understand how Alaknanda managed to create its spiral arms so early in cosmic history.

“This galaxy shows that Universe was much more mature early on and that sophisticated structures were being built in our universe much earlier than we thought possible,” Ms Jain adds.

The discovery underscores that the keys to understanding our present and future may lie in studying the distant past of our universe.