Pune researchers find massive, grand-design spiral galaxy existing since universe's infancy
Pune (PTI): Two researchers from an astrophysics institute in Pune have discovered one of the most distant spiral galaxies ever observed - a massive, well-formed system that existed when the universe was just 1.5 billion years old.
The finding adds to growing evidence that the early universe was more evolved than previously assumed, they said.
Named 'Alaknanda' after a Himalayan river, the grand-design spiral galaxy challenges existing theories on how early complex galactic structures formed, the researchers said.
"Finding such a well-formed spiral galaxy at this early epoch is quite unexpected. It shows that sophisticated structures were being built much earlier than we thought possible," one of the researchers said.
Despite being present when the universe was only 10 per cent of its current age, Alaknanda appears strikingly similar to the Milky Way. The findings have been published in the European journal 'Astronomy & Astrophysics'.
Using NASA's James Webb Space Telescope (JWST), researchers Rashi Jain and Yogesh Wadadekar from the Pune-based National Centre for Radio Astrophysics (NCRA-TIFR) identified the galaxy.
"Alaknanda lies at a redshift of about 4, meaning its light has travelled more than 12 billion years to reach Earth," Jain said.
"We are seeing this galaxy as it appeared just 1.5 billion years after the Big Bang. Finding such a well-formed spiral galaxy at this early epoch is quite unexpected. It shows that sophisticated structures were being built much earlier than we thought possible," she said.
Using JWST's infrared sensitivity and resolution, the team found that Alaknanda contains roughly "10 billion times the mass of the sun in stars" and is forming new stars at about 63 solar masses per year, nearly 20 to 30 times the Milky Way's current rate, the researchers said in a release.
Before JWST, astronomers believed early galaxies were chaotic and clumpy, with stable spiral structures emerging only after several billion years, they said.
Dominant models suggested that early galaxies were too "hot" and turbulent to form ordered disks capable of sustaining spiral arms, the release said.
"Alaknanda tells a different story," Wadadekar said. "This galaxy had to assemble 10 billion solar masses of stars and build a large disk with spiral arms in just a few hundred million years. That's incredibly rapid by cosmic standards," he said.
The discovery adds to growing JWST evidence that the early universe was more evolved than previously assumed. "While other disk galaxies have been spotted at similar distances, Alaknanda is among the clearest examples of a spiral galaxy with well-defined arms at such a high redshift," the release said.
Jain said the team chose the name Alaknanda - one of the two main headstreams of the river Ganga - because of its connection to the Milky Way.
"Just as the Alaknanda is the sister river of the Mandakini, which is the Hindi name for our own Milky Way, we thought it fitting to name this distant spiral galaxy after the Alaknanda river," she said.
Although Alaknanda's photometric redshift is well-established, follow-up observations with JWST's NIRSpec instrument or the Atacama Large Millimeter/submillimeter Array (ALMA) are needed to measure its disk rotation, the researchers said.
"These measurements will reveal whether the galaxy's disk is 'cold' and orderly or 'hot' and turbulent, helping scientists understand how its spiral arms formed," they added.
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'Sharjeel Imam not a disciple of Umar Khalid,' his counsel tells court
New Delhi (PTI): The counsel for the jailed activist Sharjeel Imam told a court here on Thursday that Umar Khalid never mentored his client before the 2020 Delhi riots, and the prosecution's allegation that Imam was a disciple of Khalid was "absurd."
The submissions were made before Additional Sessions Judge Sameer Bajpai, who was hearing arguments on the charge against Imam, an accused in the 2020 Northeast Delhi riots conspiracy case.
Counsels for Imam, Ahmad Ibrahim, and Talib Mustafa submitted before the court that, despite their client and Khalid being the students of the same varsity, Jawaharlal Nehru University, there was no direct or indirect communication between them.
"The allegations find no support from the materials relied upon by the prosecution. Rather, the applicant (Imam) never spoke to Umar Khalid. It is highly improbable and rather unbelievable that the applicant, who, as per the prosecution, was mentored by Umar Khalid, never had any calls or messages with him," Imam's counsel Mustafa said in the court.
He said both were added to two groups, the Muslim Students of JNU (MSJ) and the CAB TEAM, just because they were students of the same university.
Referring to the prosecution's allegation that Imam hatched a criminal conspiracy with the other accused persons to cause a 'chakka jam,' which was later escalated into violent riots, his counsel said that there was no evidence that showed that at any point in time Imam had any intention to incite violence.
"In none of the materials relied upon by the prosecution, including speeches. pamphlets, chats and Facebook posts of Imam, there is nothing which could even remotely suggest that the applicant at any point of time had any intention to incite violence," he said.
He also contended that the prosecution tried to create a narrative of religious extremism around Imam by conflating purported discussions of issues affecting a particular religious community.
"Notably, mere academic criticism of events perceived by the applicant to be against a community doesn't make one communal, much less an extremist," he said.
According to the prosecution, Imam, along with other MSJ members, participated in a protest called by Jamia Milia Islamia students, where allegedly pamphlets were distributed to incite communal feelings among the Muslim community and induce them to protest against the CAA.
"Nothing communal in the alleged pamphlet. Merely talks about the discriminatory nature of CAA and its possible consequence if implemented coupled with NRC (National Register of Citizens)," his counsel said, concluding his arguments.
The case pertains to the February 2020 riots in northeast Delhi that left 53 people dead and more than 700 injured.
The violence erupted during widespread protests against the Citizenship (Amendment) Act (CAA) and the National Register of Citizens (NRC).
The Delhi Police has alleged that Imam was involved in deliberate mobilisation, radicalisation and preparation of ground conditions through organised chakka jams, blockage of arterial roads, and disruption of essential services.
He allegedly created and administered the WhatsApp group, Muslim Students of JNU, which functioned as a coordinating mechanism for mobilisation, identification of protest sites.
Police accused Imam of attending and participating in conspiratorial meetings in Jangpura, where the strategy of chakka jam and escalation of protests was discussed.
Imam's role was allegedly not geographically confined to Delhi and acted as a mobiliser and ideologue, as the appellant travelled to Aligarh and other locations, police said.
Police also accused Imam of playing a decisive role in the creation and sustenance of the Shaheen Bagh protest site, which evolved into a prolonged round-the-clock blockade of a major arterial road.
They alleged that the Imam's role was foundational and preparatory, and that liability for conspiracy does not require physical presence at the scene of violence once the plan has been set in motion.
