Veteran scientist C.V. Vishveshwara, known as a pioneer in black hole research in India, has died, researchers associated with LIGO said on Tuesday.

Celebrated as the 'Black Hole Man of India', the 78-year-old died on Monday evening in Bengaluru following a bout of illness, LIGO India said on its Facebook page.

Popularly called 'Vishu', his contribution to black hole physics dates even before the word 'black hole' was coined, said US-based India researcher Karan Jani.

"In the late 1960s, as a graduate student at the University of Maryland, he published three ground-breaking single-author papers, which combined shaped our understanding of black holes. Stephen Hawking, Roger Penrose all came later in the picture," said Jani, who is associated with LIGO.

Vishveswara made an important calculation that was used in the discovery of gravitational waves by LIGO (Laser Interferometer Gravitational Wave Observatory) detectors in 2015, from the merger of black holes.

LIGO India paid homage to the scientist with a photograph that showed his reactions when the waveform predicted by him was first observed.

"On February 11, 2016, he was invited to the synchronised announcement of the first discovery of gravitational waves at IUCAA. The first picture shows a visibly emotional Vishu reacting to observational revelation of quasi-normal modes (now more popularly dubbed the 'ring down' signal) of black holes predicted by him long back as a graduate student in 1972," said LIGO India.

"At this event, he also witnessed the growing community of #LIGOIndia and was thrilled to see the energy and enthusiasm among the young researchers. In the second picture, he is shown with a large part of the rapidly growing group of Indian researchers of the gravitational wave.

Besides his larger than life stature as an excellent academic, he endeared himself to the entire science world with his witty comments, humorous after-dinner speeches and amazing science cartoons."

Fred Raab, associate director for operations, LIGO Laboratory, who was in the eastern metropolis for a lecture, also highlighted his contributions with regards to the 'ring down' signal, akin to a bell, ringing and fading away, when black holes merge.

"It is such a shame that very few realised how seminal his contribution was to physics. In his lifetime, he received no Padma awards, nor any major distinction from Indian government or academic community," Jani said.

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