A postmortem on an Oxford University physicist who was found dead at the home of a colleague has proved inconclusive. Astrophysicist Steve Rawlings, 50, a fellow at St Peter's College in Oxford, was found dead on the evening of Wednesday 11 January. Thames Valley Police have now launched a murder investigation following the arrest of a 49-year-old man – reported to be Oxford mathematician Devinder Sivia – in connection with the incident.

Thames Valley Police were called to a house in Laurel Drive, Southmoor, at 11.22 p.m. on Wednesday night by a neighbour who reported that there had been an incident within the property – alleged to be Sivia's home – and that a man had been injured. The neighbour attempted to resuscitate him but when officers and paramedics arrived on the scene, Rawlings was pronounced dead. Thames Valley Police say that a postmortem examination carried out on Rawlings yesterday has proved inconclusive.

It is alleged that Rawlings and Sivia had an argument after returning to Sivia's house late on Wednesday evening. Sivia remained in police custody until late this morning but has now been released on bail until 18 April. Rawlings and Sivia co-wrote a book called Foundations of Science Mathematics, which was published in 1999 by Oxford University Press. "We are all stunned here," Roger Davies, head of astrophysics at Oxford University, told physicsworld.com.

Saddened and shocked

Rawlings was an observational cosmologist who worked on the physics of extragalactic radio sources and active galactic nuclei. He was involved in the Square Kilometre Array – a next-generation radio telescope that will be built in Australia or Southern Africa – and played a prominent role in the redevelopment of the Goonhilly Satellite Earth Station in Cornwall as a radio-astronomy facility.

Rawlings completed a PhD at the University of Cambridge in astrophysics and remained there to do postdoctoral work before moving to Oxford in 1992. He became a lecturer in astrophysics and later a professor, serving as head of astrophysics at Oxford from 2006 to 2010. Until his death he taught vector calculus to first-year undergraduates and was a Tutorial Fellow at St Peter's college.

A statement on Oxford University’s website says "We are immensely sad to report the death of our much-loved colleague Professor Steve Rawlings. Steve has for many years been a creative and inspirational colleague, and we shall miss him greatly. The heartfelt condolences and sympathies of all of us go out to his wife and family."

At the closing of the 219th American Astronomical Society meeting in Texas, Austin, yesterday a minute's silence was held in memory of Rawlings. "The entire university community has been profoundly saddened and shocked by the tragic and untimely death of Professor Steve Rawlings," says Andrew Hamilton, vice-chancellor of Oxford University. "Our thoughts are with his family and friends."

"He was a much liked and admired tutor and colleague within the College and will be greatly missed," says Mark Damazer, master of St Peter's College. "We extend our deepest sympathy to his wife Linda."