The body of professor Steven Rawlings, 50, was found in the bungalow of colleague and rival astrophysicist Dr Devinder Sivia, 49, in Oxfordshire on Wednesday.
Police were called reporting an injured man and said they arrested a 49-year-old man at the property.
It is believed that Rawlings had a heart attack after being assaulted, but a postmortem was inconclusive. Police are treating the death as a murder.
Reports say that the Rawlings and Sivia were arguing that night over “academic matters”.
The pair are thought to have known each other for 15 years and have written a book together called Foundations of Science Mathematics, published in 1999.
Oxford University students and staff were said to be stunned to hear about the popular astrophysics professor’s death.
Rawlings was a world expert on black holes and has lectured alongside Stephen Hawking.
The Vice Chancellor of the university, Professor Andrew Hamilton, said: “The entire university community has been profoundly saddened and shocked by the tragic and untimely death of Professor Steve Rawlings. Our thoughts are with his family and friends.”
Former BBC Radio 4 controller Mark Damazer, now master at St Peter’s College, said he was “much liked and admired” and that he “will be greatly missed”.
Rawlings lived with his wife Linda in Wantage, Oxfordshire, and they celebrated her 50th birthday last week.