What is the name of an old Robert Silverberg story where there are colonies of people who have died, who don't interact well with the living. A curious journalist tries to get answers by infiltrating, is of course detected, and is killed so he can finally stop pestering them and fit in. I think there was an epigram from T.S. Eliot.
That is Robert Silverberg's novella "Born with the Dead", first published in The Magazine of Fantasy and Science Fiction, April 1974, available at the Internet Archive. Here's a description from The Quasi-Official Robert Silverberg Web Site:
This story was written for a special Silverberg issue of F&SF and won the Nebula Award for best novella, 1975.
In the 1990s, doctors have discovered how to rekindle dead people, re-animating the bodies and minds. But the deads are different, aloof, unconcerned with the matters of warms — those still alive — and mostly keep to the Cold Towns. Jorge Klein finds that he cannot let go of his dead wife Sybille, and seeks her out obsessively, following her around the globe. This is just not done, but Jorge can't stop himself.
One interesting scene involves an African preserve set aside for vacationing deads, where they must leave the native animals alone and hunt instead genetically recreated extinct species — aurochs, ground sloth, quagga, passenger pigeon, dodo. Many aspects of the situation are explored, including the attitudes people of different cultures have towards death. Definitely one of the high points of Silverberg's career and the culmination of his intense and intimate writing of the 1970s.
And what the dead had no speech for, when living,
They can tell you, being dead: the communication
Of the dead is tongued with fire beyond the language of the living.