Which is correct: "has died" or "died"?

The Present Perfect Construction in English has the following uses (cf. McCawley 1971):

• (a) The Universal sense of the Perfect, used to indicate that a state of affairs prevailed throughout some interval stretching from the past into the present
  • I've known Max since 1960.

• (b) The Existential sense of the Perfect, used to indicate the existence of past events,
  • I have read Principia Mathematica five times.

• (c) The Stative/Resultative sense of the Perfect,
  used to indicate that the direct effect of a past event still continues
  • I can't come to your party tonight - I've caught the flu.

• (d) The Hot News sense of the Perfect, used to report hot news
  • Malcolm X has just been assassinated.

This, coupled with the prohibition on the use of Present Perfect with subjects who are dead

• Madonna has visited Chicago.
• *Einstein has visited Chicago.

means that X has died is only appropriate in a context in which
the speaker believes that the addressee would not yet know that X is dead.

Executive Summary: If it's Hot News, use the Present Perfect; but if it's Old News, simple past.

McCawley, James D. 1971. Tense and time reference in English.
In C. Fillmore and T. Langendoen (eds.), Studies in Linguistic Semantics
New York: Holt, Rinehart and Winston, pp 96-113.