Testing the relation between the local and cosmic star formation histories

Research output: Contribution to journalArticlepeer-review


Recently, there has been great progress toward observationally determining the mean star formation history of the universe. When accurately known, the cosmic star formation rate could provide much information about Galactic evolution, if the Milky Way's star formation rate is representative of the average cosmic star formation history. A simple hypothesis is that our local star formation rate is proportional to the cosmic mean. In addition, to specify a star formation history, one must also adopt an initial mass function (IMF); typically it is assumed that the IMF is a smooth function, which is constant in time. We show how to test directly the compatibility of all these assumptions by making use of the local (solar neighborhood) star formation record encoded in the present-day stellar mass function. Present data suggest that at least one of the following is false: (1) the local IMF is constant in time; (2) the local IMF is a smooth (unimodal) function; and/or (3) star formation in the Galactic disk was representative of the cosmic mean. We briefly discuss how to determine which of these assumptions fail and also improvements in observations, which will sharpen this test.

Original languageEnglish (US)
Pages (from-to)603-609
Number of pages7
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - Apr 20 1999


  • Cosmology: observations
  • Galaxy: evolution
  • Stars: formation
  • Stars: luminosity function, mass function

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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