Halo stars, starbursts, and distant globular clusters: A survey of unresolved objects in the Hubble Deep Field

Abstract

We present a survey of unresolved objects in the Hubble Deep Field. We find 59 such objects with I₈₁₄≤ 28. Only nine are candidates for low mass ( m ≤ 0.5M _⊙) halo stars. This rules out a steeply rising luminosity function fainter than M _v = 12, and precludes low mass stars as a major constituent of halo dark matter. Although 50 of the unresolved objects have colors consistent with those of white dwarfs, we argue that they are unlikely to be. They are more probably regions of intense star formation with size less than about a kiloparsec. We find no candidate quasars, but the small size of the field does not allow us to put many constraints on quasar number densities. Finally, we identify 11 globular clusters candidates associated with an elliptical galaxy with a distance modulus of ~ 39.