Rest‐Frame Ultraviolet to Near‐Infrared Observations of an Interacting Lyman Break Galaxy at z = 4.42 Academic Article uri icon


  • We present the rest-frame ultraviolet through near-infrared spectral energy distribution for an interacting Lyman break galaxy at a redshift z = 4.42, the highest redshift merging system known with clearly resolved tidal features. The two objects in this system, HDF-G4 and its previously unidentified companion, are both B435 -band dropouts, have similar V606 - i 775 and i775 - z850 colors, and are separated by 1″, which at z = 4.42 corresponds to 7 kpc projected nuclear separation; these are all indicators of an interacting system. Fits to stellar population models indicate a stellar mass of M* = 2.6 × 10 10M⊙, an age of τ* = 720 Myr, and an exponential star formation history, with an e-folding time τ0 = 440 Myr. Using these derived stellar populations as constraints, we model the HDF-G4 system using hydrodynamical simulations, and find that it will likely evolve into a quasar by z ∼ 3.5, and a quiescent, compact spheroid by z ∼ 2.5, similar to those observed at z ≥ 2. The existence of such an object supports galaxy formation models in which major mergers drive the high-redshift buildup of spheroids and black holes. © 2007. The American Astronomical Society. All rights reserved.

author list (cited authors)

  • Younger, J. D., Huang, J., Fazio, G. G., Cox, T. J., Lai, K., Hopkins, P. F., ... Shapley, A. E.

citation count

  • 4

publication date

  • December 2007