Rest-Frame Ultraviolet to Near Infrared Observations of an Interacting Lyman Break Galaxy at z = 4.42
Abstract
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-i775 and i775-z850 colors, and are separated by 1", which at z=4.42 corresponds to 7 kpc projected nuclear separation; all indicative of an interacting system. Fits to stellar population models indicate a stellar mass of M = 2.6× 1010 M, age of τ = 720 My, and exponential star formation history with an e-folding time τ0 = 440 My. 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 z3.5, and a quiescent, compact spheroid by z 2.5 similar to those observed at z > 2. And, the existence of such an object supports galaxy formation models in which major mergers drive the high redshift buildup of spheroids and black holes.