Abstract
We present near-infrared photometry of all available gravitationally lensed ‘arcs’ with spectroscopic redshifts. By combining this photometry with optical data, we find that the bulk of the systems with z ~ 1 are intrinsically blue across the rest-frame spectral region 2000 A to 1 μm. Using a combination of optical and optical-infrared colours, we demonstrate that these systems cannot be blue by virtue of a secondary burst of star formation superimposed on an evolved population, but we are unable to distinguish directly between major star formation events in a generic young galaxy and an extended era of constant star formation typical of late-type spirals. Using various arguments, we conclude that our arcs represent modest gravitational magnification of typical field galaxies. Consequently, if the star formation seen is representative of that in field galaxies at z ≥ 1, the absence of high-redshift galaxies in current deep spectroscopic surveys to bJ≃24bJ≃24 supports the hypothesis that the bulk of the star formation in normal galaxies occurred over an extended era up to the epoch corresponding to z ~ 1.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
