An Infrared Emission Line Galaxy at z = 2.43

Abstract

An object discovered during an infrared survey of the field near the quasar B2 0149+33 has an emission line at 2.25$μ$m that we interpret as H$α$ at a redshift of 2.43. The K-band image shows two compact components 10 kpc apart surrounded by more extended emission over ~20 kpc. The H$α$ emission appears to be extended over ~15 kpc (2") in a coarsely sampled (0".8/pixel) image. The star formation rate may be as high as 250 - 1000 M$_\odot$ yr$^{-1}$, depending on the extinction. Alternatively, the line may be powered by an active nucleus, although the probability of serendipitously discovering an AGN in the survey volume is only ~0.02. The increasing number of similar objects reported in the literature indicate that they may be an important, unstudied population in the high redshift universe.