Infrared observations of the Z = 3.8 radio galaxy, 4C 41.17, with the W. M. Keck telescope
The near-infrared camera on the W. M. Keck telescope has been used to image the z = 3.8 radio galaxy 4C 41.17. The 2 μm continuum consists of a thin arc of emission aligned along the radio axis. There is close correlation between the optical, infrared, and radio emission. The color of 4C 41.17 is blue (R-K_s = 2.7 ± 0.1 mag). This may indicate ongoing star formation, but the origin of the continuum emission remains unclear. [O III] and H/β emission makes a large contribution to the K-band flux. A number of faint red companions of 4C 41.17 are detected in the 2 μm image. If these sources are at the same redshift as 4C 41.17, then their red colors indicate ages of more than - 0.5 Gyr and an epoch of formation at z ≳ 8.
© 1994 American Astronomical Society. Received 1993 July 14; accepted 1993 October 12 The W. M. Keck Observatory is a scientific partnership between the University of California and the California Institute of Technology, made possible by the generous gift of the W. M. Keck Foundation and support of its president, Howard Keck. We are most grateful for their visionary endowment that has made possible the first of the next generation of telescopes. It is a pleasure to thank E. Stone, W. Frazier, W. Sargent, S. Faber, E. Romano, and W. Lupton and all of the many devoted people whose unflagging efforts have made possible the success of the W. M. Keck Observatory. We thank M. Dickinson and H. Spinrad for permission to use their R-band image of 4C 41.17. Thanks are also due to M. Dickinson for advice and practical help on data reduction and valuable discussions on the nature of high-redshift radio galaxies.
Published - 1994ApJ___420L___5G.pdf