Deep HST1 imaging of distant weak radio and field galaxies

Rogier Windhorst, J. M. Gordon, S. M. Pascarelle, P. C. Schmidtke, W. C. Keel, J. M. Burkey, J. S. Dunlop

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We present deep Hubble Space Telescope (HST) Wide-Field Camera V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring FWHM of ≤ 0″.2, (nearly) preserve photons and signal-to-noise ratio at low spatial frequencies, and produce consistent light profiles down to our 2 σ surface brightness sensitivity limit of V ∼ 27.2 and I ∼ 25.9 mag arcsec-2. Multicomponent image modeling was used to provide deconvolution-independent estimates of structural parameters for symmetric galaxies. We present 12-band (W2750 U BV RIgriJHK) photometry for a subset of the galaxies and bootstrap the unknown FOC/48 zero point at 2750 Å in three independent ways (yielding m2750 = 21.34 ± 0.09 mag for 1.0 e- s-1). Two radio galaxies with z = 0.311 and 0.528, as well as one field galaxy with z = 0.58, have the colors and spectra of early-type galaxies, and a1/4-like light profiles in the HST images. The two at z > 0.5 have little or no color gradients in V-I and are likely giant ellipticals, while the z = 0.311 radio galaxy has a dim exponential disk and is likely an SO. Six of the seven field galaxies have light profiles that indicate (small) inner bulges following a1/4 laws and outer exponential disks, both with little or no color gradients. These are (early-type) spiral galaxies with z = 0.131-0.528. About half have faint companions or bars. One shows lumpy structure, possibly a merger. The compact narrow-line galaxy 53W002 at z = 2.390 has ≤ 30% ± 10% of its HST V and I flux in the central kiloparsec (due to its weak AGN). Most of its light (V ≃ 23.3) occurs in a symmetric envelope with a regular a1/4-like profile of effective radius a ≃ 1″.1 (≃ 12 kpc for H0 = 50, q0 = 0.1). Its (HST) V-I color varies at most from ∼0.3 mag at a ≃ 0″.2 to ∼ 1.2 mag at a ≳ 0″.4, and possibly to ≳2.2 mag at a ≳ 1″.2. Together with its I - K color (≃2.5 mag for a ≳ 1″.0-2″.0), this is consistent with an aging stellar population ∼0.3-0.5 Gyr old in the galaxy center (a ≲ 2 kpc radius), and possibly ∼0.5-1.0 Gyr old at a ≳ 10 kpc radius. While its outer part may thus have started to collapse at z = 2.5-4, its inner part still is aligned with its redshifted Lya cloud and its radio axis, possibly caused by star formation associated with the radio jet, or by reflection from its AGN cone.

Original languageEnglish (US)
Pages (from-to)577-598
Number of pages22
JournalAstrophysical Journal
Issue number2
StatePublished - Nov 10 1994


  • Galaxies: evolution
  • Galaxies: photometry
  • Galaxies: stellar content
  • Galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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