5 research outputs found
The field surrounding NGC 7603: cosmological or non-cosmological redshifts?
We present new observations of the field surrounding the Seyfert galaxy NGC
7603, where four galaxies with different redshifts--NGC 7603 (z=0.029), NGC
7603B (z=0.057) and two fainter emission line galaxies (z=0.245 and
z=0.394)--are apparently connected by a narrow filament, leading to a possible
case of anomalous redshift. The observations comprise broad and narrow band
imaging and intermediate resolution spectroscopy of some of the objects in the
field. The new data confirm the redshift of the two emission-line objects found
within the filament connecting NGC 7603 and NGC 7603B, and settles their type
with better accuracy. Although both objects are point-like in ground based
images, using HST archive images we show that the objects have structure with a
FWHM=0.3-0.4 arcsec. This and the relative strength and width of the main
spectral lines allow us to classify these as HII galaxies with very vigorous
star formation, while the rest of the filament and NGC 7603B lack star
formation. We delineate the halo of NGC 7603 out to 26.2 mag/square arcsec in
the Sloan r band filter and find evidence for strong internal distortions. New
narrow emission line galaxies at z=0.246, 0.117 and 0.401 are also found at
respectively 0.8, 1.5 and 1.7 arcmin to the West of the filament within the
fainter contour of this halo. The probability of three background galaxies of
any type with apparent B-magnitudes up to 16.6, 21.1 and 22.1 (the observed
magnitudes, extinction correction included) being randomly projected on the
filament of the fourth galaxy (NGC 7603) is computed resulting ~ 3 x 10^(-9).Comment: 34 pages, 9 figures, Astronomy & Astrophysics accepte