A DEEP FIELD SURVEY FOR LOW SURFACE BRIGHTNESS GALAXIES

We have carried out a deep CCD survey of 'blank', i.e. non-cluster, fi elds near the South Galactic Pole, in order to search for geld low sur face brightness galaxies (LSBGs). We have detected over 500 objects in a total of 1.2 deg(2) which have low observed central surface brightn esses, mu(0) below 22.5 V mu, and exponential scale size greater than 2 arcsec. The faintest have mu(0) greater than or equal to 26.5 V mu. The surface brightness distribution appears to increase towards the fa intest surface brightness bins. A variety of arguments, including a st udy of their clustering on the sky, imply that the large majority of t hese objects - which constitute only a small fraction of the total fai nt galaxy sample - are genuine LSBGs at low redshifts, and not cosmolo gically dimmed distant giants. The number density of field LSBGs with scale sizes greater than 0.8 h(-1) kpc is estimated to be approximatel y 1 h(3) Mpc(-3), an order of magnitude greater than the density of 'n ormal' galaxies brighter than 0.1 L(). This is very similar to the ra tio of LSBGs to giants seen in a previous study of a particularly spir al-rich cluster.