The contribution of dwarf and low surface brightness galaxies to absorption

Low surface brightness galaxies (LSB) with a wide range of properties may be important in understanding the nature of Lyalpha absorbers at low redshifts and the distribution of gas relative to galaxies. LSB and dwarf galaxies are now being found to make a substantial contribution to damped Lyalpha absorption, and the gas surrounding these objects is likely to be important for producing weaker absorption lines as well. Galaxy selection strongly affects our ability to establish the nature of Lyalpha absorbers. Absorption arising in LSB galaxies may be attributed to high surface brightness galaxies at larger impact parameters from the quasar line of sight. Numerous LSB dwarf galaxies are being found which are located around nearby isolated spiral galaxies. These newly discovered objects raise questions about the nature of absorbers which are often seen when a bright galaxy is within similar to 200 kpc of a quasar line of sight.