Summary and Conclusion

• Observation gives

  0 > 0.1 (uses infall velocities, COBE results, Tully-Fischer relation)

• Inflation theory demands

  0 = 1.0000000000000

• Catalogs of visible matter give

  0 = 0.003

• 90% - 99% of the matter in the universe must be nonluminous

  • Much could be in the form of exotic particles or a fifth force

  • Predictions from the R-W metric, through, demand 1% - 10% be baryonic

• Knowledge of the total baryonic density of the universe from conventional catalogs

  • Catalogs are severely affected by selection effects

  • Selection effects due to limited resolving power and sky brightness

• To overcome biases we surveyed regions of the universe employing three different search techniques

• All three methods were successful, resulting in an increase by at least 50% in the number of known galaxies in the studied regions

• Primary search employed the McDonald Observatory 30" telescope

  • 127 galaxies were found with µ(0) > 22.0 mag arcsec

  • Found flat central surface brightness distribution through 24.0 mag arcsec

    • Drop-off probably due to selection effects, but reduced noise/sky brightness is necessary to say definitively

  • Galaxies had colors from the very blue through the very red

    • Very blue galaxies indicate LSB galaxies aren't only faded HSB galaxies

    • Very blue LSB galaxies could be the local counterpart to the high redshift faint blue galaxies found

    • First discovery of very red LSB galaxies

    • Proof galaxies do fade and redden with time

    • Also found contingent of galaxies with old stellar population andergiong significant starburst

  • Modeled of starburst activity with LSB galaxies

    • Starburst activity in LSB galaxies can significantly alter the colors

    • Starburst does not affect the galaxy's central surface brightness

  • LSB galaxies therefore probably have a low overall SFR with sporadic bursts of non-centralized star formation

• Second search employed Astro-1 UIT to determine if VUV imaging would detect optically faint galaxies

  • Surveyed the Fornax cluster

  • Ten galaxies detected, including true dEs

  • Showed longer exposures in the VUV would be successful at detecting faint local galaxies

• Third survey used HST WFPC2 to survey parts of the Virgo cluster

  • 160" x 160" were surveyed with the F814W and F300W filters

  • 215 galaxies found, from bright ellipticals through amorphous LSB blobs

  • 60% of the galaxies were classified as irregular/peculiar/merging (IPM)

  • Found the local counterparts to the high redshift (z > 0.5) IPM galaxies

  • Showed the WFPC2 to be a valuable tool in identifying and analysiing faint galaxies

• Sheer number of galaxies discovered shows our view of the universe has been severely constrained

• Past surveys of the local universe have underestimated the galaxy density by at least 50%

• It is likely that much (or even all) of the `missing' baryonic matter lies in these faint and diffuse galaxies

• Further studies of LSB galaxies could ultimately define both the galaxy number density of the universe and provide a far more complete picture of the processes of galaxy formation and evolution