Observational Constraints on Ultra-Dense Dark Matter T. Marshall Eubanks Asteroid Initiatives LLC, 7243 Archlaw Drive, Clifton, Va 20124, USA E-mail:tme@asteroidinitiatives.com. There have been numerous suggestions that macroscopic ultra-dense objects, either quark nuggets or Primordial Black Holes (PBH), formed in the early universe, persisted until the present, and provide the Dark Matter (DM) required by a variety of astrophysical and cosmological observations. An important check on these DM theories comes from the condensed object mass spectrum, observational estimates of space density or flux compared to the known DM density. The three conventional checks on macroscopic DM, observations of the flux through laboratory detectors, planetary detectors and ground-based gravitational microlensing surveys, allow two disjoint mass regions for viable macroscopic DM particle masses. New Kepler satellite microlensing data restrict the allowed DM region somewhat, while a search for femtolensing of Gamma Ray Bursts (GRBs) provides a new set of DM constraints, greatly restricting the allowed region for larger masses and leaving three allowed “windows” in the mass spectrum. Combining all of these constraints, DM made up exclusively of a particle of mass M_DM would not violate current observational constraints if 6 × 10^−6 kg ≤ M_DM ≤ 10 kg, or 10^5 kg ≤ M_DM ≤10^18 kg, or 10^20 kg ≤ M_DM ≤ 10^22 kg. Primordial capture of any macroscopic DM in the Solar System and other planetary systems provide a different means of observing DM that may provide profound constraints on DM over a wide range of particle masses. In particular, primordial capture can be immediately used to derive severe restrictions in the mass range of PBH, which would consume any ordinary matter objects they come in contact with, a process easily detectable in the Solar System. Capela et al. considered primordial capture as part of stellar formation, and concluded that it can be used to exclude PBH with MP BH > 10^13 kg, with smaller PBH not being excluded as they would not have sufficient time to consume their host stars. The extension of primordial capture of PBH to planetary formation can be used to exclude all smaller masses of PBH as such PBH, if captured, would rapidly consume their host planets or asteroids. As the Solar System has manifestly not been consumed, and as other planetary systems appear not to be in the process of being consumed, this implies that M_PBH must be > 10^−8 M⊙, or > 10^22 kg, to be viable. If this exclusion is combined with the Kepler and other microlensing constraints, then there is very little possibility of PBH making the DM at any mass up to ∼ 30 M⊙, effectively ruling out PBH as a viable DM candidate.