Deflationary cosmology: Constraints from angular size and ages of globular clusters

Observational constraints to a large class of decaying vacuum cosmologies are derived using the angular size data of compact radio sources and the latest age estimates of globular clusters. For this class of deflationary Lambda(t) models, the present value of the vacuum energy density is quantified by a positive beta parameter smaller than unity. In the case of milliarcsecond compact radio-sources, we find that the allowed intervals for beta and the matter density parameter Omega(m) are heavily dependent on the value of the mean projected linear size l. For lsimilar or equal to20h(-1)-30h(-1) pc, the best fit occurs for betasimilar to0.58, Omega(m)similar to0.58, and betasimilar to0.76, Omega(m)similar to0.28, respectively. This analysis shows that if one minimizes chi(2) for the free parameters l, Omega(m) and beta, the best fit for these angular size data corresponds to a decaying Lambda(t) with Omega(m)=0.54, beta=0.6, and l=22.64h(-1) pc. Constraints from age estimates of globular clusters and old high redshift galaxies are not so restrictive, thereby suggesting that there is no age crisis for this kind of Lambda(t) cosmologies.