1993/10/07 by T. Padmanabhan, Padmanabhan, T., K. Subramanian +1
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9310015
4 pages,IUCAA-23/93; sept,93; submitted for publication
arxiv created 1993/10/07 · arxiv updated 2009/12/01
The recent detection of microlensing of stars of LMC by compact objects in the halo of our galaxy suggests that our galaxy is surrounded by a non-luminous halo made of compact objects with mass of about (0.03-0.5) \msun. The rate of detection could be consistent with the assumption that these halo objects are distributed with a softened isothermal profile with a core radius of (2-8)Kpc and asymptotic circular velocity of 220\kms. Taken in isolation, this observation is consistent with a universe having only baryonic dark matter (BDM, hereafter) contributing Ωb=Ωtotal≃0.06 which will, however, violently contradict several other large scale observations, notably the COBE-DMR results. Alternatively one can assume that galaxies like ours are surrounded by both BDM and non-baryonic dark matter (NBDM, hereafter). A model with a single component for NBDM with, say, Ωb≃0.06,Ωcdm≃0.94, is also ruled out if we demand that: (i) at least thirty percent of the dark matter density within 100 kpc is baryonic and (ii) galactic structures should have collapsed by redshift of z=1. Further if half or more of the dark matter within 100 kpc is baryonic then the maximum value of Ωdm, contributed by NBDM clustered at galactic scales, can only be about Ωmax≃0.29. Models with C+HDM cannot satisfy this constraint but Λ+ CDM models are still