Formation of voids from negative density perturbations

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view Abstract Citations (12) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Formation of Voids from Negative Density Perturbations de Araujo, J. C. N. ; Opher, R. Abstract The formation of voids from negative density perturbations, present in the recombination era, is of appreciable interest, and a number of investigations on the subject have recently been made. These investigations, in general, include only the effect of gravity and neglect nongravitational physical processes (NPP) such as photon drag and photon cooling. In the present investigation we study the effect of NPP in the formation of voids, following the analysis published by de Araujo and Opher in 1988 made for positive density perturbations. Previous investigations made similarity analysis or postulated the magnitude of the initial density perturbation, δ_i_. We obtain the magnitude of δ_i_ using the same mass dependence as previously used for positive perturbations (e.g., de Araujo and Opher). In general we find that the inclusion of NPP act as a drag, impeding the formation of underdense regions and increasing their present density. We study a spectrum of negative perturbations of the form δ_i_ = -(M/M_0_)^-α^(1 + z_rec_)^-1^, where M_0_ is the mass scale, and z_rec_ is the redshift at recombination. We find, for example, for α = 1/2 (corresponding to a white noise spectrum) and M_0_ ~ 10^15^ M_sun_ (corresponding to a galactic cluster) that the inclusion of the NPP increases the final density of the underdense regions ~ 35%-75% for M ~ 10^9^-10^12^ M_sun_. Our calculations produce underdense regions over several megaparsecs. It is of interest to obtain (for a given range of redshifts), for small neighbor distances (< 1^deg^), the distribution of dwarf galaxies of mass ~ 10^9^ M_sun_ ( ~5 optical mag greater than average galaxies). Our results predict the existence of regions <~ 1/10 the average density for regions of mass ~10^9^-10^10^ M_sun_, and the distribution of dwarf galaxies of mass M ~ 10^9^ M_sun_ are sensitive to these underdense regions. Publication: The Astrophysical Journal Pub Date: February 1990 DOI: 10.1086/168405 Bibcode: 1990ApJ...350..502D Keywords: Cosmology; Mass Distribution; Perturbation Theory; Density (Mass/Volume); Galactic Clusters; Galactic Evolution; Astrophysics; COSMOLOGY; GALAXIES: CLUSTERING; GALAXIES: FORMATION full text sources ADS |