Astronomy and Astrophysics – Astrophysics
Scientific paper
1994-10-06
Astronomy and Astrophysics
Astrophysics
submitted to ApJ, 31 pages including one table and 6 figures, uuencoded compressed postscript, SCIPP 94/09
Scientific paper
Damped Ly$\alpha$ systems provide possibly the most significant evidence for early structure formation, and thus a stringent constraint on the Cold + Hot Dark Matter (CHDM) cosmology. Using the numbers of halos in N-body simulations to normalize Press-Schechter (PS) estimates of the number densities of protogalaxies as a function of redshift, we find that CHDM with $\Omega_c/\Omega_\nu/\Omega_b = 0.6/0.3/0.1$ is compatible with the damped Ly$\alpha$ data only at $z<2.5$, but that it is probably incompatible with data at $z>3$. The predictions of CHDM are quite sensitive to the neutrino fraction. We find that $\Omega_c/\Omega_\nu/\Omega_b = 0.725/0.20/0.075$ is compatible with the $z>3$ data. With one massive neutrino species, this corresponds to lowering the neutrino mass from 7.0 to 4.7 eV, for $H_0=50\kmsMpc$ and $T=2.726$ K. By analysing our numerical simulations with different resolutions and box sizes as well as those of Ma \& Bertchinger (1994), we show that for the CHDM models with $\Omega_\nu$=0.2--0.3 the PS approximation should be used with Gaussian filter with $\delta_c=1.3-1.4$ if one tries to recover the total mass of a collapsed halo and to include nonlinear effects, due to waves both longer and shorter than those within the simulation box.
Borgani Stefano
Holtzman Jon
Klypin Anatoly
Primack Joel
No associations
LandOfFree
Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-244227