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Physical Sciences and Mathematics Commons™
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Full-Text Articles in Physical Sciences and Mathematics
How Do Galaxies Get Their Gas?, D Keres, N Katz, Dh Weinberg, R Dave
How Do Galaxies Get Their Gas?, D Keres, N Katz, Dh Weinberg, R Dave
Astronomy Department Faculty Publication Series
We examine the temperature history of gas accreted by forming galaxies in smoothed particle hydrodynamics simulations. About half of the gas follows the track expected in the conventional picture of galaxy formation, shock heating to roughly the virial temperature of the galaxy potential well (T∼ 106 K for a Milky Way type galaxy) before cooling, condensing and forming stars. However, the other half radiates its acquired gravitational energy at much lower temperatures, typically T < 105 K, and the histogram of maximum gas temperatures is clearly bimodal. The ‘cold mode’ of gas accretion dominates for low-mass galaxies (baryonic …
Ly Alpha Flux Power Spectrum And Its Covariance, H Zhan, R Dave, D Eisenstein, N Katz
Ly Alpha Flux Power Spectrum And Its Covariance, H Zhan, R Dave, D Eisenstein, N Katz
Astronomy Department Faculty Publication Series
We analyse the flux power spectrum and its covariance using simulated Lyα forests. We find that pseudo-hydro techniques are good approximations of hydrodynamical simulations at high redshift. However, the pseudo-hydro techniques fail at low redshift because they are insufficient for characterizing some components of the low-redshift intergalactic medium, notably the warm–hot intergalactic medium. Hence, to use the low-redshift Lyα flux power spectrum to constrain cosmology, one would need realistic hydrodynamical simulations. By comparing (one-dimensional) mass statistics with flux statistics, we show that the non-linear transform between density and flux quenches the fluctuations so that the flux power spectrum is much …