Publications (8)
Metal Lines in Cosmological Models of Lyman-Alpha Absorbers
Uffe Hellsten, Lars Hernquist, Neal Katz +1
The metal absorption lines found in association with \lya absorbers of moderate to high HI column density contain valuable information about the metallicity and ionization conditio…
Metal Lines Associated with Lyman Alpha Absorbers: A Comparison of Theory and Observations
Uffe Hellsten, Romeel Dave, Lars Hernquist +2
We study metal line absorption of CIV, CII, SiIV, and NV at redshifts z=3.5 to z=2 within the framework of a cosmological model for the Lyman alpha forest, comparing the results of…
The X-Ray Forest: A New Prediction of Hierarchical Structure Formation Models
Uffe Hellsten, Nickolay Y. Gnedin, Jordi Miralda-Escude
We use numerical simulations of structure formation in a Cold Dark Matter model to predict the absorption lines in the soft X-rays produced by heavy elements in the shock-heated in…
The Structure of Isothermal, Self-gravitating Gas Spheres for Softened Gravity
Jesper Sommer-Larsen, Henrik Vedel, Uffe Hellsten
A theory for the structure of isothermal, self-gravitating gas spheres in pressure equilibrium in a softened gravitational field is developed. The one parameter spline softening pr…
On the Global Structure of Self-gravitating Disks for Softened Gravity
Jesper Sommer-Larsen, Henrik Vedel, Uffe Hellsten
Effects of gravitational softening on the global structure of self-gravitating disks in centrifugal equillibrium are examined in relation to hydrodynamical/gravitational simulation…
Constraining the Metallicity of the Low Density Lyman-alpha Forest Using OVI Absorption
Romeel Davé, Uffe Hellsten, Lars Hernquist +2
We search for OVI absorption in a Keck HIRES spectrum of the z=3.62 quasar Q1422+231. Comparison of CIV measurements to cosmological simulations shows that \lya forest absorbers wi…
On the Minimum Metallicity and Mass of the Population II Stars
Uffe Hellsten, D. N. C. Lin
Within collapsing protogalaxies, thermal instability leads to the formation of a population of cool fragments which are confined by the pressure of a residual hot background medium…
The Observability of Metal Lines Associated with the Lyman-alpha Forest
Uffe Hellsten, Lars Hernquist, Neal Katz +1
We develop a prescription for characterizing the strengths of metal lines associated with Lyman-alpha forest absorbers (LYFAs) of a given neutral hydrogen column density N_HI and m…