1508.01525
Large-scale mass distribution in the Illustris-Simulation
Haider, et al
Observations at low redshifts thus far fail to account for all the baryons expected the Universe according to cosmo constraints. A large fraction of the baryons presumably resides in a thin and warm-hot medium between the galaxies, where they are difficult to observe due to their low densities and high temperatures. Cosmo sims of structure formation can be used to verify this picture and provide quantitative predictions for the distribution of mass in different large-scale structure components. Study the distribution of baryons and dark matter at different epochs using data from the Illustris Sim. Identify regions of different DM density with the primary constituents of LSS, allowing measurements of mass and volume of haloes, filaments and voids. At redshift zero, find that 49% of the DM and 23% of the baryons are within haloes. The filaments of the cosmic web host a further 45% of the DM and 46% of the baryons. The feedback models used in Illustris have a significant impact on the baryon distribution at large scales, leading to 31% of the baryons residing in DM voids. Categorizing the baryons according to their density and temperature, find that 17.8% of them are in a condensed state, 21.6% are present as cold, diffuse gas, and 53.9% are found in the state of warm-hot intergalactic medium.
1508.01615
The relation between star formation rate and stellar mass of galaxies at z $\sim$ 1-4
Katsianis, Tescari, Wyithe
The relation between SFR and M* of galaxies represents a fundamental constraint on galaxy formation. However, the observed amplitude of the SFR - M* relation has not been successfully reproduced in sims, indicating either that the halo accretion history and baryonic physics are poorly understood or that observations contain biases. In this paper, examine the evolution of the SFR-M* relation of z~1-4 galaxies and display the inconsistency between observed relations that are obtained using different techniques. Employ cosmological hydrodynamic simulations from various groups and compare these with a range of observations. The comparison suggests that using SEDs to estimate SFRs, dust corrections and stellar masses produces the most reliable SFR-M* relations. On the contrary, the combination of IR and UV luminosities (UV+IR) over predicts the SFR and dust corrections at a fixed stellar mass almost by a factor of 5 for z~1.5-4. For z<1.5, the SED fitting technique and IR+UV conversion agree well. Find remarkable agreement between the numerical results from various authors who have employed different cosmo codes and run simulations with different resolutions. This is interesting for 2 regions. A) simulations can produce realistic populations of galaxies within representative cosmo volumes even at relatively modest resolutions. B) It is likely that current numerical codes that rely on similar subgrid multiphase ISM models and are tuned to reproduce statistical properties of galaxies, produce similar results for the SFR-M* relation by construction, regardless of resolution, box size and, to some extent, the adopted feedback prescriptions.
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