Simulating the stacked spectrum of the Lyman alpha forest
Michael Mortonson (OSU/CCAPP)
The large sample of quasar spectra observed in the Sloan Digital Sky Survey has made it possible to study properties of the intergalactic medium along quasar sightlines using a statistical approach that identifies absorption correlated with features in the Lyman alpha forest. Lyman series and metal lines detected in the stacked spectrum provide information about the physical conditions and metal content of relatively low-density gas that is not accessible in individual quasar spectra. Interpreting the features detected in the stacked Lyman alpha forest spectrum requires detailed modeling of the observations using cosmological hydrodynamic simulations. I will present results of a simulated stacking analysis using spectra extracted from a large hydrodynamic simulation at redshift 2.5. The similarities and discrepancies between the simulated and observed stacked spectrum can be used to improve models of metal enrichment used in simulations and to refine the stacking methods applied to data.
Black hole mass estimates:
From the local universe AGN to the highest redshift QSOs
Gisella DeRosa (OSU/Astronomy)
Supermassive black holes (BHs) are thought to play a key role in the evolution of galaxies. Therefore, it is of fundamental importance to properly characterize the masses and accretion rates of BHs through cosmic time. While direct dynamical measurements of BH masses are possible only for nearby quiescent galaxies, reverberation mapping can be used to obtain direct measurements of BH masses powering distant active galactic nuclei. A major result of the RM campaigns is the identification of the relationship between the size of the broad line region and the luminosity of the AGN, which allows to estimate the BH masses from single epoch spectral measurements up to very high redshift. After a brief review of reverberation mapping and single epoch measurements techniques, I will present preliminary results for both AGN in the local universe and a new sample of z~7 QSOs.
