The talks are in the same order as the Program Schedule.
Mantz, Adam - Constraints on dark energy from the observed growth of X-ray luminous galaxy clusters
Nicastro, Fabrizio - Probing the WHIM through OVII K-alpha Fluctuations
Marshall Bautz (MIT Kavli Institute for Astrophysics & Space Research)
I review the long-understood potential role of galaxy clusters in illuminating the large-scale structure and expansion history of the Universe, and the equally well-appreciated difficulties in realizing this potential. The spectacular progress made in our understanding of clusters since the launch of Chandra has sharpened our appreciation of these difficulties at least as much as it has resolved them. I survey some recent work by others attacking this problem, focussing on contributions by X-ray observers to our understanding of cluster mass and distance measurement, as well as to the scatter of and evolution in relations between cluster structural parameters. I briefly compare cosmological results obtained from cluster studies, on the one hand, with inferences drawn from other cosmological measurements. I try to assess the impact on cluster cosmology of some planned future surveys in the microwave, visible and X-ray bands.
Adam Mantz (KIPAC/Stanford) , Steve Allen (KIPAC), Harald Ebeling (IfA, U. Hawaii), David Rapetti (KIPAC)
I will present cosmological constraints obtained from measurements of the growth of cosmic structure in the most X-ray luminous galaxy clusters in the universe. Our results are consistent with the cosmological constant model and are in good agreement with findings from a variety of independent data, notably the cosmic microwave background (CMB), type Ia supernovae (SNIa), galaxy cluster gas-mass fraction (fgas), cosmic shear, and galaxy redshift surveys. Using the growth of structure data alone, we find the dark energy equation of state
for a constant-w model; this result is remarkably insensitive to the choice of priors and to systematic uncertainties in the analysis. The combination of growth of structure data with CMB, SNIa and fgas data has the potential to significantly improve constraints on dark energy by breaking a key degeneracy between 
and w.
Max Bonamente (UA - Huntsville) , Marshall Joy (MSFC), Samuel LaRoque (U.Chicago), John Carlstrom (U.Chicago), Daisuke Nagai (Caltech), Dan Marrone (U.Chicago)
We present Sunyaev-Zel'dovich Effect (SZE) scaling relations for 38 massive galaxy clusters at redshifts 0.14 <= z <= 0.89, observed with both the Chandra X-ray Observatory and the centimeter-wave SZE imaging system at the BIMA and OVRO interferometric arrays. An isothermal beta-model with central 100 kpc excluded from the X-ray data is used to model the intracluster medium and to measure global cluster properties. For each cluster, we measure the X-ray spectroscopic temperature, SZE gas mass, total mass and integrated Compton-y parameters within r2500. Our measurements are in agreement with the expectations based on a simple self-similar model of cluster formation and evolution. We compare the cluster properties derived from our SZE observations with and without Chandra spatial and spectral information and find them to be in good agreement. We compare our results with cosmological numerical simulations, and find that simulations that include radiative cooling, star formation and feedback match well both the slope and normalization of our SZE scaling relations.
Fabrizio Nicastro (SAO/INAF-OAR) , M. Elvis (SAO), J. Drake (SAO), Y. Krongold (UNAM), S. Mathur (OSU), F. Fiore (INAF-OAR), R. Williams (University of Leiden)
According to hydrodynamical simulations the local Universe is permeated of tenuous warm-hot baryonic matter, distributed in filaments throughout the intergalactic space. These filaments imprint extremely weak high-ionization metal absorption in the X-ray spectra of background sources. The strongest of these transitions is the OVII Kalpha resonant, at lambda=21.6 A. Due to the steepness of the number density distribution of OVII WHIM absorbers with an equivalent width larger than a given threshold, however, less than one OVII Kalpha absorber with individually detectable (with current spectrometers) equivalent width (EW > 10 mA) is expected to be found along a random line of sight up to z=1. Many more numerous of these absorbers, instead, are expected to produce non-resolvable absorption lines, which still, when integrated, give rise to broad and shallow residual opacity. This signature can be searched for in the binned stacked spectra of the brightest blazars in the Chandra archive, up to the minimum common redshift (the redshift of Mkn 421, z=0.03). We have performed this search, and found a 3 ignal which we attribute to unresolved WHIM absorption (but note that Chandra-LETG calibrations are also known to a similar accuracy). This signal is in excellent agreement with theoretical expectations: 45 random lines of sight up to z=0.03 extracted from the latest Cen & Ostriker (2006) simulations, show average WHIM opacity of the order of -1.5