Cycle 6 Accepted Theory Proposals

Title: MHD Simulation of Magnetically Confined Wind Shock (MCWS) Model for Hot Star X-ray Emission

We propose to use 3D dynamical simulations to model the X-ray spectrum from early-type stars with magnetic fields that channel their radiatively driven stellar winds into strong, Magnetically Confined Wind Shocks (MCWS). Building on our recent success in applying the MCWS model for interpreting the Chandra spectrum of the slowly rotating, moderately magnetic hot star theta-1 Ori C, our development will now focus on accounting for cases with much more rapid rotation and/or a much stronger degree of magnetic confinement. The results will yield predicted X-ray spectra for a range of rotation periods, wind mass loss rates, field strengths and orientations. This will provide an important new tool for interpreting X-ray observations of early-type stars with relatively hard X-ray spectra.

Title: A Systematic Calculation of Helium-like and Hydrogenic Electron Collisional Rates for Chandra

We propose to recalculate electron impact excitation rates for all helium-like and hydrogenic ions that can be observed with Chandra, using the latest version of the relativistic Breit-Pauli R-matrix codes. Our results will be the first complete and systematic calculation of such rates using modern, sophisticated computational tools which allow for accurate treatment of relativistic, correlation, and resonance/channel coupling effects. The rates will be put into the publicly-available atomic database APED. The collisional rates resulting from this proposed work will be the best available, and the systems will have been treated self-consistently such that systematic errors caused by incorporating different calculations of varying quality and extensivity will be largely eliminated.

Ultraluminous X-ray sources (ULXs) with Lx > 10^{39} ergs/s are an important class of objects studied extensively with Chandra. The central question is whether they represent an extension in the luminosity function of binary X-ray sources containing neutron stars and stellar-mass black holes (BHs), or a new class of object, e.g., systems containing intermediate mass BHs (100-1000 Msun). We propose to carry out a theoretical study to test whether a large fraction of the ULXs, especially those in galaxies with recently active star formation, can be explained with binary systems containing stellar mass BHs. We will apply a unique set of evolution models for BH binaries, coupled to a population synthesis code, to model the ULXs observed by Chandra in external galaxies.

Title: X-RAY BINARY FORMATION IN ELLIPTICAL GALAXIES: THE ROLE OF DYNAMICAL PROCESSES

We propose a theoretical research program to address the question of the degree to which globular clusters contribute to or even dominate the formation of X-ray binaries in elliptical galaxies. Our research will be focused on (i) the development of models for X-ray binary formation and evolution within old and dense stellar environments with dynamical processes taken into account, and (ii) interpretation of observed X-ray luminosity functions of elliptical galaxies. The observational data will be compared with predictions given by models with and without dynamical effects. We expect that the proposed calculations will not only help in the interpretation of current observations, but will also lead to predictions that will drive future Chandra observations.

Title: Comprehensive Models for the Ionized Environment of AGN at High Spectral Resolution

We propose to develop a photoionization modeling package appropriate for modeling the ionized gas in AGN environments. We will (1) bring together existing software and atomic data; (2) develop new emission line models to compute scattering for different velocity fields in the outflowing wind; (3) apply these models to high quality AGN spectra, addressing atomic data needs and additional physics as needed; and, (4) make this package available publicly in a timely manner. Our collaboration has a strong track record for producing public plasma models. The proposed project will help realize the potential of the deep grating observations of bright AGN.

Accretion of gas onto clusters of galaxies inevitably produces soft X-ray line emission that could be the long-sought source of the putative soft X-ray excesses in clusters. This line emission occurs because ions that have recently accreted are likely to be underionized relative to collisional ionization equilibrium. These non-equilibrium ions will therefore emit a predictable amount of so ft X-ray radiation until they reach their equilibrium state. We are proposing to develop a set of spectral templates for this form of emission so that it can be compared with cluster observations. These models will provide a way to measure the gas accretion rate onto clusters and to improve the accuracy of cluster temperature measurements, furthering precision cosmology with X-ray clusters.

Title: The Answer is Blowing in the Wind: Simulations of Jets in Non-Sperical Clusters of Galaxies

We propose to conduct simulations of the interaction of radio jets with the intra-cluster medium in a realistic, three-dimensional cluster environment, including, for the first time, effects of asphericity and cluster sub-structure on the evolution of radio galaxies and their impact on the ICM. The cluster initial conditions will be taken from existing simulations of cosmological structure formation. Our results will be presented in a manner allowing direct comparison to individual Chandra observations and will be analyzed to infer parameters critical to the interpretation of existing observations of clusters and X-ray cavities.

Proposal Number	Subject Category	PI Name	Title
06200493	STARS AND WD	Stanley Owocki	MHD Simulation of Magnetically Confined Wind Shock (MCWS) Model for Hot Star X-ray Emission
06200544	STARS AND WD	Kate Kirby	A Systematic Calculation of Helium-like and Hydrogenic Electron Collisional Rates for Chandra
06400318	BH AND NS BINARIES	Saul Rappaport	ULXs AS STELLAR MASS BLACK HOLE BINARIES
06620202	NORMAL GALAXIES: X-RAY POPULATIONS	Natalia Ivanova	X-RAY BINARY FORMATION IN ELLIPTICAL GALAXIES: THE ROLE OF DYNAMICAL PROCESSES
06700784	ACTIVE GALAXIES AND QUASARS	Nancy Brickhouse	Comprehensive Models for the Ionized Environment of AGN at High Spectral Resolution
06800146	CLUSTERS OF GALAXIES	Mark Voit	Soft X-ray Emssion from Accreting Gas in Clusters
06800240	CLUSTERS OF GALAXIES	Sebastian Heinz	The Answer is Blowing in the Wind: Simulations of Jets in Non-Sperical Clusters of Galaxies

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