Accepted Cycle 15 Theory Proposals

Proposal Number	Subject Category	PI Name	Title
15200174	STARS AND WD	Cranmer	Improved Models of X-Ray Emission from Accreting Young Stars with Complex Magnetic Fields
15700603	ACTIVE GALAXIES AND QUASARS	Dorodnitsyn	WARM ABSORBER SPECTRA FOR TESTING AGN OUTFLOW MODELS
15400572	BH AND NS BINARIES	Gorczyca	Comprehensive X-Ray Absorption Models for Oxygen and Neon
15800455	CLUSTERS OF GALAXIES	Heinz	Metal Transport in Galaxy Clusters by AGN Jets
15400673	BH AND NS BINARIES	Kallman	A New Model for Interstellar X-ray Absorption
15800765	CLUSTERS OF GALAXIES	Nagai	Modeling the Cosmic Melting Pots in the Outskirts of Galaxy Clusters
15400255	BH AND NS BINARIES	Smith	Practical Models of Extinction for Spectral Analysis
15200282	STARS AND WD	ud-Doula	Radiative cooling in 2-D and 3-D models of magnetically confined wind shocks

Subject Category: STARS AND WD

Proposal Number: 15200174

Title: Improved Models of X-Ray Emission from Accreting Young Stars with Complex Magnetic Fields

PI Name: Steven Cranmer

We propose to construct a new generation of self-consistent models of magnetospheric accretion, shock formation, and coronal heating for T Tauri stars. We will produce 3D distributions of circumstellar plasma parameters and synthesize X-ray spectral diagnostics for direct comparison with observations. Existing models will be improved by accounting for more realistic magnetic fields and a more physically consistent thermal/ionization state. The new models will be highly computationally efficient in order to enable the production of thousands of trial cases, each with different accretion and magnetic properties. This work will further the understanding of Chandra data by providing versatile tools for the testing of many ideas regarding low-mass stellar evolution and planet formation.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 15700603

Title: WARM ABSORBER SPECTRA FOR TESTING AGN OUTFLOW MODELS

PI Name: Anton Dorodnitsyn

Warm absorber spectra contain information about the elemental abundances, kinematics, and ionization state of the gas in AGN. A key goal is to use these features to determine the flow rate and geometry, and thereby to constrain the nature of the central engine and the forces which drive the outflow. There have been a variety of published models which describe the dynamics of warm absorber flows. Testing of these models requires computation of synthetic spectra seen by a distant observer. The resulting spectra must use a realistic treatment of the microphysics and must be done in a consistent way for as many choices of dynamics as possible. This is the goal of the proposed research; the result will be a library of model spectra for use in fitting engines by observers and others.

Subject Category: BH AND NS BINARIES

Proposal Number: 15400572

Title: Comprehensive X-Ray Absorption Models for Oxygen and Neon

PI Name: Thomas Gorczyca

We propose to perform state-of-the-art R-matrix calculations for the oxygen and neon photoabsorption cross sections to improve upon earlier, incomplete data. Several important higher-order effects will be addressed: orbital relaxation, Auger line broadening, two-electron shake, and elimination of pseudoresonances. The computed atomic cross sections will first be fit by a recently-developed analytical fitting formula, and then benchmarked further to experimental and Chandra observed absorption lines. The resulting data will be uploaded into the AtomDB, XSPEC, and ISIS databases for spectral modeling use. These definitive cross sections will resolve an outstanding discrepancy between XSTAR and SPEX spectral modeling predictions of molecular (dust and/or ice) abundances in the ISM.

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 15800455

Title: Metal Transport in Galaxy Clusters by AGN Jets

PI Name: Sebastian Heinz

We propose to develop a set of numerical simulations of the effects of jet-induced feedback on the metal distribution in galaxy clusters. We aim to (a) explore the theoretical underpinnings of the observed relation between jet power and iron radius found in clusters with actively inflated cavities, (b) to derive detailed diagnostics for differential abundance measurements in clusters, (c) to investigate the effects of cluster magnetization and dynamic sub-structure on metal transport, and (d) to develop post-processing tools for numerical simulations of clusters as part of the XIM package.

Subject Category: BH AND NS BINARIES

Proposal Number: 15400673

Title: A New Model for Interstellar X-ray Absorption

PI Name: Timothy Kallman

Edges and near-edge resonances from interstellar (ISM) absorption have diagnostic power which can be exploited by grating observations in order to derive elemental abundances and other quantities. Chandra grating observations reveal the presence of ionized as well as neutral absorbers, while models most widely used assume neutral gas. Atomic data for absorption by most atoms and ions of astrophysical interest are now available with accuracy sufficient for interpreting such spectra, but there is not a convenient way to apply them to fitting of observations. We propose to build a model which can be used to fit to the ISM absorption features imprinted on X-ray spectra. Our model will use state of the art atomic data and will include ions of abundant elements as well as neutrals.

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 15800765

Title: Modeling the Cosmic Melting Pots in the Outskirts of Galaxy Clusters

PI Name: Daisuke Nagai

Recently, exploration of the outskirts of galaxy clusters has emerged as one of the new frontiers for studying the cosmological growth of structures at the interface between the IGM and the ICM. However, initial results from Suzaku were puzzling, because its lack of angular resolution complicates modeling of point sources. Superb angular resolution of Chandra is needed to mask them out and measure the diffuse and clumpy ICM components individually. Recent Chandra XVP observations of A133 has done just such measurements, revealing an unprecedentedly detailed view. But, their interpretation requires theoretical support. The goal of this proposal is to advance our understanding of the outskirts of galaxy clusters by comparing hydrodynamical simulations and the Chandra observations of A133.

Subject Category: BH AND NS BINARIES

Proposal Number: 15400255

Title: Practical Models of Extinction for Spectral Analysis

PI Name: Randall Smith

Spectral extinction includes both the effects of absorption and scattering, but while multiple absorption models exist, no useful scattering model exists in standard spectral tools. Nonetheless X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources and their impact on an observed source spectrum can be equivalent to direct absorption. By convolving the scattering cross section with dust models we will create a spectral model as a function of energy, type of dust, and extraction region that can be used with models of direct absorption (e.g. XSPEC s phabs ). This will ensure the extinction model is consistant and enable direct connections between a source s X-ray spectral fits and its UV/optical extinction.

Subject Category: STARS AND WD

Proposal Number: 15200282

Title: Radiative cooling in 2-D and 3-D models of magnetically confined wind shocks

PI Name: Asif ud-Doula

We propose a three-parameter magnetohydrodynamic (MHD) study of the effects of radiative cooling in magnetic massive stars involving cooling length, magnetic confinement and stellar rotation. This is an extension of our earlier study that included the last two of these three parameters. With radiative cooling included, we will now be able to compute a broad 2-D MHD simulation grid in these three parameters and develop tools that will facilitate the interpretation of planned and archival Chandra observations of a growing list of magnetic massive-stars. We shall also develop general 3-D MHD simulations of magnetically confined wind shock (MCWS) model with application to stars with tilted-dipole or multipole fields.

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