Accepted Cycle 17 Theory Proposals

Proposal Number	Subject Category	PI Name	Title
17200424	STARS AND WD	Jeremy Drake	THE CONTRIBUTION TO PROTOPLANETARY DISK IONIZATION FROM T TAURI FLARE ENERGETIC PARTICLES
17500237	SN, SNR AND ISOLATED NS	Patrick Slane	Modeling the Structure of Composite Supernova Remnants
17500486	SN, SNR AND ISOLATED NS	Daniel Patnaude	Modeling the Dynamics and X-ray Emission of Shocked Ejecta in the Remnants of Core-Collapse Supernovae
17500602	SN, SNR AND ISOLATED NS	Roger Chevalier	Supernova Remnants in Molecular Clouds
17620358	NORMAL GALAXIES: X-RAY POPULATIONS	Vassiliki Kalogera	A Novel Approach to the Common Envelope Evolution
17700093	ACTIVE GALAXIES AND QUASARS	Feryal Ozel	X-ray Variability of Sgr A* as a Probe of Plasma Physics in Accretion Flows
17700614	ACTIVE GALAXIES AND QUASARS	Daniel Proga	Synthetic X-ray spectra of gaseous clouds in AGN
17800306	CLUSTERS OF GALAXIES	Christopher Reynolds	The plasma physics of conduction in intracluster medium
17800406	CLUSTERS OF GALAXIES	Randall Smith	The Impact of Kappa Distributions on X-ray Spectra from Clusters of Galaxies
17910568	GALACTIC DIFFUSE EMISSION AND SURVEYS	Lia Corrales	Modeling the Unique Dust Distribution in the Cyg X-3 and Cyg OB2 Sight Line

Subject Category: STARS AND WD

Proposal Number: 17200424

Title: THE CONTRIBUTION TO PROTOPLANETARY DISK IONIZATION FROM T TAURI FLARE ENERGETIC PARTICLES

PI Name: Jeremy Drake

Protoplanetary disk evolution and planet formation are largely controlled by MHD turbulent viscosity driven by stellar X-ray ionization. However, a recent estimate of the ionization rate from flare-generated energetic particle (EPs) is forty times larger than from X-rays if the particles propagate in straight lines. Disk viscosities, ionization fractions, and planet formation models could need substantial revision. In reality, EPs will be deflected by the turbulent, magnetized T Tauri wind and might not even reach the disk. We propose to use Chandra observations of T Tauri flares combined with solar flare scaling laws for EPs, a state-of-the-art MHD model for T Tauri winds, and rigorous particle transport through the wind, to determine the true EP flux and ionization rate at the disk.

Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 17500237

Title: Modeling the Structure of Composite Supernova Remnants

PI Name: Patrick Slane

The dynamical structure of a composite SNR, along with its broadband emission, provides crucial constraints on the ejecta mass and explosion energy, the properties of the pulsar that powers the associated wind nebula, and the ultimate fate of the particles that it injects. Of particular importance is the effect of asymmetries introduced through spatial variations in the ambient medium density and by rapid motion of the pulsar. Here we propose hydrodynamical and semi-analytical modeling of G21.5-0.9 and G292.0+1.8, SNRs for which deep Chandra observations have provided key input parameters for these models. We will derive ambient conditions and pulsar properties that lead to the observed morphology, broadband emission, and shock conditions in these important composite systems.

Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 17500486

Title: Modeling the Dynamics and X-ray Emission of Shocked Ejecta in the Remnants of Core-Collapse Supernovae

PI Name: Daniel Patnaude

With more than 15 years of observations of young SNRs, we have a unique sample for the evolution of core-collapse SNe with ages between 15 and 2000 yrs. The connection between SNRs and SNe remains vague though. We propose to couple the detailed density and velocity structure and spatially dependent composition derived from SNe models to a hydrodynamics code which includes time dependent ionization and radiative losses. We will extend these models from ages of 100 days to 1000 yrs, producing synthetic X-ray spectra, and study the bulk properties of the simulated X-ray emission, including the computed X-ray line ratios and centroids. We will compare these models to the integrated thermal X-ray emission from young Galactic SNRs such as Cas A and nearby SNe such as SN 1987A and SN 1996cr.

Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 17500602

Title: Supernova Remnants in Molecular Clouds

PI Name: Roger Chevalier

The mixed morphology supernova remnants show centrally peaked X-ray emission and shell-like radio emission, and are found to be interacting with molecular clouds. They have been widely observed with Chandra. We propose a model in which the density structure of molecular clouds is determined by supersonic turbulence, with a lognormal distribution of density with regard to volume and mass. Most of the gas is near the median density. When most of the supernova remnant becomes radiative, there is lower density gas that remains nonradiative and fills a small fraction of the volume. The hot gas of the supernova remnant preferentially flows through low density channels, with implications for the X-ray emission from the remnants. We will develop approximate models and numerical simulations.

Subject Category: NORMAL GALAXIES: X-RAY POPULATIONS

Proposal Number: 17620358

Title: A Novel Approach to the Common Envelope Evolution

PI Name: Vassiliki Kalogera

We now have a detailed observational census of X-ray binary (XRB) populations, largely due to Chandra's unprecedented capabilities. However, theoretical studies of XRBs are limited by our ability to accurately simulate binary interactions. In particular, models of the unstable mass transfer phase known as a common envelope (CE) are either prohibitively imprecise or computationally expensive. We propose a novel method to evolve a binary through a CE using the state-of-the-art stellar evolution code MESA, taking advantage of its highly-optimized 1D hydrodynamic solver. After developing and benchmarking our new CE treatment, we will generate grids of CE calculations and ultimately use them to simulate a synthetic XRB population that will be compared with the sample of Galactic XRBs.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 17700093

Title: X-ray Variability of Sgr A* as a Probe of Plasma Physics in Accretion Flows

PI Name: Feryal Ozel

The long observations of the Galactic Center will be one of Chandra's legacies, as it has the richness to fundamentally improve our understanding of the black hole and its environment. The developments in the algorithms and the computational power in the last 2 years put us in a unique position to investigate the physics responsible for generating the enigmatic X-ray flares from Sgr A*. In the proposed project, we will perform the first 3D GRMHD+ray-tracing simulations that will self-consistently incorporate sub-grid models for particle acceleration in regions of enhanced magnetic dissipation via reconnection. Comparing our results to the observed amplitude and duration distribution of X-ray flares will improve our understanding of reconnection and particle acceleration in accretion flows.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 17700614

Title: Synthetic X-ray spectra of gaseous clouds in AGN

PI Name: Daniel Proga

We propose to study warm absorbers (WAs) in AGN. We plan to combine a quantitative theory for cloud formation, destruction, and acceleration with a global model for the dynamics of the inflowing and outflowing gas and radiative transfer calculations to make quantitative predictions for the X-ray spectral signatures that might be associated with WAs. Our goal is to test this theory by direct comparison with the Chandra observations of objects such as NGC3516, NGC3783, NGC5548, and NGC7469. In particular, we will address the following questions: 1) How do the outflow inhomogeneity and time variability affect spectra? 2) How do X-ray spectra depend on the sight-line? 3) What is the shape of the absorption measure distribution? 4) Are WAs and the so-called ultra-fast outflows related?

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 17800306

Title: The plasma physics of conduction in intracluster medium

PI Name: Christopher Reynolds

The potential importance of thermal conduction in the intracluster medium (ICM) has long been recognized; it can channel heat into a cooling cluster core, mediate the dissipation of sound waves and turbulence, and dictate the presence or absence of molecular gas. However, the ICM is a weakly collision, weakly magnetized (high-beta) plasma and so the microphysics of conduction is still very much an open issue. Plasma instabilities driven by the heat flux and pressure anisotropies may kill conduction dead. We will examine this problem with a particle-in-cell code, characterizing thermal conduction in ICM-like plasmas as a function of temperature gradient and magnetization levels. A microphysical understanding of conduction will have direct impact on the interpretation of Chandra data.

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 17800406

Title: The Impact of Kappa Distributions on X-ray Spectra from Clusters of Galaxies

PI Name: Randall Smith

Shocks, turbulence and winds all influence the electron velocity distribution in hot plasmas, exciting lower-energy electrons and generating a high energy tail that in extreme cases becomes relativistic, leading to radio and X-ray synchrotron emission. Even modest examples of this effect, typically described as a kappa distribution can significantly affect both the line and continuum X-ray spectrum emitted by the plasma. We show what impact such cases could have on measured cluster temperatures - and all properties derived from them - and propose to develop a new spectral model that will use the recently-released AtomDB v3.0 atomic database to model the emission from a plasma with a kappa-distribution.

Subject Category: GALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 17910568

Title: Modeling the Unique Dust Distribution in the Cyg X-3 and Cyg OB2 Sight Line

PI Name: Lia Corrales

The eclipsing high mass X-ray binary (HMXB) Cygnus X-3 is one of the brightest X-ray objects in the sky, and has one of the brightest X-ray scattering halos. At a distance of 7-13 kpc, the foreground of Cyg X-3 contains many interesting structures: the Perseus arm of the Milky Way; stellar cluster Cygnus OB2, which is embedded in the larger molecular region of Cygnus X; and the Little Friend, a distant Bok globule imaged via X-ray scattering by dust. With the Cyg OB2 Legacy Survey, we have the opportunity to examine the extended scattering halo of Cyg X-3 and study the unique properties of dust in the Cyg OB2 region.

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