Chandra X-Ray Observatory
	(CXC)


Cycle 4 Accepted Theory Proposals


Subject CategoryPI Name Title
ACTIVE GALAXIES AND QUASARSNANCY BRICKHOUSEA COMPREHENSIVE OPACITY MODEL FOR X-RAY SPECTROSCOPY
ACTIVE GALAXIES AND QUASARSROGER BLANDFORDELECTROMAGNETIC MODELS OF ULTRARELATIVISTIC OUTFLOWS
BH AND NS BINARIESFREDERIC RASIOTHEORETICAL MODELS OF X-RAY BINARIES AND MILLISECOND PULSARS IN GLOBULAR CLUSTERS
BH AND NS BINARIESVASSILIKI KALOGERATHEORETICAL STUDIES OF X-RAY BINARY POPULATIONS IN NEARBY GALAXIES
BH AND NS BINARIESTIMOTHY KALLMANAUGER DECAYS AND THEIR EFFECTS ON X-RAY ABSORPTION EDGES
CLUSTERS OF GALAXIES AUGUST EVRARDA VIRTUAL CLUSTER EXPLORATORY PROTOTYPE: MOCK OBSERVATIONS OF SIMULATED GALAXY CLUSTERS
CLUSTERS OF GALAXIES PATRICK MOTLA PUBLIC ARCHIVE OF NUMERICAL GALAXY CLUSTERS: TESTING A HIERARCHICAL MERGER MODEL FOR COOLING CORES
NORMAL GALAXIES EDISON LIANGMICROBLAZAR MODELS OF ULTRALUMINOUS X-RAY SOURCES IN NEARBY GALAXIES
NORMAL STARS AND WDJOSEPH CASSINELLIMODELING X-RAY LINE FORMATION IN MAGNETICALLY TORQUED DISKS AROUND EARLY-TYPE STARS



Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Title: A COMPREHENSIVE OPACITY MODEL FOR X-RAY SPECTROSCOPY

PI Name: NANCY BRICKHOUSE

We propose to develop a comprehensive opacity model for X-ray absorption spectroscopy. While reasonable opacity models for K-shell and Fe L-shell ions are publicly available, the atomic data for other L-shell ions are far less complete. We propose to calculate new oscillator strengths using the HULLAC atomic physics package to produce complete opacity models for Ne, Mg, Si, S, Ar, and Ca L-shell ions up to principal quantum number n=5. These opacity data will contribute to the Astrophysical Plasma Emission Database (APED). As we produce new atomic data, we will test the simplifying assumptions usually invoked for X-ray absorption models. Finally, we will prioritize our efforts by comparing models with archival data on line-rich sources.


Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Title: ELECTROMAGNETIC MODELS OF ULTRARELATIVISTIC OUTFLOWS

PI Name: ROGER BLANDFORD

It is proposed to develop electromagnetic models of ultrarelativistic outflows for specific application to Chandra observations of extragalactic jets, pulsar wind nebulae and GRBs where the cooling times of the X-ray emitting electrons are short compared with the flow times. It is hypothesized that these sources are (electro)magnetically not particle-dominated and that particle acceleration is triggered by instability in the current flow which, in turn,drives a turbulence cascade. It is intended to perform numerical simulations of this turbulence and then use the results to describe particle acceleration. The final goal is to create a toolkit that will allow spectral and polarization measurements, in combination with observations at other energies,to test the electromagnetic hypothesis.


Subject Category: BH AND NS BINARIES

Proposal Title: THEORETICAL MODELS OF X-RAY BINARIES AND MILLISECOND PULSARS IN GLOBULAR CLUSTERS

PI Name: FREDERIC RASIO

We will construct dynamical models of globular clusters taking into account stellar evolution and primordial binaries. Single and binary star evolution will be computed using a state-of-the-art population synthesis code. All dynamical interaction processes involving binaries and neutron stars will be incorporated using a simple Monte Carlo approach. Our models will help in the interpretation of the many Chandra observations of X-ray binaries and millisecond pulsars in Galactic globular clusters such as 47 Tuc and NGC 6397, and will provide guidance in planning future observations.


Subject Category: BH AND NS BINARIES

Proposal Title: THEORETICAL STUDIES OF X-RAY BINARY POPULATIONS IN NEARBY GALAXIES

PI Name: VASSILIKI KALOGERA

This is a proposal for a theoretical research program focused on (i) modeling of X-ray binary formation and evolution, and (ii) interpretation of recent and upcoming results from observational studies with Chandra of point source populations of nearby galaxies. The comparison with data will be based on predictions from population synthesis calculations of the X-ray binary luminosity functions in galaxies with different star formation histories, and, for a subset of observed galaxies, of spatial distributions. We expect that the proposed theoretical calculations will not only contribute to the interpretation of current observations, but will also have an impact extending beyond the duration of this project with theoretical predictions that will drive future Chandra observations.


Subject Category: BH AND NS BINARIES

Proposal Title: AUGER DECAYS AND THEIR EFFECTS ON X-RAY ABSORPTION EDGES

PI Name: TIMOTHY KALLMAN

Existing models for the structure of inner shell photoabsorption edges are not sufficiently accurate for interpretation of high resolution X-ray spectra. This is because of the effect of many resonant absorption features which occur at energies just below the edge, and to the fact that the levels excited by these transitions decay primarily by inner shell (Auger and radiative) transitions. As a result these resonances are broad and tend to overlap below the edge energy. The net effect is a shifting and smearing of the edge by an amount detectable by Chandra gratings. Calculation of these cross sections for the most abundant elements: C, N, O, Ne, Mg, Si, S, Ar, Ca and Fe is the goal of the proposed research.


Subject Category: CLUSTERS OF GALAXIES

Proposal Title: A VIRTUAL CLUSTER EXPLORATORY PROTOTYPE: MOCK OBSERVATIONS OF SIMULATED GALAXY CLUSTERS

PI Name: AUGUST EVRARD

We propose to develop a prototype Virtual Cluster Exploratory (VCE) toolkit that will serve data products from libraries of simulated clusters to the cluster community. We will develop a common data format for model input, and return output in a form familiar to observers. Classes of dynamically accessible data products, including mock Chandra spectral images, will be geared toward studies of individual systems, deep sky images, or statistical samples. We will seek input from the observational community (for products and services), from computational modelers (for base libraries and data standards) and VO/ADC data management experts (for interface protocols and data packaging). The toolkit will help accelerate convergence to a complete physical description of the ICM.


Subject Category: CLUSTERS OF GALAXIES

Proposal Title: A PUBLIC ARCHIVE OF NUMERICAL GALAXY CLUSTERS: TESTING A HIERARCHICAL MERGER MODEL FOR COOLING CORES

PI Name: PATRICK MOTL

Recent, high-resolution, Eulerian cosmology simulations have led us to propose a new model for the formation of cooling cores via hierarchical mergers. Our initial comparison with Chandra data suggests good agreement with newly discovered features including cooling bullets and complex distributions of cool material. We propose to simulate 50 clusters with radiative cooling in a realistic environment, probing a range of mass and merger histories. The catalog of numerical clusters will be placed in an on-line archive with interactive tools to construct X-Ray surface brightness and temperature maps for direct comparison with Chandra data. We will also use archived observations from Chandra to test our hierarchical merger model for galaxy cluster cooling cores.


Subject Category: NORMAL GALAXIES

Proposal Title: MICROBLAZAR MODELS OF ULTRALUMINOUS X-RAY SOURCES IN NEARBY GALAXIES

PI Name: EDISON LIANG

We propose to perform detailed numerical simulations of the radiative output of mildly relativistic jets of Galactic microquasars, to see if "microblazars" with jets aligned close to our line of sight can be viable models of ultraluminous x-rays sources (ULXs) of nearby galaxies. Our simulations will focus on the observable signatures such as time-resolved x-ray spectra and multiwavelength variability based on the Compton upscattering of photons from both the accretion disk and the companion star. We will also compare in detail the model predictions with archival and future data of both ULXs of nearby galaxies and Galactic microquasars.


Subject Category: NORMAL STARS AND WD

Proposal Title: MODELING X-RAY LINE FORMATION IN MAGNETICALLY TORQUED DISKS AROUND EARLY-TYPE STARS

PI Name: JOSEPH CASSINELLI

There is evidence that magnetic fields can be present in the outflows of hot stars and can have a major effect on the X-ray fluxes and line profiles that are produced. This is a theory proposal to determine the observational consequences of magnetically channeled flows from a star. In particular we propose using the recently developed Magnetically Torqued Disk model for hot stars, to explain several anomalies associated with Chandra observations. These include the $fir$ line evidence that hot X-ray source regions can lie near the base of the winds, and that the line profiles are broad and nearly symmetric and with negligible shift of the centroid of the lines.




Last modified: 12/02/10



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