Accepted Cycle 21 Theory Proposals

Proposal Number Subject Category PI Name Title
21100139SOLAR SYSTEM AND EXOPLANETSJeremy DrakeThe Ionization of M dwarf Exoplanet Atmospheres by Flare Energetic Particles
21200202STARS AND WDSofia MoschouMODELING CHANDRA OBSERVATIONS OF CEPHEID ACTIVITY
21400247BH AND NS BINARIESDaniel ProgaSynthetic X-ray spectra of coronae and winds from irradiated disks in LMXBs.
21500394SN, SNR AND ISOLATED NSCarles BadenesDO TYPE IA SUPERNOVAE REALLY EXPLODE INSIDE PLANETARY NEBULAE?
21500466SN, SNR AND ISOLATED NSPrasiddha ArunachalamLinking Type Ia Supernovae and Supernova Remnants: Understanding the explosion mechanism
21500508SN, SNR AND ISOLATED NSDaniel PatnaudeWhere have all the young remnants gone?
21610551NORMAL GALAXIES: DIFFUSE EMISSIONAkos BogdanTracing the Missing Baryons in the EAGLE Simulation
21900172EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYSMassimiliano BonamenteDISTRIBUTIONS OF THE C STATISTIC FOR LOWCOUNT POISSON DATA
21900223EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYSChang-Goo KimProbing Galactic Disk Winds Driven by Supernova Feedback
Subject Category: SOLAR SYSTEM AND EXOPLANETS

Proposal Number: 21100139

Title: The Ionization of M dwarf Exoplanet Atmospheres by Flare Energetic Particles

PI Name: Jeremy Drake

Ionization in the atmospheres of exoplanets is driven by the host star's EUV-X-ray emission and flare-associated energetic particles (EPs). Ionizing radiation is particularly extreme for planets in the close-in habitable zones of M dwarfs. EPs cannot be observed directly, but if they travel in straight lines EPs could be more important than X-rays. In reality, EPs can be trapped and deflected by the turbulent, magnetized stellar wind. We propose to use Chandra observations of M dwarf flares combined with solar flare EP scaling laws, state-of-the-art MHD models for M dwarf winds and particle transport, and a sophisticated atmosphere photo-particle-chemistry code to determine the true EP flux exoplanets experience and their contribution to atmospheric ionization and chemistry.

 Subject Category: STARS AND WD

Proposal Number: 21200202

Title: MODELING CHANDRA OBSERVATIONS OF CEPHEID ACTIVITY

PI Name: Sofia Moschou

Cepheids are variable pulsating stars with a well known periodic chromospheric response at UV wavelengths close to their minimum radius phase. Recently, an X-ray variable signature was captured in observations during the \emph{maximum} radius phase indicating an X-ray source located higher in the Cepheid atmosphere. This X-ray emission came as a surprise and is not understood. In the proposed study, the two most prominent mechanisms of thermal X-ray emission, namely shocks and magnetic reconnection, will be explored as possible explanations of that X-ray variability. Both ideal and resistive MHD simulations will be performed and finally X-ray light curves will be synthesized to evaluate the heating efficiency of each mechanism.

 Subject Category: BH AND NS BINARIES

Proposal Number: 21400247

Title: Synthetic X-ray spectra of coronae and winds from irradiated disks in LMXBs.

PI Name: Daniel Proga

We propose to study disk irradiation in X-ray binaries. Irradiation produces a disk corona and wind and therefore impacts X-ray spectra. We will use photoionization and radiative transfer calculations to predict X-ray spectral signatures that might be associated with such coronae and winds. These calculations will utilize our hydrodynamical simulations of irradiated disks computed for the actual observed luminosity and spectral energy distribution. Our goal is to test whether thermally driven winds with or without a boost due to radiation pressure on free electrons can produce spectra that reproduce the Chandra HETGS observations. In this study, we will focus on the Chandra spectra that do not demand magnetic driving of systems such as GRS 1915+105, 4U 1630-47, and GX 13+1.

 Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 21500394

Title: DO TYPE IA SUPERNOVAE REALLY EXPLODE INSIDE PLANETARY NEBULAE?

PI Name: Carles Badenes

We propose to create a grid of SNR models to investigate whether Type Ia SNe do explode inside post-Common Envelope Planetary Nebulae, an idea that has generated a great deal of interest in the community in recent years. We will calculate the dynamics and X-ray spectra of SNR models produced by the interaction between SN Ia ejecta and the post-CE PN models of Garcia-Segura et al. (2018), and compare the results to the bulk dynamical and spectral properties of Type Ia SNRs

 Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 21500466

Title: Linking Type Ia Supernovae and Supernova Remnants: Understanding the explosion mechanism

PI Name: Prasiddha Arunachalam

We propose to conduct a detailed study of two supernova remnants (SNRs) of Type Ia origin- SNR 0509-67.5 and SNR DEM L71 using 1-dimensional hydrodynamic modeling for SNR evolution and non-equilibrium ionization calculations for the state of the shocked plasma. Our models for the two remnants are based on realistic constraints from dynamical parameters inferred from their HST and Chandra observations. The results of our hydro simulations will allow us to constrain the explosion mechanism for both the remnants, establish the applicability of our models in the context of SNR evolution, and connect the explosion physics of Type Ia Supernovae to the properties of their respective SNRs.

 Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 21500508

Title: Where have all the young remnants gone?

PI Name: Daniel Patnaude

Despite an emperical supernova rate of ~ 1/galaxy/century, supernova remnant (SNR) population studies of nearby galaxies reveal a distinct lack of young, ejecta dominated remnants such as Cassiopeia A. Instead, studies detect populations of either compact, ISM-dominated SNRs such as in M83, or large, low surface brightness remnants. This has led some to suggest that host galaxy metallicity may drive remnant evolution. Here we propose to investigate the role that environmental metallicity plays in the evolution and detection of young remnants. We will develop models for the evolution of core collapse supernovae in high and low metallicity environments, synthesize broadband luminosity functions, and compare our models to X-ray, optical, and radio populations of SNRs in nearby galaxies.

 Subject Category: NORMAL GALAXIES: DIFFUSE EMISSION

Proposal Number: 21610551

Title: Tracing the Missing Baryons in the EAGLE Simulation

PI Name: Akos Bogdan

About one-third of the baryons are unaccounted for in the present universe, which gives rise to the missing baryon problem. Simulations suggest that the missing baryons are in the form of X-ray emitting gas in large-scale filaments. A promising approach to resolve the missing baryon problem is to probe X-ray absorption lines imprinted on the spectrum of background quasars. Recently, we developed a novel approach and detected an O VII absorption line toward H1821+643. Here, we propose to utilize EAGLE, a self-consistent structure formation model, to probe whether cosmological simulations can reproduce the characteristics of the observed O VII absorption line. Moreover, we will use EAGLE to probe the origin of the absorption line and to provide predictions for other sightlines.

 Subject Category: EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 21900172

Title: DISTRIBUTIONS OF THE C STATISTIC FOR LOWCOUNT POISSON DATA

PI Name: Massimiliano Bonamente

This proposal addresses open questions with the use of the C statistic for low-count Poisson X-ray data. The project aims to determine (a) how well is the C statistic approximated by chi^2 in the low-count regime and (b) whether the parameterization of the model plays a role in the distribution of the C statistic. Results from this analysis are necessary to accurately model X-ray data with low counts, without the need to bin the spectra.

 Subject Category: EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 21900223

Title: Probing Galactic Disk Winds Driven by Supernova Feedback

PI Name: Chang-Goo Kim

We propose to build synthetic observations from fully self-consistent magnetohydrodynamic simulations of the star-forming ISM. We will develop and test observational diagnostics to derive physical properties of the multiphase outflows using the combined synthetic data from X-ray and other wavelengths. Our objectives are (1) to quantify launching properties of different outflowing gas phases, including both cool fountains and hot winds, (2) to provide X-ray properties of the hot component galactic outflows, (3) to reinterpret previous observations in the context of detailed wind/fountain simulations, and (4) to assess the requirements for future long exposure Chandra observations and future X-ray missions to accurately characterize hot winds in the nearby disk galaxies.