Accepted Cycle 23 Theory Proposals

Proposal Number	Subject Category	PI Name	Title
23200580	STARS AND WD	Alexandre David-Uraz	Modeling rotationally modulated X-ray variability in massive star winds using co-rotating interaction regions
23500114	SN, SNR AND ISOLATED NS	John P. Hughes	Measuring Clumping in SN Ia Ejecta from their Remnants
23610258	NORMAL GALAXIES: DIFFUSE EMISSION	Christopher Russell	Dynamic modeling of ~100 stellar winds in the Galactic center's inner parsec
23610292	NORMAL GALAXIES: DIFFUSE EMISSION	Benjamin Oppenheimer	Galaxy Formation's Indelible Imprints Upon Groups
23700128	ACTIVE GALAXIES AND QUASARS	Claude-Andre Faucher-Giguere	Testing the Predicted Two-phase Growth of SMBHs with X-ray Observations Across Mass and Redshift
23700161	ACTIVE GALAXIES AND QUASARS	Daniel Angles-Alcazar	Interpreting Chandra surveys with cosmological hyper-refinement simulations of AGN fueling and feedback
23800273	CLUSTERS OF GALAXIES	Sebastian Heinz	Heat Pumps in the Hearts of Galaxy Clusters

Subject Category: STARS AND WD

Proposal Number: 23200580

Title: Modeling rotationally modulated X-ray variability in massive star winds using co-rotating interaction regions

PI Name: Alexandre David-Uraz

Massive stars represent an important source of soft X-rays, generally thought to be produced by instabilities in their dense, radiatively-driven winds. In recent years, variable X-ray emission has been reported in an increasing number of O stars, leading to the hypothesis that large-scale wind structures lead to its rotational modulation. Current numerical models assume isothermal winds. We propose to conduct the first detailed, non-isothermal 2D and 3D hydrodynamic simulations to assess the role of these so-called Co-rotating Interaction Regions in the production and modulation of X-rays and predict X-ray emission. These new models will help interpret data from large X-ray surveys, shedding light on the puzzling photospheric physics that is at the origin of the wind structures.

Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 23500114

Title: Measuring Clumping in SN Ia Ejecta from their Remnants

PI Name: John P. Hughes

We propose to build models of the morphological structure of the ejecta debris field in young Type Ia supernova remnants for specific application to SN 1572 and SN1006. We will use the VH-1 hydrodynamics code, initiating simulations with a parameterized clumping model varying the density contrast, spatial scale and location of clumps within the ejecta. Models will be run to the relevant age of the remnant and images will be generated for a quantitative comparison with Chandra high resolution ACIS images using the advanced morphological estimators known as Minkowski functionals.

Subject Category: NORMAL GALAXIES: DIFFUSE EMISSION

Proposal Number: 23610258

Title: Dynamic modeling of ~100 stellar winds in the Galactic center's inner parsec

PI Name: Christopher Russell

Chandra is the only high-energy observatory able to resolve the Galactic center's inner parsec. Over 5 Ms of observations have characterized the flow of hot gas through the Bondi radius towards Sgr A* via a RIAF. Recent radio observations found evidence of a cold disk around Sgr A*, adding another ingredient to the accretion picture, while subsequent hydrodynamic simulations of the WR stars and winds orbiting Sgr A* also formed such a disk, prompting this proposed theoretical study. We aim to perform the most-complete simulations of the central parsec by including all massive stars and their winds (~100 WR, O, and Bs), all while synthesizing X-ray spectra and images to firmly anchor this numerical work in Chandra observations.

Subject Category: NORMAL GALAXIES: DIFFUSE EMISSION

Proposal Number: 23610292

Title: Galaxy Formation's Indelible Imprints Upon Groups

PI Name: Benjamin Oppenheimer

The intragroup medium (IGrM) represents an intermediate scale between the well-studied intracluster medium and the circumgalactic medium around normal galaxies (M_500=10^13.0-14.5 M_sol). We propose a theoretical study of the IGrM and its resident galaxies using a forward modeling approach to simulate X-ray observations from at least 3 state-of-the-art simulations: EAGLE, IllustrisTNG, and SIMBA. We will 1) determine the location and phase of the IGrM baryons within and beyond R_500, 2) understand the role of self-consistently modeled AGN feedback in setting X-ray-observed profiles, 3) model the connection between IGrM metallicity profiles and the dynamics of group formation and enrichment, and 4) determine how the IGrM processes infalling satellites and the connection between the two.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 23700128

Title: Testing the Predicted Two-phase Growth of SMBHs with X-ray Observations Across Mass and Redshift

PI Name: Claude-Andre Faucher-Giguere

Recent galaxy formation simulations predict that massive BHs grow in two distinct phases. In early or low-mass galaxies, gas ejection by bursty stellar feedback starve BHs; accretion is highly intermittent and BHs are under-massive. At later times or when galaxies become sufficiently massive, accretion accelerates and BHs converge to the usual scaling relations. This project will use FIRE galaxy formation simulations to make detailed predictions for X-ray AGN vs. galaxy mass and redshift. The predictions will be compared with extensive Chandra data on AGN properties (including duty cycles, mean accretion rates, and accretion rate distributions) as a function of these variables. This will test whether the two-phase growth predicted by the simulations is consistent with observations or not.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 23700161

Title: Interpreting Chandra surveys with cosmological hyper-refinement simulations of AGN fueling and feedback

PI Name: Daniel Angles-Alcazar

While Chandra extragalactic surveys have dramatically improved our understanding of active galactic nuclei (AGN) across redshifts, progress has been limited by uncertainties in current theoretical models of massive black hole (MBH) growth and feedback. We propose to maximize the science return of Chandra by using a new class of cosmological hyper-refinement simulations that for the first time explicitly resolve MBH accretion and feedback on sub-pc scales while including state-of-the-art galaxy formation physics in a full cosmological setting. We will predict accretion rates, Eddington ratios, and obscuration as a function of host galaxy properties and redshift with unprecedented fidelity, significantly improving our understanding of AGN triggering mechanisms and the AGN-galaxy connection.

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 23800273

Title: Heat Pumps in the Hearts of Galaxy Clusters

PI Name: Sebastian Heinz

One of Chandra's great legacies is the discovery of cavities in virtually all cool core clusters, putting the argument for AGN feedback as an explanation for the cooling flow poblem on firm observational footing. Yet, the microphysical details of how feedback occurs remain unsettled. Conduction had generally been discounted as too slow to meaningfully contribute to heating of cool cores. However, it was recently proposed that jets can act as heat pumps by bringing low entropy gas into thermal contact with the hot cluster atmosphere. Even if conduction is substantially suppressed, this mechanism may boost the AGN heating efficiency above 100%. We propose to conduct MHD simulations to test the heat pump hypothesis, to quantify the heating efficiency, and to create observational diagnostics.