Accepted Cycle 22 Archive Proposals

Proposal Number	Subject Category	PI Name	Title
22200253	STARS AND WD	Maurice Leutenegger	Where are the shocks in O star winds? Understanding constraints from $f/i$ ratios in He-like ions
22200363	STARS AND WD	Leisa Townsley	Still Finding MAGiX in the Chandra Archive
22400069	BH AND NS BINARIES	Pragati Pradhan	A systematic study of super-orbital modulation in X-ray binaries with Chandra/HETG
22400463	BH AND NS BINARIES	Rafael Martínez-Galarza	Machine Learning Discovery of X-Ray Transients in the Chandra Source Catalog 2.0
22500145	SN, SNR AND ISOLATED NS	Jeonghee Rho	An X-ray study of dust destruction using 1 Mega-sec Chandra observation of Cas A
22700041	ACTIVE GALAXIES AND QUASARS	Qingling Ni	Probing the relation between black-hole growth and host-galaxy compactness among star-forming galaxies
22700153	ACTIVE GALAXIES AND QUASARS	Adi Foord	Dual AGN Across Cosmic Time
22700216	ACTIVE GALAXIES AND QUASARS	Shifu Zhu	The Nature of the Nuclear X-ray Emission in Radio-Loud Quasars
22700278	ACTIVE GALAXIES AND QUASARS	Jon Miller	A New Look at the Paradigmatic Compton-thick Sy-2 NGC 1068
22700376	ACTIVE GALAXIES AND QUASARS	Gordon Richards	A Novel Method to Probe UV-X-ray Correlations in Luminous Quasars
22800542	CLUSTERS OF GALAXIES	Megan Donahue	ACCEPT 2.0: PUBLIC RELEASE & SCIENCE RESULTS
22900370	EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS	Dong-Woo Kim	Chandra Galaxy Catalog
22900618	EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS	Alexey Vikhlinin	Development of the next-generation source detection tool for maximizing science output from key Chandra surveys
22910352	GALACTIC DIFFUSE EMISSION AND SURVEYS	Shuo Zhang	A Survey of Galactic Center X-ray Filaments Using 11.7 Ms Archival Chandra Data from 1999 to 2019

Subject Category: STARS AND WD

Proposal Number: 22200253

Title: Where are the shocks in O star winds? Understanding constraints from $f/i$ ratios in He-like ions

PI Name: Maurice Leutenegger

One of the most important results of high-resolution X-ray grating spectroscopy of massive stars has been to constrain the location of the onset of X-ray emitting shocks (a key test of theory) using the f/i line ratios of He-like ions, which are sensitive to the local UV field strength, and thus distance from the star. The high quality spectra in the archive can yield precise constraints on plasma location, but results are currently dominated by modeling uncertainties. We propose to address uncertainties in the model UV flux as well as in the atomic data used to model the X-ray spectra, and to apply our results to fits of archival spectra, resulting in reduced and better characterized uncertainties in the X-ray emitting plasma location.

Subject Category: STARS AND WD

Proposal Number: 22200363

Title: Still Finding MAGiX in the Chandra Archive

PI Name: Leisa Townsley

Massive star-forming regions (MSFRs) are engines of change across the Galaxy, providing its ionization, fueling the hot ISM, and seeding spiral arms with tens of thousands of new stars. Resolvable MSFRs are microscopes for understanding their more distant extragalactic counterparts, which provide the basis for star formation rate calibrations and form the building blocks of starburst galaxies. This archive program will extend Chandra's lexicon of Galactic MSFRs with in-depth analysis of 12 complexes, studying star formation and evolution on scales of tenths to tens of parsecs and distances <1 to >12 kpc. It fuses a "Physics of the Cosmos" mission with "Cosmic Origins" science, bringing new insight into star formation and feedback through Chandra's unique X-ray perspective.

Subject Category: BH AND NS BINARIES

Proposal Number: 22400069

Title: A systematic study of super-orbital modulation in X-ray binaries with Chandra/HETG

PI Name: Pragati Pradhan

We propose to investigate the physical origin of super-orbital modulation in accreting X-ray binaries through archival HETG data. Out of available 4.4Ms HETG data, only 15% have been studied in relation to their super-orbital modulation. We will study these high resolution data to perform plasma diagnostics and emission line studies for each super-orbital source. Through variability in line fluxes, energies, Doppler velocities etc, we will investigate the physical origin of super-orbital modulation and constrain the geometry/dynamics of the line-emitting regions. This first systematic study will shed light on the physics of super-orbital modulation and also has broader astrophysical implications in understanding formation/stability of accretion disk/warps, donor star variability etc.

Subject Category: BH AND NS BINARIES

Proposal Number: 22400463

Title: Machine Learning Discovery of X-Ray Transients in the Chandra Source Catalog 2.0

PI Name: Rafael Martínez-Galarza

We propose a systematic study of the time-domain properties of the Chandra Source Catalog 2.0 (CSC2), with a machine learning approach that we have developed and tested on a subset of CSC2 sources. Among the most interesting objects yet to be discovered in the CSC2 are high energy transients that might signal the presence of the most energetic events in the universe: tidal disruption events (TDEs), jets in X-ray binaries, and flaring young stars. Our exploratory mining of the complex, multi-parameter space of CSC2 has already uncovered over 100 puzzling variable sources, including potential transients in ~2% of CSC2. We propose to statistically characterize the entire CSC2 transient content. We expect that our study will also uncover new unclassified types of variability.

Subject Category: SN, SNR AND ISOLATED NS

Proposal Number: 22500145

Title: An X-ray study of dust destruction using 1 Mega-sec Chandra observation of Cas A

PI Name: Jeonghee Rho

The large quantities of dust observed in high-z galaxies raise the fundamental question of the origin of the dust. The dust mass of Cas A is ~0.5 Msun in agreement with dust formation models, which suggests that supernovae could indeed be major dust factories. However, a fraction of dust will be destroyed due to the reverse shock with estimates ranging from 1-100 percent in literature. Our far-IR [O III] maps of Cas A show emission both at and outside the dense knots, and we find two different regions with significantly different strengths of X-ray lines, probably due to dust destruction. We propose a Chandra archival study of Cas A to characterize the X-ray properties and to investigate the dust destruction by combining IR data and models.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 22700041

Title: Probing the relation between black-hole growth and host-galaxy compactness among star-forming galaxies

PI Name: Qingling Ni

Likely connections between black-hole (BH) growth and host-galaxy compactness have been found among star-forming (SF) galaxies, which may provide insight into BH-galaxy co-evolution: compact SF galaxies might have large amounts of gas in their centers that can boost BH accretion. However, it is not yet clear if the relation between BH growth and host-galaxy compactness among SF galaxies is more fundamental than the relation between BH growth and stellar mass (or star formation rate). We propose to address this question by carrying out systematic partial-correlation studies for a large galaxy sample selected in the COSMOS field, utilizing deep Chandra archival observations to estimate the amount of BH growth.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 22700153

Title: Dual AGN Across Cosmic Time

PI Name: Adi Foord

We propose to carry out a large, uniform, survey for dual AGNs in distant galaxies using archival Chandra surveys. Currently, there is no systematic study of the evolution of dual AGN at high-z; and observational constraints on the dual AGN fraction in the nearby universe are higher than predicted from simulations, resulting in an inconsistent expected dual AGN rate at z>1. We will be able to accurately determine the dual AGN rate (<0.5%), as well as a measure the dual AGN fraction as a function of redshift (<2%). Our tight constraint on the dual AGN fraction as a function of z will allow us to statistically differentiate between the low- and high-end predictions for the fraction of dual AGN across cosmic time.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 22700216

Title: The Nature of the Nuclear X-ray Emission in Radio-Loud Quasars

PI Name: Shifu Zhu

We propose an archival analysis of ~850 radio-loud quasars (RLQs) with largely serendipitous Chandra/XMM-Newton observations that will let us assess, far better than ever before, their X-ray spectral properties and relations between their X-ray, optical/UV, and radio luminosities. Specifically, the improved X-ray and multiwavelength data of our sample will let us determine clearly if the disk/corona and jets in RLQs are substantially coupled or are instead largely distinct. This work is timely, being energized by a resurgence in powerful radio surveys, the three-quarter-million SDSS spectroscopic quasars, and the growth of the Chandra/XMM-Newton archives.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 22700278

Title: A New Look at the Paradigmatic Compton-thick Sy-2 NGC 1068

PI Name: Jon Miller

By virtue of its proximity and flux, NGC 1068 is a unique laboratory to study Compton-thick Sy-2 AGN, and to test the ability of high-resolution spectroscopy to reveal both physical parameters and geometry. In this source, spatially resolved nuclear emission can provide limits on spectroscopic inferences and feedback in the form of mass outflow rates. Past imaging and spectroscopy of the nuclear region in NGC 1068 have yielded important results, but a great deal of new science remains that will set the stage for the calorimeter era ahead. We propose a comprehensive, systematic archival analysis of all prior Chandra observations of NGC 1068, with equal emphasis on novel spectral diagnostics and combining gratings and ACIS data to better understand this AGN.

Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 22700376

Title: A Novel Method to Probe UV-X-ray Correlations in Luminous Quasars

PI Name: Gordon Richards

We propose to perform a Chandra archival investigation of SDSS quasars that have been sub-classed based on their UV emission-line features in a novel manner using Independent Component Analysis. This analysis captures the full covariance of the UV emission features (both weak and strong) in a way that maximizes our knowledge of the diversity of intrinsic quasar properties. We will investigate how evidence for accretion disk winds changes as a function of their combined UV and X-ray properties, including alpha_ox, Gamma, and X-ray weak/normal fraction using both detected objects and stacking analysis. A preliminary query of the Chandra Source Catalog reveals that there is sufficient data to carry out the project and to test the archive for potential aggregated target-selection biases.

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 22800542

Title: ACCEPT 2.0: PUBLIC RELEASE & SCIENCE RESULTS

PI Name: Megan Donahue

Both theorists and observers studying galaxy clusters have made extensive use of the ACCEPT database during the last decade. It has been considered useful because it provides easy access to a large archival sample of uniformly reduced Chandra data. An upgrade of the original database ACCEPT 2.0 was begun with a Cycle 14 Chandra archival grant, which enabled construction of a new reduction pipeline but not public release of the data products. We require funds for public release of ACCEPT 2.0 along with scientific analysis of its data products on 606 galaxy clusters. Our scientific focus will be on incidence and evolution of cool cores in clusters, including their relationships to cluster relaxation, as measured from 2D morphology.

Subject Category: EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 22900370

Title: Chandra Galaxy Catalog

PI Name: Dong-Woo Kim

We propose to build the Chandra Galaxy Catalog by cross-matching Chandra Source Catalog V2 with major sky survey catalogs, covering from radio to X-ray. Carefully selecting X-ray sources with high quality and conservatively classifying galaxies with multi-wavelength data, we will produce a large (about 10,000), clean (with least confusion and contamination) X-ray selected galaxy catalog and make it publicly available. We will further investigate focused galaxy sciences, which can be done only with a large, unbiased sample. They include the X-ray luminosity function of galaxies, X-ray scaling relations and unusual, but interesting types of galaxies (e.g., XBONGs, E+A galaxies).

Subject Category: EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 22900618

Title: Development of the next-generation source detection tool for maximizing science output from key Chandra surveys

PI Name: Alexey Vikhlinin

In the course of the Lynx mission concept study, we have developed just such a theoretically optimal method, based on the detection filter derived from the likelihood function. Compared with traditional approaches, this method will lead to approximately a factor of two savings in exposure time needed to reach the given sample purity at a given flux threshold. Similar improvements in sensitivity should be possible for Chandra exposures >~ 100 ksec. We propose to turn the detection method developed for Lynx into a general-purpose, portable tool for use with the Chandra data. This relatively low-cost effort will significantly boost the science value of the tens of Msec worth of data in the Chandra archive, e.g. those from iconic deep and moderately deep surveys such as the CDFS and Cosmos.

Subject Category: GALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 22910352

Title: A Survey of Galactic Center X-ray Filaments Using 11.7 Ms Archival Chandra Data from 1999 to 2019

PI Name: Shuo Zhang

The most unique and striking phenomenon in the Galactic center region is the existence of numerous radio and X-ray filaments within a few hundred parsecs of Sgr A*. Recently, the MeerKAT observatory revealed more than 100 radio filaments, which are associated with the newly discovered bi-polar radio bubbles. In the X-ray regime, two dozens of filaments have been discovered so far. We propose to use the rich 11.7 Ms Chandra archival observations of the central 1.5 degrees of the Galaxy, largely overlapping with the MeerKAT survey region, to conduct an X-ray filament survey. Our main science goal is to discover and map X-ray filaments in this region, and to reveal the powerful engine in the Galactic center that powers these filaments.