Accepted Cycle 25 Archive Proposals

Proposal Number Subject Category PI Name Title
25200460STARS AND WDScott EngleA Chandra Archival Study of M dwarfs on Opposite Sides of the Dynamo Divide
25400255BH AND NS BINARIESJon MillerA High Resolution View of the Accretion Flow in SMC X-1
25400263BH AND NS BINARIESJon MillerThe Accretion Disk Wind in GX 13+1
25620274NORMAL GALAXIES: X-RAY POPULATIONSMustafa MuhibullahThe First Comprehensive Study of Hypersoft X-ray Sources in the Chandra Archive
25620316NORMAL GALAXIES: X-RAY POPULATIONSLaura LopezA Chandra Archival Survey of Nearby Galaxies
25700002ACTIVE GALAXIES AND QUASARSDaniel SchwartzX-ray varstrometry: A new technique to search for AGN pairs at sub-kpc separation.
25700079ACTIVE GALAXIES AND QUASARSSebastian LopezUnveiling the Origin of Cool Galactic Winds with Chandra
25700139ACTIVE GALAXIES AND QUASARSZhibo YuUnderstanding the Black-Hole Accretion - Stellar-Mass Relation Over All of Cosmic Time
25700305ACTIVE GALAXIES AND QUASARSIsaiah CoxIdentifying and Studying N_H Variable AGN
25700322ACTIVE GALAXIES AND QUASARSDaniel WilkinsMapping of the inner accretion flows of gravitationally lensed quasars
25800097CLUSTERS OF GALAXIESGerrit SchellenbergerGalaxy cluster with misaligned jets and cavities
25800140CLUSTERS OF GALAXIESIrina ZhuravlevaChandra's View of Merger-Driven ICM Dynamics: Testing Cosmological Simulations and Plasma Physics
25800293CLUSTERS OF GALAXIESFrançois MernierMetals under the microscope: revisiting the enrichment in the core of the Perseus cluster
25900203EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYSErwin LauConstraining S8 with X-ray Angular Power Spectrum of Galaxy Clusters
Subject Category: STARS AND WD

Proposal Number: 25200460

Title: A Chandra Archival Study of M dwarfs on Opposite Sides of the Dynamo Divide

PI Name: Scott Engle

We propose to analyze 4 archival Chandra visits, not pointed at, but serendipitously including 2 M dwarfs with known rotation periods & determined ages. GJ 2130 AB are a common proper motion pair, and each component is resolved and detected in the 4 exposures. Optical photometry has returned well-determined rotation rates for both stars and evidence of frequent flaring from GJ 2130 B. We will analyze the multiple exposures, derive an accurate mean level of X-ray activity for the targets, and also separate out and individually analyze and model any X-ray flares. This proposal will provide highly accurate coronal properties for the targets, useful data for stellar evolution and planetary habitability studies, but also important information on the different behaviors of early vs mid M dwarfs

 Subject Category: BH AND NS BINARIES

Proposal Number: 25400255

Title: A High Resolution View of the Accretion Flow in SMC X-1

PI Name: Jon Miller

SMC X-1 is a luminous, slow pulsar with a massive companion. A number of properties make it an excellent source in which to (1) explore accretion flows onto magnetized neutron stars, and (2) study accretion at or above the Eddington limit for comparison to super-Eddington flows in ultra-luminous X-ray sources (ULXs), which are difficult to study owing to their distances. We propose to make a complete analysis of 10 archival, unpublished HETG spectra of SMC X-1. We will search for and characterize ultra-fast outflows, and employ plasma diagnostics to locate emission regions within the accretion flow. We will also determine the relative contributions of direct and scattered emission in the continuum, enhancing our understanding of ULX spectral components.

 Subject Category: BH AND NS BINARIES

Proposal Number: 25400263

Title: The Accretion Disk Wind in GX 13+1

PI Name: Jon Miller

GX 13+1 is a bright, persistent neutron star X-ray binary, viewed at a high inclination. The system drives a persistent disk wind, with a rich absorption spectrum in the Fe K band. The source flux and high wind column give rise to sensitive 3rd-order HEG spectra, in addition to excellent 1st-order spectra. With a resolution of just 15 eV, the 3rd order spectra will both rival and complement future XRISM studies. We propose an archival study of all 11 HETG observations of GX 13+1 (272 ks) that will improve our view of wind speeds, mass outflow rates, and feedback power by orders of magnitude. We will compare our results to theoretical predictions, from alpha-disk models to numerical simulations of disks and winds.

 Subject Category: NORMAL GALAXIES: X-RAY POPULATIONS

Proposal Number: 25620274

Title: The First Comprehensive Study of Hypersoft X-ray Sources in the Chandra Archive

PI Name: Mustafa Muhibullah

We propose a Chandra archival study of an extreme class of X-ray emitters that we refer to as hypersoft X-ray sources that only emit <0.3 keV. These sources have gone largely unnoticed in the literature due to Chandra's small collecting area/poor calibration below 0.3 keV. Yet, our careful, systematic survey using archival long-exposure ACIS-S observations provides compelling evidence of their existence in several targets. We found that the large majority of sources are distributed around external galaxies, but cannot rule out that some are at Milky Way or cosmological distances. We will conduct a large-scale analysis of the hypersoft sources in deep galactic and non-galactic fields to explore their origin, spatial distribution, relationship to the host environment, and transient nature.

 Subject Category: NORMAL GALAXIES: X-RAY POPULATIONS

Proposal Number: 25620316

Title: A Chandra Archival Survey of Nearby Galaxies

PI Name: Laura Lopez

We propose an archival program to investigate deep X-ray imaging of eight nearby, star-forming galaxies that have complementary observations with JWST, ALMA, VLT, HST, VLA/MeerKAT, and AstroSAT. Comparison to Chandra X-ray images is the key missing element from achieving a complete view of the interstellar medium, the baryon cycle, and the energy cycle in these galaxies. X-ray observations offer unique access to the feedback-driven hot ionized medium (via diffuse emission) and the remnants of high-mass stars (X-ray binaries), and they represent the best way to constrain AGN activity, stellar winds, and supernova feedback. With Chandra's superb spatial resolution, we will make key measurements to constrain stellar feedback, the structure of the ISM, and high-mass stellar evolution.

 Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 25700002

Title: X-ray varstrometry: A new technique to search for AGN pairs at sub-kpc separation.

PI Name: Daniel Schwartz

We propose to use rich archival Chandra observations of multiply observed and highly magnified lensed quasars to search for active galactic nuclei (AGN) pairs at sub-kpc separations. The varstrometry technique uses small astrometric jitter in the centroid of unresolved pairs to deduce the presence of multiple vs. single emitters. The technique has been successfully applied to GAIA data based on the sub-milli-arcsec (mas) precision of the optical centroids. The native Chandra astrometry is only hundreds of mas, but can be extended down to a milli-arcsec via highly magnified strong gravitational lensing. X-ray varstrometry has a potential large advantage over optical varstrometry due to the much larger typical variations in the X-ray flux from quasars.

 Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 25700079

Title: Unveiling the Origin of Cool Galactic Winds with Chandra

PI Name: Sebastian Lopez

We propose an archival study to constrain the likely origin of cool galactic winds in a sample of 12 nearby edge-on starburst galaxies using Chandra data. Simulations have been able to produce hot galactic winds that match observations; however a major uncertainty is how the cooler winds form. In our sample we will investigate two leading theories on how cool winds form - rapid cooling from the hot phase and cool cloud entrainment. We will determine the origin by measuring the hot phase cooling times to see if they are brief and by using readily available H alpha data for the sample galaxies to find entrained clouds, measure their column densities using the X-ray data, and determine if they lie in the parameter space predicted by theory that will survive shredding and produce cool winds.

 Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 25700139

Title: Understanding the Black-Hole Accretion - Stellar-Mass Relation Over All of Cosmic Time

PI Name: Zhibo Yu

The relation between long-term black-hole accretion rate (BHAR) and galaxy stellar mass (M*) is central to understanding cosmic supermassive black-hole (SMBH) growth and SMBH-galaxy co-evolution. We will perform the best study of this BHAR-M* relation to date, using greatly improved samples from ultradeep to wide Chandra/XMM-Newton/eROSITA surveys and state-of-the-art methodology. Our results will consistently span 90% of cosmic time (z = 0-4) and a wide range of M* (log M* = 9.5-12) with excellent source statistics throughout, allowing superior assessments of SMBH growth in star-forming vs. quiescent systems. Critically, we will also characterize the effects of mergers upon the SMBH growth history by combining our results with large cosmological simulations of galaxy formation.

 Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 25700305

Title: Identifying and Studying N_H Variable AGN

PI Name: Isaiah Cox

We propose to use archival Chandra observations to identify and study AGN with variable line-of-sight column density. This will allow us to constrain fundamental properties of the obscuring torus surrounding the central SMBH. In this program, we will analyze the data of 124 local AGN with 602 observations. Hardness ratios will be used to discover the sources experiencing absorbing column variability. These AGN will then be carefully studied by performing a full X-ray spectral analysis on each observation to accurately determine the column density along with other important torus parameters. We will use these results to model cloud distribution parameters (sizes, distances, etc.) within the torus of local AGN.

 Subject Category: ACTIVE GALAXIES AND QUASARS

Proposal Number: 25700322

Title: Mapping of the inner accretion flows of gravitationally lensed quasars

PI Name: Daniel Wilkins

We propose a Chandra archival study to detect X-ray reverberation from the inner accretion disks in quasars that are magnified by gravitational lensing. We will measure time lags between the continuum and iron K line emission, corresponding to the light travel time between the X-ray emitting corona and the disk, that are expected to accompany the X-ray reflection signatures previously detected in the spectra of lensed quasars. By combining measurements of X-ray reverberation with the reflection spectrum, we will be able to constrain the location and geometry of the corona, enhancing our understanding of the extreme modes of black hole accretion onto the rapidly growing black holes that are responsible for AGN feedback, and addressing a key systematic uncertainty in spin measurement.

 Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 25800097

Title: Galaxy cluster with misaligned jets and cavities

PI Name: Gerrit Schellenberger

The complex process of AGN outbursts in the central dominant galaxies of clusters and groups, triggering reheating of the gas, is still not well understood. The connection of macro-scale signs of feedback (X-ray cavities), and micro-scale process of launching of jets, is the key for a conclusive feedback model. Cases of spatial misalignment between the radio jets and large scale feedback imprints point toward jet reorientation, which would enable a more isotropic feedback distribution. We construct a sample of 17 cool core galaxy clusters and groups, all with archival Chandra data, to understand the connection between cavities and small-scale radio jets. We will quantify the abundance of misaligned jets and cavities, and determine the role of environmental factors.

 Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 25800140

Title: Chandra's View of Merger-Driven ICM Dynamics: Testing Cosmological Simulations and Plasma Physics

PI Name: Irina Zhuravleva

Measuring gas motions in the intracluster medium (ICM) remains a challenge and will be one of the primary goals for XRISM. Chandra's spatial resolution allows us to indirectly measure velocity amplitudes via surface brightness fluctuations. We propose to measure merger-driven velocity and density power spectra within R_{2500c}. Preliminary results indicate this is possible in 70+ clusters in the Chandra archive. With these measurements, we will test numerical predictions and use subsamples to study the hydrostatic mass bias, constrain bulk ICM viscosity, probe turbulent re-acceleration of cosmic rays. This project will identify interesting targets for XRISM follow-up.

 Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 25800293

Title: Metals under the microscope: revisiting the enrichment in the core of the Perseus cluster

PI Name: François Mernier

The presence of metals in the hot intracluster medium constitutes a unique fossil record of chemical enrichment at the largest scales of our Universe. Whereas the enrichment history of cluster outskirts starts to be well understood, the origin of the metal peak in cluster cool cores remains largely unknown. This archive proposal aims to take advantage of the exceptional legacy from two decades of Chandra ACIS observations (~2 Ms) of the Perseus cluster core to constrain with unprecedented accuracy the spatial distribution of Fe, Mg, and Si via 2D, physically-motivated binned maps. Search for *local* correlations between gas metallicity and entropy, as well as comparison with simulations, will finally shed light on the origin and evolution of central enrichment in clusters.

 Subject Category: EXTRAGALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 25900203

Title: Constraining S8 with X-ray Angular Power Spectrum of Galaxy Clusters

PI Name: Erwin Lau

Recent cosmological observations have revealed the S8 tension, where low-redshift cosmological probes consistently give lower values for sigma_8 and Omega_M than measurements from the cosmic microwave background. As the angular power spectrum of galaxy clusters is very sensitive to sigma_8 and Omega_M, we propose to measure the small-scale X-ray angular power spectrum from the survey fields in the Chandra archive. We show that, by combining the small-scale power spectra from Chandra fields with the large-scale power spectra from the eROSITA-All-Sky Survey, one can achieve percent-level constraints on sigma_8 and Omega_M that are competitive to other Large-Scale Structure probes, providing a major step towards resolving the outstanding S8 tension.