Publications (66)
Cathode depth sensing in CZT detectors
J. Hong, E. C. Bellm, J. E. Grindlay +1
Measuring the depth of interaction in thick Cadmium-Zinc-Telluride (CZT) detectors allows improved imaging and spectroscopy for hard X-ray imaging above 100 keV. The Energetic X-ra…
Cohen--Macaulayness versus the vanishing of the first Hilbert coefficient of parameter ideals
L. Ghezzi, S. Goto, J. Hong +3
The conjecture of Wolmer Vasconcelos on the vanishing of the first Hilbert coefficient is solved affirmatively, where is a parameter ideal in a Noetherian local ring.…
Neutron star atmosphere composition: the quiescent, low-mass X-ray binary in the globular cluster M28
Mathieu Servillat, C. O. Heinke, W. C. G. Ho +4
Using deep Chandra observations of the globular cluster M28, we study the quiescent X-ray emission of a neutron star in a low-mass X-ray binary in order to constrain the chemical c…
Identification of a Population of X-ray Emitting Massive Stars in the Galactic Plane
G. E. Anderson, B. M. Gaensler, D. L. Kaplan +15
We present X-ray, infrared, optical and radio observations of four previously unidentified Galactic plane X-ray sources, AX J163252-4746, AX J184738-0156, AX J144701-5919 and AX J1…
A Monte Carlo study of early gas expulsion and evolution of star clusters: new simulations with the MOCCA code in the AMUSE framework
A. Leveque, M. Giersz, S. Banerjee +3
We introduce a new prescription for the evolution of globular clusters (GCs) during the initial embedded gas phase into a Monte Carlo method. With a simplified version of the Monte…
Revealing the First Stellar and Supermassive Black Holes to EXIST
J. Grindlay, J. Bloom, P. Coppi +8
The epochs of origin of the first stars and galaxies, and subsequent growth of the first supermassive black holes, are among the most fundamental questions. Observations of the hig…
The unexpected kinematics of multiple populations in NGC6362: do binaries play a role?
E. Dalessandro, A. Mucciarelli, M. Bellazzini +9
We present a detailed analysis of the kinematic properties of the multiple populations (MPs) in the low-mass Galactic globular cluster NGC6362 based on a sample of about 500 member…
Magnetic properties of (FeCo)B alloys and the effect of doping by 5 elements
A. Edström, M. WerwiÅski, Diana IuÅan +12
We have explored, computationally and experimentally, the magnetic properties of \fecob{} alloys. Calculations provide a good agreement with experiment in terms of the saturation m…
Negativity Conjecture for the First Hilbert Coefficient
L. Ghezzi, S. Goto, J. Hong +3
This gives an alternate proof of the Theorem by the authors that shows the first Hilbert coefficient of parameter ideals in an unmixed Noetherian local ring is always negative unle…
The Proposed High Energy Telescope (HET) for EXIST
J. Hong, J. Grindlay, B. Allen +10
The hard X-ray sky now being studied by INTEGRAL and Swift and soon by NuSTAR is rich with energetic phenomena and highly variable non-thermal phenomena on a broad range of timesca…
Detector and Telescope Development for ProtoEXIST and Fine Beam Measurements of Spectral Response of CZT Detectors
J. Hong, A. Copete, J. E. Grindlay +5
We outline our plan to develop ProtoEXIST, a balloon-borne prototype experiment for the Energetic X-ray Imaging Survey Telescope (EXIST) for the Black Hole Finder Probe. EXIST will…
Discovery of a Supercluster at 0.91 and Testing the CDM Cosmological Model
J. -W. Kim, M. Im, S. -K. Lee +13
The CDM cosmological model successfully reproduces many aspects of the galaxy and structure formation of the universe. However, the growth of large-scale structures (LSSs) in t…
Chandra Multiwavelength Plane (ChaMPlane) Survey: an Introduction
J. E. Grindlay, J. Hong, P. Zhao +7
We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designed to measure or constrain the populations of low-luminosity (Lx > ~10^31 erg/s) accreting white dwarfs, ne…
Developing an Automated Detection, Tracking and Analysis Method for Solar Filaments Observed by CHASE via Machine Learning
Z. Zheng, Q. Hao, Y. Qiu +3
Studies on the dynamics of solar filaments have significant implications for understanding their formation, evolution, and eruption, which are of great importance for space weather…
Dynamical Evolution of Multiple-Population Globular Clusters
E. Vesperini, J. Hong, M. Giersz +1
We have carried out a set of Monte Carlo simulations to study a number of fundamental aspects of the dynamical evolution of multiple stellar populations in globular clusters with d…
Possibilities of direct production of superheavy nuclei with Z=112--118 in different evaporation channels
J. Hong, G. G. Adamian, N. V. Antonenko +2
The production cross sections of heaviest isotopes of superheavy nuclei with charge numbers 112--118 are predicted in the --, --, and --evaporation channels of the $…
Three Years of ChaMPlane Northern Field WIYN Spectroscopy
A. B. Rogel, P. M. Lugger, H. N. Cohn +4
We present initial results of WIYN spectroscopic observations of selected objects detected in the Chandra Multiwavelength Plane (ChaMPlane) Survey in fields towards the Galactic an…
EXIST's Gamma-Ray Burst Sensitivity
D. L. Band, J. E. Grindlay, J. Hong +7
We use semi-analytic techniques to evaluate the burst sensitivity of designs for the EXIST hard X-ray survey mission. Applying these techniques to the mission design proposed for t…
Energy equipartition in multiple-population globular clusters
A. R. Livernois, F. I. Aros, E. Vesperini +7
We present the results of Monte Carlo simulations aimed at exploring the evolution towards energy equipartition of first- (1G) and second-generation (2G) stars in multiple-populati…
Limb Shift of the Fe I 6569 Ã line on the Sun
H. C. Yu, M. D. Ding, J. Hong +2
The convective motions of solar granules generate a center-to-limb variation of Doppler velocity in the photospheric lines, known as the limb shift effect. This study presents a co…
Building Large Area CZT Imaging Detectors for a Wide-Field Hard X-ray Telescope - ProtoEXIST1
J. Hong, B. Allen, J. Grindlay +10
We have constructed a moderately large area (32 cm2), fine pixel (2.5 mm pixel, 5 mm thick) CZT imaging detector which constitutes the first section of a detector module (256 cm2)…
The Hubble Space Telescope UV Legacy Survey of galactic globular clusters. VI. The internal kinematics of the multiple stellar populations in NGC 2808
A. Bellini, E. Vesperini, G. Piotto +9
Numerous observational studies have revealed the ubiquitous presence of multiple stellar populations in globular clusters and cast many hard challenges for the study of the formati…
Evaluation of different recipes for chromospheric radiative losses in solar flares
J. Tian, J. Hong, Y. Li +1
Context. Radiative losses are an indispensable part in the numerical simulation of flares. Detailed calculations could be computationally expensive, especially in the chromosphere.…
A multi-observatory database of X-ray pulsars in the Magellanic Clouds
J. Yang, S. G. T. Laycock, J. J. Drake +5
Using hundreds of XMM-Newton and Chandra archival observations and nearly a thousand RXTE observations, we have generated a comprehensive library of the known pulsars in the Small…
The decline rate of the production cross-section of superheavy nuclei with at high excitation energies
J. Hong, G. G. Adamian, N. V. Antonenko +2
The production cross sections of superheavy nuclei with charge numbers are predicted in the -evaporation channels of the Ca-induced complete fusion reactio…
Monte-Carlo simulations of the expected imaging performance of the EXIST high-energy telescope
S. V. Vadawale, J. Hong, J. E. Grindlay +1
EXIST is being studied as the Black Hole Finder Probe, one of the 3 Einstein Probe missions under NASA's Beyond Einstein program. The major science goals for EXIST include highly s…
Specialization and Integral Closure
J. Hong, B. Ulrich
We prove that the integral closedness of any ideal of height at least two is compatible with specialization by a generic element. This opens the possibility for proofs using induct…
Optimizing wide-field coded aperture imaging: radial mask holes and scanning
J. Grindlay, J. Hong
Imaging at hard X-ray energies (~10-600 keV) over very large fields of view (~60 deg per telescope) is required to conduct a high sensitivity all-sky and all-time survey for black…
Simulations of solar filament fine structures and their counterstreaming flows
Y. H. Zhou, P. F. Chen, J. Hong +1
Solar filaments, also called solar prominences when appearing above the solar limb, are cold, dense materials suspended in the hot tenuous solar corona, consisting of numerous long…
Development of the Gaseous Antiparticle Spectrometer for Space-based Antimatter Detection
C. J. Hailey, W. W. Craig, F. A. Harrison +5
We report progress in developing a novel antimatter detection scheme. The gaseous antiparticle spectrometer (GAPS) identifies antimatter through the characteristic X-rays emitted b…
Particle creation in a tunneling universe
J. Hong, A. Vilenkin, S. Winitzki
An expanding closed universe filled with radiation can either recollapse or tunnel to the regime of unbounded expansion, if the cosmological constant is nonzero. We re-examine the…
The High Energy Telescope on EXIST
J. Hong, J. E. Grindlay, B. Allen +4
The Energetic X-ray Imaging Survey Telescope (EXIST) is a proposed next generation multi-wavelength survey mission. The primary instrument is a High Energy telescope (HET) that con…
Different Signatures of Chromospheric Evaporation in Two Solar Flares Observed with IRIS
Y. Li, M. D. Ding, J. Hong +2
We present different signatures of chromospheric evaporation in two solar flares observed by the Interface Region Imaging Spectrograph (IRIS). In the B1.6 flare on 2016 December 6…
Multiple stellar populations in MOCCA globular cluster models: Transient spatial over-concentration of pristine red giant stars driven by strong dynamical encounters
M. Giersz, A. Askar, A Hypki +3
Recent findings show that, in some Milky Way globular clusters (GCs), pristine red giant branch (RGB) stars are more centrally concentrated than enriched RGB stars. This contradict…
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXI. Binaries among multiple stellar populations
A. P. Milone, E. Vesperini, A. F. Marino +17
A number of scenarios for the formation of multiple populations in globular clusters (GCs) predict that second generation (2G) stars form in a compact and dense subsystem embedded…
Variation of the first Hilbert coefficients of parameters with a common integral closure
L. Ghezzi, S. Goto, J. Hong +3
A problem posed by Wolmer V. Vasconcelos on the variation of the first Hilbert coefficients of parameter ideals with a common integral closure in a local ring is studied. Affirmati…
Multipixel characterization of imaging CZT detectors for hard X-ray imaging and spectroscopy
S. V. Vadawale, J. Hong, J. Grindlay +8
We report our in-depth study of Cd-Zn-Te (CZT) crystals to determine an optimum pixel and guard band configuration for Hard X-ray imaging and spectroscopy. We tested 20x20x5mm crys…
Laboratory coded aperture imaging experiments: radial hole coded masks and depth-sensitive CZT detectors
J. Hong, S. V. Vadawale, M. Zhang +5
The proposed black-hole finder mission EXIST will consist of multiple wide-field hard X-ray coded-aperture telescopes. The high science goals set for the mission require innovation…
EXIST: Mission Design Concept and Technology Program
J. E. Grindlay, W. W. Craig, N. Gehrels +2
The Energetic X-ray Imaging Survey Telescope (EXIST) is a proposed very large area coded aperture telescope array, incorporating 8m^2 of pixellated Cd-Zn-Te (CZT) detectors, to con…
CZT imaging detectors for ProtoEXIST
J. Hong, J. E. Grindlay, N. Chammas +9
We describe the detector development for a balloon-borne wide-field hard X-ray (20 - 600 keV) telescope, ProtoEXIST. ProtoEXIST is a pathfinder for both technology and science of t…
A New Large-Well 1024x1024 Si:As Detector for the Mid-Infrare
A. K. Mainzer, J. Hong, M. Stapelbroek +7
We present a description of a new 1024x1024 Si:As array designed for ground-based use from 5 - 28 microns. With a maximum well depth of 5e6 electrons, this device brings large-form…
On the homology of two-dimensional elimination
J. Hong, A. Simis, W. V. Vasconcelos
We study birational maps with empty base locus defined by almost complete intersection ideals. Birationality is shown to be expressed by the equality of two Chern numbers. We provi…
Imaging and burst location with the EXIST high-energy telescope
G. K. Skinner, S. D. Barthelmy, M. H. Finger +5
The primary instrument of the proposed EXIST mission is a coded mask high energy telescope (the HET), that must have a wide field of view and extremely good sensitivity. It will be…
Inversion of CHASE H Spectral Line during Solar Flares Based on RADYN Dataset via Deep Learning
W. Xu, Q. Hao, Z. Zheng +6
Solar flares represent one of the most intense forms of solar activity. Understanding the evolution of physical parameters in the solar atmosphere during flares is key to studying…
The Bi-Canonical Degree of a Cohen-Macaulay Ring
L. Ghezzi, S. Goto, J. Hong +2
This paper is a sequel to [8] where we introduced an invariant, called canonical degree, of Cohen-Macaulay local rings that admit a canonical ideal. Here to each such ring with a c…
CZT in Space Based Hard-X-ray Astronomy
A. Garson, H. Krawczynski, G. Weidenspointner +4
One of the key aspects of a detector material for space-borne hard X-ray and gamma-ray telescopes is the rate of prompt and delayed background events generated inside the material…
The Peculiar Radial Distribution of Multiple Populations in the massive globular cluster M80
E. Dalessandro, M. Cadelano, E. Vesperini +7
We present a detailed analysis of the radial distribution of light-element multiple populations (LE-MPs) in the massive and dense globular cluster M80 based on the combination of U…
Overview of EXIST mission science and implementation
J. Grindlay, N. Gehrels, J. Bloom +14
The Energetic X-ray Imaging Survey Telescope (EXIST) is designed to i) use the birth of stellar mass black holes, as revealed by cosmic Gamma-Ray Bursts (GRBs), as probes of the ve…
ChaMPlane Discovery of Candidate Symbiotic Binaries in Baade's and Stanek's Windows
M. van den Berg, J. Grindlay, S. Laycock +10
We have searched the OGLE-II archive for candidate counterparts of X-ray sources detected in two low-extinction windows included in our Galactic bulge Chandra/HST survey. We find t…
Proposed Next Generation GRB Mission: EXIST
J. Grindlay, N. Gehrels, F. Harrison +7
A next generation Gamma Ray Burst (GRB) mission to follow the upcoming Swift mission is described. The proposed Energetic X-ray Imaging Survey Telescope, EXIST, would yield the lim…
Canonical Degrees of Cohen-Macaulay Rings and Modules: a Survey
J. P. Brennan, L. Ghezzi, J. Hong +2
The aim of this survey is to discuss invariants of Cohen-Macaulay local rings that admit a canonical module. Attached to each such ring R with a canonical ideal C, there are intege…
Spectroscopic Observations of a Current Sheet in a Solar Flare
Y. Li, J. C. Xue, M. D. Ding +6
Current sheet is believed to be the region of energy dissipation via magnetic reconnection in solar flares. However, its properties, for example, the dynamic process, have not been…
Sun-as-a-star analysis of simulated solar flares
H. C. Yu, J. Hong, M. D. Ding
Context: Stellar flares have an impact on habitable planets. To relate the observations of the Sun with those of stars, one needs to use a Sun-as-a-star analysis, that is, to degra…
Flight Performance of an advanced CZT Imaging Detector in a Balloon-borne Wide-Field Hard X-ray Telescope - ProtoEXIST1
J. Hong, B. Allen, J. Grindlay +6
We successfully carried out the first high-altitude balloon flight of a wide-field hard X-ray coded-aperture telescope ProtoEXIST1, which was launched from the Columbia Scientific…
A family picture: tracing the dynamical path of the structural properties of multiple populations in globular clusters
E. Dalessandro, M. Cadelano, E. Vesperini +6
We studied the spatial distributions of multiple stellar populations (MPs) in a sample of 20 globular clusters (GCs) spanning a broad range of dynamical ages. The differences betwe…
Constraining the Nature of the Galactic Center X-ray Source Population
S. Laycock, J. Grindlay, M. van den Berg +5
We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic Center Region (GCR). While the sources could be white dwarfs, neut…
Pion Production in Rare Isotope Collisions
M. B. Tsang, J. Estee, H. Setiawan +15
Pion energy spectra are presented for central collisions of neutron-rich 132Sn+124Sn and neutron-deficient 108Sn+112Sn systems using simulations with Boltzmann-Uehling-Uhlenbeck tr…
The interfacial spin modulation of graphene on Fe(111)
J. Hong, H. -N. Hwang, A. T. NDiaye +13
When Fe, which is a typical ferromagnet using d- or f-orbital states, is combined with 2D materials such as graphene, it offers many opportunities for spintronics. The origin of 2D…
On the intensity ratio variation of the Si IV 1394/1403 Ã lines during solar flares
Hao-Cheng Yu, J. Hong, M. D. Ding
Context. The Si IV lines at 1394 Ã and 1403 Ã form in the solar atmosphere at a temperature of K. They are usually considered optically thin, but their opacity can b…
Exploring the dynamical evolution of binary stars in multiple-population globular clusters
J. Bruce, E. Vesperini, A. Askar +5
The presence of multiple stellar populations in globular clusters leads to a complex dynamical environment that significantly influences the evolution of binary stars, which in tur…
Spectroscopic Follow-up of X-ray Sources in the ChaMPlane Survey: Identification of a New Cataclysmic Variable
Mathieu Servillat, J. Grindlay, M. van den Berg +3
We present a multi-object optical spectroscopy follow-up study of X-ray sources in a field along the Galactic Plane (l=327.42 deg, b=2.26 deg) which is part of the Chandra Multi-wa…
Wide Field Hard X-ray Survey Telescope: ProtoEXIST1
J. Hong, J. E. Grindlay, N. Chammas +17
We report our progress on the development of pixellated imaging CZT detector arrays for our first-generation balloon-borne wide-field hard X-ray (20 - 600 keV) telescope, ProtoEXIS…
Variation of Hilbert Coefficients
L. Ghezzi, S. Goto, J. Hong +1
For a Noetherian local ring $(\RR, \m)$, the first two Hilbert coefficients, and , of the -adic filtration of an $\m$-primary ideal are known to code for properti…
Experimental verification of Landauer's principle in erasure of nanomagnetic memory bits
J. Hong, B. Lambson, S. Dhuey +1
In 1961, R. Landauer proposed the principle that logical irreversibility is associated with physical irreversibility and further theorized that the erasure of information is fundam…
Chasing the Identification of ASCA Galactic Objects (ChIcAGO) - An X-ray Survey of Unidentified Sources in the Galactic Plane I: Source Sample and Initial Results
G. E. Anderson, B. M. Gaensler, D. L. Kaplan +18
We present the Chasing the Identification of ASCA Galactic Objects (ChIcAGO) survey, which is designed to identify the unknown X-ray sources discovered during the ASCA Galactic Pla…
IGR J18293-1213 is an eclipsing Cataclysmic Variable
Maïca Clavel, J. A. Tomsick, A. Bodaghee +7
Studying the population of faint hard X-ray sources along the plane of the Galaxy is challenging because of high-extinction and crowding, which make the identification of individua…