A5069039589- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Calibration and Measurement Techniques
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Mechanics and Biomechanics Studies
- Advanced X-ray Imaging Techniques
- Scientific Research and Discoveries
- Advanced Semiconductor Detectors and Materials
- Statistical and numerical algorithms
University of Utah
2017-2024
Goddard Space Flight Center
2011-2019
Johns Hopkins University
2014-2017
Deleted Institution
2011-2016
Kavli Institute for Particle Astrophysics and Cosmology
2016
Japan Aerospace Exploration Agency
2016
Ohio University
2001-2010
University of Virginia
2004-2010
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates band from 3 to 79 keV, extending sensitivity of far beyond ∼10 keV cutoff achieved by all previous satellites. inherently low background associated with concentrating light enables probe hard sky a more than 100-fold improvement over collimated or coded mask instruments that have operated this bandpass. Using its unprecedented...
The search for diffuse non-thermal inverse Compton (IC) emission from galaxy clusters at hard X-ray energies has been undertaken with many instruments, most detections being either of low significance or controversial. Background and contamination uncertainties present in the data non-focusing observatories result lower sensitivity to IC a greater chance false detection. We 266ks NuSTAR observations Bullet cluster, detected 3-30 keV. NuSTAR's unprecedented focusing capability largely...
We present two complementary NuSTAR x-ray searches for keV-scale dark matter decaying to mono-energetic photons in the Milky Way halo. In first, we utilize known intensity pattern of unfocused stray light across detector planes -- dominant source from diffuse sources separate astrophysical emission internal instrument backgrounds using ${\sim}$7-Ms/detector deep blank-sky exposures. second, an updated parametric model full background, allowing us leverage statistical power independent...
Abstract Diffuse radio sources known as relics are direct tracers of shocks in the outskirts merging galaxy clusters. PSZ2 G200.95–28.16, a low-mass cluster ( M 500 = (2.7 ± 0.2) × 10 14 ⊙ ), features prominent relic, first identified by R. Kale et al. We name this relic Seahorse. The MeerKAT Galaxy Cluster Legacy Survey has confirmed two additional relics, R2 and R3, cluster. present new observations with upgraded Giant Metrewave Radio Telescope (uGMRT) at 400 650 MHz, paired Chandra X-ray...
Abell 3667 is the archetype of a merging cluster with radio relics. The NW relic brightest or halo known, and believed to be due strong merger shock. We have observed for 40 ksec net XMM time. observe global decline temperature across from 6 1 keV, similar Suzaku results. Our new observations reveal sharp change both surface brightness near position relic. increased X-ray emission on can equivalently well described by either thermal nonthermal spectral model. parameters model are consistent...
We use a combined 1.2 Ms of NuSTAR observations M31 to search for x-ray lines from sterile neutrino dark matter decay. For the first time in analysis, we consistently take into account signal contribution both focused and unfocused fields view. also reduce modeling systematic uncertainty by performing spectral fits each observation individually statistically combining results, instead stacking spectra. find no evidence unknown lines, thus derive limits on parameters. Our results place...
The distribution of elements produced in the inner-most layers a supernova explosion is key diagnostic for studying collapse massive stars. Here we present results 2.4 Ms \textit{NuSTAR} observing campaign aimed at remnant Cassiopeia A (Cas A). We perform spatially-resolved spectroscopic analyses $^{44}$Ti ejecta which use to determine Doppler shift and thus three-dimensional (3D) velocities ejecta. find an initial mass 1.54 $\pm$ 0.21 $\times 10^{-4}$ M$_{\odot}$ has day average momentum...
We analyze two dedicated NuSTAR observations with exposure ${\sim}190$ ks located ${\sim}10^\circ$ from the Galactic plane, one above and other below, to search for x-ray lines radiative decay of sterile-neutrino dark matter. These fields were chosen minimize astrophysical backgrounds while remaining near densest region matter halo. find no evidence anomalous in energy range 5--20 keV, corresponding sterile neutrino masses 10--40 keV. Interpreted context neutrinos produced via mixing, these...
We present high-energy (3–30 keV) NuSTAR observations of the nearest quasar, ultraluminous infrared galaxy (ULIRG) Markarian 231 (Mrk 231), supplemented with new and simultaneous low-energy (0.5–8 data from Chandra. The source was detected, though at much fainter levels than previously reported, likely due to contamination in large apertures previous non-focusing hard X-ray telescopes. full band (0.5–30 spectrum suggests active galactic nucleus (AGN) Mrk is absorbed by a patchy Compton-thin...
We present the first direct measurements of rest-frame 10-40 keV X-ray luminosity function (XLF) Active Galactic Nuclei (AGNs) based on a sample 94 sources at 0.1 < z <3, selected 8-24 energies from in NuSTAR extragalactic survey program. Our results are consistent with strong evolution AGN population seen prior, lower-energy studies XLF. However, different models intrinsic distribution absorption, which used to correct for selection biases, give significantly predictions total number our...
ABSTRACT We present the 3–8 keV and 8–24 number counts of active galactic nuclei (AGNs) identified in Nuclear Spectroscopic Telescope Array ( NuSTAR ) extragalactic surveys. has now resolved 33%–39% X-ray background band, directly identifying AGNs with obscuring columns up to <?CDATA $\sim {10}^{25}\,{\mathrm{cm}}^{-2}$?> . In softer band are general agreement those measured by XMM-Newton Chandra over flux range $5\times {10}^{-15}\,\lesssim $?> S (3–8 keV)/...
Abstract The Ophiuchus galaxy cluster exhibits a curious concave gas density discontinuity at the edge of its cool core. It was discovered in Chandra X-ray image by Werner and collaborators, who considered possibility it being boundary an active galactic nucleus (AGN)-inflated bubble located outside core, but discounted this because required much too powerful AGN outburst. Using low-frequency (72–240 MHz) radio data from Murchison Widefield Array/GLEAM Giant Metrewave Radio Telescope, we...
We present X-ray and optical analysis of 188 AGN identified from 497 hard (f (2.0-8.0 keV) > 2.7x10^-15 erg cm^-2 s^-1) sources in 20 Chandra fields (1.5 deg^2) forming part the Multi-wavelength Project. These medium depth observations enable us to detect a representative subset those responsible for bulk 2-8 keV Cosmic Background. Brighter than our spectroscopic limit, we achieve reasonable degree completeness (77% with counter-parts r'< 22.5 have been classified): broad emission line...
We present follow-up optical g', r', and i' imaging spectroscopy of serendipitous X-ray sources detected in six archival Chandra images included the Multiwavelength Project (ChaMP). Of 486 between 3 × 10-16 2 10-13 (with a median flux 10-15) ergs cm-2 s-1, we find counterparts for 377 (78%), or 335 (68%) counting only unique counterparts. spectroscopic classifications 125 objects, representing 75% with r* < 21 (63% to = 22). all classified 63 (50%) are broad-line active galactic nuclei...
We present deep (>2.4 Ms) observations of the Cassiopeia A supernova remnant with NuSTAR, which operates in 3–79 keV bandpass and is first instrument capable spatially resolving above 15 keV. find that emission not entirely dominated by forward shock nor a smooth "bright ring" at reverse shock. Instead we >15 knots near center dimmer filaments remnant's outer rim. These regions are fit unbroken power laws 15–50 bandpass, though central have steeper (Γ ∼ −3.35) spectrum than −3.06). argue...
Pairs of radio relics are believed to form during cluster mergers, and best observed when the merger occurs in plane sky. Mergers can also produce halos, through complex processes likely linked turbulent re-acceleration cosmic-ray electrons. However, only some clusters with double show a halo. Here, we present novel method derive upper limits on halo emission, analyse archival X-ray Chandra data, as well galaxy velocity dispersions lensing order understand key parameter that switches...
The low-mass X-ray binary (LMXB) Cen X-4 is the brightest and closest (<1.2 kpc) quiescent neutron star transient. Previous 0.5–10 keV observations of in quiescence identified two spectral components: soft thermal emission from atmosphere a hard power-law tail unknown origin. We report here on simultaneous observation with NuSTAR (3–79 keV) XMM-Newton (0.3–10 2013 January, providing first sensitive spectrum 0.3–79 luminosity was erg s−1, ≃60% component. clearly detect cutoff above 10 keV,...
Deep (103 ks) Chandra observations of Abell 665 have revealed rich structures in this merging galaxy cluster, including a strong shock and two cold fronts. The newly discovered has Mach number M = 3.0 ± 0.6, propagating front disrupted cloud. This makes the second after Bullet where merger been detected. velocity from jump conditions is consistent with (2.7 0.7) × 103 km s−1. new data also reveal prominent southern potentially heated gas ahead it. hosts giant radio halo. There hint diffuse...
To provide the census of sources contributing to X-ray background peak above 10 keV, NuSTAR is performing extragalactic surveys using a three-tier "wedding cake" approach. We present survey COSMOS field, medium sensitivity and area tier, covering 1.7 deg2 overlapping with both Chandra XMM-Newton data. This consists 121 observations for total exposure ~3 Ms. fully exploit these data, we developed new detection strategy, carefully tested through extensive simulations. The at 20% completeness...
The brightest cluster radio halo known resides in the Coma of galaxies. relativistic electrons producing this diffuse synchrotron emission should also produce inverse Compton that becomes competitive with thermal from ICM at hard X-ray energies. Thus far, claimed detections are controversial (Fusco-Femiano et al. 2004; Rossetti & Molendi 2004). We present a Suzaku HXD-PIN observation order to nail down its non-thermal content. contribution spectrum is constrained by simultaneously fitting...
Abstract Wide-band Suzaku data on the merging cluster Abell 3667 were examined for hard X-ray emission in excess to known thermal component. detected signals a wide energy band from 0.5 40 keV. The ($\gt$10 keV) flux observed by HXD around center cannot be explained simple extension of with an average temperature $\sim$7 is most likely very hot ($kT$$\gt$ 13.2 component center, produced via strong heating process merger. In north-west radio relic, no signature non-thermal was observed. Using...
From optical spectroscopy of X-ray sources observed as part the Chandra Multi-wavelength Project (ChaMP), we present redshifts and classifications for a total 1569 from our targeted spectroscopic follow-up using FLWO/1.5 m, SAAO/1.9 WIYN 3.5 CTIO/4 KPNO/4 Magellan/6.5 MMT/6.5 Gemini/8 m telescopes, archival Sloan Digital Sky Survey (SDSS) spectroscopy. We classify counterparts 50% broad-line active galactic nuclei (AGNs), 16% emission line galaxies, 14% absorption 20% stars. detect QSOs out...
We present initial results and the source catalog from NuSTAR survey of Extended Chandra Deep Field South (hereafter, ECDFS) - currently deepest contiguous component extragalactic program. The covers full ~30 arcmin x 30 area this field to a maximum depth ~360 ks (~220 when corrected for vignetting at 3-24 keV), reaching sensitivity limits ~1.3 10^-14 erg/cm2/s (3-8 ~3.4 (8-24 keV) ~3.0 (3-24 keV). Fifty four (54) sources are detected over field, although five these found lie below our...