A5039553136- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Particle Detector Development and Performance
- High-pressure geophysics and materials
- Dark Matter and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Mechanics and Biomechanics Studies
- Astro and Planetary Science
- Atomic and Subatomic Physics Research
- Astrophysics and Star Formation Studies
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Sensor Technology
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Scientific Measurement and Uncertainty Evaluation
Columbia University
2015-2024
Goddard Space Flight Center
2024
Osservatorio Astronomico di Cagliari
2024
University of Potsdam
2023
New York University Abu Dhabi
2021
Queen's University
2021
North Carolina State University
2021
Chungbuk National University
2021
University of Manitoba
2021
Los Alamos National Laboratory
2021
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...
We report the discovery of 3.76 s pulsations from a new burst source near Sgr A* observed by NuSTAR observatory. The strong signal SGR J1745−29 presents complex pulse profile modulated with pulsed fraction 27% ± 3% in 3–10 keV band. Two observations spaced nine days apart yield spin-down rate =(6.5 1.4) × 10−12. This implies magnetic field B = 1.6 1014 G, power =5 1033 erg s−1, and characteristic age P/2 =9 103 yr for rotating dipole model. However, current may be erratic, especially during...
Abstract We present volume-limited samples of cataclysmic variables (CVs) and AM CVn binaries jointly selected from SRG/eROSITA eRASS1 Gaia DR3 using an X-ray + optical color–color diagram (the “X-ray Main Sequence”). This tool identifies all CV subtypes, including magnetic low-accretion rate systems, in contrast to most previous surveys. find 23 CVs, 3 which are CVns, out 150 pc the Western Galactic Hemisphere. Our sample is spectroscopically verified complete down L X = 1.3 × 10 29 erg s...
We report the results of a multi-band observing campaign on famous blazar 3C 279 conducted during phase increased activity from 2013 December to 2014 April, including first observations it with NuSTAR. The $\gamma$-ray emission source measured by Fermi-LAT showed multiple distinct flares reaching highest flux level in this object since beginning Fermi mission, $F(E > 100\,{\rm MeV})$ $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and doubling time scale as short 2 hours. spectrum one was very hard,...
Stellar metals shine toward our eyes only Taking a different look at familiar star may still yield surprises. Boggs et al. trained the x-ray vision of NuSTAR observatory on well-studied supernova 1987A. Core-collapse explosions such as SN 1987A produce titanium isotope, 44 Ti, whose radioactive decay yields hard emission lines. All associated with 44Ti appears to be from material moving us, none away. This implies that explosion was not symmetric. These findings help explain mechanics and...
We present coordinated multiwavelength observations of the bright, nearby BL Lac object Mrk 421 taken in 2013 January-March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations instruments, providing data from radio to very-high-energy (VHE) gamma-ray bands. NuSTAR yielded previously unattainable sensitivity 3-79 keV range, revealing that spectrum softens when source is dimmer until X-ray spectral shape saturates into a steep power law with photon index...
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 present the first fully simultaneous fits to NIR and X-ray spectral slope (and its evolution) during a very bright flare from Sgr A*, supermassive black hole at Milky Way's center. Our study arises ambitious multi-wavelength monitoring campaigns with XMM-Newton, NuSTAR SINFONI. The average spectrum is well reproduced by broken power-law $\Gamma_{NIR}=1.7\pm0.1$ $\Gamma_X=2.27\pm0.12$. difference in slopes ($\Delta\Gamma=0.57\pm0.09$) strongly supports synchrotron emission cooling break....
The <i>Nuclear Spectroscopic Telescope Array (NuSTAR)</i> is a NASA Small Explorer mission that will carry the first focusing hard X-ray (6 - 80 keV) telescope to orbit. <i>NuSTAR</i> offer factor 50 100 sensitivity improvement compared previous collimated or coded mask imagers have operated in this energy band. In addition, provides sub-arcminute imaging with good spectral resolution over 12-arcminute eld of view. After launch, out two-year primary science focuses on four key programs:...
Starting in 2013 February, Swift has been performing short daily monitoring observations of the G2 gas cloud near Sgr A* with X-Ray Telescope to determine whether interaction leads an increase flux from Galactic center. On April 24 detected order magnitude rise X-ray region A*. Initially thought be a flare A*, detection hard burst same by Burst Alert suggested that was unresolved new Soft Gamma Repeater, SGR J1745−29. Here we present discovery J1745−29 Swift, including analysis data before,...
We present a study of the X-ray flaring activity Sgr A⋆ during all 150 XMM–Newton and Chandra observations pointed at Milky Way centre over last 15 years. This includes latest campaigns devoted to monitoring closest approach very red Brγ emitting object called G2. The entire data set analysed extends from 1999 September through 2014 November. employed Bayesian block analysis investigate any possible variations in characteristics (frequency, energetics, peak intensity, duration) events that...
We present an analysis of a short NuSTAR observation the stellar-mass black hole and low-mass X-ray binary 4U 1630$-$472. Reflection from inner accretion disk is clearly detected for first time in this source, owing to sensitivity NuSTAR. With fits reflection spectrum, we find evidence rapidly spinning hole, $a_{*}=0.985^{+0.005}_{-0.014}$ ($1\sigma$ statistical errors). However, archival data show that source has relatively low radio luminosity. Recently claimed relationships between jet...
We present the X-ray timing and spectral evolution of Galactic Center magnetar SGR J1745-2900 for first ~4 months post-discovery using data obtained with Nuclear Spectroscopic Telescope Array (NuSTAR)} Swift observatories. Our analysis reveals a large increase in spin-down rate by factor 2.60 +/- 0.07 over our span. further show that change spin was likely coincident bright burst observed 2013 June Swift, if so, there no accompanying discontinuity frequency. find source 3-10 keV flux has...
We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare Sgr A*. obtained light curves in $M$-, $K$-, $H$-bands mid- $2-8~\mathrm{keV}$ $2-70~\mathrm{keV}$ bands X-ray. The observed slope band is $\nu L_\nu\propto \nu^{0.5\pm0.2}$; L_\nu \propto \nu^{-0.7\pm0.5}$. tested synchrotron self-Compton (SSC) scenarios. brightness faintness, together with slopes, pose challenges for all models explored. rule out scenario which emission SSC. A one-zone model...
Abstract White dwarfs (WDs) are the most abundant compact objects, and recent surveys have suggested that over a third of WDs in accreting binaries host strong ( B ≳ 1 MG) magnetic field. However, origin evolution WD magnetism remain under debate. Two pulsars, AR Sco J191213.72–441045.1 (J1912), been found, which non-accreting hosting rapidly spinning (1.97 minutes 5.30 minutes, respectively) WDs. The is slowing down on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
We construct models for strongly magnetized neutron star atmospheres composed of mid-Z elements (carbon, oxygen and neon) with magnetic fields B= 1012–1013 G effective temperatures Teff= (1 – 5) × 106 K; this is done by first addressing the physics relevant to plasmas calculating equation state polarization-dependent opacities. then obtain atmosphere structure spectrum solving radiative transfer equations in hydrostatic equilibrium. In contrast hydrogen opacities at temperatures, element are...
We describe the fabrication of two NuSTAR flight optics modules. The modules are glass-graphiteepoxy composite structures to be employed for first time in space-based X-ray by NuSTAR, a NASA Small Explorer schedule launch February 2012. discuss manufacturing process, qualification and environmental testing performed, briefly results performance integration alignment completed into instrument is described as module thermal shields.
Sagittarius A* harbors the supermassive black hole that lies at dynamical center of our Galaxy. spends most its time in a low luminosity emission state but flares frequently infrared and X-ray, increasing up to few hundred fold brightness for hours time. The physical processes giving rise X-ray are uncertain. Here we report detection with NuSTAR observatory Summer Fall 2012 four medium amplitude energies 79 keV. For first time, clearly see power-law spectrum extends high energy, no evidence...
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)/...
The hard X-ray emission from magnetars and other isolated neutron stars remains under-explored. An instrument with higher sensitivity to X-rays is critical understanding the physics of star magnetospheres also relationship between Fast Radio Bursts (FRBs). High required determine number tails, track transient non-thermal these sources for years post-outburst. This would enable previously impossible studies faint middle-aged rotation-powered pulsars (RPPs), detailed phase-resolved...
Abstract A recent report on the detection of very-high-energy gamma rays from V4641 Sagittarii (V4641 Sgr) up to ≈0.8 PeV has made it second confirmed “PeVatron” microquasar. Here we observation Sgr with X-Ray Imaging and Spectroscopy Mission (XRISM) in 2024 September. Thanks large field view low background, CCD imager Xtend successfully detected for first time X-ray extended emission around a significance ≳4.5 σ >10 based our imaging spectral analysis, respectively. The spatial extent is...
White dwarfs (WDs) are the most abundant compact objects, and recent surveys have suggested that over a third of WDs in accreting binaries host strong (B $\gtrsim$ 1 MG) magnetic field. However, origin evolution WD magnetism remain under debate. Two pulsars, AR Sco J191213.72-441045.1 (J1912), been found, which non-accreting hosting rapidly spinning (1.97-min 5.30-min, respectively) WDs. The is slowing down on $P/\dot{P}\approx 5.6\times 10^6$ yr timescale. It believed they will eventually...