A5012229831- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Calibration and Measurement Techniques
- Atomic and Molecular Physics
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Astro and Planetary Science
- Advanced Measurement and Metrology Techniques
- Optical Coatings and Gratings
- Mechanics and Biomechanics Studies
- Radio Astronomy Observations and Technology
- Scientific Measurement and Uncertainty Evaluation
Columbia University
2015-2024
Center for Astrophysics Harvard & Smithsonian
2019
Michigan United
2019
University of Michigan–Ann Arbor
2019
Smithsonian Astrophysical Observatory
2016-2017
Ames Research Center
2017
The Aerospace Corporation
2016
SRON Netherlands Institute for Space Research
1985-2009
K Lab (United States)
2003-2006
Menlo School
2006
We present detailed spatially-resolved spectroscopy results of the observation Abell 1835 using European Photon Imaging Cameras (EPIC) and Reflection Grating Spectrometers (RGS) on XMM-Newton observatory. is a luminous (1046 ergs ), medium redshift (), X-ray emitting cluster galaxies. The observations support interpretation that large amounts cool gas are in multi-phase surrounded by hot ( keV) outer envelope. detect O VIII Lyα two Fe XXIV complexes RGS spectrum. emission measure below keV...
The initial results from XMM-Newton observations of the rich cluster galaxies Abell 1795 are presented. spatially-resolved X-ray spectra taken by European Photon Imaging Cameras (EPIC) show a temperature drop at radius $\sim 200$ kpc center, indicating that ICM is cooling. Both EPIC and Reflection Grating Spectrometers (RGS) extracted center can be described an isothermal model with 4$ keV. volume emission measure any cool component ($<1$ keV) less than few % hot center. A strong OVIII...
We present the first high-resolution, soft X-ray spectrum of prototypical Seyfert 2 galaxy, NGC 1068. This was obtained with XMM-Newton Reflection Grating Spectrometer (RGS). Emission lines from H-like and He-like low-Z ions (from C to Si) Fe L-shell dominate spectrum. Strong, narrow radiative recombination continua (RRCs) for several are also present, implying that most observed emission arises in low-temperature plasma (kTe ~ a few eV). is photoionized by inferred nuclear continuum...
We present spatially resolved X-ray spectra taken with the EPIC cameras of XMM-Newton a sample 17 cooling clusters and three non-cooling for comparison. The deprojected are analyzed multi-temperature model, independent any priori assumptions about physics behind heating mechanisms. All show central decrement average temperature, most them factor . Three (Sérsic 159-3, MKW 3s Hydra A) only weak temperature decrement, while two others (A 399 A 2052) have very strong decrement. pressure...
We present the first high spectral resolution X-ray observation of giant elliptical galaxy NGC 4636, obtained with Reflection Grating Spectrometer on-board XMM-Newton Observatory. The resulting spectrum contains a wealth emission lines from various charge states oxygen, neon, magnesium, and iron. Examination cross-dispersion profiles several these provides clear, unambiguous evidence resonance scattering by highest oscillator strength lines, as well weak temperature gradient in inner regions...
We present the first X-ray spectrum obtained by Low-Energy Transmission Grating Spectrometer (LETGS) aboard Chandra X-Ray Observatory. The is of Capella and covers a wavelength range 5-175 Å (2.5-0.07 keV). measured resolution, which in good agreement with ground calibration, Deltalambda approximately 0.06 (FWHM). Although in-flight calibration LETGS progress, high spectral resolution unique coverage are well demonstrated results from Capella, coronal source rich emission lines. While...
The cluster of galaxies Sérsic 159-03 was observed with the XMM-Newton X-ray observatory as part Guaranteed Time program. spectra taken EPIC and RGS instruments show no evidence for strong cooling flow derived from previous observations. There is a significant lack cool gas below 1.5 keV compared to standard isobaric models. While oxygen distributed more or less uniformly over cluster, iron shows concentration in center slightly offset brightness but within central cD galaxy. This points...
We present the results from a 500 ks Chandra observation of Seyfert 1 galaxy NGC 5548. detect broadened (full width half maximum = 8000 km s-1) emission lines and in spectra, similar to those observed optical UV bands. The source was continuously variable, with 30% increase luminosity second observation. gradual occurred over timescale ~300 ks. No variability warm absorber detected between spectra first 170 part longer wavelength range LETGS resulted detection absorption broad ions,...
We present a preliminary analysis of the first high-resolution X-ray spectrum Seyfert 2 galaxy, Markarian 3, obtained with High-Energy Transmission Grating Spectrometer on board Chandra X-Ray Observatory. The high-energy (λ ≲ 4 Å) is dominated by reflection active galactic nucleus continuum radiation in cold, optically thick medium and contains bright Kα fluorescent lines from iron silicon as well weak, blended sulfur magnesium. soft emission (4 Å λ 23 spatially extended along [O III]...
We present Chandra high-energy transmission grating spectra of seven cataclysmic variables. find that they divide unambiguously into two distinct types. Spectra the first type are remarkably well fitted by a simple cooling flow model, which assumes only steady-state isobaric radiative cooling. The maximum temperature, kTmax, and normalization, provides highly precise measurement accretion rate, free parameters this model. second grossly inconsistent with They instead exhibit hard continuum...
We present a quantitative analysis of the X-ray spectrum eclipsing high mass binary Vela X-1 (4U 0900-40) using archival data from ASCA Solid-State Imaging Spectrometer. The observation covers time interval centered on eclipse pulsar by companion. exhibits two distinct sets discrete features: (1) recombination lines and radiative continua mostly hydrogenic helium-like species produced photoionization in an extended stellar wind; (2) fluorescent K-shell associated with near-neutral also...
We present X-ray spectra taken with XMM-Newton of RX J1605.3+3249, the third brightest in class nearby, thermally emitting neutron stars. In contrast to what is case for object, J1856.5-3754, we find that spectrum J1605.3+3249 cannot be described well by a pure black body, but shows broad absorption feature at 27Å(0.45 keV). With this, it joins handful isolated stars which spectral features arising from surface have been detected. discuss possible mechanisms might lead features, as overall...
In a series of papers, Nicastro et al. have reported the detection z > 0 O VII absorption features in spectrum Mrk 421 obtained with Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate this result context high-quality same source Reflection (RGS) on XMM-Newton. The data comprise over 955 ks usable exposure time and more than 2.6 × 104 counts per 50 mÅ at 21.6 Å. concentrate spectrally clean region (21.3 < λ 22.5 ), where sharp due to astrophysically abundant may reveal...
The prototypical accretion-powered millisecond pulsar SAX J1808.4-3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) burst detected, brightest yet by Chandra from any source, second-brightest RXTE. We found no evidence for discrete spectral features during burst; absorption edges have been predicted to be present such bursts, but may require greater degree photospheric expansion than rather...
Due to observational challenges, our knowledge of low-level accretion flows around neutron stars is limited. We present NuSTAR, Swift and Chandra observations the low-mass X-ray binary IGR J17062-6143, which has been persistently accreting at ≃0.1 per cent Eddington limit since 2006. Our simultaneous NuSTAR/Swift show that 0.5–79 keV spectrum can be described by a combination power law with photon index Γ ≃ 2, blackbody temperature kTbb 0.5 (presumably arising from star surface) disc...
Arcus will be proposed to the NASA Explorer program as a free-flying satellite mission that enable high-resolution soft X-ray spectroscopy (8-50) with unprecedented sensitivity – effective areas of >500 sq cm and spectral resolution >2500. The key science goals are (1) determine how baryons cycle in out galaxies by measuring effects structure formation imprinted upon hot gas is predicted lie extended halos around galaxies, groups, clusters, (2) black holes influence their surroundings...
The ASCA SIS spectrum of the X-ray binary Cygnus X-3 is shown to contain a narrow recombination continuum hydrogenic sulfur near 3.5 keV, which indicates that temperature emission-line region far below coronal equilibrium required support S15+. presence this feature immediately confirms photoionization produces extreme overionization in circumsource medium, and emission features are energized by hard continuum. Therefore, we conclude spectral analyses and, most likely, other...
Recently the first detections of highly ionised gas associated with two Warm-Hot Intergalactic Medium (WHIM) filaments have been reported. The evidence is based on X-ray absorption lines due to O VII and other ions observed by Chandra towards bright blazar Mrk 421. We investigate robustness this detection a re-analysis original LETGS spectra, analysis large set XMM-Newton RGS spectra 421, additional observations. address reliability individual spectral features belonging components, assess...
Gravitationally redshifted absorption lines from highly ionized iron have been previously identified in the burst spectra of neutron star EXO 0748–676. To repeat this detection we obtained a long, nearly 600 ks observation source with XMM-Newton 2003. The spectral features seen initial data are not reproduced new data. In paper present 2003 observations and discuss sensitivity structure to changes photospheric conditions.