Herman L. Marshall
A5020887298- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Particle Detector Development and Performance
- Radio Astronomy Observations and Technology
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Calibration and Measurement Techniques
- Mechanics and Biomechanics Studies
- Adaptive optics and wavefront sensing
- X-ray Spectroscopy and Fluorescence Analysis
- Geophysics and Gravity Measurements
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Statistical and numerical algorithms
- Particle accelerators and beam dynamics
- Advanced X-ray and CT Imaging
- Astrophysics and Star Formation Studies
Massachusetts Institute of Technology
2015-2024
Kavli Institute for Particle Astrophysics and Cosmology
2015-2024
Goddard Space Flight Center
1993-2023
Hiroshima University
2023
University College London
2023
University of Hong Kong
2023
Nagoya University
2023
University of Maryland, Baltimore County
2023
University of Turin
2023
Moscow Institute of Thermal Technology
2001-2021
The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days 12 days, respectively, with ASCA RXTE (and EUVE S180). These represent the most intensive monitoring of any such soft-spectrum to date. Light curves constructed in six bands spanning 0.1-10 keV five 0.7-10 keV. short-timescale (hours-days) variability patterns very similar across energy bands, no evidence lags between studied. fractional amplitude was almost independent band, unlike...
Launched on 2021 December 9, the Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Small Mission in collaboration with Italian Space Agency (ASI). The mission will open new window of investigation—imaging x-ray polarimetry. observatory features three identical telescopes, each consisting mirror module assembly polarization-sensitive imaging detector at focus. A coilable boom, deployed orbit, provides necessary 4-m focal length. utilizes three-axis-stabilized spacecraft, which services such...
The Imaging X-ray Polarimetry Explorer (IXPE) expands observation space by simultaneously adding polarization measurements to the array of source properties currently measured (energy, time, and location). IXPE will thus open new dimensions for understanding how emission is produced in astrophysical objects, especially systems under extreme physical conditions—such as neutron stars black holes. Polarization singularly probes anisotropies—ordered magnetic fields, aspheric matter...
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto hole, which heats the sufficiently to emit x-rays. We report polarimetric observation of XRB Cygnus X-1 using Imaging Polarimetry Explorer. The electric field position angle aligns with outflowing jet, indicating that jet launched inner emitting region. polarization degree (4.01+-0.20)% at 2 8 kiloelectronvolts, implying accretion disk viewed closer edge-on than orbit. observations reveal...
Abstract Most of the light from blazars, active galactic nuclei with jets magnetized plasma that point nearly along line sight, is produced by high-energy particles, up to around 1 TeV. Although are known be ultimately powered a supermassive black hole, how particles accelerated such high energies has been an unanswered question. The process must related magnetic field, which can probed observations polarization jets. Measurements radio optical polarization—the only range available until...
ABSTRACT We present an X-ray spectropolarimetric analysis of the bright Seyfert galaxy NGC 4151. The source has been observed with Imaging Polarimetry Explorer (IXPE) for 700 ks, complemented simultaneous XMM–Newton (50 ks) and NuSTAR (100 pointings. A polarization degree Π = 4.9 ± 1.1 per cent angle Ψ 86° 7° east north (68 confidence level) are measured in 2–8 keV energy range. shows that could be entirely due to reflection. Given low reflection flux IXPE band, this requires, however, a...
Abstract We report on an observational campaign the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by Imaging Polarimetry Explorer. These track for first time evolution of polarization a BH across hard to soft state transition. The 2–8 keV degree decreased from ∼4% ∼3% observations, but angle remained oriented in north–south direction throughout. Based with Australia Telescope Compact Array, we find that intrinsic 7.25 GHz radio aligns polarization....
Details of the design, fabrication, ground and flight calibration High Energy Transmission Grating, HETG, on Chandra X-ray Observatory are presented after five years experience. Specifics include theory phased transmission gratings as applied to Rowland design spectrometer, details grating fabrication techniques, results testing HETG. For nearly six HETG has operated essentially designed, although it some subtle effects.
The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with High-Energy Transmission Grating (HETG) readout by Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at resolution comparable to that best ground-based visible-light observations. HETG-ACIS-S reveal, for first time, an inner ring within torus, suggestion hollow-tube knots along (perhaps) inward extension jet. Although...
We present the first high-resolution X-ray image of jet in M87 using Chandra X-Ray Observatory. There is clear structure and almost all optically bright knots are detected individually. The unresolved core brightest feature but only 2-3 times brighter than knot A (123 from core) inner HST-1 (10 core). optical positions consistent at 01 level, emission (A) marginally upstream peak. Detailed Gaussian fits to one-dimensional profile show distinct that not associated with specific features....
Deep Chandra Low Energy Transmission Grating and High Resolution Camera spectroscopic observations of the isolated neutron star candidate RX J1856.5-3754 have been analyzed to search for metallic resonance cyclotron spectral features pulsation behavior. As found from earlier observations, X-ray spectrum is well represented by an ~60 eV (7 × 105 K) blackbody. No unequivocal evidence line or edge has found, arguing against metal-dominated models. The data contain no pulsation, we place a 99%...
view Abstract Citations (221) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Analysis of complete quasar samples to obtain parameters luminosity and evolution functions Marshall, H. L. ; Tananbaum, Avni, Y. Zamorani, G. A parametric likelihood analysis the joint redshift-luminosity distribution is presented for a composite, sample 32 quasars with B between 17.0 19.2 selected on basis ultraviolet excess. Best estimates confidence regions are...
view Abstract Citations (231) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A high-sensitivity X-ray survey using the Einstein Observatory and discrete source contribution to extragalactic background. Giacconi, R. ; Bechtold, J. Branduardi, G. Forman, W. Henry, P. Jones, C. Kellogg, E. van der Laan, H. Liller, Marshall, Murray, S. Pye, Schreier, Sargent, L. Seward, F. Tananbaum, Surveys of two fields have been carried out utilizing imaging...
MARX is a portable ray-trace program that was originally developed to simulate event data from the trans- mission grating spectrometers on-board Chandra X-ray Observatory (CXO). has since evolved include detailed models of all CXO science instruments and been further modified serve as an simulator for future observatory design concepts. We first review number applications demonstrate roles such could play throughout life mission, including its calibration, production input products...
ABSTRACT On behalf of the International Astronomical Consortium for High Energy Calibration, we present results from cross-calibration campaigns in 2012 on 3C 273 and 2013 PKS 2155-304 between then active X-ray observatories Chandra , NuSTAR Suzaku Swift, XMM-Newton . We compare measured fluxes instrument pairs two energy bands, 1–5 keV 3–7 keV, calculate an average cross-normalization constant each range. review known features provide a series tables figures to be used evaluating constants...
Abstract Particle acceleration mechanisms in supermassive black hole jets, such as shock acceleration, magnetic reconnection, and turbulence, are expected to have observable signatures the multiwavelength polarization properties of blazars. The recent launch Imaging X-Ray Polarimetry Explorer (IXPE) enables us, for first time, use X-ray band (2–8 keV) probe jet synchrotron emission high-synchrotron-peaked BL Lac objects (HSPs). We report discovery linear (degree Π x = 15% ± 2% electric...
We report on the first detection of linearly polarized x-ray emission from an ultra-magnetized neutron star with Imaging X-ray Polarimetry Explorer (IXPE). The IXPE 35 observations anomalous pulsar 4U 0142+61 reveal a linear polarization degree $(12\pm 1)\%$ throughout 2--8 keV band. detect substantial variation energy: is $(14\pm at 2--4 and $(41\pm 7)\%$ 5.5--8 keV, while it drops below instrumental sensitivity around 4--5 where angle swings by $\sim 90^\circ$. give us completely new...
We report on the first observation of a radio-quiet Active Galactic Nucleus (AGN) using polarized X-rays: Seyfert 1.9 galaxy MCG-05-23-16. This source was pointed with Imaging X-ray Polarimetry Explorer (IXPE) starting May 14, 2022 for net observing time 486 ks, simultaneously XMM-Newton (58 ks) and NuSTAR (83 ks). A polarization degree smaller than $\Pi<4.7\%$ (at 99% c.l.) is derived in 2-8 keV energy range, where emission dominated by primary component ascribed to hot corona. The...
Abstract We present the IXPE observation of GRB 221009A, which includes upper limits on linear polarization degree both prompt and afterglow emission in soft X-ray energy band. 221009A is an exceptionally bright gamma-ray burst (GRB) that reached Earth 2022 October 9 after traveling through dust Milky Way. The Imaging Polarimetry Explorer (IXPE) pointed at 11 to observe, for first time, 2–8 keV a afterglow. set limit 13.8% 99% confidence level. This result provides constraints jet opening...
ABSTRACT We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy IC 4329A. The Imaging Polarimetry Explorer (IXPE) observed source for ∼500 ks, supported by XMM–Newton (∼60 ks) and NuSTAR (∼80 exposures. detect polarization in 2–8 keV band with 2.97σ confidence. report a degree 3.3 ± 1.1 per cent angle 78° 10° (errors are 1σ confidence). is consistent being aligned radio jet, albeit partially due to large uncertainties on position angle. jointly fit spectra from three...
Abstract We report the first detection of X-ray polarization bright transient Swift J1727.8−1613 with Imaging Polarimetry Explorer. The observation was performed at beginning 2023 discovery outburst, when source resided in hard state. find a time- and energy-averaged degree 4.1% ± 0.2% angle 2.°2 1.°3 (errors 68% confidence level; this translates to ∼20 σ significance detection). This finding suggests that hot corona emitting bulk detected X-rays is elongated, rather than spherical....