Search Publications
Improved Reflection Models of Black Hole Accretion Disks: Treating the Angular Distribution of X-Rays
Reynolds, C. S.; García, J.; Dauser, T. +8 more
X-ray reflection models are used to constrain the properties of the accretion disk, such as the degree of ionization of the gas and the elemental abundances. In combination with general relativistic ray tracing codes, additional parameters like the spin of the black hole and the inclination to the system can be determined. However, current reflect…
Discriminating the Progenitor Type of Supernova Remnants with Iron K-shell Emission
Safi-Harb, Samar; Maeda, Yoshitomo; Petre, Robert +11 more
Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-st…
The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku
Hailey, Charles J.; Fürst, Felix; Pottschmidt, Katja +21 more
The black hole binary Cygnus X-1 was observed in late 2012 with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku, providing spectral coverage over the ~1-300 keV range. The source was in the soft state with a multi-temperature blackbody, power law, and reflection components along with absorption from highly ionized material in the sys…
Confirmation via the Continuum-fitting Method that the Spin of the Black Hole in Cygnus X-1 Is Extreme
Steiner, James F.; Remillard, Ronald A.; McClintock, Jeffrey E. +6 more
In Gou et al., we reported that the black hole primary in the X-ray binary Cygnus X-1 is a near-extreme Kerr black hole with a spin parameter a * > 0.95 (3σ). We confirm this result while setting a new and more stringent limit: a * > 0.983 at the 3σ (99.7%) confidence level. The earlier work, which was based on an analy…
Broadband X-Ray Spectra of the Ultraluminous X-Ray Source Holmberg IX X-1 Observed with NuSTAR, XMM-Newton, and Suzaku
Harrison, F. A.; Ptak, A.; Stern, D. +16 more
We present results from the coordinated broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 performed by NuSTAR, XMM-Newton, and Suzaku in late 2012. These observations provide the first high-quality spectra of Holmberg IX X-1 above 10 keV to date, extending the X-ray coverage of this remarkable source up to ~30 …
The Variable Hard X-Ray Emission of NGC 4945 as Observed by NuSTAR
Hailey, Charles J.; Brandt, William N.; Comastri, Andrea +19 more
We present a broadband (~0.5-79 keV) spectral and temporal analysis of multiple NuSTAR observations combined with archival Suzaku and Chandra data of NGC 4945, the brightest extragalactic source at 100 keV. We observe hard X-ray (>10 keV) flux and spectral variability, with flux variations of a factor of two on timescales of 20 ks. A variable p…
The Broad-band X-Ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation
Harrison, F. A.; Stern, D.; Zhang, W. W. +16 more
We have obtained a deep, simultaneous observation of the bright, nearby Seyfert galaxy IC 4329A with Suzaku and NuSTAR. Through a detailed spectral analysis, we are able to robustly separate the continuum, absorption, and distant reflection components in the spectrum. The absorbing column is found to be modest ({\sim }6 \times 10^{21} {\, cm^{-2}\…
Are X-Ray Emitting Coronae around Supermassive Black Holes Outflowing?
Wang, Jun-Xian; Zhu, Fei-Fan; Zhou, You-Yuan +2 more
Hard X-ray emission in radio-quiet active galactic nuclei (AGNs) is believed to be produced via inverse Compton scattering by hot and compact coronae near the supermassive black hole. However, the origin and physical properties of the coronae, including geometry, kinematics, and dynamics, remain poorly known. In this work, taking [O IV] 25.89 &mic…
New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant
Petre, Robert; Yamaguchi, Hiroya; Hughes, John P. +7 more
Although collisionless shocks are ubiquitous in astrophysics, certain key aspects of them are not well understood. In particular, the process known as collisionless electron heating, whereby electrons are rapidly energized at the shock front, is one of the main open issues in shock physics. Here, we present the first clear evidence for efficient c…
Observations of MCG-5-23-16 with Suzaku, XMM-Newton and NuSTAR: Disk Tomography and Compton Hump Reverberation
Harrison, F. A.; Craig, W.; Stern, D. +12 more
MCG-5-23-16 is one of the first active galactic nuclei (AGNs) where relativistic reverberation in the iron K line originating in the vicinity of the supermassive black hole was found, based on a short XMM-Newton observation. In this work, we present the results from long X-ray observations using Suzaku, XMM-Newton, and NuSTAR designed to map the e…