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…
Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy
Reynolds, Christopher S.
I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic …
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…
Ultrafast outflows in radio-loud active galactic nuclei
Cappi, M.; Guainazzi, M.; Tombesi, F. +5 more
Recent X-ray observations show absorbing winds with velocities up to mildly relativistic values of the order of ∼0.1c in a limited sample of six broad-line radio galaxies. They are observed as blueshifted Fe XXV-XXVI K-shell absorption lines, similarly to the ultrafast outflows (UFOs) reported in Seyferts and quasars. In this work we extend the se…
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 …
Possible Evidence for Free Precession of a Strongly Magnetized Neutron Star in the Magnetar 4U 0142+61
Hiraga, J. S.; Enoto, T.; Murakami, H. +5 more
Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching ∼1011 T. The magnetar 4U 0142+61, one of the prototypes of this class, was studied in broadband x rays (0.5-70 keV) with the Suzaku observatory. In hard x rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by …
Azimuthally resolved X-ray spectroscopy to the edge of the Perseus Cluster
Simionescu, A.; Fabian, A. C.; Allen, S. W. +9 more
We present the results from extensive, new observations of the Perseus Cluster of galaxies, obtained as a Suzaku Key Project. The 85 pointings analysed span eight azimuthal directions out to 2° = 2.6 Mpc, to and beyond the virial radius r200 ∼ 1.8 Mpc, offering the most detailed X-ray measurements of the intracluster medium (ICM) at lar…
Iron Kα emission in type-I and type-II active galactic nuclei
Paltani, S.; Gandhi, P.; Ricci, C. +3 more
The narrow Fe Kα line is one of the main signatures of the reprocessing of X-ray radiation from the material surrounding supermassive black holes, and it has been found to be omnipresent in the X-ray spectra of active galactic nuclei (AGN). In this work, we study the characteristics of the narrow Fe Kα line in different types of AGN. Using the res…