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Full-Text Articles in Physical Sciences and Mathematics
Hard X-Ray Lags In Active Galactic Nuclei: Testing The Distant Reverberation Hypothesis With Ngc 6814, D. J. Walton, A. Zoghbi, E. M. Cackett, P. Uttley, F. A. Harrison, A. C. Fabian, E. Kara, J. M. Miller, R. C. Reis, C. S. Reynolds
Hard X-Ray Lags In Active Galactic Nuclei: Testing The Distant Reverberation Hypothesis With Ngc 6814, D. J. Walton, A. Zoghbi, E. M. Cackett, P. Uttley, F. A. Harrison, A. C. Fabian, E. Kara, J. M. Miller, R. C. Reis, C. S. Reynolds
Physics and Astronomy Faculty Research Publications
We present an X-ray spectral and temporal analysis of the variable active galaxy NGC 6814, observed with Suzaku during 2011 November. Remarkably, the X-ray spectrum shows no evidence for the soft excess commonly observed amongst other active galaxies, despite its relatively low level of obscuration, and is dominated across the whole Suzaku bandpass by the intrinsic powerlaw-like continuum. Despite this, we clearly detect the presence of a low-frequency hard lag of ~1600 s between the 0.5-2.0 and 2.0-5.0 keV energy bands at greater than 6σ significance, similar to those reported in the literature for a variety of other active galactic …
Calculating Time Lags From Unevenly Sampled Light Curves, A. Zoghbi, C. Reynolds, E. M. Cackett
Calculating Time Lags From Unevenly Sampled Light Curves, A. Zoghbi, C. Reynolds, E. M. Cackett
Physics and Astronomy Faculty Research Publications
Timing techniques are powerful tools to study dynamical astrophysical phenomena. In the X-ray band, they offer the potential of probing accretion physics down to the event horizon. Recent work has used frequency- and energy-dependent time lags as tools for studying relativistic reverberation around the black holes in several Seyfert galaxies. This was achieved due to the evenly sampled light curves obtained using XMM-Newton. Continuously sampled data are, however, not always available and standard Fourier techniques are not applicable. Here, building on the work of Miller et al., we discuss and use a maximum likelihood method to obtain frequency-dependent lags that …
Discovery Of High-Frequency Iron K Lags In Ark 564 And Mrk 335, E. Kara, A. C. Fabian, E. M. Cackett, P. Uttley, D. R. Wilkins, A. Zoghbi
Discovery Of High-Frequency Iron K Lags In Ark 564 And Mrk 335, E. Kara, A. C. Fabian, E. M. Cackett, P. Uttley, D. R. Wilkins, A. Zoghbi
Physics and Astronomy Faculty Research Publications
We use archival XMM-Newton observations of Ark 564 and Mrk 335 to calculate the frequency-dependent time lags for these two well-studied sources. We discover high-frequency Fe K lags in both sources, indicating that the red wing of the line precedes the rest-frame energy by roughly 100 and 150 s for Ark 564 and Mrk 335, respectively. Including these two new sources, Fe K reverberation lags have been observed in seven Seyfert galaxies. We examine the low-frequency lag-energy spectrum, which is smooth, and shows no feature of reverberation, as would be expected if the low-frequency lags were produced by distant reflection …
Discovery Of Fe Kα X-Ray Reverberation Around The Black Holes In Mcg-5-23-16 And Ngc 7314, A. Zoghbi, C. Reynolds, E. M. Cackett, G. Miniutti, E. Kara, A. C. Fabian
Discovery Of Fe Kα X-Ray Reverberation Around The Black Holes In Mcg-5-23-16 And Ngc 7314, A. Zoghbi, C. Reynolds, E. M. Cackett, G. Miniutti, E. Kara, A. C. Fabian
Physics and Astronomy Faculty Research Publications
Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in active galactic nuclei. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe Kα line peaks, lags the bands at lower …
Revealing The X-Ray Source In Iras 13224-3809 Through Flux-Dependent Reverberation Lags, E. Kara, A. C. Fabian, E. M. Cackett, G. Miniutti, P. Uttley
Revealing The X-Ray Source In Iras 13224-3809 Through Flux-Dependent Reverberation Lags, E. Kara, A. C. Fabian, E. M. Cackett, G. Miniutti, P. Uttley
Physics and Astronomy Faculty Research Publications
IRAS 13224-3809 was observed in 2011 for 500 ks with the XMM-Newton observatory. We detect highly significant X-ray lags between soft (0.3-1 keV) and hard (1.2-5 keV) energies. The hard band lags the soft at low frequencies (i.e. hard lag), while the opposite (i.e. soft lag) is observed at high frequencies. In this paper, we study the lag during flaring and quiescent periods. We find that the frequency and absolute amplitude of the soft lag are different during high-flux and low-flux periods. During the low-flux intervals, the soft lag is detected at higher frequencies and with smaller amplitude. Assuming that …
Evidence Of Light-Bending Effects And Its Implication For Spectral State Transitions, R. C. Reis, J. M. Miller, M. T. Reynolds, A. C. Fabian, D. J. Walton, E. Cackett, J. F. Steiner
Evidence Of Light-Bending Effects And Its Implication For Spectral State Transitions, R. C. Reis, J. M. Miller, M. T. Reynolds, A. C. Fabian, D. J. Walton, E. Cackett, J. F. Steiner
Physics and Astronomy Faculty Research Publications
It has long been speculated that the nature of the hard X-ray corona may be an important second driver of black hole state transitions, in addition to the mass accretion rate through the disk. However, a clear physical picture of coronal changes has not yet emerged. We present results from a systematic analysis of Rossi X-Ray Timing Explorer observations of the stellar-mass black hole binary XTE J1650-500. All spectra with significant hard X-ray detections were fit using a self-consistent, relativistically blurred disk reflection model suited to high ionization regimes. Importantly, we find evidence that both the spectral and timing properties …
Regulation Of Black Hole Winds And Jets Across The Mass Scale, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, K. Gültekin, E. M. Cackett, S. W. Allen, D. Proga, T. R. Kallman
Regulation Of Black Hole Winds And Jets Across The Mass Scale, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, K. Gültekin, E. M. Cackett, S. W. Allen, D. Proga, T. R. Kallman
Physics and Astronomy Faculty Research Publications
We present a study of the mechanical power generated by both winds and jets across the black hole mass scale. We begin with the study of ionized X-ray winds and present a uniform analysis using Chandra grating spectra. The high-quality grating spectra facilitate the characterization of the outflow velocity, ionization, and column density of the absorbing gas. We find that the kinetic power of the winds, derived from these observed quantities, scales with increasing bolometric luminosity as log (L wind, 42/Cv ) = (1.58 ± 0.07)log (L Bol, 42) - (3.19 ± 0.19). This suggests that supermassive …
Hypervelocity Planets And Transits Around Hypervelocity Stars, Idan Ginsburg, Abraham Loeb, Gary A. Wegner
Hypervelocity Planets And Transits Around Hypervelocity Stars, Idan Ginsburg, Abraham Loeb, Gary A. Wegner
Dartmouth Scholarship
The disruption of a binary star system by the massive black hole at the Galactic Centre, SgrA*, can lead to the capture of one star around SgrA* and the ejection of its companion as a hypervelocity star (HVS). We consider the possibility that these stars may have planets and study the dynamics of these planets. Using a direct N-body integration code, we simulated a large number of different binary orbits around SgrA*. For some orbital parameters, a planet is ejected at a high speed. In other instances, a HVS is ejected with one or more planets orbiting around it. …
The Similarity Of Broad Iron Lines In X-Ray Binaries And Active Galactic Nuclei, D. J. Walton, R. C. Reis, E. M. Cackett, A. C. Fabian, J. M. Miller
The Similarity Of Broad Iron Lines In X-Ray Binaries And Active Galactic Nuclei, D. J. Walton, R. C. Reis, E. M. Cackett, A. C. Fabian, J. M. Miller
Physics and Astronomy Faculty Research Publications
We have compared the 2001 XMM-Newton spectra of the stellar mass black hole binary XTE J1650-500 and the active galaxy MCG-6-30-15, focusing on the broad, excess emission features at ˜4-7 keV displayed by both sources. Such features are frequently observed in both low-mass X-ray binaries and active galactic nuclei (AGN). For the former case it is generally accepted that the excess arises due to iron emission, but there is some controversy over whether their width is partially enhanced by instrumental processes, and hence also over the intrinsic broadening mechanism. Meanwhile, in the latter case, the origin of this feature is …
A Chandra Survey Of Supermassive Black Holes With Dynamical Mass Measurements, Kayhan Gültekin, Edward M. Cackett, Jon M. Miller, Tiziana Di Matteo, Sera Markoff, Douglas O. Richstone
A Chandra Survey Of Supermassive Black Holes With Dynamical Mass Measurements, Kayhan Gültekin, Edward M. Cackett, Jon M. Miller, Tiziana Di Matteo, Sera Markoff, Douglas O. Richstone
Physics and Astronomy Faculty Research Publications
We present Chandra observations of 12 galaxies that contain supermassive black holes (SMBHs) with dynamical mass measurements. Each galaxy was observed for 30 ks and resulted in a total of 68 point-source detections in the target galaxies including SMBH sources, ultraluminous X-ray sources (ULXs), and extragalactic X-ray binaries. Based on our fits of the X-ray spectra, we report fluxes, luminosities, Eddington ratios, and slope of the power-law spectrum. Normalized to the Eddington luminosity, the 2-10 keV band X-ray luminosities of the SMBH sources range from 10-8 to 10-6, and the power-law slopes are centered at ~2 with …
A Distinctive Disk-Jet Coupling In The Seyfert-1 Active Galactic Nucleus Ngc 4051, A. L. King, J. M. Miller, E. M. Cackett, A. C. Fabian, S. Markoff, M. A. Nowak, M. Rupen, K. Gültekin, M. T. Reynolds
A Distinctive Disk-Jet Coupling In The Seyfert-1 Active Galactic Nucleus Ngc 4051, A. L. King, J. M. Miller, E. M. Cackett, A. C. Fabian, S. Markoff, M. A. Nowak, M. Rupen, K. Gültekin, M. T. Reynolds
Physics and Astronomy Faculty Research Publications
We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six Very Large Array/Extended Very Large Array (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz radio band; this builds on mounting evidence that jet production may be prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local diffuse emission in the nucleus, the results also demonstrate an inverse correlation of L radio ∝ L -0.72±0.04 X-ray . If the A configuration is excluded in the case where diffuse emission plays a significant …
On Neutral Absorption And Spectral Evolution In X-Ray Binaries, J. M. Miller, E. M. Cackett, R. C. Reis
On Neutral Absorption And Spectral Evolution In X-Ray Binaries, J. M. Miller, E. M. Cackett, R. C. Reis
Physics and Astronomy Faculty Research Publications
Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low-energy portion of the spectrum should be attributed to evolution in the source, or instead to evolution in neutral photoelectric absorption. Dispersive spectrometers make it possible to address this problem. We have analyzed a small but diverse set of X-ray binaries observed with the Chandra High Energy Transmission Grating Spectrometer across a range in luminosity and different spectral states. The column density in individual …
The Fundamental Plane Of Accretion Onto Black Holes With Dynamical Masses, Kayhan Gültekin, Edward M. Cackett, Jon M. Miller, Tiziana Di Matteo, Sera Markoff, Douglas O. Richstone
The Fundamental Plane Of Accretion Onto Black Holes With Dynamical Masses, Kayhan Gültekin, Edward M. Cackett, Jon M. Miller, Tiziana Di Matteo, Sera Markoff, Douglas O. Richstone
Physics and Astronomy Faculty Research Publications
Black hole accretion and jet production are areas of intensive study in astrophysics. Recent work has found a relation between radio luminosity, X-ray luminosity, and black hole mass. With the assumption that radio and X-ray luminosities are suitable proxies for jet power and accretion power, respectively, a broad fundamental connection between accretion and jet production is implied. In an effort to refine these links and enhance their power, we have explored the above relations exclusively among black holes with direct, dynamical mass-measurements. This approach not only eliminates systematic errors incurred through the use of secondary mass measurements, but also effectively …
Constraining The Spin Of The Black Hole In Fairall 9 With Suzaku, S. Schmoll, J. M. Miller, M. Volonteri, E. Cackett, C. S. Reynolds, A. C. Fabian, L. W. Brenneman, G. Miniutti, L. C. Gallo
Constraining The Spin Of The Black Hole In Fairall 9 With Suzaku, S. Schmoll, J. M. Miller, M. Volonteri, E. Cackett, C. S. Reynolds, A. C. Fabian, L. W. Brenneman, G. Miniutti, L. C. Gallo
Physics and Astronomy Faculty Research Publications
We report on the results of spectral fits made to data obtained from a 168 ks Suzaku observation of the Seyfert 1 galaxy Fairall 9. The source is clearly detected out to 30 keV. The observed spectrum is fairly simple; it is well described by a power law with soft excess and disk reflection. A broad iron line is detected, and easily separated from distinct narrow components owing to the resolution of the CCDs in the X-ray Imaging Spectrometer (XIS). The broad line is revealed to be asymmetric, consistent with a disk origin. We fit the XIS and Hard X-ray …