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Full-Text Articles in Physical Sciences and Mathematics
The Variable Quiescent X-Ray Emission Of The Neutron Star Transient Xte J1701-462, Joel K. Fridriksson, Jeroen Homan, Rudy Wijnands, Edward M. Cackett, Diego Altamirano, Nathalie Degenaar, Edward F. Brown, Mariano Méndez, Tomaso M. Belloni
The Variable Quiescent X-Ray Emission Of The Neutron Star Transient Xte J1701-462, Joel K. Fridriksson, Jeroen Homan, Rudy Wijnands, Edward M. Cackett, Diego Altamirano, Nathalie Degenaar, Edward F. Brown, Mariano Méndez, Tomaso M. Belloni
Physics and Astronomy Faculty Research Publications
We present the results of continued monitoring of the quiescent neutron star low-mass X-ray binary XTE J1701-462 with Chandra and Swift. A new Chandra observation from 2010 October extends our tracking of the neutron star surface temperature from ≃ 800 days to ≃ 1160 days since the end of an exceptionally luminous 19 month outburst. This observation indicates that the neutron star crust may still be slowly cooling toward thermal equilibrium with the core; another observation further into quiescence is needed to verify this. The shape of the overall cooling curve is consistent with that of a broken power law, …
Quiescent X-Ray Variability From The Neutron Star Transient Aql X-1, E. M. Cackett, J. K. Fridriksson, J. Homan, J. M. Miller, R. Wijnands
Quiescent X-Ray Variability From The Neutron Star Transient Aql X-1, E. M. Cackett, J. K. Fridriksson, J. Homan, J. M. Miller, R. Wijnands
Physics and Astronomy Faculty Research Publications
A number of studies have revealed variability from neutron star low-mass X-ray binaries during quiescence. Such variability is not well characterized, or understood, but may be a common property that has been missed due to lack of multiple observations. One such source where variability has been observed is Aql X-1. Here, we analyse 14 Chandra and XMM-Newton observations of Aql X-1 in quiescence, covering a period of approximately 2 yr. There is clear variability between the epochs, with the most striking feature being a flare-like increase in the flux by a factor of 5. Spectral fitting is inconclusive as to …
Megamaser Detection And Nuclear Obscuration In Seyfert Galaxies, M. Ramolla, M. Hass, V. N. Bennert, R. Chini
Megamaser Detection And Nuclear Obscuration In Seyfert Galaxies, M. Ramolla, M. Hass, V. N. Bennert, R. Chini
Physics
We revisit the relation between H2O maser detection rate and nuclear obscuration for a sample of 114 Seyfert galaxies drawn from the CfA, 12 μm, and IRAS F25/F60 catalogs. These sources have mid-infrared spectra from the Spitzer Space Telescope and we search for accompanying X-ray and [O III] 5007 Å fluxes from the literature. We use the strength of the [O IV] 25.9 μm emission line as a tracer of the intrinsic AGN strength. After the normalization by [O IV], the observed X-ray flux provides information about X-ray absorption. The distribution of X-ray/[O IV] flux ratios …
Further X-Ray Observations Of Exo 0748-676 In Quiescence: Evidence For A Cooling Neutron Star Crust, N. Degenaar, M. T. Wolff, P. S. Ray, K. S. Wood, J. Homan, W. H. G. Lewin, P. G. Jonker, E. M. Cackett, J. M. Miller, E. F. Brown, R. Wijnands
Further X-Ray Observations Of Exo 0748-676 In Quiescence: Evidence For A Cooling Neutron Star Crust, N. Degenaar, M. T. Wolff, P. S. Ray, K. S. Wood, J. Homan, W. H. G. Lewin, P. G. Jonker, E. M. Cackett, J. M. Miller, E. F. Brown, R. Wijnands
Physics and Astronomy Faculty Research Publications
In late 2008, the quasi-persistent neutron star X-ray transient and eclipsing binary EXO 0748-676 started a transition from outburst to quiescence, after it actively accreted for more than 24 yr. In a previous work, we discussed Chandra and Swift observations obtained during the first 5 months of this transition. Here, we report on further X-ray observations of EXO 0748-676, extending the quiescent monitoring to 1.6 yr. Chandra and XMM-Newton data reveal quiescent X-ray spectra composed of a soft, thermal component that is well fitted by a neutron star atmosphere model. An additional hard power-law tail is detected that changes non-monotonically …
Multistate Observations Of The Galactic Black Hole Xte J1752-223: Evidence For An Intermediate Black Hole Spin, R. C. Reis, J. M. Miller, A. C. Fabian, E. M. Cackett, D. Maitra, C. S. Reynolds, M. Rupen, D. T. H. Steeghs, R. Wijnands
Multistate Observations Of The Galactic Black Hole Xte J1752-223: Evidence For An Intermediate Black Hole Spin, R. C. Reis, J. M. Miller, A. C. Fabian, E. M. Cackett, D. Maitra, C. S. Reynolds, M. Rupen, D. T. H. Steeghs, R. Wijnands
Physics and Astronomy Faculty Research Publications
The Galactic black hole candidate XTE J1752-223 was observed during the decay of its 2009 outburst with the Suzaku and XMM-Newton observatories. The observed spectra are consistent with the source being in the ‘intermediate’ and ‘low-hard’ states, respectively. The presence of a strong, relativistic iron emission line is clearly detected in both observations and the line profiles are found to be remarkably consistent and robust to a variety of continuum models. This strongly points to the compact object in XTE J1752-223 being a stellar mass black hole accretor and not a neutron star. Physically motivated and self-consistent reflection models for …
Is There A Core Set Of Skills For Visual Analysis Across Different Imaging Technologies?, Craig Hm Donald
Is There A Core Set Of Skills For Visual Analysis Across Different Imaging Technologies?, Craig Hm Donald
Australian Security and Intelligence Conference
This research examines the technological challenges posed by security imaging technologies for human visual analysis of images. Imaging technologies are increasing becoming part of an overall security strategy that incorporates a range of camera technologies, x-ray technologies, and other electromagnetic imaging such as millimetre wave and terahertz based systems. Still and video image types are increasingly becoming presented to viewers or screeners in forms that are only representative in nature and highly abstract, and the use of filters is increasing the complexity of interpretation. Despite a range of factors that are being looked at to enhance visual analysis, the contribution …
Scaling Relations And Overabundance Of Massive Clusters At Z ≳ 1 From Weak-Lensing Studies With The Hubble Space Telescope, M J. Jee, Ks Dawson, H Hoekstra, S Perlmutter, P Rosati, M Brodwin, N Sukuzi, B Koester, M Postman, L Lubin, J Meyers, Sa Stanford, K Barbary, F Barrientos, P Eisenhardt, Hc Ford, Dg Gibank, Md Gladders, A Gonzalez, Dw Harris, Xiaosheng Huang, C Lidman, Es Rykoff, D Rubin, Al Spadafora
Scaling Relations And Overabundance Of Massive Clusters At Z ≳ 1 From Weak-Lensing Studies With The Hubble Space Telescope, M J. Jee, Ks Dawson, H Hoekstra, S Perlmutter, P Rosati, M Brodwin, N Sukuzi, B Koester, M Postman, L Lubin, J Meyers, Sa Stanford, K Barbary, F Barrientos, P Eisenhardt, Hc Ford, Dg Gibank, Md Gladders, A Gonzalez, Dw Harris, Xiaosheng Huang, C Lidman, Es Rykoff, D Rubin, Al Spadafora
Physics and Astronomy
We present weak gravitational lensing analysis of 22 high-redshift (z 1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other high-z clusters, we compare gravitational lensing masses of these clusters with other observables. We revisit the question whether the presence of the most massive clusters in our sample is in tension with the current ΛCDM structure formation paradigm. We find that the lensing masses are tightly correlated with the …
Grb071028b, A Burst Behind Large Amounts Of Dust In An Unabsorbed Galaxy, C. Clemens, J. Greiner, T. Krühler, D. Pierini, S. Savaglio, S. Klose, P.M.J. Afonso, R. Filgas, F.E. Olivares, A. Rau, P. Schady, A. Rossi, A. Küpcü Yoldas, Adria Updike, A. Yoldas
Grb071028b, A Burst Behind Large Amounts Of Dust In An Unabsorbed Galaxy, C. Clemens, J. Greiner, T. Krühler, D. Pierini, S. Savaglio, S. Klose, P.M.J. Afonso, R. Filgas, F.E. Olivares, A. Rau, P. Schady, A. Rossi, A. Küpcü Yoldas, Adria Updike, A. Yoldas
Arts & Sciences Faculty Publications
No abstract provided.
Grb 091127: The Cooling Break Race On Magnetic Fuel, R. Filgas, J. Greiner, P. Schady, T. Krühler, Adria Updike, S. Klose, M. Nardini, D.A. Kann, A. Rossi, V. Sudilovsky, P.M.J. Afonso, C. Clemens, J. Elliott, A. Nicuesa Guelbenzu, F. Olivares E., A. Rau
Grb 091127: The Cooling Break Race On Magnetic Fuel, R. Filgas, J. Greiner, P. Schady, T. Krühler, Adria Updike, S. Klose, M. Nardini, D.A. Kann, A. Rossi, V. Sudilovsky, P.M.J. Afonso, C. Clemens, J. Elliott, A. Nicuesa Guelbenzu, F. Olivares E., A. Rau
Arts & Sciences Faculty Publications
No abstract provided.
The Two-Component Jet Of Grb 080413b, R. Filgas, T. Krühler, J. Greiner, A. Rau, E. Palazzi, S. Klose, P. Schady, A. Rossi, P. M.J. Afonso, L. A. Antonelli, C. Clemens, S. Covino, P. D’Avanzo, A. Küpcü Yoldas, M. Nardini, A. Nicuesa Guelbenzu, F. Olivares, Adria Updike, A. Yoldas
The Two-Component Jet Of Grb 080413b, R. Filgas, T. Krühler, J. Greiner, A. Rau, E. Palazzi, S. Klose, P. Schady, A. Rossi, P. M.J. Afonso, L. A. Antonelli, C. Clemens, S. Covino, P. D’Avanzo, A. Küpcü Yoldas, M. Nardini, A. Nicuesa Guelbenzu, F. Olivares, Adria Updike, A. Yoldas
Arts & Sciences Faculty Publications
Aims. The quick and precise localization of GRBs by the Swift telescope allows the early evolution of the afterglow light curve to be captured by ground-based telescopes. With GROND measurements we can investigate the optical/near-infrared light curve of the afterglow of gamma-ray burst 080413B in the context of late rebrightening. Methods. Multi-wavelength follow-up observations were performed on the afterglow of GRB 080413B. X-ray emission was detected by the X-ray telescope onboard the Swift satellite and obtained from the public archive. Optical and near-infrared photometry was performed with the seven-channel imager GROND mounted at the MPG/ESO 2.2 m telescope and additionally …