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Full-Text Articles in Astrophysics and Astronomy
Cooling Of The Crust In The Neutron Star Low-Mass X-Ray Binary Mxb 1659-29, Edward M. Cackett, Rudy Wijnands, Jon M. Miller, Edward F. Brown, Nathalie Degenaar
Cooling Of The Crust In The Neutron Star Low-Mass X-Ray Binary Mxb 1659-29, Edward M. Cackett, Rudy Wijnands, Jon M. Miller, Edward F. Brown, Nathalie Degenaar
Physics and Astronomy Faculty Research Publications
In quasi-persistent neutron star transients, long outbursts cause the neutron star crust to be heated out of thermal equilibrium with the rest of the star. During quiescence, the crust then cools back down. Such crustal cooling has been observed in two quasi-persistent sources: KS 1731-260 and MXB 1659-29. Here we present an additional Chandra observation of MXB 1659-29 in quiescence, which extends the baseline of monitoring to 6.6 yr after the end of the outburst. This new observation strongly suggests that the crust has thermally relaxed, with the temperature remaining consistent over 1000 days. Fitting the temperature cooling curve with …
Investigating The Nature Of Absorption Lines In The Chandra X-Ray Spectra Of The Neutron Star Binary 4u 1820-30, E. M. Cackett, J. M. Miller, J. Raymond, J. Homan, M. Van Der Klis, M. Méndez, D. Steeghs, R. Wijnands
Investigating The Nature Of Absorption Lines In The Chandra X-Ray Spectra Of The Neutron Star Binary 4u 1820-30, E. M. Cackett, J. M. Miller, J. Raymond, J. Homan, M. Van Der Klis, M. Méndez, D. Steeghs, R. Wijnands
Physics and Astronomy Faculty Research Publications
We use four Chandra gratings spectra of the neutron star low-mass X-ray binary 4U 1820-30 to better understand the nature of certain X-ray absorption lines in X-ray binaries, including the Ne II, Ne III, Ne IX, O VII, and O VIII lines. The equivalent widths of the lines are generally consistent between the observations, as expected if these lines originate in the hot interstellar medium. No evidence was found that the lines were blueshifted, again supporting the interstellar medium origin, although this may be due to poor statistics. There is apparent variability in the O VIII Lyα line equivalent width …
Relativistic Iron Emission Lines In Neutron Star Low-Mass X-Ray Binaries As Probes Of Neutron Star Radii, Edward M. Cackett, Jon M. Miller, Sudip Bhattacharyya, Jonathan E. Grindlay, Jeroen Homan, Michiel Van Der Klis, M. Coleman Miller, Tod E. Strohmayer, Rudy Wijnands
Relativistic Iron Emission Lines In Neutron Star Low-Mass X-Ray Binaries As Probes Of Neutron Star Radii, Edward M. Cackett, Jon M. Miller, Sudip Bhattacharyya, Jonathan E. Grindlay, Jeroen Homan, Michiel Van Der Klis, M. Coleman Miller, Tod E. Strohmayer, Rudy Wijnands
Physics and Astronomy Faculty Research Publications
Using Suzaku observations of three neutron star low-mass X-ray binaries (Ser X-1, 4U 1820-30, and GX 349+2) we have found broad, asymmetric, relativistic Fe K emission lines in all three objects. These Fe K lines can be well fit by a model for lines from a relativistic accretion disk (``diskline''), allowing a measurement of the inner radius of the accretion disk and hence an upper limit on the neutron star radius. These upper limits correspond to 14.5-16.5 km for a 1.4 Msolar neutron star. The inner disk radii that we measure with Fe K lines are in good agreement …
Cooling Of The Quasi-Persistent Neutron Star X-Ray Transients Ks 1731-260 And Mxb 1659-29, Edward M. Cackett, Rudy Wijnands, Manuel Linares, Jon M. Miller, Jeroen Homan, Walter H. G. Lewin
Cooling Of The Quasi-Persistent Neutron Star X-Ray Transients Ks 1731-260 And Mxb 1659-29, Edward M. Cackett, Rudy Wijnands, Manuel Linares, Jon M. Miller, Jeroen Homan, Walter H. G. Lewin
Physics and Astronomy Faculty Research Publications
We present Chandra and XMM-Newton X-ray observations that monitor the neutron star cooling of the quasi-persistent neutron star X-ray transients KS 1731-260 and MXB 1659-29 for approximately 4 yr after these sources returned to quiescence from prolonged outbursts. In both sources the outbursts were long enough to significantly heat the neutron star crust out of thermal equilibrium with the core. We analyse the X-ray spectra by fitting absorbed neutron star atmosphere models to the observations. The results of our analysis strengthen the preliminary findings of Wijnands et al. that in both sources the neutron star crust cools down very rapidly …
Xmm-Newton Discovery Of The X-Ray Transient Xmmu J181227.8-181234 In The Galactic Plane, Edward M. Cackett, Rudy Wijnands, Ron Remillard
Xmm-Newton Discovery Of The X-Ray Transient Xmmu J181227.8-181234 In The Galactic Plane, Edward M. Cackett, Rudy Wijnands, Ron Remillard
Physics and Astronomy Faculty Research Publications
We report the discovery of an X-ray transient, observed in outburst with XMM-Newton on 2003 March 20, and with position (J2000, approximate positional error 2arcsec). No known source is present at this position and the source was not detected during published ROSAT or ASCA observations of that region. However, the source may be associated with 1H1812-182 detected by HEAO 1, although the error bars on the HEAO 1 position are very large and the two sources could also be unrelated. Therefore, we name the source XMMU J181227.8-181234. Initially, the source was not detected using the All-Sky Monitor (ASM) on-board the …
A Chandra X-Ray Observation Of The Globular Cluster Terzan 1, E. M. Cackett, R. Wijnands, C. O. Heinke, D. Pooley, W. H. G. Lewin, J. E. Grindlay, P. D. Edmonds, P. G. Jonker, J. M. Miller
A Chandra X-Ray Observation Of The Globular Cluster Terzan 1, E. M. Cackett, R. Wijnands, C. O. Heinke, D. Pooley, W. H. G. Lewin, J. E. Grindlay, P. D. Edmonds, P. G. Jonker, J. M. Miller
Physics and Astronomy Faculty Research Publications
We present a ~19-ks Chandra Advanced CCD Imaging Spectrometer (ACIS)-S observation of the globular cluster Terzan 1. 14 sources are detected within 1.4arcmin of the cluster centre with two of these sources predicted to be not associated with the cluster (background active galactic nuclei or foreground objects). The neutron star X-ray transient, X1732-304, has previously been observed in outburst within this globular cluster with the outburst seen to last for at least 12yr. Here, we find four sources that are consistent with the ROSAT position for this transient, but none of the sources are fully consistent with the position of …
X-Ray Variability During The Quiescent State Of The Neutron Star X-Ray Transient In The Globular Cluster Ngc 6440, Edward M. Cackett, Rudy Wijnands, Craig O. Heinke, Peter D. Edmonds, Walter H. G. Lewin, David Pooley, Jonathan E. Grindlay, Peter G. Jonker, Jon M. Miller
X-Ray Variability During The Quiescent State Of The Neutron Star X-Ray Transient In The Globular Cluster Ngc 6440, Edward M. Cackett, Rudy Wijnands, Craig O. Heinke, Peter D. Edmonds, Walter H. G. Lewin, David Pooley, Jonathan E. Grindlay, Peter G. Jonker, Jon M. Miller
Physics and Astronomy Faculty Research Publications
The globular cluster NGC 6440 is known to harbor a bright neutron star X-ray transient. We observed the globular cluster with Chandra on two occasions when the bright transient was in its quiescent state, in 2000 July and 2003 June (both observations were made nearly 2 yr after the end of their preceding outbursts). The quiescent spectrum during the first observation is well represented by a two-component model (a neutron star atmosphere model plus a power-law component that dominates at energies above 2 keV). During the second observation (which was roughly of equal duration to the first observation) we found …