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Articles 1 - 9 of 9
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 …
Sdss J162520.29+120308.7 – A New Su Ursae Majoris Star In The Period Gap, A. Olech, E. De Miguel, M. Otulakowska, J. R. Thorstensen
Sdss J162520.29+120308.7 – A New Su Ursae Majoris Star In The Period Gap, A. Olech, E. De Miguel, M. Otulakowska, J. R. Thorstensen
Dartmouth Scholarship
We report results of an extensive world-wide observing campaign devoted to the recently discovered dwarf nova SDSS J162520.29+120308.7 (SDSS J1625). The data were obtained during the July 2010 eruption of the star and in August and September 2010 when the object was in quiescence.
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 …
A Fast X-Ray Disk Wind In The Transient Pulsar Igr J17480-2446 In Terzan 5, Jon M. Miller, Dipankar Maitra, Edward M. Cackett, Sudip Bhattacharyya, Tod E. Strohmayer
A Fast X-Ray Disk Wind In The Transient Pulsar Igr J17480-2446 In Terzan 5, Jon M. Miller, Dipankar Maitra, Edward M. Cackett, Sudip Bhattacharyya, Tod E. Strohmayer
Physics and Astronomy Faculty Research Publications
Accretion disk winds are revealed in Chandra gratings spectra of black holes. The winds are hot and highly ionized (typically composed of He-like and H-like charge states) and show modest blueshifts. Similar line spectra are sometimes seen in "dipping" low-mass X-ray binaries (LMXBs), which are likely viewed edge-on; however, that absorption is tied to structures in the outer disk, and blueshifts are not typically observed. Here, we report the detection of blueshifted He-like Fe XXV (3100 ± 400 km s-1) and H-like Fe XXVI (1000 ± 200 km s-1) absorption lines in a Chandra/HETG spectrum of …
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 …
Grb 090426: Discovery Of A Jet Break In A Short Burst Afterglow, A. Nicuesa Guelbenzu, S. Klose, A. Rossi, D.A. Kann, T. Krühler, J. Greiner, A. Rau, F. Olivares E., P.M.J. Afonso, R. Filgas, A. Küpcü Yoldas, S. Mcbreen, M. Nardini, P. Schady, S. Schmidl, Adria Updike, A. Yoldas
Grb 090426: Discovery Of A Jet Break In A Short Burst Afterglow, A. Nicuesa Guelbenzu, S. Klose, A. Rossi, D.A. Kann, T. Krühler, J. Greiner, A. Rau, F. Olivares E., P.M.J. Afonso, R. Filgas, A. Küpcü Yoldas, S. Mcbreen, M. Nardini, P. Schady, S. Schmidl, Adria Updike, A. Yoldas
Arts & Sciences Faculty Publications
Context. The link between the duration of GRBs and the nature of their progenitors remains disputed. Short bursts (with durations of less than ∼2 s) are less frequently observed, technically more difficult to localize, and exhibit significantly fainter afterglows. Aims. It is of critical importance to establish whether the burst duration can reliably distinguish the different GRB population models of collapsars and compact stellar mergers. The Swift GRB 090426 provides an unique opportunity to address this question. Its duration (T90 = 1.28 s) places GRB 090426 firmly in the short burst population, while the high redshift (z = 2.609), host …
On The Nature Of The Extremely Fast Optical Rebrightening Of The Afterglow Of Grb 081029, M. Nardini, J. Greiner, T. Krühler, R. Filgas, S. Klose, P. Afonso, C. Clemens, A. N. Guelbenzu, F. Olivares E., A. Rau, A. Rossi, Adria Updike, A. Küpcü Yoldas, A. Yoldas, D. Burlon, J. Elliott, D. A. Kann
On The Nature Of The Extremely Fast Optical Rebrightening Of The Afterglow Of Grb 081029, M. Nardini, J. Greiner, T. Krühler, R. Filgas, S. Klose, P. Afonso, C. Clemens, A. N. Guelbenzu, F. Olivares E., A. Rau, A. Rossi, Adria Updike, A. Küpcü Yoldas, A. Yoldas, D. Burlon, J. Elliott, D. A. Kann
Arts & Sciences Faculty Publications
Context. After the launch of the Swift satellite, the gamma-ray burst (GRB) optical light-curve smoothness paradigm has been questioned thanks to the faster and better sampled optical follow-up, which has unveiled a very complex behaviour. This complexity is triggering the interest of the whole GRB community. The GROND multi-channel imager is used to study optical and near-infrared (NIR) afterglows of GRBs with unprecedented optical and near-infrared temporal and spectral resolution. The GRB 081029 has a very prominent optical rebrightening event and is an outstanding example of the application of the multi-channel imager to GRB afterglows. Aims. Here we exploit the …
The Swift/Fermi Grb 080928 From 1 Ev To 150 Kev, A. Rossi, S. Schulze, S. Klose, D. A. Kann, A. Rau, H. A. Krimm, G. Jóhannesson, A. Panaitescu, F. Yuan, P. Ferrero, T. Krühler, J. Greiner, P. Schady, S. B. Pandey, L. Amati, P. M.J. Afonso, C. W. Akerlof, L. A. Arnold, C. Clemens, R. Filgas, D. H. Hartmann, A. Küpcü Yoldas, S. Mcbreen, T. A. Mckay, A. Nicuesa Guelbenzu, F. E. Olivares, B. Paciesas, E. S. Rykoff, G. Szokoly, Adria Updike, A. Yoldas
The Swift/Fermi Grb 080928 From 1 Ev To 150 Kev, A. Rossi, S. Schulze, S. Klose, D. A. Kann, A. Rau, H. A. Krimm, G. Jóhannesson, A. Panaitescu, F. Yuan, P. Ferrero, T. Krühler, J. Greiner, P. Schady, S. B. Pandey, L. Amati, P. M.J. Afonso, C. W. Akerlof, L. A. Arnold, C. Clemens, R. Filgas, D. H. Hartmann, A. Küpcü Yoldas, S. Mcbreen, T. A. Mckay, A. Nicuesa Guelbenzu, F. E. Olivares, B. Paciesas, E. S. Rykoff, G. Szokoly, Adria Updike, A. Yoldas
Arts & Sciences Faculty Publications
We present the results of a comprehensive study of the gamma-ray burst 080928 and of its afterglow. GRB 080928 was a long burst detected by Swift/BAT and Fermi/GBM. It is one of the exceptional cases where optical emission had already been detected when the GRB itself was still radiating in the gamma-ray band. For nearly 100 s simultaneous optical, X-ray and gamma-ray data provide a coverage of the spectral energy distribution of the transient source from about 1 eV to 150 keV. In particular, we show that the SED during the main prompt emission phase agrees with synchrotron radiation.We constructed …