Calibration of the
                    <i>Rossi X‐Ray Timing Explorer</i>
                    Proportional Counter Array

Jahoda, K.; Markwardt, C.; Radeva, Y. L.; Rots, A. H.; Stark, M. J.; Swank, J. H.; Strohmayer, Tod E.; Zhang, William

doi:10.1086/500659

Cited by 596 publications

(691 citation statements)

References 35 publications

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“…The 16 years of mainly bi-weekly Cyg X-1 observations (1996-2011) with Rossi X-ray Timing Explorer's (RXTE's) Proportional Counter Array (PCA; Jahoda et al 2006) and High Energy X-ray Timing Experiment (HEXTE; Rothschild et al 1998) allowed us to study the long term spectral and X-ray timing evolution of the source in unprecedented detail in the previous papers of the series (Pottschmidt et al 2003;Gleissner et al 2004b,a;Wilms et al 2006;Grinberg et al 2013Grinberg et al , 2014. In this paper, we use these data to analyze the orbital variability of absorption due to the focussed wind.…”

Section: Introductionmentioning

confidence: 99%

Long term variability of Cygnus X-1

Grinberg

Leutenegger

Hell

et al. 2015

A&A

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Binary systems with an accreting compact object offer a unique opportunity to investigate the strong, clumpy, line-driven winds of early-type supergiants by using the compact object's X-rays to probe the wind structure. We analyze the two-component wind of HDE 226868, the O9.7Iab giant companion of the black hole Cyg X-1, using 4.77 Ms Rossi X-ray Timing Explorer (RXTE) observations of the system taken over the course of 16 years. Absorption changes strongly over the 5.6 d binary orbit, but also shows a large scatter at a given orbital phase, especially at superior conjunction. The orbital variability is most prominent when the black hole is in the hard X-ray state. Our data are poorer for the intermediate and soft state, but show signs for orbital variability of the absorption column in the intermediate state. We quantitatively compare the data in the hard state to a toy model of a focussed Castor-AbbottKlein wind: as it does not incorporate clumping, the model does not describe the observations well. A qualitative comparison to a simplified simulation of clumpy winds with spherical clumps shows good agreement in the distribution of the equivalent hydrogen column density for models with a porosity length on the order of the stellar radius at inferior conjunction; we conjecture that the deviations between data and model at superior conjunction could either be due to lack of a focussed wind component in the model or to a more complicated clump structure.

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Section: Introductionmentioning

confidence: 99%

Long term variability of Cygnus X-1

Grinberg

Leutenegger

Hell

et al. 2015

A&A

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“…the root-mean-square amplitude of the unmodeled deviations is ∼0.02−0.03 cnts/s/PCU/beam in the 3−8 keV energy band, which corresponds to ∼3 × 10 −13 erg s −1 cm −2 deg −2 for a Crab-like spectrum (e.g. Markwardt et al 2002;Jahoda et al 2006, see also Fig. 1), or ∼2−3% of the average CXB intensity.…”

Section: Background Subtractionmentioning

confidence: 94%

“…We similarly analyzed observations of the Crab nebula, 6 background pointings (see Jahoda et al 2006) and "dark" Earth 1 .…”

Section: Rxte/pca Slew Datamentioning

confidence: 99%

“…The efficiency of the PCA detectors slightly changed during the large time span considered here (1996−2007) for different reasons, including slow drift of the energy scale of the detectors and a slight change of the gas purity or pressure within the signal volumes (see e.g. Jahoda et al 2006). This small (∼5%) drift of the detector effective area manifests itself in the measured count rates from the Crab, a constant X-ray source which has been regularly observed by RXTE (see Fig.…”

Section: Drift In the Detector Parametersmentioning

confidence: 99%

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Large-scale variations of the cosmic X-ray background and the X-ray emissivity of the local Universe

Revnivtsev

Molkov

Sazonov

2008

A&A

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We study the cosmic X-ray background (CXB) intensity variations on large angular scales using the slew data from the RXTE observatory. We detect intensity variations up to ∼2% on angular scales of 20−40 • . These variations are partly correlated with the local large-scale structure, which allowed us to estimate the emissivity of the local Universe in the energy band 2−10 keV at (8 ± 4) × 10 38 h 75 erg s −1 Mpc −3 . The spectral energy distribution of the large-angular-scale variations is hard and is compatible with that of the CXB, which implies that normal galaxies and clusters of galaxies, whose spectra are typically much softer, do not contribute more than 15% to the total X-ray emissivity of the local Universe. Most of the observed CXB anisotropy (after exclusion of point sources with fluxes > ∼ 10 −11 erg s −1 cm −2 ) can be attributed to low-luminosity AGNs.

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“…Both instrument packages consist of proportional counters with similar efficiency curves and spectral resolution (20% full-width at half maximum), and bandpasses that start at 2 keV. The PCA (Jahoda et al 2006) consists of 5 proportional counter units (PCUs) that each have a propane-filled and a xenon-filled gas layer. The xenon layer is the main detector and is read out at high time and energy resolution between 2 and 60 keV.…”

Section: Search For Superexpansion Burstsmentioning

confidence: 99%

Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion

Zand¹,

Weinberg

2010

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A small subset of thermonuclear X-ray bursts on neutron stars exhibit such a strong photospheric expansion that for a few seconds the photosphere is located at a radius r ph > ∼ 10 3 km. Such "superexpansions" imply a large and rapid energy release, a feature characteristic of pure He burst models. Previous calculations have shown that during a pure He burst, the freshly synthesized heavy-element ashes of burning can be ejected in a strong radiative wind and produce significant spectral absorption features. We search the burst data catalogs and literature and find 32 superexpansion bursts, 24 of which were detected with BeppoSAX and three with RXTE at high time resolution. We find that these bursts exhibit the following interesting features: (1) At least 31 are from (candidate) ultracompact X-ray binaries in which the neutron star accretes hydrogen-deficient fuel, suggesting that these bursts indeed ignite in a helium-rich layer. (2) In two of the RXTE bursts we detect strong absorption edges during the expansion phase. The edge energies and depths are consistent with the H-like or He-like edge of iron-peak elements with abundances > ∼ 100 times solar, suggesting that we are seeing the exposed ashes of nuclear burning. (3) The superexpansion phase is always followed by a moderate expansion phase during which r ph ∼ 30 km and the luminosity is near the Eddington limit. (4) The decay time of the bursts, τ decay , ranges from short (≈10 s) to intermediate ( > ∼ 10 3 s). However, despite the large range of τ decay , the duration of the superexpansion is always a few seconds, independent of τ decay . By contrast, the duration of the moderate expansion is always of order τ decay . (5) The photospheric radii r ph during the moderate expansion phase are much smaller than steady state wind models predict. We show that this may be further indication that the wind contains highly non-solar abundances of heavy elements.

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Calibration of the Rossi X‐Ray Timing Explorer Proportional Counter Array

Cited by 596 publications

References 35 publications

Long term variability of Cygnus X-1

Long term variability of Cygnus X-1

Large-scale variations of the cosmic X-ray background and the X-ray emissivity of the local Universe

Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion

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