Effective area calibration of the reflection grating spectrometers   of XMM-Newton

Kaastra, J. S.; Lanz, T.; Hubený, I.; Paerels, F.

doi:10.1051/0004-6361/200809868

Cited by 5 publications

(3 citation statements)

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“…The authors also provided a model for the latter based on a dominant T ∼ 32 eV black-body plus a T ∼ 63 eV "hot spot," absorbed by an interstellar column, N H ∼ 1.1 × 10 20 cm −2 . More recently, Kaastra et al (2009) published model atmospheres for HZ 43; their "model 2" agrees best with the Beuermann et al photon densities. Finally, Pollock (2004) listed photon power law indices (describing the photon flux density in pht cm −2 s −1 keV −1 ) and galactic columns for several blazars including Mrk 421 and PKS 2155-304.…”

Section: Low Energy Transmission Grating Spectrometermentioning

confidence: 60%

The Far-Ultraviolet Ups and Downs of Alpha Centauri

Ayres

2015

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Four years (2010)(2011)(2012)(2013)(2014) of semiannual pointings by Hubble Space Telescope Imaging Spectrograph (STIS) on nearby Alpha Centauri have yielded a detailed time history of far-ultraviolet (FUV: 1150-1700Å) emissions of the solar-like primary (A: G2 V) and the cooler, but more active, secondary (B: K1 V). This period saw A climbing out of a prolonged coronal X-ray minimum, as documented contemporaneously by Chandra, while B was rising to, then falling from, a peak of its long-term (∼ 8 yr) starspot cycle. The FUV fluxes of the primary were steady over most of the STIS period, although the [Fe XII] λ1242 coronal forbidden line (T ∼ 1.5 MK) partly mirrored the slowly rising X-ray fluxes. The FUV emissions of the secondary more closely tracked the rise and fall of its coronal luminosities, especially the "hot lines" like Si IV, C IV, and N V (T ∼ 0.8-2 × 10 5 K), and coronal [Fe XII] itself. The hot lines of both stars were systematically redshifted, relative to narrow chromospheric emissions, by several km s −1 , showing little change in amplitude over the 4-year period; especially for α Cen B, despite the significant evolution of its coronal activity. Further, the hot lines of both stars, individually and epoch-averaged, displayed non-Gaussian shapes, which most trivially could be decomposed into two components, one narrow (FWHM ∼ 25-45 km s −1 ), the other broad (60-80 km s −1 ). The bimodal Gaussian strategy had been applied previously to the α Cen stars, but this was the first opportunity to evaluate any time dependence. In fact, not much variation of the component properties was seen, even over the major cycle changes of B. Curiously, the line fluxes were about equally divided between the narrow and broad components for both stars. The fact that there is minimal activitydependence of the narrow/broad flux partition, as well as densities derived from O IV] line ratios, either during the cycle evolution of B, or between A and B, suggests that there is a dominant "quantum" of FUV surface activity that is relatively unchanged during the cycle, aside from the fractional area covered.The Chandra High-Resolution Camera (HRC) imaging of α Cen AB up to mid-2013 has been described by Ayres (2014), where details concerning the instrument configurations and data analysis can be found. Since that study, two additional Chandra pointings have been carried out, in late-2013 and mid-2014. These are summarized in Table 1. The new L X /L bol ratios, together with the previous time series, are illustrated in Figure 1.The solar values in Fig. 1 are 81 day averages (three rotations), over Cycles 23 and (beginning of) 24; error flags are 1 σ standard deviations of the daily measurements in each 81 day bin, a rough measure of temporal variability. A three-cycle average is shaded gray, projected into the future as dashed curves, highlighting the unusual extended minimum of Solar Cycle 23. Larger solid dots represent X-ray fluxes of α Cen AB from the Chandra HRC pointings (Y2000 and later) and four earlier epochs from the R...

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Section: Low Energy Transmission Grating Spectrometermentioning

confidence: 60%

The Far-Ultraviolet Ups and Downs of Alpha Centauri

Ayres

2015

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“…The most recent calibrations of the RGS and pn instruments (see Kaastra et al 2009, for the RGS) show that the uncertainty in the effective area of the RGS can be reduced to 3%, while the pn absolute effective area calibration has an accuracy of 10% 1 . Our aim is to obtain a more accurate relative calibration for RGS and pn.…”

Section: Introductionmentioning

confidence: 99%

The outflow in Mrk 509

Detmers¹,

Kaastra

Costantini³

et al. 2010

A&A

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We analyzed three XMM-Newton observations of the Seyfert 1 galaxy Mrk 509, with the goal of detecting small variations in the ionized outflow properties. Measurements such as these are limited by the quality of the cross-calibration between RGS, the best instrument for characterizing the spectrum, and EPIC-pn, the best instrument for characterizing the variability. For all three observations we are able to improve the relative calibration of RGS and pn consistently to 4%. In all observations we detect three different outflow components and, thanks to our accurate cross-calibration, we are able to detect small differences in the ionization parameter and column density in the highest ionized component of the outflow. This constrains the location of this component of the outflow to within 0.5 pc of the central source. Our method for modeling the relative effective area is not restricted to just this source and can in principle be extended to other types of sources as well.

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“…This paper is the first of a series of three papers. In paper II (Kaastra et al 2008b) we present a new analysis of the X-ray model spectra of the white dwarfs Sirius B and HZ 43. We show in that paper how these models can be used to calibrate the long wavelength absolute effective area of the LETGS of Chandra with an accuracy of a few percent.…”

Section: Introductionmentioning

confidence: 99%

Effective area calibration of the reflection grating spectrometers of XMM-Newton

Kaastra

Vries²,

Costantini

et al. 2009

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Context. The Crab nebula and pulsar have been widely used as a calibration source for X-ray instruments. The in-flight effective area calibration of the Reflection Grating Spectrometers (RGS) of XMM-Newton depend upon the availability of reliable calibration sources. Aims. We investigate how the absolute effective area calibration of RGS can be obtained using Crab as a standard candle. Methods. We have analysed RGS observations of the Crab using different instrument configurations and spatial offsets, and made use of previous determinations of the continuum spectrum of the nebula plus pulsar. Due to the high spectral resolution of the RGS, we resolve the main absorption edges and detect the strong 1s−2p absorption lines of neutral oxygen. Results. We get an excellent fit to the Crab spectrum using this fixed continuum and the absorption spectrum determined by RGS.We get accurate column densities for the neutral atoms of H, N, O, Ne, Mg, and Fe, as well as a clear detection of Fe ii and firm upper limits for other ions. Our data are in good agreement with earlier optical and UV spectroscopic measurements of some of these ions. We find solar abundances for N and O, while Ne is overabundant by a factor of 1.7 and Fe is underabundant by a factor of 0.8. We confirm that there is less dust in the line of sight compared to the prediction based on the absorption column. Our spectra suggest a more prominent role of ferric iron in the dust compared to ferrous iron. Conclusions. Our high-resolution observations confirm that Crab can be used as an X-ray calibration source. RGS spectra have determined the absorption spectrum towards Crab with unprecedented detail.

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Effective area calibration of the reflection grating spectrometers of XMM-Newton

Cited by 5 publications

References 32 publications

The Far-Ultraviolet Ups and Downs of Alpha Centauri

The Far-Ultraviolet Ups and Downs of Alpha Centauri

The outflow in Mrk 509

Effective area calibration of the reflection grating spectrometers of XMM-Newton

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