2009A&A...497..291K


Query : 2009A&A...497..291K

2009A&A...497..291K - Astronomy and Astrophysics, volume 497, 291-310 (2009/4-1)

Effective area calibration of the reflection grating spectrometers of XMM-Newton. I. X-ray spectroscopy of the Crab nebula.

KAASTRA J.S., DE VRIES C.P., COSTANTINI E. and DEN HERDER J.W.A.

Abstract (from CDS):

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. We investigate how the absolute effective area calibration of RGS can be obtained using Crab as a standard candle. 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. 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 FeII 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. 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.

Abstract Copyright:

Journal keyword(s): instrumentation: spectrographs - ISM: abundances - dust, extinction - ISM: supernova remnants - X-rays: ISM - X-rays: individual: Crab

Simbad objects: 13

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Number of rows : 13
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 M 1 SNR 05 34 30.9 +22 00 53           ~ 6120 1
2 V* CM Tau Psr 05 34 31.9474694616 +22 00 52.153698024           ~ 5197 0
3 M 42 HII 05 35 17 -05 23.4           ~ 4036 0
4 NAME Gal Anticenter reg 05 46 +28.9           ~ 890 0
5 * alf CMa B WD* 06 45 09.3041925037 -16 43 00.724740067   8.41 8.44     DA1.9 541 1
6 NAME Vela Pulsar Psr 08 35 20.65525 -45 10 35.1545     15.10     ~ 2283 1
7 NAME Lockman Hole reg 10 45 00.0 +58 00 00           ~ 825 0
8 Mrk 421 BLL 11 04 27.3140835504 +38 12 31.798495872   13.50 12.90 8.31   ~ 2625 1
9 HZ 43A WD* 13 16 21.8532409720 +29 05 55.411186877   12.52 12.66     DAwk 467 0
10 X Sgr X-4 LXB 18 23 40.57 -30 21 40.6   19.06 18.81     ~ 979 1
11 RX J1856.6-3754 Psr 18 56 35.11 -37 54 30.5     25.7     ~ 429 0
12 HD 226868 HXB 19 58 21.6757355952 +35 12 05.784512688 9.38 9.72 8.91 8.42   O9.7Iabpvar 4283 0
13 QSO B2155-304 BLL 21 58 52.0652249880 -30 13 32.118447792   13.36 13.09 12.62   ~ 1708 1

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