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Evaluation of the EPIC flux cross-calibration from 2XMM sources

Evaluation of the EPIC flux cross-calibration from 2XMM sources. R. Saxton, S. Mateos, A. Read, S. Sembay. Mateos et al., 2009, A&A, arXiv.0901.4026. 2XMM sources. pn vs MOS1 energy dependence. Distributions of flux ratios fitted with Gaussian profiles:. MOS1 vs MOS2 energy dependence.

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Evaluation of the EPIC flux cross-calibration from 2XMM sources

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  1. Evaluation of the EPIC flux cross-calibrationfrom 2XMM sources R. Saxton, S. Mateos, A. Read, S. Sembay Mateos et al., 2009, A&A, arXiv.0901.4026

  2. 2XMM sources

  3. pn vs MOS1 energy dependence Distributions of flux ratios fitted with Gaussian profiles: MOS1 vs MOS2 energy dependence

  4. pn vs MOS1:energy dependence pn / MOS agreement better than 3% in 0.2-0.5 keV band 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV ~constant offset from MOS cameras of 7-9% from 0.5-4.5 keV pn / MOS agreement worse above ~4.5 keV (12.5%)

  5. MOS1 vs MOS2:energy dependence 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV MOS cameras agree to better than 4% at all energies

  6. pn vs MOS1:offaxis dependence 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV Variations of MOS vs pn relative flux calibration vs offaxis ARF effect: • QE: spatial variation in QE offaxis (MOS and pn) • Vignetting: General vignetting function • PSF: Uncertainties in offaxis PSF

  7. Azimuthal dependence - PN v MOS-2 1 4 2 4 1 3 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV 3 2 Strong azimuthal-angle dependence at high energies

  8. RGA obscuration: Azimuthal dependence Excluded sources at offaxis<2 arcmin B-4 B-4 1 4 B-4 B-4 B-4 2 4 1 3 B-5 B-5 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV Sources divided in 4 azimuthal angle bins based on DETX/DETY coordinates 3 2 Strong azimuthal angle dependence at high energies Sources lying along the RGA dispersion axis show a large gradient in relative flux Calibration of RGA blocking factor incorrect at high energies?

  9. RGA obscuration: Azimuthal depencence Excluded sources at offaxis <2 arcmin 1 4 B-5 B-4 B-4 B-4 2 4 1 B-5 B-4 3 B-5 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV Sources divided in 4 azimuthal angle bins based on DETX/DETY coordinates 3 2 Strong azimuthal angle dependence at high energies Sources lying along the RGA dispersion axis show a large gradient in relative flux Calibration of RGA blocking factor incorrect at high energies?

  10. Current azimuthal vignetting factor for MOS-1 1.5 keV @ 9 amin offax 9 keV @ 9 amin offax

  11. Low-energy azimuthal dependence: MOS-1 Excluded sources at offaxis< 2arcmin 1 4 B-5 B-4 B-4 B-4 2 4 1 B-5 B-4 3 B-5 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV Sources divided in 4 azimuthal angle bins based on DETX/DETY coordinates 3 2 Strong azimuthal angle dependence at low energies Sources lying on CCDs from different batches show a large gradient in relative flux

  12. Low-energy azimuthal dependence: MOS-2 Excluded sources at offaxis<2 arcmin B-4 B-4 1 4 B-4 B-4 B-4 2 4 1 3 B-5 B-5 1:0.2-0.5 keV 2:0.5-1 keV 3:1-2 keV 4:2-4.5 keV 5:4.5-12 keV Sources divided in 4 azimuthal angle bins based on DETX/DETY coordinates 3 2 Smallish azimuthal angle dependence at low energies. Batch effect not so strong here ?

  13. Consistent improvements in the MOS2/pn flux ratio, with some evidence for similar improvements for MOS1/pn Large scatter, low stats at very lowest energy so far

  14. Conclusions • Excellent agreement of the two MOS cameras (<4%) at all energies • MOS cameras register 7-9% higher flux than pn below 4.5 keV 10-13% flux excess at the highest energies • No evolution of flux ratios with time except in the 0.2-0.5 keV band Gradual degrading of the MOS redistribution function • MOS to pn excess increases with offaxis: ARF effect • Strong dependency of MOS to pn excess 4.5-12 keV flux on azimuthal-angle

  15. TO DO • Fudge RGA obscuration to give larger azimuthal effect for MOS’s at high energies ? Use SCISIM to justify physical parameters ? • Put in a batch-specific, low-energy QE contribution for MOS-CCDs ? • 2XMM could benefit from: - MOS RMFs made spatially, temporally dependent. - EBG PSF ? - Spectral dependence in flux calculation • Strong dependency of MOS to pn excess 4.5-12 keV flux on azimuthal-angle Calibration of RGA blocking factor (RGA absorption) incorrect at high energies?

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