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Status of XMM-Newton cross-calibration with SAS-6.1 B.Altieri

Status of XMM-Newton cross-calibration with SAS-6.1 B.Altieri with inputs/support from whole cross-calibration team (XMM SOC, Leicester, MPE ). Talk outline. Response stability at low energies : SNR (extended) AGN view (trend analysis)

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Status of XMM-Newton cross-calibration with SAS-6.1 B.Altieri

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  1. Status of XMM-Newtoncross-calibration with SAS-6.1 B.Altieri with inputs/support from whole cross-calibration team (XMM SOC, Leicester, MPE)

  2. Talk outline • Response stability at low energies : • SNR (extended) • AGN view (trend analysis) • Low-energy problem: effect of the new pn redistribution in SAS-6.1 • Spectral fitting examples on various type of sources • Chandra/Newton cross-calibration • Other cross-calibration problems: • MOS low-energy overestimated redistribution • EPIC high-energy discrepancy • Fudging RGS low-energy (<0.5 keV) effective area proposal • Conclusions

  3. EPIC-pn flux stability: N132D M.P. Esquej • EPIC-pn is stable

  4. EPIC-pn Flux stability: RXJ1856 • Confirmed by the Isolated Neutron star: • EPIC-pn is extremely stable F. Haberl

  5. MOS flux stability: N132D Rev 771 Rev 828 • Rev771: • flux decrease in 0.5-1 keV • Redistributed below 0.4 keV • Rev 828 : • Less clear, especially MOS2, while at the same distance relative to low-E on-axis patch. • Some changes at low energies (0.5-1keV) at ~5% level. • spatial dependent • time dependent

  6. MOS flux stability: N132D (2) • Why MOS’s see more flux deficit in 0.5-1 keV band in rev.771 than rev.828 ? While it is relatively at the same distance from the on-axis patch.

  7. EPIC flux stability: N132D • N132D 0.4-0.8 keV band: • EPIC-pn: • pn flux is stable • pn-LW lower fluxes than pn-SW due to pile-up • MOSs : • MOS1 lower than MOS2 by 5% • Both MOSs have decreased by 6% since launch • MOS2 lower than pn by 10% at launch up to 15% by rev.~800 • MOS1 lower than pn by 15% at launch up to 20% by rev.~800 • But MOS/pn normalisation TBD because of possible small pile-up for MOSs. M.P. Esquej

  8. MOS flux stability: 1ES0102 • 1ES0102 0.4-0.8 keV band: • MOS cameras seems stable in flux since launch but .. • for off-axis positions • also consistent with a 5% decrease. • 10% lower flux observed on-axis where a spatially dependent degraded redistribution has developed (‘patch’) A.M.R. Read

  9. MOS on-axis low-E patch (1) • When the SNR is centered close to on-axis position one observes : • a deficit in 0.35-0.7 keV • an excess below 0.3 keV A.M.R. Read

  10. MOS on-axis low-E patch (2) • MOS low-E patch elongated along the line joining the 2 bore-sights. A.M.R. Read

  11. EPIC Low-energy flux stability :The SNR story • EPIC-pn stable below 2 keV and particularly in the 0.4-0.8 keV band • MOSs were possibly ~10% below EPIC-pn at launch in 0.4-0.8 keV with MOS1 5% lower than MOS2 • MOSs seem to have lost 5%+ since launch, in the 0.4-1 keV band • possibly redistributed to lower energies (< 0.4 keV) where a low-energy patch is observed on-axis.

  12. Flux stability: The AGN view (I) cooling • Sample of AGNs mostly in SW/Medium analysed in 15-40 arcsec annulus used, hence excluding the “MOS patch.” • Low-energy problem : • Either MOSs & RGSs loose flux relative to pn at the same rate : 8% in 800 revs (I) because of : • MOS on-axis redistribution ? • RGS ?? • contamination of MOSs and RGSs, cooler CCDs than pn. • or pn is gaining flux at the same rate (II) : • filters degradation discarded from SNRs • redistribution ? (II) S. Sembay

  13. RGS flux stability: 1ES0102 • RGS flux in 0.4-0.8 keV band consistent with a 5-8% decrease but : • very little flux below 0.55 keV • background subtraction not easy for extended source, ~20% of the flux • not confirmed by Zeta Puppis Nitrogen line flux monitoring (preliminary result, full analysis underway, by A. Pollock) M. Smith red: 0.33-0.7 keV, green: 0.7-0.972 keV, blue: 0.972-1.74 keV • At other energies > 0.7 keV, it seems stable  contamination ? A.Pollock

  14. Interim cross-cal. results • Somewhat contradictory results : • EPIC-pn seems stable • MOS response is changing • loosing flux in 0.4-1 keV- redistributed below 0.4 keV • In the on-axis area (‘patch’) only ? • RGS constant ? Study of RGS stability crucial • MOS: Contamination or redistibution only ? • Exact amount of variations ? • Why RGS and MOS relative calibration is unchanged ? • RGS and MOS CCDs are cooler • mirror contamintion ?

  15. SAS-6.1 : effect of new pn RMF (1) SAS 6.0 SAS 6.1 H1426+428, rev278, single MOS/OM power-law model

  16. H1426: new pn rmf residuals Strange residuals shape below 0.6 keV but could be due to a CTI/gain problem at low energies hence residuals around the O-edge.

  17. SAS-6.1 : effect of new pn RMF (2) M.Kirsch M.Kirsch SAS-6.0 SAS-6.1 • Same 0.5 keV non-physical dip of pn residuals • combined fit is possibly the “truth” ? PKS 2155-504, rev 545

  18. SAS-6.1 : effect of new pn RMF (3) • Another case of “0.5 keV dip” on a continuum spectrum • black : MOS1 • Red: pn SAS-6.0 • Green: pn SAS-6.1 R. Saxton

  19. H1426 second revisit Although the increasing pn/MOS discrepancy could be attributed to MOS … MOS seem to have the right spectral slope at low energies even in late revs Assuming a single power-law from UV to soft X-ray

  20. Early mission : no excess ? • MS0737.9+7441 • (BL Lac) • rev.63 (Cal/PV) • Best fit MOSs • model: wabs *power • very nice agreement overall • No excess of pn wrt to MOS at low energies (pn/MOS=0.95 ! ) R. Saxton

  21. Very soft sources • RXJ 1856 • pn exhibits a strong excess attributed to pile-up from photons below detection threshold. • MOS agree well with Chandra (nH, kT) • EPIC-pn cannot be used on very soft sources

  22. Extremely soft sources • GD153, White Dwarf, kT=25eV, maximum below detection threshold • OM-MOSs can be fitted with a WD SED model • EPIC-pn displays an excess by a factor 2 in the range 0.2-0.3 keV.

  23. Bright (extended) galaxy cluster • Good combined fit overall • 0.5-1 keV : • ~ 10% pn excess • (or MOS deficit) • above 3keV : • >10% MOS excess • pn residuals at Fe-K (CTI or gain)

  24. Hot Compact high-z cluster • Rather good combined fit (but lower statistics) • 0.5-1 keV : • about 15% pn excess • (or MOS deficit) • MOS1: kT=15 keV • MOS2: kT=12 keV • pn : kT=10 keV

  25. MOS vs EPIC-pn • Why MOSs -the apparently varing instrument- is making good or better fits than EPIC-pn -the constant instrument - on various types of objects/spectras at any epoch ?

  26. Newton/Chandra cross-cal.: PKS2155 Rev 362 Rev 545 • LETG agrees very well with MOSs • pn low-energy excess higher in rev.545 Model: wabs*bknpower Best fit: MOSs

  27. Newton/Chandra cross-cal.: 3C273 (1) Rev.277

  28. Newton/Chandra cross-cal.: 3C273 (2) Rev.655 EPIC-pn excess also higher with time MOS/LETG agreement excellent.

  29. Newton/Chandra cross-cal. • MOSs agree very well with Chandra (LETG, HETG & HRC) • RGSs too low in 0.3-0.5 keV • EPIC-pn too high at E < 1 keV wrt too all other instruments.

  30. Zeta Puppis wide cross-correlation • Assuming zeta Puppis is a stable source… • All measurement agree except pn SAS-6.0

  31. RGS low-E effective area • Effective area correction of up to 20% below 0.5 keV suggested by a statistical analysis of BL Lacs (Pollock) • It is unavoidable to be fudged. • The exact function will be based on upcoming Crab observation (special set-up) • This will bring MOSs and RGSs in very good agreement on the whole RGS energy range

  32. MOS low-E redistribution Still too much redistribution at low energies ?

  33. EPIC high-E discrepancy • MOSs return higher fluxes than pn above 3 keV • F5-10 keV (MOS) higher than F5-10 keV(pn) by 10-15% • MOS1 > MOS2 > pn • MOS (MOS1) finds always • Harder spectra (AGNs) • Hotter temperature (galaxy clusters)

  34. Low-energy status • A MOS/RGS deficit wrt EPIC-pn is developing with time at low energies (<1keV) increasing by up to 10% apparently due to a loss of flux from MOS/RGS • Was there a deficit a launch ? • Did the trend accelerate after cooling ? • Is it due to the MOS on-axis degraded response (“patch”)? • If due to contamination why at same rate for MOSs & RGSs ? • Why Chandra agree better with MOSs at any epoch ? • On very soft sources pn shows a strong excesses •  EPIC pn cannot be used for very soft sources • To what extent bright & soft ( >1.7) AGNs are affected ?

  35. XMM-Newton cross-cal. : To do • Document current status with SAS-6.1 • Extend the statistical analysis on AGNs • Investigate possible flux/mode and spatial dependence and spatial of MOS/pn relative calibration. • EPIC-pn redistribution • NRCOs: • Hz43 : comparison with early rev.89 obs. (June 2005) • H1426+428 simultaneously with FUSE (June 2005 ) • Fudge RGS effective area below 0.55 keV • Need for a change of boresight for MOSs ?

  36. The End

  37. H1426+428, rev852, pn fit

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