The XMM-Newton Slew Survey

1. The XMM-Newton Slew Survey Richard Saxton1, M. Pilar Esquej1, Andy Read2, Michael Freyberg3, Bruno Altieri1, Diego Bermejo4, Veronica Lazaro4, Pedro Rodriguez1 1 ESAC 2 University of Leicester, U.K. 3 MPE, Garching, Germany 4 University of Madrid, Spain

2. Overview - 390 slew datasets in archive (since Rev 314) - PN, MOS-1/2 exposures in Medium filter with the observing mode set to that of previous pointed observation - Average slew length is 70 degrees - Data available for slews longer than 30 mins duration - Closed slew, open slew, closed slew. Open slew speed = 90 degrees / hour, i.e. on-source time ~14 secs - Area covered to date ~10000 deg2 (~25% of sky)

3. Initial impressions We can process slew data with a small s/w change (available in SAS 6.5) PN PN (eFF) MOS Slew direction Extended full frame streak of 18 arcsecs Source extended into a 4 arcmin streak due to 2.6 second frame time New operations strategy: • MOS slews will be used for calibration • All PN slews longer than 15 mins will be down-linked and processed and used for science • Medium filter if FF,EFF,LW and Closed for other modes Full frame (73ms) mode streak = 6 arcsecs – not noticeable Extra pn sensitivity + additional MOS background means little to be gained from analysing MOS slews Epic-pn attitude reconstruction good

4. Extended source analysis Source 2: 2x2 arcmin Low background and tight PSF gives good sensitivity To extended sources FF mode point sources are fitted well by a PSF, e.g. source 4 Enough counts to detect extension in brightest sources

5. Example extended sources Abell 3581 2 SNRs in SMC Easily detected as extended in 14 second exposure

6. Processing strategy Tangential projection not valid over whole slew. Divide slew into 1 deg2 images and recalculate sky positions. Source search using near-standard pipeline eboxdetect/emldetect combination tuned for ~zero background. Use sources with DET_ML > 10 equivalent to 3.9 sigma Search independently in three bands and produce three catalogues - soft (0.2-2 keV) - hard (2-12 keV) - total (0.2-12 keV)

7. UY Vir Total band (0.2-12 keV) DSS Image 2’×2’ Soft band (0.2-2 keV) Hard band (2-12 keV) (RASS src)

8. (15/05/05) Current Status • Initial processing of 374 slews (297 are FF, eFF or LW) – 20% have high background • Images created and source searched for 106 slews giving • 1407 sources in total band • 1144 sources in soft (0.2-2.0 keV) band • 223 sources in hard (2.0-12.0 keV) band • At faint end, 157 soft-band and • 57 hard-band sources, not detected in the total band • Total of 1600 sources in ~3500 deg² ~0.5 sources per square degree • 60% have RASS counterpart Completeness * Including high background slews

9. Survey Characteristics Source Count Distribution Exposure Time Distribution Minimum @ ~ 4 counts Maximum @ ~ 10 seconds - Can calculate flux limits for the XMM-Slew survey

10. Flux limits RASS 5.0x10-13 (92% of sky) EMSS 3.0x10-12 (2% 0f sky) HEAO-1 3.6x10-11 (all-sky) Exosat 5.0x10-11 (?% of sky) RXTE 1.0x10-11 (all-sky), but with only 1° positional accuracy

11. Astrometry Blue squares: Number of 2MASS sources vs. distance to slew source Green diamonds: Equivalent distribution for random sky positions (same number of sources) Red triangles: Difference in distributions i.e. Blue minus Green Pointing accuracy of Slew survey ~6″ … but long tail…?

12. Attitude Problem Two types of positional error (1) Real error of ~6″ (2) Error of 0-60″ (mean 30″) but only in slew direction AB Dor Slew direction ‘Error ellipse’ around source (slew-oriented) Optimistically we can remove error (2) by re-processing the raw attitude data (RAF) A timing error of 1 sec = 90”. Timing supposed to be good to 10 ms while individual attitude points expected to be ok to within 10”.

13. Correlations with ROSAT Mean XMM/ROSAT=6.2 Mea Mean XMM/ROSAT = 6.2 ROSAT XMM soft

14. Correlations with ROSAT All Slew sources: Hardness ratio vs Galactic latitude Green circles: No RASS counterpart Red crosses: RASS counterpart Hard sources not seen by ROSAT RASS sources on average softer than non-RASS sources

15. Schedule - Initial processing of slew data(finished) - Solve attitude/astrometry problems – asap - Creation of images, source searching, rejection of spurious sources(Feb to July) - Investigate optimum extended source extraction methods(April to Oct) - Creation of final catalogue for ingestion into XSA (Aug to Oct) - Ingestion into XSA (end of November) - Provide flux / upper limits server (early 2006) • Search co-added slews (?) • Investigate going down to DET_ML=8 (?) - Regular updates with newly processed slews

16. Conclusions from current Slew analysis • - 106 Slews source-searched (using best strategies): • 1600 sources found in 3500 deg² (~9% of sky) • ~0.5 sources per square degree • - Soft X-ray band detection limit close to ROSAT BS cat • Hard X-ray band detection limit deepest ever • Good sensitivity to extended sources, investigating optimum detection techniques • - XMM-Slew positional accuracy ~6″ • Additional ‘attitude-error’ (30″ mean), but only along slew • Hopeful that this attitude error can be drastically reduced • Aim to recover science from high-background slews • Aim to issue first slew source catalogue before end of 2005 • - Encountering & solving problems en route – Still on schedule…

18. Detector problems Detector map shows events Confined to 1 CCD. Affects one CCD so must be detector related Often appear as non-single events Very soft spectrum with a peak at 100 eV Events occur within 1 frame

19. Spurious Sources… Sources 1 & 3 of Pilot#1 … due to crab off-axis !

20. Well Known Sources N132D