1. Swift/BAT Census of Black Holes Preliminary results in Markwardt et al 2005 35' energy coded color

2. Why is the Swift/BAT census of Black Holes so good? Hard X-rays are a unique signature of an accreting black hole hard X-ray Image UV image joint spectra BAT XRT X-ray Image complete x-ray follow- up with Swift/XRT and UVOT The last all-sky hard X-ray survey was HEAO1 in 1977– BAT is 17 times more sensitive. –detect rare sources –high galactic latitudes for optical follow-up hard X-rays unaffected by absorption yielding a complete census

3. Burst Alert Telescope (BAT) BAT Detector Array Coded Aperture Mask BAT Characteristics hard X-ray energies similar to medical X-rays wide field of view (100°X70°) 1/8 of the whole sky resolution 22 arcmin = 300000 independent pixels whole sky Location accuracy <5 arcmin Spectroscopy (~10%)

4. Stacking of Images in Sky Coordinates Single Snapshot (<40 min)

5. Stacking of Images in Sky Coordinates Ten Snapshots (~5.5 hours)

6. Stacking of Images in Sky Coordinates One Calendar Day Sun Anti-sun

7. 9-month Survey Sky Coverage > 1.5 Ms 1-1.5 Ms 0.5-1 Ms Ecliptic Plane

8. 9-month Sensitivity vs. Exposure extragalactic BAT sources are easily to identify at high latitudes –very bright IR galaxy –low redshift (z<0.06) –optical AGN –high X-ray absorption (XRT) With time, the survey will keep detecting more sources. A longer survey also makes better spectra for the previously detected sources. 8.5 mCrab (T/20 ks) -0.5

9. 9 months --------------------- 323 sources 39 unidentified sources 158 galactic 5 galaxy clusters 158 AGN 16 beamed |Galactic b| >15 (74%) ---------------------- 159 sources 9 unidentified sources 29 galactic 2 galaxy clusters 121 AGN 15 beamed already the most sensitive all-sky hard x-ray survey At 3 years expect 450 AGN. BAT Source Detections

10. BACKUP SLIDES

11. BAT GALAXY Identifications 70% of the galaxies with no Sy classification are absorbed. Most unknown galaxies are absorbed Sy2's or edge on spiral galaxies with no lines (3 with no spectroscopy) Sy2/Sy1 ratio is 1.2 (0.5 Sy1.5/Sy1) and 52% of Seyfert galaxies are absorbed confirming Markwardt et al 2005 Much lower than 75% predicted by the standard model for the CXB absorbed Log nH > 22 |Gal b| >15 abs unabs total Sy1 3 31 34 Sy1.5 5 11 16 Sy2 36 3 40 no Sy ID 9 4 13 total 53 49 103

12. Swift/BAT AGN

13. Swift/BAT survey: a Census of AGN What do you need for an accurate census? It must be unbiased –cover whole country –must not discriminate against minorities It must be a statistically significant sample

14. BAT Time Histories

15. BAT Imaging  Cross correlate mask aperture pattern with detector image (search all possible points on sky) DPI Aperture Pattern batfftimage Sky Image

16. Astronomy Misconceptions of BAT imaging No focusing optics Each detector can be illuminated by many points on the sky; and Each point on the sky illuminates many detectors Two distinct spaces: –Detector space –Sky space Transform between two spaces with special cross-correlation software Normally background dominated –1 Crab = ~10% of background Detector Space Sky Space