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Deep Chandra image in the Bo ö tes Field

Deep Chandra image in the Bo ö tes Field. Junxian Wang Johns Hopkins University. 172 ks Chandra exposure on LALA Bo ö tes field. One of the deepest Chandra exposures on extra galactic sky, only 2 Ms CDF-N and 1 Ms CDF-S are substantially deeper. 174 ks Chandra exposure on LALA Cetus field.

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Deep Chandra image in the Bo ö tes Field

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  1. Deep Chandra image in the Boötes Field Junxian Wang Johns Hopkins University

  2. 172 ks Chandra exposure on LALA Boötes field • One of the deepest Chandra exposures on extra galactic sky, only 2 Ms CDF-N and 1 Ms CDF-S are substantially deeper

  3. 174 ks Chandra exposure on LALA Cetus field

  4. 350 X-ray sources detected (346 in 1 Ms CDF-S, 503 in 2 Ms CDF-N), mostly are extragalactic sources harboring super massive black holes. • With NDWFS Bw, R, I, and LALA V, z‘band images, optical counterparts have been found for 90% of the X-ray sources in the Boötes field. • Around 10 R and bluer bands nondetected sources with soft X-ray colors are candidate z >5 AGNs. • Spectroscopic identifications are on-going

  5. Resolves >70% of 2-10 keV background • Variation in X-ray source count, due to large scale structure • Wang et al. 2004, AJ

  6. Deep Chandra imaging on high redshift Ly emitters

  7. Large equivalent widths of LALA Ly emitters • Median EW ~ 240Å (Malhotra & Rhoads 2002) • stellar populations are expected to produce peak equivalent widths 100Å< EWmax<200Å (Charlot & Fall 1993). • Stellar populations with high proportions of young, massive stars (Malhotra &Rhoads 2002) can explain the larger equivalent widths.

  8. The high EWs can also be reproduced by active galactic nuclei, most likely type 2 AGNs, • The broad-lined (type I) AGNs are ruled out because we see no evidence of broad emission lines from either narrow-band imaging or spectroscopy. • Ly line luminosities comparable to those of Type II QSOs • Would be Chandra detectable if they are similar type II QSOs

  9. None of 101 imaged Ly emitters were detected in X-ray individually

  10. Or in stacked images with effective exposure time of 11.2 Ms • Left: all Ly emitters • Right: Ly emitter with Ly  EW > 240Å

  11. Lyman-α to X-ray ratios • Individual Lyman-α emitters are consistent with some but not all Type-II QSOs. • The composite Ly-α to X-ray ratio strongly rules out a large fraction of AGN in the Ly-α sample. Figure from Wang et al 2004, ApJ Letter

  12. Keck/LRIS spectrum of LALA “Boomer”

  13. Conclusion • None of 101 Ly emitters were detected in X-ray • <4.8% of them could be AGNs based on their average Ly to X-ray flux ratio. • No evidence of AGN feature was detected in the optical spectra either (Dawson et al.)

  14. Collaborators • Sangeeta Malhotra, James Rhoads (STScI) • Michael Brown, Arjun Dey, Buell Jannuzi (NOAO) • Steve Dawson, Hy Spinrad (UC Berkeley) • Timothy Heckman, Colin Norman (JHU) • Daniel Stern (CalTech) • Glenn Tiede (BGSU) • Paolo Tozzi (INAF)

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