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X-ray selected z>3 QSOs in the XMM-COSMOS field

Explore the population of z>3 QSOs in the XMM-COSMOS field through X-ray observations, revealing intriguing properties and challenges for structure formation models. Learn about pioneering X-ray works on high-z QSOs, redshift predictions, X-ray source compilation, AGN properties, and source counts from the X-ray Universe research.

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X-ray selected z>3 QSOs in the XMM-COSMOS field

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  1. X-ray selected z>3 QSOs in the XMM-COSMOS field Marcella Brusa (MPE) The XMM-COSMOS and COSMOS teams .. and in particular: A. Comastri, R. Gilli, G. Hasinger, K. Iwasawa, V. Mainieri,M. Mignoli, M. Salvato, G. ZamoraniA. Bongiorno, N. Cappelluti, F. Civano, F. Fiore, A. Merloni, J. Silverman, J. Trump, C. Vignali, P. Capak, M. Elvis, O. Ilbert, C. Impey, S. Lilly Granada - X-ray Universe 2008

  2. Why high-z AGNs are interesting? locally: MBH~0.0013MBulge SDSS QSO z>6 => MBH~3-7109MSun (Willott +03)  Either M~1012MSunbulges are in place at z>6 or the MBH-Bulges-properties relationships must break down at high-z Forming (enough) 109-10MSun BHs and (possibly) 1012MSun Bulges at z>6 can be a challenge for models of structure formation. As well as forming metals and dust. Strong constraints on cosmological models adapted from Ferrarese & Merritt 2000, Gebhardt et al. 2000 Granada - X-ray Universe 2008

  3. X-rays from High-z QSOs 1990-1994: pioneering works with ROSAT Wilkes+92 Elvis+94 Bechtold+94 (record QSO z=4) 2002-2005: Chandra/XMM contribution Follow-up of optically SDSS QSOs Brandt+02 Mathur+02 Vignali+03,05 (record QSO z=6.4) 2015-2020: XEUS … ? record z = 10? Vignali+05 Granada - X-ray Universe 2008

  4. The population of z>3 QSO • Radio QSO • (Wall et al., 2005) • Optical QSOs • (Schmidt+95, Fan+01,04, • Richards+06) • Exponential decline in space density • at z=2.7 • X-ray: What happens at z>3? • decline or ~costant ? • Soft X-ray ROSAT/Chandra/ XMM • (Hasinger, Miyaji & Schmidt 2005) • Chandra/ROSAT • (Silverman et al. 2005/2008) • statistics still low at z~3-5 (NO statistics at z>6) XMM Chandra ROSAT ? eROSITA XEUS Granada - X-ray Universe 2008

  5. 1608 soft 0.5-2.0 keV 1103 medium 2.0-4.5 keV 250 hard 4.5-10.0 keV Cosmos Survey 2deg2 (PI: N. Scoville) with deep multiwavelength coverage at all lambda XMM-COSMOS survey (PI: G. Hasinger) Mosaic of 55 XMM observations, 1.4 Ms ~35 ks average One of the main goal: “Characterization of The z>3 QSO population” Hasinger+07, Cappelluti+07 See poster by Nico Cappelluti Granada - X-ray Universe 2008

  6. z>3 QSO counts: expectations at S(0.5-2 keV) >1e-15 cgs Predictions: (from XRB models Gilli, Comastri & Hasinger 07) unabs+abs 30 deg-2(exponential cutoff at z.2.7) Schmidt et al. 1995 80 deg-2(constant evolution extrapolating Hasinger+05 / La Franca+05 LF) Models from Gilli+07 Granada - X-ray Universe 2008

  7. XMM-COSMOS sources redshifts compilation from ongoing spectroscopic projects[IMACS/Magellan+VLT/ESO + SDSS + literature data] • Flux limited sample (50% of the area coverage in at least one band) at 10-15 cgs • 1651 XMM sources <10% problematic ID thanks to IR+Chandra info • ~670 “secure” spectroscopic redshifts (40%) • Incompleteness especially for high-z and Type 2 AGN Blue = BL AGN Black = ALL AGN (adapted from Brusa et al. 2007 ApJS) Granada - X-ray Universe 2008

  8. AGN photometric redshifts Photo-z computed using >30 bands: SDSS, Subaru including IB, CFHT, J, K, IRAC.. • LESS than 10% catastrophic outliers • (to be compared with • COMBO-17, Wolf et al. 2004) Salvato et al. (in prep) Granada - X-ray Universe 2008

  9. AGN redshift distribution in XMM-COSMOS X-ray sample (AGN) Empty: specz+photz Filled: specz z>3 sample: 40 objects (22 specz + 18 photoz) Additional 14 objects, no photoz available. Candidates very high-z AGN (EXOs, Koekemoer et al. 2004) Brusa et al. ApJ submitted Granada - X-ray Universe 2008

  10. BALQSO QSO2? QSO2 BALQSO Optical spectra (from VIMOS and IMACS) Granada - X-ray Universe 2008

  11. Photometric redshifts Granada - X-ray Universe 2008

  12. General properties Magnitude distribution: I=20-26 (25% I>24) Luminosities distribution: Log(Lx) = 44 - 45 ACS image, 15”x15” I=23.5 Granada - X-ray Universe 2008

  13. Optical colors Color color selection v-I vs. b-v (proposed, e.g. in Casey et al. 2008, Siana et al. 2007) Lower-z (0-2) Interm-z (2-3) High-z (>3) locus 8 objects would not have been selected ~40 (magenta/yellow) contaminants Granada - X-ray Universe 2008

  14. X-ray properties logNH<23 HR vs. redshift logNH>23 logNH<23, BL logNH<23 NOT BL • Ratio of obscured/unobscured objects is ~20% Granada - X-ray Universe 2008

  15. Contribution to source counts Lower bound: 22 spectro-z Upper-bound: adding 10 EXOs Dashed line: Expectations from XRB models extrapolating Hasinger+05 LF Solid line: Exponential decay introduced at z=2.7 (Schmidt+95) Flat evolution completely ruled out Tightest constraints to date (largest and cleanest sample) Models: Gilli, Comastri & Hasinger 2007, A&A Granada - X-ray Universe 2008

  16. Space densities Red curve: predictions logLx>44.2 AGN (unobs+obs) [Gilli+07 using Hasinger+05 and La Franca+05] Dashed area: (rescaled) space density for optically selected bright QSO [Richards+2006, Fan+2001] Blue curve: Silverman+08 LF, I<24 sample Granada - X-ray Universe 2008

  17. Summary • Results based only on XMM-COSMOS selection and exploitation of COSMOS database (no need to combine with other X-ray surveys… ) • Flat evolution at z>3 definitively ruled out(space densities & number counts) • 32/40 (80%) X-ray selected quasars would have been selected also by optical color-color criteria (but with a comparable number of low-z contaminants) not a significant population with unusual optical colors… • Sizable sample of obscured AGN (BAL, NL..) Granada - X-ray Universe 2008

  18. What’s next? • High-z quasars:  eROSITA (high-L) ~2500 z>3 QSOs in the “Deep survey”: 400 deg2 on “north+south pole”, F(0.5-2) > 4e-15 cgs ~25000 z>3 QSOs in the All Sky survey: 30.000 deg2 all sky, F(0.5-2) > 1e-14 cgs  XEUS (low-L and very high-redshift)  joint multiwavelength campaigns Synergies with other (big) observatories is mandatory… - PanSTARRS (all sky) + GROND (for faintest sources) - SDSS-like survey? LAMOST ? - (ESO facilities can be used on 200 deg2 – South pole) - LBT/GTC deep U+Bband imaging (on 200 deg2…) - CFHTLS Wide Survey ~100 deg2 (u,g,r,i,z) AB~25-26 Granada - X-ray Universe 2008

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