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IXO and high- z Universe

IXO and high- z Universe. R. Gilli ( INAF – Oss. Bologna) in collaboration with A. Comastri , C. Vignali , F. Marulli , M. Brusa , F. Civano and many others. Two main topics. The first collapsed objects E arly (super)-massive black holes @ z =6-10 How and where do they form?

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IXO and high- z Universe

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  1. IXO and high-z Universe R. Gilli (INAF – Oss. Bologna) in collaboration with A. Comastri, C. Vignali, F. Marulli, M. Brusa, F. Civano and many others

  2. Twomaintopics The first collapsed objects Early (super)-massive black holes @ z=6-10 How and where do they form? Distant hidden AGN BH/galaxy coevolution up to z=4-5 What is the role of heavily obscured AGN?

  3. The first collapsed objects

  4. How and where did they form? BH seeds, light or heavy? Light (~100 Msun): remnants of PopIIIstars (Madau&Rees01) zero metallicity, no mass loss, Mseed~ MpopIII Heavy (~104-5 Msun): direct, monolithic collapse of dense gas clouds (Begelman+06, Koushiappas+04, Volonteri+08). Seed in DM halos: widespread or rare? Widespread: low σpeaks, DM mini-halos (~107Msun) Rare: high σ peaks, “large” DM halos (109-10Msun) Do they drive or follow the formation of early galaxies?

  5. Where do we stand About50QSOs at z>5.8, ~20 at z>6 from SDSS and CFHQS (i-dropout selection) Most are already “mature”: high metallicity and dust content, large BH masses ~108-9Msun(Beelen+06, Juarez +09, Kurk +09) Accretion rate is ~ Eddington MBH/M* larger than in the local Universe Juarez +09 Lamastra+10 Multiple mergersofearlygas-richgalaxies (Li+07) can explain some butnotalloftheseproperties

  6. Two interesting counter-examples? Two z~6 QSOswithout NIR bump: no hot-dust (T~1000 K): no torus? Young, just formedobjects? Hot-dustabundance Log MBH (Msun) Jiang+10

  7. Evolution and LF of SDSS/CFHQS QSOs Richards+06 z~6 decline Willott+09 These are luminous, highly biased, L > L* QSOs (logLx>~44.5, logLbol>45.5)

  8. Optical vs X-ray selection • SDSS/CFHQS QSO at z~6 are • brightbutvery rare • 1objectevery ~500 deg2 • down to zAB~20 • 1every 30-40 deg2 • down to zAB~22 • X-rayselection can pick upfainter, • low-lum and obscured AGN • and thensample • the bulkofthe AGN population Spectroscopically confirmed high-zAGN to date SDSS X-rays z > 3 8000 50 z > 4 1500 11 z > 5 150 3 z > 6 10 0 Noteven in CDFS/N CurrentX-raysurveysare limitedbysensitivityoversolid angle

  9. Evolution of X-rayselected AGN up to z~4 Lessluminous (Lx>~afewx 1044 erg/s), moderatelyobscured (NH< a few 1023 cm-2) AGN alsodeclinewithz (evolutionoflow-lum and heavilyobscured AGN stillunknown) decline decline Brusa+10 Civano+11, submitted

  10. Wild range of predictions for high-z AGN Observations of significant samples at z>6 would constrain the physics of early BH formation disentangling between several scenarios BH seeds(light or heavy) BH location (Nσpeaks) Recipes for accretion Eddingtonratio, AGN lightcurves, room for secular accretion, i.e. not related to mergers max XLF Salvaterra, smallhalos decline IXO-WFI Marulli, largehalos

  11. IXO-WFI multi-tiered survey strategy Simulationwithdeclinemodel ~ 1yrobservingtime Exampleof ~ 1yrobservingtime @ 60% efficiency: shallowmedium-deepultradeep 100 x 60ks + 20 x 300ks + 3x 2Ms confusionlimit@ 5” HEW About 20 AGN at z>6 in oneyear (butnumberslargelyuncertain)

  12. Dottedlines: numberofz>6 AGN in X-raysurveys assuming a high-zdecline at allluminosities and columns ~40 z>6QSOs in 4-yr eROSITA, mostlySDSS-like see Rosati+11 Murray+10 for WFXT design NEED LARGE AREAS TO DEEP SENSITIVITY IXO graspwouldneedtobemaximizedwhilekeepingsharp (~5” HEW) angularresolutiontofully exploit itssurveypotentialforhigh-zpopulationstudies (XLF, evolution, clustering). Studiestodeviseanoptimalsurveystrategy (e.g. more investment on ~ 100ks exposures) are alsoneeded

  13. Follow-up studies of known objects Comastri+10 z~6 High-qualityX-rayspectraofearly BH: IXO wouldbeanexcellenttoolto follow-up individualobjects selectedbyothermeans, e.g. wide area optical/IR surveys, eROSITA (see talk by M. Brusa) Faint CFHQS QSO (Lx=3 1044 erg/s) in 100 ks IXO-WFI or J0005-0006 (dust-free QSO, Lx=1045 erg/s) in 30 ks IXO-WFI

  14. Heavily obscured AGN

  15. Aparadigm (and pictures) shift ? From a geometry-basedUnifiedScheme.. ..toa time-dependentsequence Urry & Padovani 1995 Hopkins+06,08

  16. The different flavours of obscuration NLR BLR Seyfert 2s Unifiedmodellikegeometry Torus Torus ULIRG / (CT) QSO 2s Merger-inducedchaoticgeometry Are they the key of BH/galaxycoevolution? BLR NLR

  17. An ULIRG / Compton-thick QSO at z~5 Gilli+11 Fs=4 10-17, Fh=7 10-16, Lx=2.5 1044, NH=1.4 1024 Onlypossibletogetthiswith 4Ms Chandra SFR = 1000 Msun/yr MH2>1010Msun, Mdust~5 108Msun LSB~6 1012Lsun ~ 2 1046 erg/s LAGN~7 1045 LAGN~LSB/3  AGN energetically relevant * * from Coppin+09,10

  18. Resp = ixo_spo_wfi_Al+PP_20100527.rsp ~1400 net cts Ironlinewith EW~1 keV clearlydetected no bkg in simu A few hundreds bkg ctsexpected in a 5” radius extraction region  source cts ~ 70% of total 1Ms IXO-WFI simulationof XID403 IXO shouldbeabletodetectup to a fewtensofobjectslikethis in ~1yr operation (seeforinstanceC-thick AGN at 1.5-3.7 in the 4Ms CDFS; Norman+02,Comastri+11,Feruglio+11)

  19. IXO-WFI surveys of high-z CT AGN Simulationformulti-tieredsurvey ~ 1yrobservingtime 500 90 20 decline (180) (100) no decline Are CT AGN following a different evolutionpathaspredictedby some models? (Menci+08, Treister+10) intrinsic

  20. Conclusions The first collapsed objects IXO wouldallowexcellent follow-upofearly galaxies @ z=6-10 discovered by means of multiwavelengthdeep-and-wide area surveys: it will measure their AGN content and physics. Population studies of early accreting BHs (XLF, evolution, clustering) are more critical and would rely on a maximization of IXO’s grasp while keeping sharp (~5” at least) angular resolution and low background. Distant hidden AGN IXO would allow to discover heavily obscured, CT AGN in distant objects, verifying whether they are the key to BH/galaxy coevolution up to z=4-5. Population studies of hidden AGN will be possible up to these redshifts

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