The quest for early Black Holes

Transcription

1 The quest for early Black Holes Andrea Comastri (INAF-Bologna) Roberto Gilli (INAF-Bologna) Cristian Vignali (Bologna University) Marcella Brusa (MPE) and many others

2 Outline High redshift (z > 3) AGN in present X-ray surveys The demography of the first (z > 6) (obscured ) SMBH : Overview of theoretical models The demography of the first (z > 6) SMBH : an observer approach Requirements for XEUS observations

3 Wall et al., 2005 Hiigh luminosity QSO High-z QSO? Radio QSO (Wall et al., 2005) Soft X-ray ROSAT/Chandra/ XMM (Hasinger, Miyaji & Schmidt 2005) Chandra/ROSAT(Silverman et al. 2004) Optical QSOs (Schmidt et al., 1995, Fan et al. (2001,2004) Very large solid angle & deep surveys required to study z>5 QSOs

4 SDSS space density of luminous Mi < optically selected QSO z < 5 (Richards+06) z ~ 6 space density (Fan+01;04) Assuming a ox ~ 1.65 (Vignali+03;Steffen+06) Lx > cgs Hasinger+05 XLF of Type1 QSO plus exp. decay Schmidt+95 (no fit)

5 Gilli,AC,Hasinger 07 AGN synthesis L x > cgs With and whitout decline at high z (> 2.7 following Schmidt+95)

6 COSMOS z > 3 QSO Model with constant evolution at high z (GCH07) Model with exponential decline at z>2.7 (Schmidt+95) model folded with selection effects (limiting flux) model folded with selection effects (limiting flux) Brusa,AC,Gilli+08

7 Observed counts kev COSMOS (> cgs) CDFN-CDFS (~ cgs) Sampling luminous Massive QSO (though less extreme than SDSS)

8 Menci Fiore +08

9 First BH According to theoretical models MBH may grow from: Direct Cloud Collapse M sun (Koushiappas+04)) Pop III remnants M sun (Volonteri+03) Mass Growth has to be efficient (SMBH in z~6) (massive seeds alleviate the problem) Eddington limited (lum & redshift dependent?) Rapid growth (N(z) skewed towards high z) Fraction of active BH as a function of time Unresolved XRB, X-ray counts, Mass function

10 Is there enough time to form Black Holes? M(t) = M(t 0 ) exp { ε L ( 1 - ε M ) / ε M * (t - t 0 ) / τ E } τ E = 0.45 Gyr ε L = L / L E ε M = L / M c 2 SuperEddington Volonteri Rees 06 The highest z QSO (z = 6.43) has a mass of ~ 10 9 M A likely candidate ε=0.1 for a seed BH is the remnant of Pop III Star with M >~ 300 M ε=0.2 The higher the efficiency (ε M ) the longer is the time needed to grow. ε=0.4 If accretion is via a thin disc the BH is efficiently spin up and ε M reach requiring about 2 Gyrs to reach the observed mass

11 Volonteri+06

12 Salvaterra+06 Rhook Salvaterra+06 & Haenelt 08 Chandra > kev Solar masses bins > Chandra > 10-16

13 The XLF of high z (> 3) AGN Consistent (by construction) with present obs. Schechter func. α= 1 log L * = 44 Matched with Declining low -z XLF (HMS05)

14 Z > x7-10x10 arcmin FOV Z >

15 The number Counts of z > 4 QSO in some models are probably too generous

16 CONFUSION? F x ~ cgs N(>S) ~ deg -2 F x ~ 4 x cgs N(>S) ~ deg -2 Galaxies counts? 1/30 source per beam (no clustering) Gaussian PSF HEW 5 arcsec

17 CT AGN only barely sampled by deep Chandra and XMM surveys (i.e. Tozzi+06) Relative fraction is steeply increasing At cgs the bulk of the population should be detected Z = 5 L min ~ Z = 10 L min ~ 10 43

18 Deep X-ray spectroscopy F soft ~ 8 x log L X ~

19 Synergies HST and Spitzer discovery of a candidate z ~ 7.6 (lensed) galaxy candidate (Bradley+08) J 110 (intrinsic) ~ 27.7 AB JWST Nirspec Sensitivity AB ~ 29 in 100 ks The high - redshift Universe is a key science driver of both JWST and ALMA NirSpec ~ AB (1-5 µm) ~ 26.2 (in 10 ks)

20 Summary First Obscured (?) spinning (?) SMBH: Large sky area (i.e. erosita/wfxt) plus ultra-deep XMM / Chandra will surely help to sharpen the case for XEUS Low Mass BH are expected to be numerous at z > 6, SDSS detected the super-rare peaks Deep X-rays are needed to pick up the very first BH (ALMA JWST SKA E-ELT) > 5 1 kev + < 5 arcsec resolution