1 / 26

X-ray Surveys of AGN: Results and Perspectives

This article presents the findings and future outlook of X-ray surveys of active galactic nuclei (AGN). Topics covered include the resolution of the X-ray background into AGN, the sampling of unobscured and Compton Thin AGN, the detection of more AGN in X-rays than in optical, the discovery of Compton thick AGN, and rapid evolution of AGN. The article also discusses the co-evolution of AGN with host galaxies, the role of AGN in quenching star formation, and the future prospects of X-ray surveys.

skong
Download Presentation

X-ray Surveys of AGN: Results and Perspectives

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. X-ray surveys of AGN:results and perspectives Andrea ComastriINAF-Osservatorio Astronomico BolognaR. Gilli (INAF-BO), A. Marconi (UniFI),C. Vignali (UniBO), K. Iwasawa (INAF-BO), M. Brusa (MPE), F. Civano (CfA), F. Fiore (INAF-Roma), E. Lusso (UniBO) and many others X-ray astronomy 2008, Granada

  2. WHAT HAVE WE LEARNED FROM X-RAY SURVEYS (1)? • Few keV (< 5) XRB mostly resolved into AGN • Unobscured and Compton Thin fairly sampled • X-rays detect more AGN than optical • Compton thick AGN are being found (@z ~2) (Georgantopoulos, Fiore talks ) • Rapid evolution up to a Lum. Dep. redshift (z ~ 1 for Seyferts z ~ 2-3 for QSO) (many talks) • High redshift QSO (Brusa, Brandt talks) X-ray astronomy 2008, Granada

  3. WHAT HAVE WE LEARNED (2)? • Type 2/1 fraction decreases with LX (Della Ceca) • The type 2/1 fraction increases with z (?) (La Franca) • AGN Host galaxy colors and morphologies (Mainieri) • AGN-Host Galaxy co-evolution (Silverman) • AGN trace the underlying LSS (Gilli) • AGN responsible for quenching SF and accretion (Laird) • … X-ray astronomy 2008, Granada

  4. Outline • Original driver (resolve the XRB…) obscured AGN • Census of SMBH (both in terms of accreted mass and emitted radiation) --> AGN evolution • Luminosity and redshift dependenceof obscuration • Compton Thick AGN or the “holy grail” of X-ray surveys • “Mildly” Compton Thick ( T ~ 1-3), “Heavily” ( T > 3 ) Compton Thick, “Ultra”-Thick” ( T >> 3), almost fully covered obscured AGN, … • Missing sources or missing XRB (wild speculations…) • Future perspectives • Special Contents X-ray astronomy 2008, Granada

  5. X-ray spectra Unabsorbed: logNH<21 Compton-Thin: 21<logNH<24 (plus Compton Reflection & scattering) Compton-Thick: logNH>24 (T = 1 NH ~ 1.5 1024) Mildly (log NH=24-25) (NGC 6240, Circinus) Heavily (log NH >25) T >> 1 (NGC1068) X-ray astronomy 2008, Granada

  6. XRB The XRB synthesis provides an integral constraint (Gilli, AC, Hasinger 07) Red -> unobscured Blue -> Compton Thin Black -> Compton Thick The evolution is folded with the adopted XLF Obscured fraction (also for mildly and Heavily CT is Lum. Dep.) 4:1 log LX ~ 42 1:1 log LX ~ 46 X-ray astronomy 2008, Granada

  7. DOWNSIZING La Franca+05 ; Ueda+03 2-10 keV surveys Hasinger+05 0.5-2 keV surveys ~ 1000 sources X-ray astronomy 2008, Granada

  8. Hasinger et al. 2005 (see also La Franca +05, Treister+05, Della Ceca+08) Fraction of absorbed sources: Luminosity dependence • fraction of obscured AGN is astrong function of L: most luminous, less obscured • Same result in DIFFERENT bandsdespite the very different selections!! Black: X-ray Hasinger 2008 Green: IR Maiolino et al. 2007 Red: Optical Simpson et al. 2005 Della Ceca+08 Treister+08 X-ray astronomy 2008, Granada

  9. Fraction of absorbed sources: Redshift dependence • more debated! Seen in (some) data[e.g. La Franca+05, Treister+06, Hasinger08],not seen in others(Ueda+03, Dwelly&Page 2006),not needed in XRB models(Gilli+07)but expected/predicted in feedback models(Menci+08) La Franca+05 La Franca +05 Hasinger 08 X-ray astronomy 2008, Granada

  10. How do the present observations constrain the current SMBH-galaxy Coevolution paradigm ? Virtually all massive galaxies host an AGN (all galaxies experienced AGN) Magorrian relation MSMBH/Mbulge ~ 0.001 AGN feedback switch off SF and subsequent accretion It is matter of timescales (different phases) sub-mm galaxies (Alexander+05; Page talk) Downsizing , luminosity & redshift dependence of obscured fraction (most likely related to mass and accretion rates) Quantitative link with host galaxy properties (mass, SF, etc) Was the Magorrian relation already in place at high-z ? Do we see feedback in action ? (cold/thick and/or warm absorbers) Compton Thick are likely to provide further hints (Daddi+07; Fiore+08) Open Questions X-ray astronomy 2008, Granada

  11. Selection of type-2 AGN at high z with MIPS/IRAC (Martinez-Sansigre+05-06;Alonso-Herrero+06; Polletta+06, Lacy+04; Stern+05; Daddi+07; Fiore+08a,b) Stack in the GOODS fields BzK selected Starforming galaxies R - K > 4.5 MIR(24)/O > 1000 X-ray astronomy 2008, Granada

  12. High Redshift Compton Thick Daddi + 07 L X > 1042 Fiore+07 L X > 1043 L X > 1044 Polletta+06 Martinez-Sansigre+06 L X > 1045 CT follows the same LDDE ev, Alexander+08 Fiore+08 X-ray astronomy 2008, Granada

  13. BH c2 = (1-)/ * UT UT = ∫dt ∫Lbol F (Lbol) dLbol Bolometric UT = kbol∫dt ∫LX F (LX) dLX XLF UT = kbol 4  I0 / C * ( 1 + <z>) XRB The Soltan argument • UT --> Comoving AGN energy density • --> Accretion efficiency I0 --> XRB energy density Kbol --> X-ray Bolometric correction Fabian & Iwasawa 99; Yu & Tremaine 02; Elvis+02; Marconi+04; Shankar+08; … X-ray astronomy 2008, Granada

  14. COSMOS Broad band SED ox ~ 1.4 x ~ 0.65 LBOL ~ 2 x 1046 erg/s Luminosity dependent KBOL OX is lum. Dep. Vignali+03; Steffen+06 Lusso, AC et al X-ray astronomy 2008, Granada

  15. BH c2 = (1-)/ * UT UT = ∫dt ∫Lbol F (Lbol) dLbol Bolometric UT = kbol∫dt ∫LX F (LX) dLX XLF UT = kbol 4  I0 / C * ( 1 + <z>) XRB Relic BH Mass Density Assume XLF, Bolometric correction and obscured AGN LF Require consistency with local value (MBH - Mbulge - ) 3-5 x 105 MSUN Mpc-3 (Salucci+99; Yu Tremaine 02; Marconi+04; … ) (8 x 104 MSUN Mpc-3 unobscured QSO optical LF in 1982) Continuity equation (differential) - Marconi+04 X-ray astronomy 2008, Granada

  16. The “only free” parameters are the accretion efficiency and Eddington ratio L = ε dM/dt c2 L = λ Ledd Good agreement  ~ 0.06-0.1 • ~ 0.3-0.4 Marconi+04 Shankar+08 X-ray astronomy 2008, Granada

  17. Radiative Efficiency and Eddington ratio Need to account for SMBH missed by X-ray surveys Compton Thick (XRB models) They come in at least two different “flavours” XRB constrain the mildly (possibly not uniquely … ) CT space density degenerates with geometry of reflecting matter 2% 10% 0.5% The higher the average scattering/ reflection intensity, the lower the number of sources, the higher the mass which goes into the BH, the lower the accretion efficiency  (and viceversa) X-ray astronomy 2008, Granada

  18. UT = U0 * kBOL * (1 + f(NH)) XLF approach, f(NH) Gilli+07 kBOL Marconi+04, lum. Dep. (1 - ) /  * (1 + Rthin+ RMthick + RHthick (0.02/f)) Luminosity dep. Constant (~150 for HL, ~ 50 for LL assuming  ~ 0.06 kBOL lum. Dep. & a “local” mass density of …) How many ultra-thick ( >> 1) and/or highly covered (f -> 0 or almost 4) AGN can be fit in without violating the mass constraints ? (1 - E)/E * (1 +  Rmodel + kE/kBOL* RE) KE E Bolometric correction and accretion efficiency of Enshrouded Beyond Compton Thick X-ray astronomy 2008, Granada

  19. Assumee=0.1 then KE / KBOL * R ~ from 2 to 7 (Luminosity dependent) If KE ~ KBOL then the putative populationof completely enshrouded AGN (X-ray quiet) maybe as numerous as the obscured AGN population Ife~ 0.3 even much more abundant (!) They radiate in the mid-far Infrared Depending from the column density and covering factor they may belong to the Daddi+07 / Fiore+08 samples May raise the SMBH contribution to the IR Background X-ray astronomy 2008, Granada

  20. SUZAKU OBSERVATION OF Mildly CT nearby galaxies AC+07 (astro-ph/0704.1253) Scattering fraction < 0.5 % NGC5728 Scatteringfraction ~ 2% Ueda+07 Mushotzky talk NGC4992 X-ray astronomy 2008, Granada

  21. ≈0.9  < 0.1 Slowly rotating BH ? • Stacking in the COSMOS • ~ 54,000 counts • ~ 1.58 +- 0.04 EW (6.4 keV) ~ 90 eV ≈0.2-0.4 Iwasawa+08 in prep ≈-0.1 Miniutti , Longinotti, Nandra .. talks X-ray astronomy 2008, Granada

  22. More peaked Narrower redshift distr.? Different sources ? (see Gandhi+08) Difference spectrum CT from GCH07 EC = 200 keV INTEGRAL results De Rosa X-ray astronomy 2008, Granada

  23. Brusa,AC,Gilli+08 Gilli poster I5 X-ray astronomy 2008, Granada

  24. Aim to have “SDSS statistic” in the X-ray to put SMBH light up and evolution in a full context A truly multiwavelength approach is mandatory Obscured SMBH may come in different flavours they could also be X-ray quiet XRB set a “very useful” integral limit but cannot by itself breaks the parameter degeneracy Ultra deep XMM / Chandra and deep XEUS fields will reveal heavily obscured SMBH up to high redshifts Hard X-ray (10-100 keV) imaging (i.e. SimbolX; NexT XEUS) Summary/Perspectives X-ray astronomy 2008, Granada

  25. Chandra 2 Ms (aim at ~ 6 Ms) 10-17 cgs over 50 arcmin2 XMM 1.3 Ms (aim at ~ 3 Ms) Confusion limited > 5 keV Luo+08 X-ray astronomy 2008, Granada

  26. September 7-11 , 2009 BOLOGNA - ITALY Aula Magna S. Lucia X-ray Astronomy 2009 : Present status, multi- approach and future perspectives Third in a decadal series of X-ray astronomy conferences in Bologna, this meeting will highlight the contribution of XMM-Newton and Chandra observatories, ten years after their launch. Emphasis will be given on cosmic sources multiwavelength studies and associated synergies with major facilities at all wavelengths, and on the perspectives for future high energy astrophysics missions. X-ray astronomy 2008, Granada

More Related