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Obscured and unobscured growth of Super-massive Black Holes. Francisco J. Carrera, X. Barcons, J. Bussons, J. Ebrero, M. Ceballos, A. Corral (IFCA, CSIC-UC, Spain) & XMM-Newton Survey Science Centre (S. Mateos, M. J. Page, M.G. Watson, J. Tedds, R. Della Ceca ...).
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Obscured and unobscured growth of Super-massive Black Holes Francisco J. Carrera, X. Barcons, J. Bussons, J. Ebrero, M. Ceballos, A. Corral (IFCA, CSIC-UC, Spain) & XMM-Newton Survey Science Centre (S. Mateos, M. J. Page, M.G. Watson, J. Tedds, R. Della Ceca ...) Extragalactic X-ray Surveys, Boston, November 6, 2006
Resolving the X-ray background:An XMM-Newton International Survey (AXIS)
NGC4291 Definition of the AXIS survey (Carrera et al 06) Mrk 205 • 36 XMM-Newton target fields: • Galactic latitude |b|>20 deg • X-ray observations with EPIC-pn detector in FULL-FRAME-MODE • ~Avoided fields with bright and/or extended targets • Good time intervals > 10 ksec • Available early on in the mission • Solid angle ~4.8 deg2 • Using SAS v6.1.1 to produce final source list and products: • Exposure and background maps • Source detection • Spectra and calibration matrices • Areas around target + OOT+ near the pn CCD gaps excluded • Own empirical sentitivity maps from detected source parameters • Very detailed source screening • Total of 1433 distinct X-ray sources with detection likelihood >15 in any of 4 bands (see below)
Soft 0.5-2 keV XID 0.5-4.5 keV Hard 2-10 keV Ultrahard 4.5-7.5 keV X-ray source counts (XMM-Newton & Chandra & ASCA)
Deep Medium Shallow The contribution to the X-ray background Surveys Medium surveys resolve the brightest 50% of the X-ray background
The XMS samples (Barcons et al. 07) • Subset of AXIS: • 25 fields chosen for follow-up: 3.3 deg2 • Flux limited in Soft, Hard and XID
Optical identification of the XMS • Optical imaging: g,r,i (SDSS), Z (Gunn), mostly at the INT/WFC to r~23-24mag • Reliable & unique candidate counterpart in r/i for virtually all sources (< 5” or < 5) • Optical spectroscopy • 50% from AXIS programme (WHT, TNG, NOT): multi-fibre and long-slit spectroscopy • 20% from Calar Alto/3.5m long-slit spectroscopy • 15% from VLT/FORS2 long-slit spectroscopy • A few from AAT/2dF, SUBARU/FOCAS, and others • Preliminary results from 2 XMM-Newton fields (~30 sources) in Barcons et al (2002)
10m spec lim 4m spec lim Deep Medium Shallow
Hard Redshift distribution Obscured population out to z~1 in Hard sample Soft Peak of QSO distribution (z~1.5) well sampled.
QSO-2 @ z=2.2 All galaxies consistent with hosting AGN LX>1042 erg/s Luminosities and redshifts Soft QSOs Hard “Seyferts”
Tips for statistical identification 90% unobscured AGN log(FHard/Fopt) ~90% Obscured AGN Stars HR2
FX/Fopt >10 X-ray to optical ratio: a marker for obscuration? log(FSoft/Fopt) • 5% of sources with fX/fopt>10 • 30% of fX/fopt>10 obscured AGN Soft FX(10-14cgs) log(FHard/Fopt) • 15% of sources with fX/fopt>10 • ~70% of fX/fopt>10 obscured AGN Hard FX(10-14cgs)
E+S0 E+S0 QSOs S+Irr QSOs S+Irr 10% of QSOs are red Optical colours r-i g-r g-r Soft Hard #
Reddening Fainter X-ray sources are redder? r-i FHard(10-14cgs)
Softer Optical versus X-ray “colours”: Hard Harder sources are >90% obscured AGN Softer sources: Optically blue: unabsorbed AGN Optically red: mix of abs & unabs AGN g-r Hard HR2
X-ray absorption vs obscuration: not equivalent • The XMS survey • 10% of type 1 AGN are absorbed • (with NH<1022 cm-2) • >40% of type 2 AGN are absorbed • The Lockman Hole survey • 15% (<30% at 3) of type 1 AGN • are absorbed (with NH<1022 cm-2) • 80% (>50% at 3) of type 2 AGN • are absorbed. But 5/28 are unabsorbed Mateos et al (2006) Mateos et al (2005)
AXIS+XMM-2dF NELGs AXIS+XMM-2dF BLAGN Averaging X-ray spectraCorral et al., in preparation • Procedure still being tested • Selecting X-ray spectra with >80cts • Unfolding with best fit Gal+Intrinsic abs. p.l. • Correcting for Galactic NH • De-redshifting • Renormalizing using flux in 2-8 keV band • Averaging in final bins (≥500 cts) • Averaging AXIS: • BLAGN (200 sources) • NELG (43) • Much improved averaging AXIS+XMM-2dF (see Xu, Mateos): • BLAGN (549): =1.95±0.02 Fe line @6.5±0.2 keV EW=130±60 eV • NELG (113): =1.53±0.02 Fe line @6.6±0.4 keV EW=130±100 eV
On-going work • Brightest 50% of the X-ray background dominated by AGN. • Unobscured accretion dominates, but increasingly important contribution from obscured objects. • X-ray absorption and optical obscuration not equivalent: • 10% of type 1 AGN are X-ray absorbed • 15% of type 2 AGN are not X-ray absorbed • 25% of fX/fopt>10 hard X-ray sources are type 1 AGN • 10% of X-ray selected type 1 AGN have red colours • Even at medium fluxes, an important fraction of the X-ray sources have optically faint and red optical counterparts. • Most unIDed objects faint (r/i>21.5) and extended: NELGs • Preliminary results from average spectra show Fe lines in both BLAGN and NELGs