Xray emission properties of BLAGN in the XMM2dF Wide Angle Survey

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X-ray emission properties of BLAGN in the
XMM-2dF Wide Angle Survey

• S. Mateos, M.G. Watson, J. A. Tedds
• and the XMM-Newton Survey Science Centre
• Department of Physics and Astronomy,
• University of Leicester

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• Motivation
• Wide field surveys are essential to compile large
  enough samples
• of objects at 2-10 keV fluxes 10-15-10-14 cgs to
  characterise the dominant population contributing
  to the Cosmic X-ray Background (CXRB)
• The sample of BLAGN in XMM-2dF Wide Angle Survey
  is one of the largest samples of X- ray selected
  BLAGN assembled so far
• Unique resource to study the overall optical and
  X-ray emission properties of the population of
  faint Active Galactic Nuclei (AGN)
• Continuum shape, soft excess and X-ray absorption
  properties
• Constrain the fraction of X-ray absorbed BLAGN
  and the distribution of column densities
• Cosmic evolution of the emission properties and
  dependence with X-ray luminosity

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• XMM-2dF Wide Angle Survey
• 2dF optical multi-fibre spectroscopy on the AAT
  obtained for 68 XMM-Newton fields (texp few
  tens of ksec) over an area of gt15deg2
• More than 3000 sources with X-ray fluxes above
  10-14 cgs and optical counterparts brighter than
  V21 observed and reduced.

978 serendipitous X-ray sources with S (0.5-4.5
keV)gt10-14 erg cm-2 s-1 spectroscopically
identified 641 BLAGN (65.5) 157 NELG (16) 57
Gal (5.8) 123 Stars (12.6)
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• BLAGN in the XMM-2dF Wide Angle Survey
• All 119 XMM-Newton observations with overlap on
  the original area covered by the 2dF observations
  reprocessed using the latest pipeline of the
  second XMM-Newton Serendipitous Source Catalogue
  2XMM (pre-release 2XMMp available at
  http//xmmssc-www.star.le.ac.uk)

2-10 keV flux
Typical fluxesbreak in the X-ray source counts
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• X-ray spectral analysis
• Co-added MOS and pn spectra obtained for each
  object
• Selected 496 from 641 BLAGN with XMM-Newton X-ray
  spectra of sufficient quality for detailed X-ray
  spectral analysis
• Simple power law and absorbed power law model
  fits
• Single-source analysis of brightest objects to
  constrain the presence and properties of
  additional spectral components (such as soft
  excess) in progress

gt70 objects with more than 150 EPIC net cts
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BLAGN overall emission properties broad band
continuum shape
Most BLAGN spectra from 0.2-12 keV (observer
frame) best fitted with a power law although
significant intrinsic dispersion in measured
values detected
?1.96 0.05 ?0.22 0.03
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BLAGN overall emission properties broad band
continuum shape
No clear trend with redshift up to z4 The
apparent hardening of ? at higher z produced by
undetected soft excess emission at lower z
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BLAGN overall emission properties broad band
continuum shape
2-10 keV lum
Continuum shape does not show obvious
dependence with X-ray luminosity
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BLAGN overall emission properties intrinsic
X-ray absorption
X-ray absorption detected (F-test95) in 38
BLAGN (8)
BLAGN at z0.132 ?1.55 0.2 NH22.2 0.3
cm-2 log (L2-10)43.53 cgs kT0.20 0.04 keV
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BLAGN overall emission properties broad band
continuum shape
Best fit ? values
0.5-2 keV flux
2-10 keV flux
The hardening of ? with X-ray flux known to be
mostly due to undetected X-ray absorption
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BLAGN overall emission properties intrinsic
X-ray absorption
No correlation between ? and NH
Typical values of absorbing column density
NH1021cm-2 For sources with NHgt1022 cm-2
existing correlation of optical and X-ray
emission properties unclear
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BLAGN overall emission properties intrinsic
X-ray absorption
Fraction of absorbed BLAGN does not depend on
X-ray luminosity or redshift
ltL2-10gt 44.2 unabsorbed BLAGN ltL2-10gt 44.3
absorbed BLAGN
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BLAGN overall emission properties intrinsic
X-ray absorption
No evident dependence of absorbing column density
with luminosity or redshift
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• Conclusions
• 0.2-12 keV emission of most BLAGN is best fitted
  with a power law
• mean continuum shape 1.96
• intrinsic dispersion 0.22
• Continuum shape
• no significant evolution up to redshifts of 4
• no luminosity dependence in range 1042-1045erg
  s-1
• Absorbed BLAGN do not seem to occur
  preferentially at any particular
• redshift or luminosity
• X-ray absorption detected in 8 of our BLAGN
• observed hardening of mean continuum shape with
  0.5-2 keV flux
• suggests that X-ray absorption is still
  undetected in a number of
• objects in our sample
• no obvious dependence with redshift or
  luminosity
• typical values 1021 cm-2 a substantial
  fraction with detected

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XMM-2dF Wide Angle Survey Leicester University
(UK) Mullard Space Science Laboratory-UCL
(UK) Instituto de Física de Cantabria CSIC-UC
(Spain) Astrophysikalisches Institut Potsdam
(Germany) on behalf of the XMM-Newton Survey
Science Centre http//xmmssc-www.star.le.ac.uk
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• Conclusions(I)
• The 0.2-12 keV emission of most BLAGN is best
  fitted with a power law with mean continuum shape
  of 1.96 although with a significant intrinsic
  dispersion of 0.22 around the mean measured
  value
• The overal X-ray emission properties (continuum
• shape and X-ray absorption) of our BLAGN do not
  
• seem to show any significant evolution up to
  redshifts
• of 4 or luminosity dependence within the
  luminosity
• range 1042-1045erg s-1
• X-ray absorption was detected in 8 of our
  BLAGN, although the observed hardening of the
  mean continuum shape with 0.5-2 keV flux suggests
  that X-ray absorption is still undetected in a
  number of objects in our sample

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• Conclusions(II)
• The observed absorption column densities in our
  sample of BLAGN have typical values 1021 cm-2,
  whithout obvious dependence with redshift or
  luminosity
• Absorbed BLAGN do not seem to occur
  preferentially at any particular redshift or
  luminosity