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The 2dF-SDSS LRG and QSO survey: QSO clustering and the L-z degeneracy
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|Title: ||The 2dF-SDSS LRG and QSO survey: QSO clustering and the L-z degeneracy|
|Authors: ||da Angela, J.|
Croom, S. M.
Brunner, R. J.
Myers, A. D.
Nichol, R. C.
Pimbblet, K. A.
de Propris, R.
Richards, Gordon T.
Ross, N. P.
Schneider, D. P.
Wake, D. A.
|Keywords: ||Surveys - Quasars|
Large-Scale Structure Of Universe
|Issue Date: ||3-Feb-2008 |
|Publisher: ||Blackwell Publishing|
|Citation: ||Monthly Notices of the Royal Astronomical Society, 383(2): pp. 565-580.|
|Abstract: ||We combine the QSO samples from the 2dF QSO Redshift Survey (2QZ) and
the 2dF-SDSS LRG and QSO Survey (2SLAQ) in order to investigate the clustering
of z 1.4 QSOs and measure the correlation function ( ). The clustering signal
in redshift-space and projected along the sky direction is similar to that previously
obtained from the 2QZ sample alone. By fitting functional forms to ( , ), the correlation
function measured along and across the line of sight, we find, as expected, that
, the dynamical infall parameter and
m, the cosmological density parameter, are
degenerate. However, this degeneracy can be lifted by using linear theory predictions
under different cosmological scenarios. Using the combination of the 2QZ and 2SLAQ
QSO data, we obtain: QSO(z = 1.4) = 0.60+0.14
m = 0.25+0.09
−0.07 which imply a value
for the QSO bias, b(z = 1.4) = 1.5 ± 0.2.
The combination of the 2QZ with the fainter 2SLAQ QSO sample further reveals
that QSO clustering does not depend strongly on luminosity at fixed redshift. This
result is inconsistent with the expectation of simple ‘high peaks’ biasing models where
more luminous, rare QSOs are assumed to inhabit higher mass haloes. The data are
more consistent with models which predict that QSOs of different luminosities reside
in haloes of similar mass. By assuming ellipsoidal models for the collapse of density
perturbations, we estimate the mass of the dark matter haloes which the QSOs inhabit.
We find that halo mass does not evolve strongly with redshift nor depend on QSO
luminosity. Assuming a range of relations which relate halo to black hole mass we
investigate how black hole mass correlates with luminosity and redshift and ascertain
the relation between Eddington efficiency and black hole mass. Our results suggest
that QSOs of different luminosities may contain black holes of similar mass.|
|Appears in Collections:||Faculty Research and Publications (Physics)|
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