Some of the discussion included here is a little out of date. We have now moved to UBR slection of candidates in place of the original UVX technique. All the science justification and objectives of the survey remain unchanged.

We are proposing to use the 2dF to make a simultaneous QSO and galaxy redshift
survey across two declination strips, one in the South Galactic Pole and
one in an equatorial region at the North Galactic Cap. The Southern strip will be
in the same area of sky as the Durham/UKST *B<17* galaxy redshift survey.
QSOs will be selected by the ultra-violet excess (UVX) method and the key
to the success of this proposal is the large amount of deep *U* plate material which
we have already obtained with the UK Schmidt Telescope.
We shall observe 120 - 130 UVX QSO candidates per fibre field to *B=21*.
The area surveyed in each strip will be 75° × 5°
and the resulting catalogue will contain 30000 *z<2·2* QSOs.
Combined with large area galaxy redshift surveys, it will form the most comprehensive
picture of the large-scale structure of the Universe in a given area of sky, with
the QSOs probing the structure up to scale lengths of 1000h
Mpc (comparable to the scales studied by COBE) and the galaxies at
*B<20* forming a more detailed picture of the topology on scales up to 500h
Mpc.

**(a) The Non - Linear Regime: ( r < 10h
Mpc).**

At small scales we will obtain information about the development of the non-linear regime of QSO clustering in the redshift range

**(b) The Intermediate Linear Regime: (10 < r < 30h
Mpc)**

Here we will determine the form of the QSO correlation function at the scales where it is most sensitive to the primordial mass spectrum. At these scales the correlation function is claimed to show excess power over what is expected for a standard CDM model, on the basis of the projected APM correlation function (Maddox et al. 1991) and, at a less significant level, on the basis of the IRAS redshift survey correlation function. In this range of scales, QSO surveys are becoming highly competitive with galaxy redshift surveys in terms of the statistical accuracy of the correlation function since they are effectively a very sparse sampled dataset (Kaiser 1987) with each QSO bringing almost completely independent correlation function information. Currently the QSO correlation function errors in this range are ± 0·15 from the 700 QSOs in the Durham/AAT+ESO+CFHT surveys and show insignificant excess power over that expected for CDM (see Mo & Fang 1993). However, a correlation function as flat as the APM result is also not significantly excluded. In the proposed 30000 QSO survey this error will reduce to ± 0·02 and we will be able to discriminate between the APM and the standard CDM correlation function slopes at the level (see Fig. 4 ). This is a powerful example of what will be possible with a QSO correlation function measured to this accuracy in this intermediate regime. In Fig. 4 we also show the different correlation function shapes expected for a canonical CDM power spectrum form with primordial index running between 0·5 <

**(c) The Fully Linear Regime: (30 < r < 1000h
Mpc)**

At these very large scales, the QSOs are clearly superior to galaxies as probes of large scale structure by virtue of both their sparse sampling and their flat

The direct correspondence between galaxy and QSO clustering implied by the Ellingson et al. (1991) result also has one final, important implication for QSO clustering. If it is assumed that comoving evolution is appropriate for QSOs and galaxies, then the scale length of QSO clustering may act as a standard measuring rod when compared to the scale-length of galaxy or QSO/Seyfert clustering at zero redshift. Already, this line of argument has started to put constraints on the cosmological constant, , because with an inflationary, non-zero , the scale-length of QSO clustering at high redshift becomes several (

**(b) QSO geometric measurement of
.**

With the 50-fold increase number of QSO pairs at small separations in the
proposed QSO survey, an even more powerful geometric test for the cosmological
constant will be available to us. The test, suggested by
Phillipps (1994), after Alcock & Pacynski (1979), comprises a comparison
of the extent of small scale QSO clustering in the redshift and angular directions.
Under the reasonable assumption that the QSO small-scale clustering will
be spherically
symmetric at least in the average, the extent of the QSO correlation function
should be the same in both directions. However, the distance between a
pair of QSOs measured in the line of sight from the redshifts has a different
dependence on the cosmological parameters from the distance measured in
the angular direction. By demanding that these two distances are in the average
the same, a powerful cosmological test emerges. Now in the case of
models the difference between the 2 extents is only small for values of
in the range 0 <
< 0·5 (see
Fig. 6
). However, the difference in extents for models with
0 can be much more significant. For example, in the
interesting case of a zero spatial curvature model with
and
0 the result is strikingly different from the conventional case.
The current constraints on
from this method are poor, since there are only 40 correlated QSO pairs with
*r* < 10h
Mpc. However in the proposed survey the number of pairs would rise to
and then, according to Phillipps (1994), there is the possibility of an almost
exact determination of
from this method. Redshift measurement errors and random small-scale
peculiar velocities are not a problem for this method, since their effects
are small if the extents are measured over 10h
comoving Mpc. Of course, it should also be noted that if the result is
consistent with
and 0 <
< 0·5 then this will be a non-negligible test of the GR theory that
relates the angular and redshift distance measurements.

Most of the examples given above discuss the measurement of QSO clustering using the correlation function, primarily for ease of comparison with existing analyses. However, we will also make extensive use of other statistics to measure QSO clustering e.g. power spectrum, higher order (3-point, 4-point) correlation functions, counts in cells etc. to extract the maximum information content from the proposed survey.

From this survey we will also be able to determine the space density and
evolution of intrinsically rare classes of QSO e.g. Broad Absorption Line
(BAL) QSOs, damped Ly
QSOs and QSOs with strong metal absorption line
systems. Based on a BAL QSO fraction of 5-10%, we expect
to identify over 1500 BAL QSOs in this survey. This is sufficient to derive
an
accurate picture of their space density and evolution at *z<2·2*,
and will
provide vital clues to the physical nature of such systems. We will also
identify
QSOs with *1·9<z<2·2*, the redshift range over which we
will be able to identify candidate damped Ly
systems. Assuming
that 2-5% of QSOs exhibit damped Ly
(Pettini, private comm.), we will identify
100-250 such systems in the survey, providing valuable data towards an accurate
determination of the space density of the galactic
disks at
thought to be responsible for the damped Ly
lines. Similar
information should be
derived for the significant number of strong metal-line absorption systems
which will also be identified in this survey. With over 6000 bright
(*B<19·5*) QSOs (
/2dF field) in the final sample, the survey will also
provide an invaluable source of material for future, more detailed,
spectroscopic campaigns of QSOs and their absorption line systems.

In passing, we note that the survey will also yield astrophysically important
information on other classes of astronomical objects. Based on the Durham/AAT
UVX survey (Boyle et al. 1990), we expect to find over 1500 hot white
dwarfs and
distant (*r>50*kpc) blue horizontal branch stars.
The white dwarfs can be used to provide an accurate measure of their
scale-height (Boyle 1989), possibly even as a function of spectroscopic
class, and the horizontal branch stars are important tracers of the dynamics of
the outer halo of our galaxy (Sommer-Larsen & Christiansen 1986).

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