Quentin A. Parker

The Durham/UKST Galaxy Redshift Survey – IV. Redshift-space distortions in the two-point correlation function

We have investigated the redshift space distortions in the optically selected Durham/UKST Galaxy Redshift Survey using the 2-point galaxy correlation function perpendicular and parallel to the observer’s line of sight, �(�,�). We present results for the real space 2-point correlation function, �(r), by inverting the optimally estimated projected correlation function, which is obtained by integration of �(�,�), and find good agreement with other real space estimates. On small, non-linear scales we observe an elongation of the constant �(�,�) contours in the line of sight direction. This is due to the galaxy velocity dispersion and is the common “Finger of God” effect seen in redshift surveys. Our result for the one-dimensional pairwise rms velocity dispersion is 1/2 = 416 ± 36kms 1 which is consistent with those from recent redshift surveys and canonical values, but inconsistent with SCDM or LCDM models. On larger, linear scales we observe a compression of the �(�,�) contours in the line of sight direction. This is due to the infall of galaxies into overdense regions and the Durham/UKST data favours a value of ( 0.6 /b)�0.5, where is the mean mass density of the Universe and b is the linear bias factor which relates the galaxy and mass distributions. Comparison with other optical estimates yield consistent results, with the conclusion that the data does not favour an unbiased critical-density universe.

Wide-field multifiber spectroscopy with FLAIR II

The 1.2-m United Kingdom Schmidt Telescope has operated a wide- field spectroscopy service for a number of years. A new common- user system has recently been completed. The instrument, known as FLAIR II, offers many more fiber channels than its predecessors, together with wider spectral coverage and faster turn-round of target fields. This paper describes FLAIR II in its present-day form, highlighting the most innovative aspects of its design, and giving a critical evaluation of its performance. Its impact has been significant, and large data-sets are being accumulated for a variety of object-classes.

Multiobject fiber spectroscopy at the UKST: it's a wide field

The FLAIR multifiber spectroscopy system on the 1.2m UK Schmidt Telescope is the worlds most powerful multi-object spectroscopy system in terms of area coverage and available fiber numbers. This has been achieved at modest cost providing an instrument of surprising flexibility, power, and robustness yet with an inherently simple design. During 1994 alone over 6500 individual target observations were made from just 30% of the telescope time. This paper describes the current status of the facility, problems encountered, modifications, and enhancements made over the last two years and those planned for the future. Continued innovation should maintain the facilitys power and competitiveness for several years to come.

KOALA: a wide-field, 1000 element integral-field unit for the Anglo-Australian Telescope

KOALA, the Kilofibre Optimised Astronomical Lenslet Array, is a wide-field, high efficiency integral field unit being designed for use with the bench mounted AAOmega spectrograph on the AAT. KOALA will have 1000 fibres in a rectangular array with a selectable field of view of either 1390 or 430 sq. arcseconds with a spatial sampling of 1.25 or 0.7 respectively. To achieve this KOALA will use a telecentric double lenslet array with interchangeable fore-optics. The IFU will feed AAOmega via a 31m fibre run. The efficiency of KOALA is expected to be ≈ 52% at 3700A and ≈ 66% at 6563°Å with a throughput of > 52% over the entire wavelength range.

New faint planetary nebulae from the DSS and SDSS

Having surveyed ≈ 10% of the sky, we have identified more than 130 PN candidates by surveying multicolour Digitized Sky Survey (DSS), Sloan Digitized Sky Survey (SDSS), and combined [O III], Hα and [S II] images. In a first imaging and spectroscopy campaign, 51 objects were identified as true and probable PNe. This work presents an additional 17 probable or possible PNe identified since that study. The majority of these candidates are situated at Galactic latitudes |b| > 5◦, with the exception of seven objects located closer to the Galactic plane. Using the techniques described here that do not require any new survey data, we anticipate that many more PNe are waiting to be found, perhaps as many as 90.

The 6dF Galaxy Survey: Z almost equal to 0 measurements of the growth rate and sigma 8

We present a detailed analysis of redshift-space distortions in the two-point correlation function of the 6dF Galaxy Survey (6dFGS). The K-band selected subsample which we employ in this study contains 81xa0971 galaxies distributed over 17xa0000xa0degree2 with an effective redshift zeff= 0.067. By modelling the 2D galaxy correlation function, , we measure the parameter combination f(zeff)σ8(zeff) = 0.423 ± 0.055, where is the growth rate of cosmic structure and σ8 is the rms of matter fluctuations in 8xa0h−1xa0Mpc spheres. n n n nAlternatively, by assuming standard gravity we can break the degeneracy between σ8 and the galaxy bias parameter b. Combining our data with the Hubble constant prior from Riess et al., we measure σ8= 0.76 ± 0.11 and Ωm= 0.250 ± 0.022, consistent with constraints from other galaxy surveys and the cosmic microwave background data from Wilkinson Microwave Anisotropy Probe 7 (WMAP7). n n n nCombining our measurement of fσ8 with WMAP7 allows us to test the cosmic growth history and the relationship between matter and gravity on cosmic scales by constraining the growth index of density fluctuations, γ. Using only 6dFGS and WMAP7 data we find γ= 0.547 ± 0.088, consistent with the prediction of General Relativity. We note that because of the low effective redshift of the 6dFGS our measurement of the growth rate is independent of the fiducial cosmological model (Alcock–Paczynski effect). We also show that our conclusions are not sensitive to the model adopted for non-linear redshift-space distortions. n n n nUsing a Fisher matrix analysis we report predictions for constraints on fσ8 for the Wide-field Australian SKA Pathfinder telescope L-band Legacy All-sky Blind surveY (WALLABY) and the proposed Transforming Astronomical Imaging surveys through Polychromatic Analysis of Nebulae (TAIPAN) survey. The WALLABY survey will be able to measure fσ8 with a precision of 4–10 perxa0cent, depending on the modelling of non-linear structure formation. This is comparable to the predicted precision for the best redshift bins of the Baryon Oscillation Spectroscopic Survey, demonstrating that low-redshift surveys have a significant role to play in future tests of dark energy and modified gravity.

DIVISION VI / COMMISSION 24 / WORKING GROUP PLANETARY NEBULAE

The aims of this Working Group are:n • To ensure that scientific symposia on planetary nebulae take place regularly, ideally every 5 years. These symposia would preferably be sponsored by the IAU; • To organize and coordinate the Joint Discussions on the subject at the IAU General Assemblies. These discussions should address topics of interest not only to our Division VI but to other Divisions as well; and • To maintain a Web page with general information about the WG, the activities related to planetary nebulae, and the future meetings and symposia.