The decade of galaxy formation: pitfalls in the path ahead

At the turn of the decade we arguably move from the era of precision cosmology to the era of galaxy formation. One approach to this problem will be via the construction of comprehensive galaxy samples. In this review I take the opportunity to highlight a number of challenges which must be overcome before we can use such data to construct a robust empirical blueprint of galaxy evolution. The issues briefly highlighted here are: the Hubble tuning fork versus galaxy components, the hierarchy of structure, the accuracy of structural decompositions, galaxy photometry, incompleteness, cosmic variance, photometric versus spectroscopic redshifts, wavelength bias, dust attenuation, and the disconnect with theory. These concerns essentially form one of the key motivations of the GAMA survey which, as one of its goals, will establish a complete comprehensive kpc-resolution 3D multi-wavelength (UV-Opt-IR-Radio) database of 250k galaxy systems to z <0.5.Comment: Review paper (12 pages, 11 figures) in "Hunting for the Dark: The Hidden Side of Galaxy Formation", Malta, 19-23 Oct. 2009, eds. V.P.Debattista & C.C.Popescu, AIP Conf. Ser., in pres

The GAMA Panchromatic Survey

The Galaxy And Mass Assembly Survey (GAMA) has now been operating for almost 5 years gathering spectroscopic redshifts for five regions of sky spanning 300 sq degrees in total to a depth of r<19.8 mag. The survey has amassed over 225,000 redshifts making it the third largest redshift campaign after the SDSS and BOSS surveys. The survey has two novel features that set it apart: (1) complete and uniform sampling to a fixed flux limit (r<19.8 mag) regardless of galaxy clustering due to multiple-visits to each sky region, enabling the construction of high-fidelity catalogues of groups and pairs, (2) co-ordination with diverse imaging campaigns which together sample an extremely broad range along the electro-magnetic spectrum from the UV (GALEX) through optical (VST KIDs), near-IR (VISTA VIKING), mid-IR (WISE), far-IR (Herschel-Atlas), 1m (GMRT), and eventually 20cm continuum and rest-frame 21cm line measurements (ASKAP DINGO). Apart from the ASKAP campaign all multi-wavelength programmes are either complete or in the final stages of observations and the UV-far-IR data are expected to be fully merged by the end of 2013. This article provides a brief flavour of the coming panchromatic database which will eventually include measurements or upper-limits across 27 wavebands for 380,000 galaxies. GAMA DR2 is scheduled for the end of January 2013.Comment: Contributed article (4 pages), IAU Symposium 295 on "The intriguing life of massive galaxies", (Eds: Daniel Thomas, Anna Pasqualis, Ignacio Ferreras

The Ccontribution of normal, dim and dwarf galaxies to the local luminosity density

From the Hubble Deep Field catalog presented in Driver et al. (1998) we derive the local (0.3 < z < 0.5) Bivariate Brightness Distribution (BBD) of field galaxies within a 326 Mpc**3 Volume-Limited sample. The sample contains 47 galaxies which uniformally sample the underlying galaxy population within the specified redshift, magnitude and surface brightness limits (0.3 < z < 0.5, -21.3 < M_{B} < -13.7 mags, 18.0 < mu_{B} < 24.55 mags/sq arcsec). We conclude: (i) A luminosity-surface brightness relation exists for both the field and cluster galaxy populations, M_{B} ~ 1.5 mu_{e} - 50, (ii) Luminous low surface brightness galaxies account for <10% of the L* population, (iii) Low luminosity low surface brightness galaxies outnumber Hubble types by a factor of ~ 1.4, however their space density is NOT sufficient to explain the faint blue excess either by themselves or as faded remnants. In terms of the local luminosity density and galaxy dynamical mass budget, normal galaxies (i.e. Hubble tuning fork) contribute 88% and 72% respectively. This compares to 7% and 12% for dim galaxies and 5% and 16% for dwarf galaxies (within the above specified limits).Comment: Accepted for publication in Astrophysical Journal Letters. Nine pages and two figure

Zeros of Quasi-Orthogonal Jacobi Polynomials

We consider interlacing properties satisfied by the zeros of Jacobi polynomials in quasi-orthogonal sequences characterised by $\alpha>-1$, $-2<\beta<-1$. We give necessary and sufficient conditions under which a conjecture by Askey, that the zeros of Jacobi polynomials $P_n^{(\alpha, \beta)}$ and $P_{n}^{(\alpha,\beta+2)}$ are interlacing, holds when the parameters $\alpha$ and $\beta$ are in the range $\alpha>-1$ and $-2<\beta<-1$. We prove that the zeros of $P_n^{(\alpha, \beta)}$ and $P_{n+1}^{(\alpha,\beta)}$ do not interlace for any $n\in\mathbb{N}$, $n\geq2$ and any fixed $\alpha$, $\beta$ with $\alpha>-1$, $-2<\beta<-1$. The interlacing of zeros of $P_n^{(\alpha,\beta)}$ and $P_m^{(\alpha,\beta+t)}$ for $m,n\in\mathbb{N}$ is discussed for $\alpha$ and $\beta$ in this range, $t\geq 1$, and new upper and lower bounds are derived for the zero of $P_n^{(\alpha,\beta)}$ that is less than $-1$

The functional effects of modal versus amodal filling-in

Comparisons between modally and amodally completed regions show that perceptual filling-in is not merely the ignoring of absences. Illusory filled-in colour arises for modal completion, but not for amodal completion in comparable displays. We find that attention spreads automatically to modally but not amodally completed regions from their inducers, revealing a functional effect of filled-in colour