On preparing for the great gift of community that climate disasters can give us

There is a widespread (if rarely voiced) assumption, among those who dare to understand the future which climate chaos is likely to yield, that civility will give way and a Hobbesian war of all against all will be unleashed. Thankfully, this assumption is highly questionable. The field of ‘Disaster Studies’, as shown in Rebecca Solnit’s A Paradise Built in Hell, makes clear that it is at least as likely that, tested in the crucible of back-to-back disasters, humanity will rise to the challenge, and we will find ourselves manifesting a truer humanity than we currently think ourselves to have. Thus the post-sustainability world will offer us a tremendous gift amidst the carnage. But how well we realise this gift depends on our preparing the way for it. In order to prepare, the fantasy of sustainable development needs to be jettisoned, along with the bargain-making mentality underpinning it. Instead, the inter-personal virtues of generosity, fraternity and care-taking need fostering. One role a philosophically informed deep reframing can play in this process of virtuous preparation for disaster is in helping people to understand that, in order to care for their children, they need to care for their children in turn, and so on, ad infinitum

Cosmological parameters from cosmic microwave background measurements and the final 2dF Galaxy Redshift Survey power spectrum

We derive constraints on cosmological parameters using the power spectrum of galaxy clustering measured from the final 2dF Galaxy Redshift Survey (2dFGRS) and a compilation of measurements of the temperature power spectrum and temperature-polarization cross-correlation of the cosmic microwave background radiation. We analyse a range of parameter sets and priors, allowing for massive neutrinos, curvature, tensors and general dark energy models. In all cases, the combination of data sets tightens the constraints, with the most dramatic improvements found for the density of dark matter and the energy density of dark energy. If we assume a flat universe, we find a matter density parameter of Ωm= 0.237 ± 0.020, a baryon density parameter of Ωb= 0.041 ± 0.002, a Hubble constant of H0= 74 ± 2 kms−1 Mpc−1, a linear theory matter fluctuation amplitude of σ8= 0.77 ± 0.05 and a scalar spectral index of ns= 0.954 ± 0.023 (all errors show the 68 per cent interval). Our estimate of ns is only marginally consistent with the scale-invariant value ns= 1; this spectrum is formally excluded at the 95 per cent confidence level. However, the detection of a tilt in the spectrum is sensitive to the choice of parameter space. If we allow the equation of state of the dark energy to float, we find wDE=−0.85+0.18−0.17, consistent with a cosmological constant. We also place new limits on the mass fraction of massive neutrinos: ƒν < 0.105 at the 95 per cent level, corresponding to ∑mν < 1.2 e

The Millennium Galaxy Catalogue: the photometric accuracy, completeness and contamination of the 2dFGRS and SDSS-EDR/DR1 data sets

The Millennium Galaxy Catalogue (MGC) is a deep (μB,lim = 26 mag arcsec−2), wide-field, charge-coupled device imaging survey, covering 37.5 deg2. The MGC survey region is completely contained within the Two-Degree Field Galaxy Redshift Survey (2dFGRS) and the Sloan Digital Sky Survey Early Data Release (SDSS-EDR). We compare the photometry and completeness of the 2dFGRS and the SDSS-EDR with the MGC over the range 16 < B < 20 mag. We have also undertaken a photometric comparison to SuperCosmos (SCOS) and the Sloan Digital Sky Survey First Data Release (SDSS-DR1). We find that BMGC−B2dF = (0.035 ± 0.005) mag with an uncertainty of 0.142 mag per galaxy; BMGC−BSCOS = (0.032 ± 0.005) mag with an uncertainty of 0.108 mag; BMGC−BSDSS-EDR = (0.032 ± 0.005) mag with an uncertainty of 0.094 mag; and BMGC−BSDSS-DR1 = (0.039 ± 0.005) mag with an uncertainty of 0.086 mag. We find that high surface brightness 2dFGRS galaxies are systematically too faint, which leads to a significant scale error in magnitude. This effect is significantly reduced with the SCOS photometry. In the SDSS there is a weak non-linear scale error, which is negligible for faint galaxies. Low surface brightness galaxies in the SDSS are systematically fainter, consistent with the relative shallowness of this survey. We find that the 2dFGRS catalogue has (5.2 ± 0.3) per cent stellar contamination, (7.0 ± 0.4) per cent of objects resolved into two or more by the MGC, and is (8.7 ± 0.6) per cent incomplete compared to the MGC. From our all-object spectroscopic survey we find that the MGC is itself misclassifying (5.6 ± 1.3) per cent of galaxies as stars, and hence the 2dFGRS misses (14.3 ± 1.4) per cent of the galaxy population. The SDSS-EDR galaxy catalogue has (1.3 ± 0.1) per cent stellar contamination and (5.3 ± 1.0) per cent of galaxies misclassified as stars, with (0.18 ± 0.04) per cent of objects resolved into two or more by the MGC, and is (1.8 ± 0.1) per cent incomplete compared to the MGC. The total fraction of galaxies missing from the SDSS-EDR galaxy catalogue to BMGC = 20 mag, from incompleteness and misclassification, is (7.1 ± 1.0) per cen

Galaxy And Mass Assembly (GAMA) : galaxy close pairs, mergers and the future fate of stellar mass

ASGR acknowledges STFC and SUPA funding that were used to do this work. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO and the participating institutions.We use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift sample to fully describe the stellar mass dependence of close pairs and mergers between 10(8) and 10(12)M(circle dot). Using the analytic form of this fit we investigate the total stellar mass accreting on to more massive galaxies across all mass ratios. Depending on how conservatively we select our robust merging systems, the fraction of mass merging on to more massive companions is 2.0-5.6 per cent. Using the GAMA-II data we see no significant evidence for a change in the close pair fraction between redshift z = 0.05 and 0.2. However, we find a systematically higher fraction of galaxies in similar mass close pairs compared to published results over a similar redshift baseline. Using a compendium of data and the function gamma(M) = A(1 + z)(m) to predict the major close pair fraction, we find fitting parameters of A = 0.021 +/- 0.001 and m = 1.53 +/- 0.08, which represents a higher low-redshift normalization and shallower power-law slope than recent literature values. We find that the relative importance of in situ star formation versus galaxy merging is inversely correlated, with star formation dominating the addition of stellar material below M* and merger accretion events dominating beyond M*. We find mergers have a measurable impact on the whole extent of the galaxy stellar mass function (GSMF), manifest as a deepening of the 'dip' in the GSMF over the next similar to Gyr and an increase in M* by as much as 0.01-0.05 dex.Publisher PDFPeer reviewe

The faint end of the 250 μm luminosity function at z < 0.5

Aims. We aim to study the 250 μm luminosity function (LF) down to much fainter luminosities than achieved by previous efforts. Methods. We developed a modified stacking method to reconstruct the 250 μm LF using optically selected galaxies from the SDSS survey and Herschel maps of the GAMA equatorial fields and Stripe 82. Our stacking method not only recovers the mean 250 μm luminosities of galaxies that are too faint to be individually detected, but also their underlying distribution functions. Results. We find very good agreement with previous measurements in the overlapping luminosity range. More importantly, we are able to derive the LF down to much fainter luminosities (~ 25 times fainter) than achieved by previous studies. We find strong positive luminosity evolution L*250(z)∝(1+z)4.89±1.07 and moderate negative density evolution Φ*250(z)∝(1+z)-1.02±0.54 over the redshift range 0.0

Upper limits on neutrino masses from the 2dFGRS and WMAP: the role of priors

Solar, atmospheric, and reactor neutrino experiments have confirmed neutrino oscillations, implying that neutrinos have non-zero mass, but without pinning down their absolute masses. While it is established that the effect of neutrinos on the evolution of cosmic structure is small, the upper limits derived from large-scale structure data could help significantly to constrain the absolute scale of the neutrino masses. In a recent paper the 2dF Galaxy Redshift Survey (2dFGRS) team provided an upper limit m_nu,tot < 2.2 eV, i.e. approximately 0.7 eV for each of the three neutrino flavours, or phrased in terms of their contributioin to the matter density, Omega_nu/Omega_m < 0.16. Here we discuss this analysis in greater detail, considering issues of assumed 'priors' like the matter density Omega_m and the bias of the galaxy distribution with respect the dark matter distribution. As the suppression of the power spectrum depends on the ratio Omega_nu/Omega_m, we find that the out-of- fashion Mixed Dark Matter Model, with Omega_nu=0.2, Omega_m=1 and no cosmological constant, fits the 2dFGRS power spectrum and the CMB data reasonably well, but only for a Hubble constant H_0<50 km/s/Mpc. As a consequence, excluding low values of the Hubble constant, e.g. with the HST Key Project is important in order to get a strong constraint on the neutrino masses. We also comment on the improved limit by the WMAP team, and point out that the main neutrino signature comes from the 2dFGRS and the Lyman alpha forest.Comment: 24 pages, 12 figures Minor changes to matched version published in JCA

The angular correlations of galaxies in the COSMOS field

We present measurements of the two-point galaxy angular correlation function w(\theta) in the COSMOS field. Independent determinations of w(\theta) as a function of magnitude limit are presented for both the HST ACS catalog and also for the ground-based data from Subaru and the CFHT. Despite having significantly different masks, these three determinations agree well. At bright magnitudes (IAB<22), our data generally match very well with existing measurements and with mock catalogs based on semi-analytic galaxy formation calculations of Kitzbichler and White from the Millennium Simulation. The exception is that our result is at the upper end of the expected cosmic variance scatter for \theta > 10 arcmin, which we attribute to a particularly rich structure known to exist at z~0.8. For fainter samples, however, the level of clustering is somewhat higher than reported by some previous studies: in all three catalogues we find w(\theta=1')~0.014 at a median IAB magnitude of 24. At these very faintest magnitudes, our measurements agree well with the latest determinations from the Canada-France Legacy Survey. This level of clustering is approximately double what is predicted by the semi-analytic catalogs (at all angles). The semi-analytic results allow an estimate of cosmic variance, which is too small to account for the discrepancy. We therefore conclude that the mean amplitude of clustering at this level is higher than previously estimated.Comment: Six pages, five figures. Accepted for publication in the ApJS COSMOS special issue, Sept. 200

Galaxy And Mass Assembly (GAMA): the 0.013 < z < 0.1 cosmic spectral energy distribution from 0.1 m to 1 mm

We use the Galaxy And Mass Assembly survey (GAMA) I data set combined with GALEX, Sloan Digital Sky Survey (SDSS) and UKIRT Infrared Deep Sky Survey (UKIDSS) imaging to construct the low-redshift (z < 0.1) galaxy luminosity functions in FUV, NUV, ugriz and YJHK bands from within a single well-constrained volume of 3.4 × 105 (Mpc h−1)3. The derived luminosity distributions are normalized to the SDSS data release 7 (DR7) main survey to reduce the estimated cosmic variance to the 5 per cent level. The data are used to construct the cosmic spectral energy distribution (CSED) from 0.1 to 2.1 μm free from any wavelength-dependent cosmic variance for both the elliptical and non-elliptical populations. The two populations exhibit dramatically different CSEDs as expected for a predominantly old and young population, respectively. Using the Driver et al. prescription for the azimuthally averaged photon escape fraction, the non-ellipticals are corrected for the impact of dust attenuation and the combined CSED constructed. The final results show that the Universe is currently generating (1.8 ± 0.3) × 1035 h W Mpc−3 of which (1.2 ± 0.1) × 1035 h W Mpc−3 is directly released into the inter-galactic medium and (0.6 ± 0.1) × 1035 h W Mpc−3 is reprocessed and reradiated by dust in the far-IR. Using the GAMA data and our dust model we predict the mid- and far-IR emission which agrees remarkably well with available data. We therefore provide a robust description of the pre- and post-dust attenuated energy output of the nearby Universe from 0.1 μm to 0.6 mm. The largest uncertainty in this measurement lies in the mid- and far-IR bands stemming from the dust attenuation correction and its currently poorly constrained dependence on environment, stellar mass and morphology

Galaxy And Mass Assembly (GAMA)

The GAMA survey aims to deliver 250,000 optical spectra (3--7Ang resolution) over 250 sq. degrees to spectroscopic limits of r_{AB} <19.8 and K_{AB}<17.0 mag. Complementary imaging will be provided by GALEX, VST, UKIRT, VISTA, HERSCHEL and ASKAP to comparable flux levels leading to a definitive multi-wavelength galaxy database. The data will be used to study all aspects of cosmic structures on 1kpc to 1Mpc scales spanning all environments and out to a redshift limit of z ~ 0.4. Key science drivers include the measurement of: the halo mass function via group velocity dispersions; the stellar, HI, and baryonic mass functions; galaxy component mass-size relations; the recent merger and star-formation rates by mass, types and environment. Detailed modeling of the spectra, broad SEDs, and spatial distributions should provide individual star formation histories, ages, bulge-disc decompositions and stellar bulge, stellar disc, dust disc, neutral HI gas and total dynamical masses for a significant subset of the sample (~100k) spanning both the giant and dwarf galaxy populations. The survey commenced March 2008 with 50k spectra obtained in 21 clear nights using the Anglo Australian Observatory's new multi-fibre-fed bench-mounted dual-beam spectroscopic system (AAOmega).Comment: Invited talk at IAU 254 (The Galaxy Disk in Cosmological Context, Copenhagen), 6 pages, 5 figures, high quality PDF version available at http://www.eso.org/~jliske/gama

The host dark matter haloes of [O II] emitters at 0.5 < z < 1.5

Emission line galaxies (ELGs) are used in several ongoing and upcoming surveys (SDSS-IV/eBOSS, DESI) as tracers of the dark matter distribution. Using a new galaxy formation model, we explore the characteristics of [OII] emitters, which dominate optical ELG selections at z ≃ 1. Model [OII] emitters at 0.5 < z < 1.5 are selected to mimic the DEEP2, VVDS, eBOSS and DESI surveys. The luminosity functions of model [OII] emitters are in reasonable agreement with observations. The selected [OII] emitters are hosted by haloes with Mhalo ≥ 1010.3h−1M⊙, with ∼90 per cent of them being central star-forming galaxies. The predicted mean halo occupation distributions of [OII] emitters have a shape typical of that inferred for star-forming galaxies, with the contribution from central galaxies, ⟨N⟩[OII]cen⁠, being far from the canonical step function. The ⟨N⟩[OII]cen can be described as the sum of an asymmetric Gaussian for discs and a step function for spheroids, which plateau below unity. The model [OII] emitters have a clustering bias close to unity, which is below the expectations for eBOSS and DESI ELGs. At z ∼ 1, a comparison with observed g-band-selected galaxy, which is expected to be dominated by [OII] emitters, indicates that our model produces too few [OII] emitters that are satellite galaxies. This suggests the need to revise our modelling of hot gas stripping in satellite galaxies