Day 793

Tuesday.

1411.6009
Multiple images of a highly magnified supernova formed by an early-type cluster galaxy lens
Kelly, ... Treu, ... Filippenko, ... Riess, Bradac, ... Linden, et al

Discovery of the first multiply-imaged gravitationally-lensed SN.  The 4 images form an Einstein cross with over 2" diameter around a z=0.544 elliptical galaxy that is a member of a galaxy cluster.  The SN appeared in HST exposures as part of the Grism Lens-Amplified Survey from Space.  The images of the SN coincide with the strongly lensed arm of a spiral galaxy at z=1.491, which is itself multiply imaged by the cluster potential.  A measurement of the time delays between the multiple images and their magnification will provide new unprecedented constraints on the distribution of luminous and DM in the lensing galaxy and in the cluster, as well as on the cosmic expansion rate.

1411.6192
Unveiling the cosmological information beyond linear scales: forecasts of sufficient statistics
Wolk, Carron, Szapudi

Beyond the linear regime, Fourier modes of cosmological random fields become correlated, and the PS of density fluctuations contains only a fraction of the available cosmo information.  To unveil this formerly hidden information, the A* NL transform was introduced; it is optimized both for the NLs induced by gravity and observational noise.  Quantifying the resulting increase of the knowledge of cosmological parameters, forecast the constraints from the angular PS and that of A* from ell~200 to 3000 for upcoming galaxy surveys such as: WFIRST, LSST, Euclid, HSC and DES.  Find that at low z this new data analysis strategy can double the extracted info, effectively doubling the survey area.  To test the accuracy of the forecasting and the power of the data analysis methods, apply the A* transformation to the latest release of the CFHTLS Wide. While this data set is too sparce to allowl for more than modest gains (~1.1-1.2), the realized gain from the method is in excellent agreement with the forecast, thus verifying the robustness of the analysis and prediction pipelines.
1411.6212
Physical properties of compact star-forming galaxies at $z\sim2-3$
Ma, Fang, Kong, Fan

Present a study on the physical properties of compact SF galaxies (cSFGs) with M*>1e10 Msun and 2<z<3 in the COSMOS and GOODS-S fields, to explore whether they are a transitional type of galaxies between extended SF galaxies (eSFGs) and compact quiescent galaxies (cQGs) on the evolutionary path.  The cSFGs distribute at nearly the same locus on the MS as eSFGs and dominate the high mass end.  On the rest-frame U-V vs V-J and U-B vs M_B diagrams, cSFGs mainly distribute at the middle of eSFGs and cQGs in all colors, but are more inclined to "red sequence" than "green valley" galaxies.  Find cSFGs have similar distributions with cQGs on the nonparametric morphology diagrams.  About 1/3 of cSFGs show signatures of post mergers, and nearly none of them can be recognized as disks.  The general distributions of cSFGs on stellar population and structural parameters are very similar to cQGs, implying the cSFGs are the direct progenitors of cQGs.  In the meanwhile, cSFGs show the highest fraction of AGNs compared to eSFGs and cQGs, supporting the expectation that the transformation from eSFG to cSFG by gas-rich dissipative processes will intensify both the SF and the BH growth.  The results of all the analysis described above suggest that cSFG is likely to be a transitional type of galaxy between eSFG towards cQG at z>2.

1411.6339
On the perturbation of the luminosity distance by peculiar motions
Kaiser, Hudson

Consider some aspects of the perturbation to the D_L(z) that are of relevance for SN1a cosmology and for future peculiar velocity surveys at non-negligible z.  1) previous work has shown that the correction to the lowest order perturbation dD/D = -dv/cz has the peculiar characteristic that it appears to depend on the absolute state of motion of sources, rather than on their motion relative to that of the observer.  The resolution of this apparent violation of the equivalence principle is that it is necessary to allow for evolution of the velocities with time, and also, when considering perturbations on the scale of the observer-source separation, to include the gravitational z effect.  Provide an expression for dD/D that provides a physically consistent way to compute the impact of peculiar motions for NS1a cosmology and peculiar velocity surveys.  2) Calculate the perturbation to the redshift as a function of source flux density, which has been proposed as an alternative probe of large-scale motions.  Show how the inclusion of surface brightness modulation modifies the relation between dz(m) and the peculiar velocity, and that, while the noise properties of this method might appear promising, the velocity signal is swamped by the effect of galaxy clustering for most scales of interest.  3) Show how, in linear theory, peculiar velocity measurements are biased downwards by the effect of smaller scale motions or by measurement errors (such as in photometric redshifts).  Results nicely explain the effects seen in simulations by Koda+2013.  Critically examine the prospects for extending peculiar velocity studies to large scales with near-term future surveys.

1411.6355
Galaxy and mass assembly (GAMA): mass-size relations of z$<$0.1 galaxies subdivided by S\'ersic index, colour and morphology
Lange, et al

8399 GAMA galaxies of 0.01<z<0.1: derive the M*-HLR relation.  Important: adopted mass limits and sample selections (rejection of outliers, use of robust fitting methods, etc).  In particular, note that for samples extending to low stellar mass limits (<1e10 Msun) the S\'ersic index bimodality, evident for high mass systems, becomes less distinct and no-longer acts as a reliable separator of early- and late-type systems.  The final set of M*-HLR relations are reported for a variety of galaxy population subsets in 10 bands (ugrizZYJHKs) and are intended to provide a comprehensive low-z benchmark for the many ongoing high-z studies.  Exploring the variation of the M*-HLR relations with wavelength, confirm earlier findings that galaxies appear more compact at longer wavelengths albeit at a smaller level than previously noted: a 1e10 Msun both spiral systems and elliptical show a decrease in size of 13% from g to Ks (which si near linear in log wavelength).  Finally, note that the sizes used in this work are derived from 2D Sersic light profile fitting (GALFIT3), i.e., elliptical semi-major HLR, improving on earlier low-z benchmarks based on circular apertures.

1411.6443
Predicted properties of multiple images of the strongly lensed supernova SN Refusal
Oguri

The best-fit model predicts 6 SN images in total; i.e., two extra images in addition to the observed 4 Einstein cross SN images S1-S4.  One extra image is predicted to have appeared about 17 years ago, whereas the other extra image is predicted to appear in about one year form the appearance of S1-S4, which is a testable prediction with near future observations.  The predicted magnification factors of individual SN images range from ~18 for the brightest image to ~4 for the faint extra images.  Confronting these predictions with future observations should provide an unprecedented opportunity to improve the understanding of cluster mass distributions.

1411.6595
Near optimal bispectrum estimators for large-scale structure
Schmittfull, Baldauf, Seljak

Clustering of LSS provides significant info through the PS of density perturbations.  Additional information can be gained from higher-order statistics like the bispectrum, especially to break the degeneracy between the linear halo bias b_1 and the amplitude of fluctuations sigma_8.  Propose new simple, computationally inexpensive bispectrum statistics that are near optimal for the specific applications like bias determination.  Corresponding to the Legendre decomposition of NL halo bias and gravitational coupling at second order, these statistics are given by the cross-spectra of the density with 3 quadratic fields: the squared density, a tidal term, and a shift term.  For haloes and galaxies the first two have associated NL bias terms b_2 and b_s2, respectively, while the shift term has none in the absence of velocity bias (valid in the k->0 limit).  Thus the linear bias b_1 is best determined by the shift cross-spectrum, while the squared density and tidal cross-spectra mostly tighten constraints on b_2 and b_s2 once b_1 is known.  Since the form of the cross-spectra is derived from optimal maximum-likelihood estimation, they contain the full bispectrum information on bias parameters. Perturbative analytical predictions for their expectation values and covariances agree with simulations on large scales, k<0.09h/Mpc at z=0.55 with Gaussan R=20Mpc/h smoothing, for MMM, and MM-halo combinations.  For halo-halo-halo cross-spectra the model also needs to include corrections to the Poisson stochasticity.