Day 696

Thursday, + catching up from Tuesday & Wednesday.

1407.1470
Supervoid origin of the cold spot in the cosmic microwave background
Kovács et al

Use a WISE-2MASS-Pan-STARRS1 galaxy catalog to search for a super void in the direction of CMB Cold Spot; use photo-z using multicolor data set.  Data consistent with a large R_void=192 Mpc/h (2sigma) super void with delta~-0.13pm0.03 centered at z=0.22 pm 0.01.  Such a super void, constituting a ~3.5 sigma fluctuation in the LCDM model, is a plausible cause for the Cold Spot.

1407.1767
LoCuSS: the near-infrared luminosity and weak-lensing mass scaling relation of galaxy clusters
Mulroy, Smith, et al

M_WL and NIR luminosity L_K scaling relation (a first), based on 17 clusters.  Power law slope of b=0.83 pm 0.25 and an intrinsic scatter of sigma_lnM_WL|L_K = 10pm5%.  Intrinsic scatter of 10% is consistent.  Find that selecting members based on their J-K colors instead of spectra-z neither increases the scatter nor modifies the slope.  Overall, results indicate that NIR luminosity measured on scales comparable with r_500 (typically 1Mpc for the sample) is a low scatter and relatively inexpensive proxy for WL mass.  NIR may therefore be a useful mass proxy for cluster cosmology experiments.

1407.1834
The interstellar medium and feedback in the progenitors of the compact passive galaxies at z~2
Williams, ... Grogin, et al

The first quenched galaxies (z>2) are both the most massive, and most compact, suggesting a physical connection between high stellar density and efficient, rapid cessation of SF.  Present rest-frame UV spectra of LBGs at z~3 selected to be candidate progenitors of the quenched galaxies at z~2, compared to other LBGs of similar mass and SFR (non-candidates).  Find that candidate progenitors have faster outflow velocities and higher EWs of interstellar absorption lines, implying larger velocity spread among absorbing clouds.  Candidates deviate from the relationship between EWs of Lyman-alpha and interstellar absorption lines in that their Lyman-alpha emission remains strong despite high interstellar absorption, possibly indicating that the neutral HI fraction is patchy, such that Lyman-alpha photons can escape.  Detect stronger CIV P-Cygni features (emission and absorption) and HeII emission in candidates, indicative of larger populations of metal-rich WR stars compared to non-candidates.  The faster outflows, broader spread of gas velocity, and LyA properties of candidates are consistent with their ISM being subject to more energetic feedback than non-candidates.  Together with their larger metallicity (implying more evolved SF activity) this leads to a (speculative) proposition that they are likely to quench sooner than non-candidates, supporting the validity of selection criteria used to identify them as progenitors of z~2 passive galaxies.  Propose that massive, compact galaxies undergo more rapid growth of their stellar mass content, perhaps because the gas accretion mechanisms are different, and quench sooner than normally-sized LBGs at these (early) epochs.

1407.1836
Dark matter and halo bispectrum in redshift space: theory and applications
Gil-Marín, Wagner, Noreña, Verde, Percival

Present a phenomenological modification of the standard perturbation theory prediction for the bispectrum in redshift space that allow extension of the model to mildly NL scales over a wide range of redshifts, z<1.5.  Test the regime of validity of this new approach with DM particles and hales with 2 different LCDM cosmologies, both consistent with current data.  Find that bispectrum of DM particles can be described to ~5% accuracy for k_i<0.10 h/Mpc at z=0, for k_i<0.15 h/Mpc at z=0.5, for k_i<0.17 h/Mpc at z=1.0 and for k_i<0.20 h/Mpc at z=1.5.  Apply this new formula to recover the bias parameters, logarithmic growth rate f and sigma_8, by combining the redshift space PS monopole and quadrupole with the bispectrum monopole for both DM particles and haloes.  Find that the combination of these 3 statistics can break the degeneracy between b_1, f and sigma_8.  From DM particles the new model can be used to recover f and sigma_8 with ~1% systematic accuracy.  For DM halos, find that f and sigma_8 present larger systematic shifts, ~10%.  The systematic offsets arise because of limitations in the modeling of the interplay between bias and redshift space distortions, and represent a limitation as the statistical errors of forthcoming surveys reach this level.  Conveniently, find that these residual systematics are mitigated for combinations of parameters.  In particular, the quantity f *sigma_8 is still recovered with ~1% accuracy.  The improvement on the modeling of the bispectrum presented in this paper will be useful for extracting information from current and future galaxy surveys.

1407.1856
The weak lensing signal and the clustering of BOSS galaxies: cosmological constraints
More, Miyatake, Mandelbaum, Takada, Spergel, Brownstein, Schneider

Perform a joint analysis of the abundance, the clustering and the gg lensing signal of galaxies from DR11 SDSS III BOSS.  Fit HOD parameters and cosmological parameters (Omega_m and sigma_8) to both of these observables simultaneously, and thus break the degeneracy between galaxy bias and cosmology.  The cosmological analysis is the first of its kind to be performed at z as high as 0.53.  Present measurements of the clustering signal of galaxies by utilizing various stellar mass threshold samples.  The gg WL signal is obtained by using the shape catalog of background galaxies from CFHTLenS, with an area overlap of ~100 deg^2.  Analyze these measurements in the frame work of the halo model.  Adopting a flat LCDM cosmology with priors on Omega_b h^2, n_s and h from the analysis of WMAP9, obtain Omega_m=0.31, sigma_8=0.78 after marginalizing over the HOD parameters and a number of other nuisance parameters in the model.  Demonstrate the robustness of the results wrt sample selection and a variety of systematics such as the halo off-centering effect and possible incompleteness in the sample.  Constraints are consistent, complementary and competitive with those obtained using other independent probes of these cosmo parameters.

1407.2240
The Sloan lens ACS survey.  XII.  Extending strong lensing to lower masses
Shu, Bolton, ... Koopmans, Treu, Gavazzi, Marshall, Moustakas, et al

Present observational results from HST snapshot program to extend the methods of SLACS survey to lower lens-galaxy masses.  Confirm and model 50 new SLs from this program, supplemented with previous 58 lenses from SLACS.  Also determine upper limits to the masses of an additional 33 galaxies (18 new and 15 from SLACS) based on single images of background sources.  Incorporating lensing measurements and upper limits into a single analysis, find an evidence at 4 sigma that the total mass-density profile of early-type galaxies varies systematically in the sense of being shallower at larger lens-galaxy velocity dispersions.  This trend provides evidence of variation in the efficiency of dissipative baryonic processes as a function of galaxy mass.  The trend is only evident when upper limits are incorporated, highlighting the importance of including both "lenses" and "non-lenses" for an unbiased treatment of the lens population when extending to lower mass ranges.  Results are nevertheless consistent with published findings of velocity-dispersion-independent mass profiles within combined uncertainties.  By scaling simple stellar population models to the HST I-band data, identify a strong trend of increasing DM fraction at higher velocity dispersions, which can alternatively be interpreted as a trend in the stellar IMF normalization.  Consistent with previous findings and the suggestion of a non-universal IMF, find a Salpeter IMF is ruled out for galaxies below 1e10.8Msun.  Considered together, the mass-profile and DM-fraction trends with increasing galaxy mass could both be explained by an increasing relative contribution on kilo parsec scales from a DM halo with a spatial profile more extended than that of the stellar component.

1407.2257
Cosmological tests using redshift space clustering in BOSS DR11
Song, Sabiu, Okumura, Oh, Linder

Analyze the clustering of LSS in a model independent method, accounting for anisotropic effects along and transverse to the LoS.  The BOSS DR11 provides a large sample of 690k galaxies, allowing determination of the Hubble expansion H, angular distance D_A, and growth rate G_T at an effective redshift of z=0.57.  After careful bias and convergence studies of the effects from small scale clustering, find that cutting transverse separations below 40 Mpc/h delivers robust results while smaller scale data leads to a bias due to unmodelled NL and velocity effects.  The converged results are in agreement with concordance LCDM cosmology, GR, and minimal neutrino mass, all within the 68% CL.  Also present results separately for the northern and southern hemisphere sky, finding a slight tension in the growth rate -- potentially a signature of anisotropic stress, or just covariance with small scale velocities -- but within 68% CL.  

1407.2260
Brightest cluster galaxies at the present epoch
Lauer, Postman, Strauss, Graves, Chisari

433 z<=0.08 BCGs in a full-sky survey of Abell clusters: BCG Hubble diagram is consistent to within 2% of Omega_m=0.3, Lambda=0.7.  The L_m-alpha relation for BCGs, which uses alpha, the log-slope of the BCG photometric curve of growth, to predict metric luminosity, L_m, has 0.27 mag residuals.  Measure central stellar velocity dispersions, sigma, of the BCGs, finding the FJ relation to flatten as the metric aperture grows to include an increasing fraction of the total BCG luminosity.  A 3-parameter "metric plane" relation using alpha and sigma together gives the best prediction of L_m, with 0.21 mag residuals.  The projected spatial offset, r_x, of BCGs from the X-ray-defined cluster center is a gamma=-2.33 power-law over 1<r_x<1e3 kpc.  The median offset is ~10 kpc, but ~15% of the BCGs have _x>100 kpc.   The absolute cluster-dispersion normalized BCG peculiar velocity |Delta V_1|/sigma_c follows an exponential distribution with scale length 0.39pm0.03.  Both L_m and alpha increase with sigma_c.  The alpha parameter is further moderated by both the spatial and velocity offset from the cluster center, with larger alpha correlated with the proximity of the BCG to the cluster mean velocity or potential center.  At the same time, position in the cluster has little effect on L_m.  The luminosity difference between the BCG and second-ranked galaxy, M2, increases as the peculiar velocity of the BCG within the cluster decreases.  [fossil systems!]  Further, when M2 is a close luminosity "rival" of the BCG, the galaxy that is closest to either the velocity or X-ray center of the cluster is most likely to have the larger alpha.  Conclude that the inner portions of the BCGs are formed outside the cluster, but interactions in the heart of the galaxy cluster grow and extend the envelopes of the BCGs.

1407.2527
A catalogue of photometric redshifts for the SDSS-DR9 galaxies
Brescia, Cavuoti, Longo, De Stefano

Application of a new method for photo-z estimation for DR9; 143e6 galaxies available.  The MLPQNA (multilayer perceptron with quasi Newton algorithm) model provided within the framework of DAMEWARE is an interpolative method derived from machine learning models.  The obtained zs have an overall uncertainty of sigma=0.023 with a very small average bias of 3e-5, and a fraction of catastrophic outliers of about 5%.  This result is slightly better than what was already available in the literature, particularly in terms of the small fraction of catastrophic outliers.