Day 391

Wednesday.

1303.4387
The 21cm power spectrum and the shapes of non-Gaussianity
Chongchitnan

f_NL can be tightened to O(1) using a radio array with a futuristic but realistic set of specifications.

1303.4389
The bulge-halo consipracy in massive elliptical galaxies: implications for the stellar initial mass function and halo response to baryonic processes
Dutton, Treu

Massive ellipticals have total mass density profiles with an effective radius that can be approximated as \rho_tot \propto r^-\gamma', with mean slope \gamma'=2.08 pm 0.03 and scatter sigma_gamma' = 0.16 pm 0.02.  The small scatter of the slope (known as the bulge-halo conspiracy) is not generic in LCDM based models, and therefore contains information about the galaxy formation process.  The observed distribution of \gamma' is well reproduced by a model with cosmologically motivated but uncontracted DM haloes, and a Salpeter-type IMF.  Models with adiabatic halo contraction (and lighter IMFs) predict too small values of \gamma'. Models with halo expansion, or mass-follows-light predict too hight values of \gamma'.  Study shows that the non-homologous structure of massive early-type galaxies can be precisely reproduced by LCDM models if the *IMF is not universal* and if *mechanisms such as feedback from AGN, or dynamical friction, effectively on average counterbalance the contraction of the halo expected as a result of baryonic cooling.*

1303.4391
The clustering of galaxies in the SDSS-III baryon oscillation spectroscopic survey: measuring H(z) and D_A(z) at z=0.57 with clustering wedges
Kazin (Eyal!), ... Eisenstein, ... Padmanabhan, Percival, Ross, Seo, Tinker, Schlegel, Schneider, et al

2D correlation function of BOSS CMASS sample of massive galaxies on DR9, measure H and D_A at <z>=0.57.  Apply a new correlation function technique called clustering wedges.  Use a physically motivated model, the anisotropic BAO feature in the galaxy sample is detected at a signifcance level of 4.7 sigma compared to a featureless model.  The baryonic acoustic feature is used to obtain model independent constraints cz/H/R_s = 12.28 pm 0.82 (7% accuracy) and D_A/r_s = 0.05 pm 0.27 (3%) with a correlation coefficient of -0.5, where r_s is the sound horizon scale at the end of the baryonic drag era.  Conduct thorough tests on data and 600 simulated realizations, finding robusetness of the results regardless of the details of the analysis method.  Combine with r_s constraints from CMB, obtain H(0.57)=90.8pm6.2 km/s/Mpc and D_A(0.57)=1386pm45 Mpc.  Use simulations to forecast results of the final BOSS CMASS data set.  Apply the reconstruction technique on the simulations demonstrating that the sharpening of the anisotropic BAO feature should improve the detection as well as tighten constraints of H and D_A by 30% on average.

1303.4396
The clustering of galaxies in the SDSS-III baryon oscillation spectroscopic survey:  cosmological constraints from the full shape of the clustering wedges
Sanchez, Kazin, ... et al

Continuation of the above:  2D correlation function xi(mu,s), average over the ranges 0<mu<0.5 and 0.5<mu<1; constraint parameter combinations D_A(z)/rs(z_d) and cz/(r_s(z_d)H(z)).  Combine clustering wedges with CMB, BAO and SNIa to obtain constraints on standard LCDM model and a number of potential extensions.  The information encoded in the clustering wedges is most useful when the DE equation of state is allowed to deviate from its standard LCDM value.  Combination of all datasets show no evidence of a deviation from a constant DE EoS, in which case we find w_DE=-1.013pm0.064, in complete agreement with a cosmological constant.  Explore potential deviations from general relativity by constraining the growth rate f(z)=dlnD(a)/dlna, in which case the combination of the CMASS clustering wedges with CMB data implies f(z=0.57)=0.719pm0.094, in accordance with the predictions of GR.  Results clearly illustrate the additional constraining power of anisotropic clustering measurements with respect to that of angle-averaged quantities.  [how?]

1303.4399
Fueling AGN-I:  How the global characteristics of the central kiloparsec of Seyferts differ from quiescent galaxies
Hicks et al

Take a matched sample of Seyfert and quiescent galaxies, simultaneously probe the stellar and molecular gas kinematics from 1 kpc down to 50pc with the aim of identifying the dynamical processes dictating BH accretion rates.  Compare 10 galaxies.  Differences within 500 pc that are correlated with AGN activity.  The Seyferts have: (1) a more centrally concentrated nuclear stellar surface brightness with lower stellar luminosities beyond a radius of 100pc, (2) a lower stellar velocity dispersion within a radius of 200pc, (3) elevated H2 luminosity out to a radius of at least 250 pc, and (4) more centrally concentrated H2 surface brightness profiles.  These observed differences can be interpreted as evidence for Seyfert galaxies having a dynamically cold (in comparison to the bulge) nuclear structure composed of a significant gas reservoir and a relatively young stellar population.  This structure is undetected (and possibly does not exist) in quiescent galaxies.  The presence of such a nuclear structure in Seyfert galaxies provides evidence for inflow of the surrounding ISM since the nuclear stellar population requires a supply of gas from which to form.  THe fueling of a Seyfert ACN is thus associated with the formation of a dynamically cold ocmponent of gas and stars on scales of hundreds of parsecs.

1303.4400
The role of major mergers in shaping galaxies at 2<z<4 in the VUDS and VVDS surveys
Tasca, Le Fevre, ..., Ilbert, Kneib, ... et al

Spec id of close pars of galaxies, discuss impact of major mergers in shaping galaxies at 2<z<4.  Use 12 physical pairs, obtain a first estimate of the merger fraction at these redshifts, _merg~15-20%.  The pair separations indicate that these pairs will merge within 1Gyr on average, with each producing a more massive galaxy by z=1-2.  From the average mass ratio of the pairs, the stellar mass of the resulting galaxy after merging will be ~60% larger than the most massive galaxy in the pair before merging.  Conclude that major merging of galaxy pairs is on-going at 2<z<4 and significantly contributing to the major assembly phase of galaxies at this epoch.

1303.4409
The evolution of the stellar mass functions of star-forming and quiescent galaxies to z=4 from the COSMOS/UltraVISTA survey
Muzzin et al

As the title says.  Up to z=4, use 95k galaxies in the COSMOS/UltraVISTA field.

1303.4525
Direct imaging discovery of 12-14 Jupiter mass object orbiting a young binary system of very low-mass stars
Delorme et al

As the title says.  Separation of 84 AU.  AO imaging.

1303.4531
A toy model to test the accuracy of cosmological N-body simulations
Labini

Simulation size vs. system size of interest problem.  Let GADGET run for a long time, observe deviation from quasi-equilibrium configuration.  This occurs in a time t_LI that depends on the values of the simulation numerical parameters such as the softening length and the time-stepping accuracy; it is a numerical artifact related to the limited spatial and temporal resolutions.  The analysis of the Layzer-Irvine cosmic energy equation confirms that this deviation corresponds to an unphysical dynamical regime.  By varying the numerical parameters of the simulation and the physical parameters of the system, show that the unphysical behaviour originates from badly integrated close scatterings of high velocity particles.  Find that the structure may remain virialized in the unphysical regime, its density and velocity profiles are modified with respect to the quasi-equilibrium configurations, converging to well defined shapes, the former characterised by NFW-type behavior.

1303.4550
Constraining neutrino properties with a Euclid-like galaxy cluster survey
Cerbolini et al

As the title says.

1303.4626
Optimal constraint on g_NL from CMB
Sekigushi, Sugiyama

With WMAP9, g_NL=(-3.3pm2.2) e5.

1303.4650
Weak lensing measurements in simulations of radio images
Patel, Abdalla, Bacon, Rowe, Smirnov, Beswick

Present a study of WL shear measurements for simulated galaxy images at radio wavelengths.  No additive bias, modest (10%) multiplicative bias on elliptiicy measurements.

1303.4666
The clustering of galaxies in the SDSS-III Baryon oscillation spectroscopic survey: measuring D_A and H and z=0.57 from the Baryon acoustic peak in the Data release 9 spectroscopic galaxy sample
Anderson, Bailey ... et al

Continuation of the above.

1303.4676
Universal doomsday: analyzing our prospects for survival
Gerig, Olum, Vilenkiin

What fraction of civilizations in the universe are long-lived?  The "universal doomsday" argument states that long-lived civilizations must be rare because if they were not, we should find ourselves living in one.  (Hence our prospect for long-term survival are poor).  Develop formalism required for universal doomsday calculations and show that while the argument has some force, our future is not as gloomy as traditional argument would suggest, at least when the number of early existential threats is small.

1303.4710
The structure of galaxies: II. fitting functions and scaling relations for ellipticals
Schombert

Fit to deVauc and Sersic models.  DeVauc performs ewell in the middle regions, but inadequate for the core (inner 5 kpcs) and the outer regions (beyond the half-light radius).  Find: Sersic produce good fits to the core regions of ellipticals (r<r_half), but is inadequate for the entire profile of an elliptical from core to halo due to competing effects on the Sersic N index and the fact that the interior shape of an elliptical is only weakly correlated with its halo shape.  In addition, there are a wide range of Sersic parameters that will equally describe the shape of the outer profile, degrading the Sersic models usefulness as a describer of the entire profile.  Empirically determined parameters, such as half-light radius and total luminosiy, have less scatter than fitting function variables.  The scaling relations for ellipticals are often non-linear, but for ellipticals brighter than M_J < -23 the following strutural relations are found: L propto r^0.8 pm 0.1, L propto Sigma^-0.5pm0.1, and Simga propto r^-1.5 pm 0.1.

1303.4722
Estimating redshift distributions with spatial correlations: method and application to data
Benard, Scranton, Schmidt, Morrison, Jeong, Budavari, Rahman

Method to estimate the z distribution of an arbitrary dataset based on spatial cross-correlation with a reference population.  Use of clustering on all available scales, in contrast to previous works focusing only on linear scales.  Infer z distribution of LRG and ELG from SDSS, IR sources from WISE, and radio sources from FIRST.  Show consistent z distribution found using both quasars and absorber systems as reference populations.  Provides ability to deproject the inherently 2d observations of the extragalactic sky.