Day 805

Monday, Tuesday, Wednesday, Thursday.

1412.3851
Fourier band-power E/B-mode estimators for cosmic shear
Becker, Rozo

New Fourier band-power estimators for cosmic shear analysis and E/B-mode separation.  Consider both the case where one performs E/B mode separation and the case where one does not.  The resulting estimators have several nice properties which make them idea for comic shear analysis.  First, they can be written as linear combinations of the binned cosmic shear correlation functions.  Second, they account for the survey window function in real space.  Third, they are unbiased by shape noise since they do not use correlation function data at zero separation.  Fourth, the band-power functions in Fourier space are compact and largely non-oscillatory.  Fifth, they can be used to construct band-power estimators with very efficient data compression properties.  In particular, find that all of the information on the parameters Omega_m, sigma8 and n_s in the shear correlation functions in the range of 10'-400' for single tomographic bin can be compressed into only 3 band-power estimates.  Lastly, can achieve these rates of data compression while excluding small-scale information where the modeling of the shear correlation functions and power spectra is very difficult.  Given these desirable properties, these estimators will be very useful for cosmic shear data analysis.

1412.3854
Designing an inflation galaxy survey: how to measure $\sigma(f_{\rm NL}) \sim 1$ using scale-dependent galaxy bias
de Putter, Doré

BAO surveys require spectroscopic redshifts; to optimize the f_NL^loc measurement, a deep, wide, multi-band imaging survey is preferred.  For sigma(f_NL^loc)~1, need i-band AB magnitude depth of i~23, number density ~8/arcmin^2, and a modest photo-z  accuracy sigma(z)/(1+z)<0.1, and the ability to measure stellar mass with a precaution ~0.2 dex or better (or another proxy for halo mass with equivalent scatter).  Even stronger constraints can potentially be obtained with the galaxy bispectrum.

1412.3862
Why do galaxies stop forming stars?  I.  The passive fraction - black hole mass relation for central galaxies
Bluck, et al

400k SDSS galaxies at z<0.2: find a strong dependence of the passive fraction on BH mass, which is largely unaffected by the details of the BH mass estimate.  Moreover, the passive fraction relationship with BH mass remains strong and tight even at fixed values of galaxy mass M*, DM halo mass Mhalo, and bulge-to-total stellar mass ratio (B/T).  The passive fraction dependence on M*, Mhalo and B/T is weak at fixed MBH.  These observations show that, for central galaxies, MBH is the strongest correlation with the passive fraction, consistent with quenching from AGN feedback.

1412.3866
Two-size approximation: a simple way of treating the evolution of grain is distribution in galaxies
Hirashita

Propose a simple model of dust enrichment in a galaxy with a simplified treatment of grain size distribution by imposing a `two-size approximation'; that is, all the grain population is represented by small (grain radius a<0.03 um) and large (a>0.03um) grains.  Include in the model  dust supply from stellar ejecta, destruction in supernova shocks, dust growth by accretion, grain growth by coagulation and grain disruption by shattering, considering how these processes work on the small and large grains.  Show that this simple framework reproduces the main features found in full calculations of grain size distributions as follows.  The dust enrichment starts with the supply of large grains from stars.  At a metallicity level referred to as the critical metallicity of accretion, the abundance of the small grains formed by shattering becomes large enough to rapidly increase the grain abundance by accretion.  Associated with the epoch, the mass ratio of the small grains to the large grains reaches the maximum.  After that, this ratio converges to the value determined by the balance between shattering and coagulation, and the dust-to-metal ratio is determined by the balance between accretion and shock destruction.  With a MC sim, demonstrate that the simplicity of the model has an advantage in predicting statistical properties.  Also show some applications for predicting observational dust properties such as extinction curves.

1412.4009
Cross-correlation of near and far-infrared background anisotropies as traced by Spitzer and Herschel
Thacker, et al

Hershel (FIR): 250, 350, 500um; Spitzer: 3.6 um.  The cross-correlation between them are detected such that the correlation coefficient at 10' angular scales decreases from 0.3 to 0.1 when the FIR wavelength increases from 250 to 500 um.  Model the cross-correlation using a halo model with 3 components: (a) FIR bright or dusty SF galaxies below the masking depth in Herschel maps, (b) NIR faint galaxies below the masking depth at 3.6 um, and (c) intra-halo light, or diffuse stars in DM haloes, that likely dominates fluctuations at 3.5 um.  The model is able to reasonably reproduce the autocorrelations at each of the FIR wavelengths and 3.6 um and their corresponding cross-correlations.  While the FIR and NIR auto-correlations are dominated by faint dusty, SF galaxies and intra-halo light, respectively, find that roughly half of the cross correlation between NIR and FIR backgrounds is due to the same galaxies that remain unmasked at 3.6 um.  The remaining signal in the cross-correlation is due to intra-halo light present in the same DM haloes as those hosting the same faint and unmasked galaxies.  In this model, the decrease in the cross-correlation signal from 250um to 500 um comes from the fact that the galaxies that are primarily contributing to 500 um fluctuations peak at a higher redshift than those at 250 um.

1412.4121
Deciphering the 3D structure of the old galactic bulge from the OGLE RR Lyrae stars
Pietrukowicz, et al

Analyzed a sample of 27k fundamental-mode RR Lyrae variable stars (type RRab) detected toward the Galactic bulge by the OGLE survey.  The data support that these metal-poor stars trace closely the barred structure formed of intermediate-age red clump giants.  The distance to the Galactic center (GC) inferred from the bulge RR Lyrae stars is R_0=8.27pm0.01(stat)pm0.40(sys) kpc.  Show that their spatial distribution has the shape of a triaxial ellipsoid with the major axis located in the Galactic plane and inclined at an angle i=20pm3 deg to the Sun-GC line of sight.  The obtained scale-length ratio of the major axis to the minor axis in the Galactic plane, and to the axis vertical to the plane is 1:0.49:0.39.  We do not see the evidence for the bulge RR Lyrae stars forming an X-shaped structure.  Based on the light curve parameters, derive metallicities of the RRab variables and show that there is a very mild but statistically significant radial metallicity gradient.  About 60% of the bulge RRab stars form 2 very close sequences on the period-amplitude (or Bailey) diagram, which is interpreted as two major old bulge populations: A and B.  Their metallicities likely differ.  Population A is about 4 times less abundant than the slightly more metal-poor population B.  Most of the remaining stars seem to represent other, even more metal-poor populations of the bulge.  The presence of multiple old populations indicates that the MW bulge was initially formed through mergers.

1412.4454
Probing gravity at large scales through CMB lensing
Pullen, Alam, Ho

Describe a methodology to probe gravity with the CMB lensing convergence kappa, specifically by measuring E_G, the ratio of the Laplacian of the gravitational scalar potential difference with the peculiar velocity divergence.  Using kappa from CMB lensing as opposed to gg lensing avoids IA while also lacking a hard limit on the lens redshift or significant uncertainties in the source plane.  Model E_G for general relativity and modified gravity, finding that E_G for f(R) gravity should be scale-dependent due to the scale-dependence of the growth rate f.  Next, construct an estimator for E_G in terms of the lensing convergence-galaxy and galaxy angular power spectra, along with the RSD parameter beta.  Also forecast statistical errors of E_G from the current Planck CMB lensing map and the CMASS and LOWZ spectroscopic galaxy samples measured from the BOSS survey, as well as BOSS spectroscopic quasars, from SDSS DR11.  Expect this experimental configuration to detect E_G at the level of 11 sigma with CMASS/LOWZ galaxies alone and 13 sigma when BOSS quasars are included.  Also find that both upcoming spectroscopic and photometric surveys, each set combined with the final Planck lensing map, can measure precisely both the redshift- and scale-dependence of E_G out to z=2 and higher, with photometric surveys having an advantage due to their large survey areas and high number densities.  Finally, advanced ACTPol CMB lensing cross-correlated with spectroscopic (photometric) surveys can differentiate between GR and modified gravity at the level of 3 sigma (13 sigma).  Performing a <1% measurement of E_G requires precision in beta on the order of 10%, which is currently achievable with a spectroscopic survey but will be difficult with only a photometric survey.

1412.4606
Intrinsic size correlations in weak lensing
Ciarlariello, Crittenden, Pace

Present a simple model for describing intrinsic correlations for galaxy sizes based on the halo model.  Studying these correlations is important both to improve the understanding of galaxy properties and because it is an important potential systematic for WL magnification measurements.  The model assumes that the density field drives these intrinsic correlations; also model the distribution of satellite galaxies.  Calculate the possible contamination to measurements of lensing convergence PS from galaxy sizes, and show that the cross-correlation of intrinsic sizes with convergence is potentially an important systematic.  Also explore how these intrinsic size correlations may affect surveys with different z depth.  Find that, in this simple approach, intrinsic size correlations cannot be neglected in order to estimate lensing convergence PS for constraining cosmo parameters.

1412.4727
Optimizing BAO measurements with non-linear transformations of Lyman-alpha forest
Wang, Font-Ribera, Seljak

Explore the effect of applying a NL transformation to the Lyman-a forest transmitted flux F=exp(-tau) and the ability of analytic models to predict the resulting clustering amplitude.  Both the large-scale bias of the transformed field (signal) and the amplitude of small scale fluctuations (noise) can be arbitrarily modified, but were unable to find a transformation that increases significantly the S/N ratio on large scales using Taylor expansion to 3rd order.  Achieve a 33% improvement in S/N for Gaussianized field in traverse direction.  On the other hand, explore analytic model for the large-scale biasing of the Lya forest, and present an extension of this model to describe the biasing of the transformed fields.  Using hydrodynamic simulations, show that the model works best to describe the biasing wrt velocity gradients, but is less successful in prediction the biasing wrt large-scale density fluctuations, especially for very NL transformations.

1412.4760
A measurement of the cosmic microwave background gravitational lensing potential from 100 square degrees of SPTpol data
Story, et al

100 sq deg coverage, arc minute resolution at 150 GHz.  Using a quadratic estimator, make maps of the CMB lensing potential from combinations of CMB temperature and polarization maps.  Combine these lensing potential maps to form a minimum-variance (MV) map.  The lensing potential is measured with a S/N ratio of greater than one for angular multipoles between 100<L<250.  This is the highest S/N mass map made from CMB to date and will be powerful in cross-correlation with other tracers of large-scale structure.  Calculate the PS of the lensing potential for each estimator, and report the value of the MV PS between 100<L<2000 as the primary result.  Constrain the ratio of the spectrum to a fiducial LCDM model to be A_MV=0.92.  Restricting to polarized data only, find A_POL=0.93.  This measurement rejects the hypothesis of no lensing at 5.8 sigma using polarization data alone, and at 14 sigma using both temperature and polarization data.

1412.4781
Measuring primordial non-Gaussianity in the galaxy power spectrum: general relativity makes a difference
Camera, Santos, Maartens

In order to reduce the errors on f_NL, need to include measurements on the largest possible scales.  Failure to include the relativistic effects on these scales can introduce significant bias in the best-fit value of f_NL.

1412.4867
Searching for extraterrestrial intelligence with the square kilometer array
Siemion et al

SKA could permit the most sensitive and exhaustive search for technologically-produced radio emission from advanced extraterrestrial intelligence (SETI) ever performed.  For example, SKA1-MID will be capable of detecting a source roughly analogous to terrestrial high-power radars (e.g. air rout surveillance or ballistic missile warning radars, EIRP (=equivalent isotropic radiated power, ~1e17 erc/sec) at 10 pc in less than 15 minutes, and with a modest 4 beam SETI observing system could, in one minute, search every star in the primary beam out to ~100 pc for radio emission comparable to that emitted by the Aracibo Planetary Radar (EIRP~2e20 erg/sec).  The flexibility of the signal detection systems used for SETI searches with the SKA will allow new algorithms to be employed that will provide sensitivity to a much wider variety of signal types than previously searched for.  Discuss the astrobiological and astrophysical motivations for radio SETI and describe how the technical capabilities of the SKA will explore the radio SETI parameter space.  Detail several conceivable SETI experimental programs on all components of SKA1, including commensal, primary-user, targeted and survey programs and project the enhancements to them possible with SKA2.  Also discuss target selection criteria for these programs, and in the case of commensal observing, how the varied use cases of other primary observers can be used to full advantage for SETI.

1412.4914
Errors on errors - estimating cosmological parameter covariance
Joachimi, Taylor

Current and forthcoming cosmological data analyses share the challenge of huge datasets alongside increasingly tight requirements on the precision and accuracy of extracted cosmological parameters.  The community is becoming increasingly aware that these requirements not only apply to the central values of parameters but, equally important, also to the error bars.  Due to NL effects in the astrophysics, the instrument, and the analysis pipeline, data covariance matrices are usually not well known a priori and need to be estimated from the data itself, or from suites of large simulations.  In either case, the finite number of realizations available to determine data covariances introduces significant biases and additional variance in the errors on cosmological parameters in a standard likelihood analysis. Review recent work on quantifying these biases and additional variances and discuss approaches to remedy these effects.

1412.5172
Neglecting primordial non-Gaussianity threatens future cosmological experiment accuracy
Camera et al

As the title says [abstract gives no more details].

1412.5186
Mesh-free free-form lensing I: methodology and application to mass reconstruction
Merten

Many applications and algorithms in the field of gravitational lensing make use of meshes with a finite number of nodes to analyze and manipulate data.  Specific examples in lensing are astronomical CCD images in general, the reconstruction of density distributions from lensing data, lens-source plane mapping or the characterization and interpolation of a PSF.  Present a numerical framework to interpolate and differentiate in the mesh-free domain, defined by nodes with coordinates that follow no regular pattern.  The framework is based on radial basis functions (RBFs) to smoothly represent data around the nodes.  Demonstrate the performance of Gaussian RBF-based, mesh-free interpolation and differentiation, which reaches the sub-percent level in both cases.  Use the newly developed framework to translate ideas of non-parametric mass reconstruction from lensing onto the mesh-free domain.  The method uses WL and SL constraints and ideally follows the distribution of input data.  By reconstruction a simulated mock lens, find that strong-lensing only reconstructions achieve <10% accuracy in the areas where these constraints are available but provide poorer results when departing from these regions.  WL only reconstructions give <10% accuracy outside the SL regime, but cannot resolve the inner core structure of the lens.  Once both regimes are combined, accurate reconstructions can be achieved over the full field of view and with a spatial resolution which is optimally adapted to the input data.

1412.5584
The stellar mass - halo mass relation from galaxy clustering in VUDS: a high star formation efficiency at z~3
Durkalec, Le Févre, et al

The relation between the galaxy stellar mass M* and the DM halo mass M_h gives important information on the efficiency in forming stars and assembling stellar mass in galaxies.  Present the stellar mass to halo mass ratio (SMHR) measurements at 2<z<5, obtained from the VIMOS Ultra Deep Survey.  Use HOD modeling of clustering measurements on ~3000 galaxies with spectroscopic redshifts to derive the DM halo mass M_h, and SED fitting over a large set of multi-wavelength data to derive the stellar mass M* and compute the SMHR=M*/M_h.  Find that the SMHR ranges from 1% to 2.5% for galaxies with M*=1.3e9 Msun to M*=7.4e9 Msun in DM haloes with M_h=1.3e11 Msun to M_h=3e11 Msun.  Derive the integrated SF efficiency (ISFE) of these galaxies and find that the SF efficiency is a moderate 6-9% for lower mass galaxies while it is relatively high at 16% for galaxies with median stellar mass of the sample 7e9 Msun.  The lower ISFE at lower masses may indicate that some efficient means of suppressing SF is at work (e.g., SNe feedback), while the high ISFE for the average galaxy at z~3 is indicating that these galaxies are efficiently building -up their stellar mass at a key epoch in the mass assembly process.  Further infer that the average mass galaxy at z~3 will start experiencing SF quenching within a few hundred million years.

1412,5593
Deconstructing thermal Sunyaev-Zel'dovich - gravitational lensing cross-correlations: implications for the intracluster medium
Battaglia, Hill, Murray

Using hydro sims, show that these cross-correlation signals are dominated by contributions from hot gas in the ICM, rather than diffuse, unbound gas located beyond the viral radius (the "missing baryons").  Thus, these cross-correlations offer a tool with which to study the ICM over a wide range of halo masses and redshifts.  In particular, show that the tSZ-CMB lensing cross-correlation is more sensitive to gas in lower-mass, higher-redshift halos and gas at larger cluster-centric radii than the tSZ-galaxy lensing cross-correlation.  Combining these measurements with primary CMB data will constrain feedback models through their signatures in the ICM pressure profile.  Forces the ability of ongoing and future experiments to constrain such ICM parameters, including the main amplitude of the pressure - mass relation, the redshift evolution of this amplitude, and the mean outer logarithmic slope of the pressure profile.  The results are promising, with ~5-20% precision constraints achievable with upcoming experiments, even after marginalizing over cosmological parameters.