Day 1178

Friday.

1610.08525
Strong lensing signatures of luminous structure and stub structure in early-type galaxies
Gilman, et al

The arrival times, positions, and fluxes of multiple images in SL systems can be used to infer the presence of dark sub haloes in the deflector, and thus test predictions of CDM models.  However, gravitational lensing does not distinguish between perturbations to a smooth gravitational potential arising from baryonic and non-baryonic mass.  In this work, quantify the extent to which the stellar mass distribution of a deflector can reproduce flux ratio and astrometric anomalies typically associated with the presence of DM subhalo.  Using HST images of nearby galaxies, simulate SL systems with real distributions of stellar mass as they would be observed at z_d=0.5.  Add a DM halo and external shear to account for the smooth DM field, omitting dark substructure, and use a MC procedure to characterize the distributions of image positions, time delays, and flux ratios for a compact background source of diameter 5pc.  By convolving high-resolution images of real galaxies with a Gaussian PSF, simulate the most detailed smooth potential one could construct given high quality data, and find scatter in flux ratios of ~10%, which is interpreted as a typical deviation from a smooth potential caused by large and small scale structure in the lensing galaxy.  Demonstrate that the flux ratio anomalies arising from galaxy-scale baryonic structure can be minimized by selecting the most massive and round deflectors, and by simultaneously modeling flux ratio and astrometric data.


1610.08948
A galaxy-halo model for multiple cosmological tracers
Bull

The information extracted from large galaxy surveys with the likes of DES, DESI, Euclid, LSST, SKA, and WFIRST will be greatly enhanced if the resultant galaxy catalogues can be cross-correlated with one another.  Predicting the nature of the information gain, and developing the tools the realize it, depends on establishing a consistent model of how the galaxies detected by each survey trace the same underlying matter distribution. Existing analytic models, such as HOD modelling, are not well-suited for this task, and can suffer from ambiguities and tuning issues when applied to multiple tracers.  Construct a simple alternative that provides a common model for the connection between galaxies and DM haloes across a wide range of wavelengths (and thus tracer populations).  This is based on a change of parameterized statistical distributions that model the connection between (a) halo mass and bulk physical properties of galaxies, such as SFR; and (b) those same physical properties and a variety of emission processes.  The result is a flexible parametric model that allows analytic halo model calculations to be carried out for multiple tracers, as well as providing semi-realistic galaxy properties for fast mock catalogue generation.

Day 1177

Thursday.

1610.08297
On the hypothesis that cosmological dark matter is composed of intra-light bosons
Hui, Ostriker, Tremaine, Witten

An intriguing alternative to CDM is that the dark matter is a light (m~1e-22 eV) boson having a de Broglie wavelength lambda ~ 1 kpc, oven called fuzzy dark matter (FDM).  Describe the arguments from particle physics that motivate FDM, review previous work on its astrophysical signatures, and analyze several unexplored aspects of its behavior.  In particular, (i) FDM haloes smaller than about 1e7 (m/1e-22 eV)^-3/2 Msun do not form.  (ii) FDM haloes are comprised of a core that is a stationary, minimum-energy configuration called a "soliton", surrounded by an envelope that resembles a CDM halo.  (iii) The transition between soliton and envelope is determined by a relaxation process analogous to 2-body relaxation in gravitating systems, which proceeds as if the halo were composed of particles with mass ~rho lambda^3 where rho is the halo density.  (iv) Relaxation may have substantial effects on the stellar disk and bulge in the inner parts of disk galaxies.  (v) Relaxation can produce FDM disks but an FDM disk in the solar neighborhood must have a half-thickness of at least 300 (m/1e-22 eV)^-2/3 pc.  (vi) Solitonic FDM sub-haloes evaporate by tunneling through the tidal radius and this limits the minimum sub-halo mass inside 30 kpc of the MW to roughly 1e8 (m/1e-22 eV)^-3/2 Msun.  (vii) If the DM in the Fornax dwarf galaxy is composed of CDM, most of the globular clusters observed in that galaxy should have long ago spiraled to its center, and this problem is resolved if the DM is FDM.

Day 1176

Wednesday.

1610.07605
The inner structure of early-type galaxies in the Illustris simulation
Xu, Sprintel, Sluse, et al

Early-type galaxies provide unique tests for the predictions of the CDM cosmology and the baryonic physics assumptions entering models for galaxy formation.  In this work, use the Illustris sim to study correlations of 3 main properties of early-type galaxies, namely, the stellar orbital anisotropies, the central dark matter fractions and the central radial density slopes, as well as their redshift evolution since z=1.0.  Find that lower-mass galaxies or galaxies at higher redshift tend to be bluer in rest-frame colour, have higher central gas fractions, and feature more tangentially anisotropic orbits and steeper central density slopes than their higher-mass or lower-z counterparts, respectively.  The projected central DM fraction within the effective radius shows no significant mass dependence but positively correlates with galaxy effective radii due to the aperture effect. The central density slopes obtained in the simulation by combining SL measurements with single aperture kinematics are found to be shallower than the true density slopes.  Identify systematic biases in this measurement due to 2 common modelling assumptions, isotropic stellar orbital distributions and power-law density profiles.  Also compare the properties of early-type galaxies in Illustris to those from the SLACS, SL2S and BOSS surveys, ending in general broad agreement but also some tension, which appears to be mostly caused by too large galaxy sizes in Illustris.

Day 1175

Tuesday.

1610.07592
The segregation of baryons and dark matter during halo assembly
Liao, et al

The standard galaxy formation theory assumes that baryons and DM are initially well-mixed before becoming segregated due to radiative cooling.  Use non-radiative hydro-sims to explicitly examine this assumption and find that baryons and DM can also be segregated during the build-up of the halo.  As a result, baryons in many haloes do not originate from the same Lagrangian region as the DM.  When using the fraction of corresponding DM and gas particles in the initial conditions (the "paired fraction") as a proxy of the DM and gas segregation strength of a halo, on average about 25% of the baryonic and DM of the final halo are segregated in the initial conditions.  A consequence of this effect is that the baryons and DM of the same halo initially experience different tidal torques and thus their angular momentum vectors are often misaligned.  This is at odds with the assumption of the standard galaxy formation model, and challenges the precision of some semi-analytical approaches which utilize DM halo merger trees to infer properties of gas associated to DM haloes.  

Day 1174

Thursday.  Friday.

1609.00037
Good enough practices in scientific computing
Wilson, et al

Present a set of computing tools and techniques that every researcher can and should adopt.  These recommendations synthesize inspiration from the authors' own work, from the experiences of the thousands of people who have taken part in Software Carpentry and Data Carpenetry workshops over the past six years, and from a variety of other guides.  The recommendations are aimed specifically at people who are new to research computing.


1610.06566
On the origin and evolution of the galaxy stellar mass function
Kelson, Benson, Abramson

Explore the evolution of galaxy ensembles at early times by working the in situ stellar mass growth of galaxies purely as a stationary stochastic (e.g., quasi-steady state) process.  By combining the mathematics of such processes with Newtonian gravity and a mean local star formation efficiency, show that the stellar mass evolution of galaxy ensembles is directly related to the average acceleration of baryons onto dark matter haloes at the onset of star formation, which explicit dependencies on the initial local matter densities and halo mass.  The density term specifically implies more rapid average rates of growth in higher density regions of the universe compared to low density regions, i.e., assembly bias.  With this framework, using standard cosmo parameters, a mean star formation efficiency derived by other authors, and knowledge of the shape of the cosmo matter power spectrum at small scales, analytically derive (1) the characteristic stellar masses of galaxies (M*), (2) the power-law low-mass slope (alpha) and normalization (phi*) of the stellar mass function, and (3) the evolution of the stellar mass function in time over 12.5>z>2.  Correspondingly, the rise in the cosmic SFR density over these epochs, while the universe can sustain unabated fueling of star formation, also emerges naturally, All of the findings are consistent with the deepest available data, including the expectation of alpha~-7/5; i.e., a stellar mass function low-mass slope that is notably shallower than that of the halo mass function, and with no systematic deviations from a mean star formation efficiency with density or mass, nor any explicit, additional feedback mechanisms.  These derivations yield a compelling richness and complexity but also show that very few astrophysical details are required to understand the evolution of cosmic ensemble of galaxies at early times.


1610.06673
Probabilistic cosmological mass mapping from weak lensing shear
Schneider, Ng, Dawson, Marshall, Meyers, Bard

Infer gravitational lensing shear and convergence fields from galaxy ellipticity catalogs under a spatial process prior for the lensing potential.  Demonstrate the performance of the algorithm with simulated Gaussian-distributed cosmo lensing shear maps and a reconstruction of the mass distribution of the merging galaxy cluster A781 using galaxy ellipticities measured with the DLS.  Given interim posterior samples of lensings shear or convergence fields on the sky, describe an algorithm to infer cosmo parameters via lens field marginalization.  In the most general formulation of the algorithm, make no assumptions about weak shear or Gaussian distributed shape noise or shears.  Because it requires solutions and matrix determinate of a linear system of dimension that scales with the number of galaxies, expect the algorithm to require parallel high-performance computing resources for application to ongoing wide field lensing surveys.


1610.06890
Weak-lensing mass calibration of redMaPPer galaxy clusters in Dark Energy Survey Science Verification data
Melchior, Gruen, et al

Use WL shear measurements to determine the mean mass of optically selected galaxy clusters in DES SV data.  In a blinded analysis, split the sample of more than 8000 redMaPPer clusters into 15 subsets, spanning ranges in the richness parameter 5<=lambda<=180 and redshifts 0.2<=z<=0.8, and fit the averaged mass density contrast profiles with a model that accounts for 7 distinct sources of systematic uncertainty: shear measurement and photometric redshift errors; cluster-member contamination; miscentering; deviations from the NFW halo profile; halo triaxiality; and line-of-sight projections.  Combine the inferred cluster masses to estimate the joint scaling relation between mass, richness and redshift, M(lambda,z)~M0 lambda^F (1+z)^G.  Find M0==<M_200m | lambda=30,z=0.5> = [2.35±0.22(stat)±0.12(sys)] x 1e14 Msun, with F=1.12±0.20(stat)±0.06(sys) and G-0.18±0.75(stat)±0.24(sys).  The amplitude of the mass-richness relation is in excellent agreement with the WL calibration of redMapPer clusters in SDSS by Simet+2016 and with the Saro+2015 calibration based on abundance matching of SPT-deteted clusters.  The results extend the z range over which the mass-richness relation of redMaPPer clusters has been calibrated with WL from z<=0.3 to z<=0.8.  Calibration uncertainties of shear measurements and photometric z estimates dominate the systematic error budget and require substantial improvements for forthcoming studies.

Day 1173

Wednesday.

1610.05310
Star formation in intermediate redshift 0.2<z<0.7 brightest cluster galaxies
Cooke, et al

Present a multi-wavelength photometric and spectroscopic study of 42 BCGs in 2 samples of clusters of galaxies chosen for the study for gravitational lensing.  The study's initial sample combines 25 BCGs from CLASH and 37 BCGs from SGAS with a a total redshift range of 0.2<z<0.7.  Using archival GALEX, HST, WISE, Herschel, and VLA data, determine the BCGs' stellar mass, radio power, and SFR.  The radio power is higher than expected if due to SF, consistent with the BCGs being AGN-powered radio sources.  This suggests that the AGN and SF are both fueled by cold gas in the host galaxy.  The sSFR is low and constant with z.  The mean sSFR is 9.42e-12/yr which corresponds to a mass doubling time of 105 billion years.  These findings are consistent with models for hierarchical formation of BCGs which suggest that SF is no longer a significant channel for galaxy growth for z<1.  Instead, stellar growth (of order a factor of at least 2) during this period is expected to occur mainly via minor dry mergers.


1610.05313
Large molecular gals reservoirs in ancestors of Milky Way-mass galaxies 9 billion years ago
Papovich, et al

Large detections of molecular gas from CO emission in galaxies at z=1.2-1.3, selected to have the stellar mass and SFR of the progenitors of today's MW-mass galaxies, reveals large molecular gas masses, comparable to or exceeding the galaxy stellar masses, implying most of the baryons are in cold gas, not stars.  The galaxies' total luminosities from SF and CO luminosities yield long gas-consumption timescales.  Compared to local spiral galaxies, the SF efficiency, estimated from the ratio of total IR luminosity to CO emission, has remained nearly constant since z=1.2, despite the order of magnitude decrease in gas fraction, consistent with results for other galaxies at this epoch.  Therefore the physical processes that determine the rate at which gas cools to form stars in distant galaxies appear to be similar to that in local galaxies.


1610.05508
The Euclid mission design
Racca, et al

Euclid is a space-based optical/NIR survey mission of ESA to investigate the nature of DE, DM and gravity by observing the geometry of the Universe and on the formation of structures over cosmo timescales.  Euclid will use 2 probes of the signature of DM and energy; WL, which requires measurement of the shape and photometric redshifts of distant galaxies, and galaxy clustering, based on the measurement of the 3d distribution of galaxies through their spectroscopic redshifts.  The mission is scheduled for launch in 2020 and is designed for 6 years of nominal survey operations.  The Euclid spacecraft is composed of a service module and a payload module.  The Service Module comprises all the conventional spacecraft subsystems, the instruments warm electronic units, the sun shield and the solar arrays.  In particular the service module provides the extremely challenging pointing accuracy required by the scientific objectives.  The Payload Module consists of a 1.2m 3-mirror Korsch type telescope and of 2 instruments, the visible imager and the NIR spectro-photometer, both covering a large common field-of-view enabling to survey more than 35% of the entire sky.  All sensor data are downlinked using K-band transmission and processed by a dedicated ground segment for science data processing.  The Euclid data and catalogues will be made available to the public at the ESA Science Data Centre.

Day 1172

Tuesday.

1610.04620
Einasto profiles and the dark matter power spectrum
Ludlow, Angulo

Study the mass accretion histories (MAHs) and density profiles of DM haloes using N-body sims of self-similar gravitational clustering from scale-free power spectra, P(k) ~ k^n.  Pay particular attention to the density profiles curvature, which is characterized using the shape parameter, alpha, of an Einasto profile.  In agreement with previous findings, the results suggest that, despite vast differences in their MAHs, the density profiles of virtualized haloes are remarkably alike.  Nonetheless, clear departures from self-similarity are evident: for a given spectral index, alpha increases slightly but systematically with "peak height", nu==delta_SC/sigma(M,z), regardless of mass or redshift.  More importantly, however, the "alpha-nu" relation depends on n: the steeper they initial power spectrum, the more gradual the curvature of both the mean MAHs and mean density profiles.  These results are consistent with previous findings connecting the shapes of halo mass profiles and MAHs and imply that DM haloes are not structurally self-similar but, through the merger history, retain a memory of the linear density field from which they form.

Day 1171

Monday.

1610.04226
Halo ellipticity of GAMA galaxy groups form KiDS weak lensing
van Uitert, et al

Constrain the average halo ellipticity of ~2600 galaxy groups from GAMA, using the WL signal measured from KiDS.  To do os, quantify the azimuthal dependence of the stacked lensing signal around 7 different proxies for the orientation of the DM distribution, as it is a priori unknown which one traces the orientation best.  On small scales, the major axis of the brightest group/cluster member (BCG) provides the best proxy, leading to a clear detection of an anisotropic signal.  In order to relate that to a halo ellipticity, a model density profile must be adopted.  Derive new expressions for the quadrupole moments of the shear field given an elliptical model surface mass density profile.  Derive new expressions for the quadruple moments of the shear field given an elliptical model surface mass density profile.  Modeling the signal with an NFW profile on scales <250 kpc, which roughly corresponds to half the virial radius, and assuming that the BCG is perfectly aligned with the DM, find an average halo ellipticity of e_h=0.38±0.12.  This agrees well with results from cold-DM-only sims, which typically report values of e_h~0.3.  On large scales, the lensing signal around the BCG does not trace the DM distribution well, and the distribution of group satellites provides a better proxy for the halo-s orientation instead, leading to a 3-4 sigma detection of a non-zero halo ellipticity at scales between 250 and 750 kpc.  The results suggest that the distribution of stars enclosed within a certain radius forms a good proxy for the orientation of the DM within that radius, which has also been observed in hydrodynamical simulations.


1610.04231
ZOMG I: how the cosmic web inhibits halo growth and generates assembly bias
Borzyszkowski, Porciani, Romano-Diaz, Garaldi

The clustering of DM haloes with fixed mass depends on their formation history, an effect known as assembly bias.  Investigate the origins of this phenomenon using zoom N-body sims.  Follow the formation of 7 galaxy-sized halos selected using a definition of collapse time that generates strong assembly bias.  Haloes at z=0 are classified according to the time in which the physical volume contains their final mass becomes stable.  For 'stalled' haloes this happens at z~1.5 while for 'accreting' haloes this has not happened yet.  The zoom simulations confirm that stalled haloes do not grow in mass while accreting haloes show a net inflow.  The reason is that accreting haloes are located at the nodes of a network of thin filaments which feed them. Conversely, each stalled halo lies within a prominent filament that is thicker than the halo size.  Infalling material from the surroundings becomes part of the filament while matter within it recess from the halo.  Conclude that assembly bias originates from quenching halo growth due to tidal forces following the formation of non-linear structures in the cosmic web.  Also the internal dynamics of the haloes change: the velocity anisotropy profile is biased towards radial (tangential) orbits in accreting (stalled) haloes  Finally, extend the excursion-set theory to account for these effects.  A simple criterion biased on the ellipticity of the linear tidal field combined with the spherical collapse model provides excellent predictions for both classes of haloes.


1610.04232
The the Jeans don't fit: how stellar feedback drives stellar kinematics and complicates dynamical modeling in low-mass galaxies
El-Badry, Wetzel, Geha, Quataert, Hopkins, et al

In low-mass galaxies, stellar feedback can drive gas outflows that generate non-equilibrium fluctuations in the gravitational potential.  Using cosmo zoom-in baryonic sims from the Feedback in Realistic Environments (FIRE) project, investigate how these fluctuations affect stellar kinematics and the reliability of Jeans dynamical modeling in low-mass galaxies.  Find that stellar velocity dispersion and anisotropy profiles fluctuate significantly over the course of galaxies starburst cycles.  Predict an observable correlation between SFR and stellar kinematics: dwarf galaxies with higher recent SFRs should have systematically higher stellar velocity dispersions.  This predictions provides an observational test of the role of stellar feedback in regulating both stellar and DM densities in dwarf galaxies.  Find that Jeans modeling, which treats galaxies as visualized systems in dynamical equilibrium, overestimates a galaxy's dynamical mass during periods of post-starburst gas outflow and underestimates it during periods of net inflow.  Short-timescale potential fluctuations lead to typical errors of ~20% in dynamical mass estimates, even if full 3d stellar kinematics -- including the orbital anisotropy -- are known exactly.  When orbital anisotropy is not known a priori, typical mass errors arising from non-equilibrium fluctuations in the potential are larger than those arising form the mass-anisotropy degeneracy.  However, Jeans modeling along cannot reliably constrain the orbital anisotropy, and problematically, it often favors anisotropy models that do not reflect the true profile.  If galaxies completely lose their gas and cease forming stars, fluctuations in the potential subside, and Jeans modeling becomes much more reliable. 


1610.04606
KiDS-450: testing extensions to the standard cosmological model
Joudaki, et al

Test extensions to the standard cosmo model with WL tomography using 450 deg2 of imaging data form KiDS.  In theses extended cosmologies, which include massive neutrinos, nonzero curvature, evolving DE, modified gravity and running of the scalar spectral index, also examine the discordance between KiDS and CMB from Planck.  The discordance between the two datasets is largely unaffected by a a more conservative treatment of the lensing systematics and the removal of angular scales most sensitive to nonlinear physics.  The only extended cosmology that simultaneously alleviates the discordance with Planck and is at least moderately favored by the data includes evolving DE with a time-dependent equation of state (in the form of the w0-wa parameterization).  In this model, the respective S8=sigma8 sqrt(Omega_m/0.3) constraints agree at the 1 sigma level, and there is 'substantial concordance' between the KiDS and Planck datasets when accounting for the full parameter space.  Moreover, the Planck constraint on the Hubble constant is wider than in LCDM and in agreement with the Reiss+2016 direct measurement of H0.  The DE model is moderately favored as compared to LCDM when combining the KiDS and Planck measurements, and remains moderately favored after including an informative prior on the Hubble constant.  In both of these scenarios, the DE parameters are discrepant with a cosmological constant at the 3 sigma level.  Moreover, KiDS constraints the sum of neutrino masses to 4.0 eV (95% CL), finds no preference for time or scale dependent modifications to the metric potentials, and is consistent with flatness and no running of the spectral index.  The analysis code is publicly available at github/sjoudaki/kids450.

Day 1170

Thursday.  Friday.

1610.03854
The observed spatial distribution of matter on scales ranging from 100kpc to 1Gpc is inconsistent with the standard dark-matter-based cosmological models
Kroupa

The spatial arrangement of galaxies (of satellites on scale of 100 kpc) as well as their 3d distribution in galaxy groups such as the Local Group (on a scale of 1Mpc), the distribution of galaxies in the nearby volume of galaxies (on a scale of 8Mpc) and in the nearby Universe (on a scale of 1Gpc) is considered.  There is further evidence that the CMB shows irregularities and for anisotropic cosmic expansion.  The overall impression one obtains, given the best data given, is matter to be arranged as not expected in the DM based standard model of cosmology (SMoC).  There appears to be too much structure, regularity and organization.  Dynamical friction on the DM haloes is a strong direct test for the presence of DM particles, but this process does not appear to be operative in the real universe.  This evidence suggests strongly that dynamically relevant DM does not exist and therefore cosmology remains largely not understood theoretically.  More-accepted awareness of this case would by itself constitute a major advance in research providing fabulous opportunities for bright minds, and the observational data strongly suggest that gravitation must be effectively Milogramian, corresponding to a generalized Poisson equation in the classical limit.  Thus, physical cosmology offers a significant historically relevant opportunity for ground-breaking work, at least for those daring to do so.

Day 1169

Wednesday.

1610.03159
The Astropy Problem
Muna, et al

The Astropy Project (astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages."  For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community.  Despite this, the project has always been and remains to this day effectively unfunded.  Further, contributors receive little or no formal recognition for creating and supporting what is now critical SW.  This paper explores the problem in detail, outlines possible solutions to correct this, and presents a few suggestions on how to address the sustainability of general purpose astronomical software.

Day 1168

Tuesday.

1610.02399
Statistics of dark matter substructure: III. Halo-to-halo variance
Jiang, van den Bosch

Present a study of unprecedented statistical power regarding the halo-to-halo variance of DM substructure.  Using a combination of N-body sims and a semi-analytical model, investigate the variance in subhalo mass fractions and subhalo occupation numbers, with an emphasis on how these statistics scale with halo formation time.  Demonstrate that the subhalo mass fraction, f_sub, is mainly a function of halo formation time, with earlier forming haloes having less substructure.  At fixed formation redshift, the average f_sub is virtually independent of halo mass, and the mass dependence of f_sub is therefore mainly a manifestation of more massive haloes assembling later.  Compare observational constraints on f_sub from gravitational lensing to the model predictions and simulations results.  Although the inferred f_sub are substantially higher than the median LCDM predictions, they fall within the 95th percentile due to halo-to-halo variance.  Show that while the halo occupation distribution of sub haloes, P(N|M), is super-poissonian for large <N>, a well established result, it becomes sub-Poissonian for <N> < 2.  Ignoring the non-Poissonity results in systematic errors of the clustering of galaxies of a few percent, and with a complicated scale-and luminosity-dependence.  Earlier-formed haloes have P(N|M) closer to a Poisson distribution, suggesting that the dynamical evolution of sub haloes drives the statistics towards Poissonian.  Contrary to a recent claim, the non-Poissonity of subhalo occupation statistics does not vanish by selecting haloes with fixed mass and fixed formation redshift.  Finally, use subhalo occupation statistics to put loose constraints on the mass and formation redshift of the MW halo.  Using observational constraints on the V_max of the most massive satellites, infer that 0.25<M_vir/1e12 Msun/h < 1.4 and 0.1<z_f<1.4 at 90% confidence.


1610.02485
An order statistics approach to the halo model for galaxies
Paul, Paranjape, Sheth

Use the Halo Model to explore the implications of assuming that galaxy luminosities in groups are randomly drawn from an underlying luminosity function.  Show that even the simplest of such order statistics models -- on in which this luminosity function p(L) is universal -- naturally produces a number of features associated with previous analyses based on the `central plus Poisson satellites' hypothesis.  These include the monotonic relation of mean central luminosity with halo mass, the Lognormal distribution around this mean, and the tight relation between the central and satellite mass scales.  In stark contrast to observations of galaxy clustering, however, this model predicts no luminosity dependence of large scale clustering.  Then show that an extended version of this model, based on the order statistics of a halo mass dependent luminosity function p(L|m), is in much better agreement with the clustering data as well as satellite luminosities, but systematically under-predicts central luminosities.  This brings into focus the idea that central galaxies constitute a distinct population that is affected by different physical processes than are the satellites.  Model this physical difference as a statistical brightening of the central luminosities, over and above the order statistics prediction.  The magnitude gap between the brightest and second brightest group galaxy is predicted as a by-product, and is also in good agreement with observations.  Propose that this order statistics framework provides a useful language in which to compare the Halo Model for galaxies with more physically motivated galaxy formation models.  


1610.02644
Quenching of satellite galaxies at the outskirts of galaxy clusters
Zinger, Dekel, Kravtsov, Nagai

Find, using cosmo sims of galaxy clusters, that the hot X-ray emitting intra-cluster medium (ICM) enclosed within the outer accretion shock extends out to R_shock~(2-3)R_vir, where R_vir is the standard virial radius of the halo.  Using a simple analytic model for satellite galaxies in the cluster, evaluate the effect of ram-pressure stripping of the gas in the inner discs and in the haloes at different distances from the cluster centre.  Find that significant removal of star-forming disc gas occurs only at r<~0.5 R_vir, while gas removal from the satellite halo is also efficient between R_vir and R_shock.  This leads to quenching of star formation by starvation over 2-3 Gyr, prior to the satellite entry to the inner cluster halo.  This can explain the presence of quenched galaxies, preferentially discs, at the outskirts of galaxy clusters, and the delayed quenching of satellites compared to central galaxies.


1610.02916
Building an inclusive AAS - The critical rote of diversity and inclusion training for AAS council and astronomy leadership
Brinkworth et al

... Diversity and inclusion training for AAS council and leadership, heads of astronomy departments, and faculty search committees should be a basic requirement throughout the field.

Day 1167

Friday.  Monday.

1610.01599
Line-of-sight effects in strong lensing: putting theory into practice
Birrer, Welschen, Amara, Refregier

Present a simple method to accurately infer LoS integrated lensing effects for galaxy scale SL systems through image reconstruction. The approach enables to separate WL LoS effects from the main SL deflector.  Test the method using mock data and show that SL systems can be accurate probes of cosmic shear with a precision on the shear terms of ±0.003.  Apply the formalism to reconstruct the lens COSMOS 0038+4133 and its LoS.  In addition, estimate the LoS properties with a halo-rendering estimate based on the COSMOS field galaxies and a galaxy-halo connection.  The two approaches are independent and complementary in their information content.  Find that when estimating the convergence at the SL system, performing a joint analysis improves the measure by a factor of 2 compared to a halo model only analysis.  Furthermore, the constraints of the SL reconstruction lead to tighter constraints on the halo masses of the LoS galaxies.  Joint constraints of multiple SL systems may add valuable information to the galaxy-halo connection and may allow independent WL shear measurement calibrations.


1610.01991
How are galaxies assigned to haloes?  Searching for assembly bias in the SDSS galaxy clustering
Vakili

Clustering of DM haloes has been shown to depend on halo properties beyond mass such as halo concentration, a phenomenon referred to as halo assembly bias.  Standard halo occupation modeling (HOD) in LSS assumes that halo mass alone is sufficient in characterizing the connection between galaxies and haloes.  Modeling of galaxy clustering can ease systematic effects if the number or properties of galaxies are correlated with other halo properties.  Using the Small MultiDark-Planck high resolution N-body simulation and the measurements of the projected 2pt correlation function and the number density of SDSS DR7 main galaxy sample, investigate the extent to which the dependence of halo occupation on halo concentration can be constrained, and to what extent allowing for this dependence can improve the modeling of galaxy clustering.  Given the SDSS clustering data, the constraints on HOD with assembly bias suggests that satellite population is not correlated with halo concentration at fixed halo mass.  Furthermore, in terms of the occupation of centrals at fixed halo mass, the results favor lack of correlation with halo concentration in the most luminous samples (Mr<-21,5,-21), modest levels of correlation of Mr<-20.5,-20,-19.5 samples, lack of correlation for Mr<-19,-18.5 samples, and anti-correlation for the faintest sample Mr<-18.  Show that in comparison with abundance-matching mock catalogs, the findings suggest qualitatively similar but modest levels of assembly bias that is only present in the central occupation.  Furthermore, by performing model comparison based on information criteria, find that in most cases, the standard mass-only HOD model is still favored by the observations.

Day 1166

Thursday.

1610.01160
Selection biases in empirical p(z) methods for weak lensing
Gruen, Brimioulle

To measure the mass of foreground objects with WL, one needs to estimate the z distribution of lensed background sources.  This is commonly done in an empirical fashion, i.e. with a reference sample of galaxies of known spec-z, matched to the source population.  In this work, develop a simple decision tree framework that, under the ideal conditions of a large, purely magnitude-limited reference sample, allows an unbiased recovery of the source z probability density function p(z), as a function of magnitude and color.  Use this framework to quantify biases in empirically estimated p(z) caused by selection effects present in realistic reference and WL source catalogs, namely (1) complex selection of reference objects by the targeting strategy and success rate of existing spec surveys and (2) selection of BG sources by the success of object detection and shape measurement at low S/N.  For intermediate-to-high redshift clusters, and for depths and filter combinations appropriate for ongoing lensing surveys, find that (1) spec selection can cause biases above the 10% level, which can be reduced to ~5% by optimal lensing weighting, while (2) selection effects in the shape catalog bias mass estimates at or below the 2% level.  This illustrates the importance of completeness of the reference catalogs for empirical z estimation.

Day 1165

Wednesday.

1610.00840
Statistical connection of peak counts to power spectrum and moments in weak lensing field
Shirasaki

The number density of local maxima of weak lensing field, referred to as weak-lensing peak counts, can be used as a cosmological probe.  However, its relevant cosmo information is still unclear.  Study the relationship between the peak counts and other statistics in weak lensing field by using 1000 ray-tracing sims.  Construct a local transformation of lensing field K to a new Gaussian field y, named local-Gaussianized transformation.  Calibrate the transformation with numerical sims so that the one-point distribution and the power spectrum of K can be reproduced from a single Gaussian field y and monotonic relation between y and K.  Therefore, the correct information of 2pt clustering and any order of moments in WL field should be preserved under local-Gaussianized transformation.  Then examine if local-Gaussianized transformation can predict WL peak counts in sims.  The local-Gaussianized transformation underestimates the simulated peak counts with a level of ~20-30% over a wide range of peak heights.  Local-Gaussianized transformation can predict the WL peak counts with a ~10% accuracy in the presence of shape noise.  The analyses suggest that the cosmo information beyond power spectrum and its moments would be necessary to predict the WL peak counts with a percent-level accuracy, which is an expected statistical uncertainty in upcoming wide-field galaxy surveys.

Day 1164

Tuesday.

1610.00637
Imprint of DES super-structures on the Cosmic Microwave Background
Kovács, et al

Small temperature anisotropies in the CMB can be sourced by density perturbations via the late-time ISW effect.  Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint.  In some cases excess signals have been reported.  Probe these claims with an independent data set, using the first year data of DES in a different footprint, and using a different super-structure finding strategy.  Identified 52 large voids and 102 superclusters at 0.2<z<0.65.  Use the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for the compensated top-hat filtering technique, and then perform a stacking measurement of the CMB temperature field based on the DES data.  For optimal configurations, detect a cumulative cold imprint of voids with Delta T_f~ -5.0±3.7 uK and a hot imprint of superclusters Delta T_f~ 5.1±3.2 uK; this is ~1.2 sigma higher than the expected |DeltaT_f|~0.6 uK imprint of such super-structures in LCDM.  If instead use an a posteriori selected filter size (R/Rv=0.6), can find a temperature decrement as large as Delta T_f~ -9.8±4.7 uK for voids, which is ~2sigma above LCDM expectations and is comparable to previous measurements made using SDSS super-structure data.

Day 1163

Monday.

1609.09579
G10/COSMOS: 38 band (far-UV to far-IR) panchromatic photometry using LAMBDAR
Andrews, Driver, Davies, Kafle, Robotham, Wright

Present a consistent total flux catalogue for a ~1 deg2 subset of the COSMOS region (RA = [149.55, 150.65], Dec = [1.8, 2.73]) with near-complete coverage in 38 bands from the far-UV to the far-IR.  Produce aperture matched photometry for 128,304 objects with i<24.5 in a manner that is equivalent to the Wright+2016 catalogue from the low-z (z<0.4) GAMA survey.  This catalogue is based on publicly available image from GALEX, CFHT, Subaru, VISTA, Spitzer and Herschel, contains a robust total flux measurement or upper limit for every object in every waveband and complements the re-reduction of publicly available spectra in the same region.  Perform a number of consistency checks, demonstrating that the catalogues is comparable to existing data sets, including the recent COSMOS2015 catalogue (Laigle+2016).  Also release an updated Davies+2015 spectroscopic catalogue that folds in new spectroscopic and photometric redshift data sets.  The catalogues are available for download at cutout.icrar.org/G10/dataRelease.php.  The analysis is optimized for both panchromatic analysis over the full wavelength range and for direct comparison to GAMA, thus permitting measurements of galaxy evolution for 0<z<1 while minimizing the systematic error resulting from disparate data reduction methods.

Day 1162

Friday (Sunday).

1609.09085
The-wiZZ: clustering redshift estimation for everyone
Morrison, et al

Present The-wiZZ, an open source and user-friendly software for estimating the redshift distributions of photometric galaxies with unknown redshifts by spatially cross-correlating them against a reference sample with known redshifts.  The main benefit of The-wiZZ is in separating the angular pair finding and correlation estimation from the computation of the output clustering redshifts allowing anyone to create a clustering redshift for their sample without the intervention of an "expert".  It allows the end user of a given surveys to select any sub-sample of photometric galaxies with unknown redshifts, match this sample's catalog indices into a value-added data file, and produce a clustering redshift estimation for this sample in a fraction of the time it would take to run all the angular correlations needed to produce a clustering redshift.  Show results with this software using photometric data from the KiDS and spec data from GAMA and SDSS.  The results presented for KiDS are consistent with the redshift distributions used in a recent cosmic shear analysis from the survey.  Also present results using a hybrid machine learning-clustering redshift analysis that enables the estimation of clustering redshifts for individual galaxies.  The-wiZZ can be downloaded at github.com/morriscb/The-wiZZ.


1609.09090
PRIMUS+DEEP2: the dependence of galaxy clustering on stellar mass and specific star formation rate at 0.2<z<1.2
Coil, Mendez, Eisenstein, Moustakas

Present results on the clustering properties of galaxies as a function of both stellar mass and sSFR using data rom PRIMUS and DEEP2 galaxy redshift surveys spanning 0.2<z<1.2.  Use spectroscopic redshifts of over 100k galaxies covering an area of 7.2 deg2 over 5 separate fields on the sky, from which cosmic variance errors are calculated.  Find that the galaxy clustering amplitude is a stronger function of sSFR than of stellar mass, and that at a given sSFR, it does not depend on stellar mass, within the range probed here.  Further find that within the SF population and at a given stellar mass, galaxies above the main sequence of SF with higher sSFR are more clustered than galaxies below the main sequence with lower sSFR.  Also find that within the quiescent population, galaxies with higher sSFR are less clustered than galaxies with lower sSFR, at a given stellar mass.  Show that the galaxy clustering amplitude smoothly increases with both increasing stellar mass and decreasing sSFR, implying that galaxies likely evolve across the main sequence, not only along it, before galaxies eventually becomes quiescent.  These results imply that the stellar mass to halo mass relation which connects galaxies to DM haloes, likely depends on sSFR.