Day 1087

Thursday.

1604.07821
Cosmic visions dark energy: technology
Donelson et al

A strong instrumentation and detector R&D program has enabled the current generation of cosmic frontier surveys.  A small investment in R&D will continue to pay dividends and enable new probes to investigate the accelerated expansion of the universe.  Instrumentation and detector R&D provide critical training opportunities for future generations of experimentalist, skills that are important across the entire Department of Energy High Energy Physics program.


1604.07836
A new method to break the mass sheet degeneracy using aperture moments
Rexroth, Natarajan, Kneib

Mass determinations from GL shear and the higher order estimator flexion are both subject to the mass sheet degeneracy.  Mass sheet degeneracy refers to the ambiguity that arises due to the fact that the addition of a constant surface mass density sheet does not alter the lensing observables.  Propose a new technique to break the mass sheet degeneracy.  The method uses mass moments of the shear or flexion fields in combination with convergence information derived from number counts which exploit the magnification bias.  The difference between the measured mass moments provides an estimator for the magnitude of the additive constant that is the mass-sheet.  For demonstrating this, derive relations that hold true in general for n-th order moments and show how they can be employed effectively to break the degeneracy.  Investigate the detectability of this degeneracy parameter from the method and find that the degeneracy parameter can be feasibly determined from stacked galaxy-galaxy lensing data and cluster lensing data.  Furthermore, compare the S/N ratios of convergence information from number counts with shear and flexion for SIS and NFW models.  Find that the combination of shear and flexion performs best on galaxy and cluster scales and the convergence information can therefore be used to break the mass sheet degeneracy without quality loss in the mass reconstruction.  In summary, there is power in the combination of shear, flexion, convergence and their higher order moments.  With the anticipated wealth of lensing data from upcoming and future satellite missions - EUCLID and WFIRST - this technique will be feasible.


1604.07871
Cosmology from large scale galaxy clustering and galaxy-galaxy lensing with Dark Energy Survey Science Verification data
Kwan, et al

Present cosmo constraints from DES using  combined analysis of angular clustering of red galaxies and their ross-correlation with WL of background galaxies.  Use a 139 sq deg contiguous patch of DES data from SV period of observations.  Using large scale measurements, constrain the matter density of the Universe as Omega_m=0.31±0.09 and the clustering amplitude of the matter power spectrum as sigma_8=0.74±0.13 after marginalizing over 7 nuisance parameters and three additional cosmo parameters.  This translates into S_*=sigma_8(Omega_m/0.3)^0.16 = 0.74±0.12 for the fiducial lens redshift bin at 0.35<z<0.5, while S_*=0.78±0.09 using two bins over the range 0.2<z<0.5.  Study the robustness of the results under changes in the data vectors, modeling and systematic treatment, including photometric redshift and shear calibration uncertainties, and find consistency in the derived cosmo parameters.  Show that the results are consistent with previous cosmo analyses from DES and other data sets and conclude with a joint analysis of DES angular clustering and gg lensing with Planck CMB data, BAO and SNIa measurements.

Day 1086

Wednesday.

1604.07626
Cosmic Visions Dark Energy: Science
Donelson, Heitmann, Hirata, Honschied, Roodman, Seljak, Slosar, Trodden

Cosmic surveys provide crucial information about high energy physics including strong evidence for DE, DM,and inflation.  Ongoing and upcoming surveys will start to identify the underlying physics of these new phenomena, including tight constraints on the equation of state of DE, the viability of modified gravity, the existence of extra light species, the masses of the neutrinos, and the potential of the field that drove inflation.  Even after the Stage IV experiments, DESI and LSST, complete their surveys, there will still be much information left in the sky.  This additional information will enable us to understand the physics underlying the dark universe at uneven deeper level and, in case Stage IV surveys find hints for physics beyond the current Standard Model of Cosmology, to revolutionize the current view of the universe.  There are many ideas for how best to supplement and aid DESI and LSST in order to access some of this remaining information and how surveys beyond Stage IV can fully exploit this regime.  These ideas flow to potential projects that could start construction in the 2020's.

Day 1085

Tuesday.

1604.07233
Dependence of GAMA galaxy halo masses on the cosmic web environment from 100 square degrees of KiDS weak lensing data
Brouwer, Cacciato, et al

Galaxies and their DM haloes are part of a complex network of mass structures, collectively called the cosmic web.  Using the tidal tensor prescription these structures can be classified into four cosmic environments: voids, sheets, filaments and knots.  As the cosmic web may influence the formation and evolution of DM haloes and the galaxies they host, aim to study the effect of these cosmic environments on the average mass of galactic haloes.  To this end, measure the gg lensing profile of 91,195 galaxies, within 0.039<z<0.263, from the spectroscopic GAMA survey, using ~100 square degrees of overlapping data form KiDS.  In each of the 4 cosmic environments, model the contributions from group centrals, satellites and neighboring groups to the stacked gg lensing profiles.  After correcting the lens samples for differences in the stellar mass distirbuitons, find no dependence of the average halo mass of central galaxies in their cosmic environment.  Find a significant increase in the average contribution of neighboring groups to the lensing profile in increasingly dense cosmic environments.  Show, however, that the observed effect can be entirely attributed to the galaxy density at much smaller scales (within 4 Mpc/h), which is correlated with the density of the cosmic environments.  Within the current uncertainties, find no direct dependence of galaxy halo mass on their cosmic environment.

Day 1084

Friday.  Monday.

1504.06463
Quantifying tensions between CMB and distance datasets in models with free curvature or lensing amplitude
Grandis, Rapetti, Saro, Mohr, Dietrich

Recent measurements of CMB by Planck have produced arguably the most powerful observational evidence in support of the standard model of cosmology, i.e. the spatially flat LCDM paradigm.  In this work, perform model selection tests to examine whether the base CMB temperature and large scale polarization anisotropy data from Planck 2015 (P15) prefer any 8 commonly used one-parameter model extension with respect to flat LCDM.  Find a clear preference for models with free curvature, Omega_K, or free amplitude of the CMB lensing potential, A_L.  Also further develop statistical tools to measure tension between datasets.  Use a Gaussianization scheme to compute tensions directly from the posterior samples using an entropy-based method, the surprise, as well as a calibrated evidence ratio presented here for the first time.  Then proceed to investigate the consistency between the base P15 CMB data and 6 other CMB and distance datasets.  In flat LCDM, find a 4.8sigma tension between the base P15 CMB data and a distance ladder measurement, whereas the former are consistent with the other datasets.  In the curved LCDM model, find significant tensions in most of the cases, arising from the well-known low power of the low-ell multipoles of the CMB data.  In the flat LCDM+A_L model, however, all datasets are consistent with the base P15 CMB observations except for the CMB lensing measurement, which remains in significant tension.  This tension is driven by the increased power of the CMB lensing potential derived rom the base P15 CMB constraints in both models, pointing at either potentially resolved systematic effects or the need for new physics beyond the standard flat LCDM model.

Day 1083

Monday.  Tuesday.  Wednesday.  Thursday.

1604.05723
ALMA imaging and gravitational lens models of South Pole Telescope-selected dusty, star-forming galaxies at high redshifts
Spilker, et al

The SPT has discovered 100 [strong-] gravitationally lensed, high-z, dusty, star-forming galaxies (DSFGs).  Present 0.5" resolution 870um ALMA imaging of a sample of 47 DSFGs spanning z=1.9-5.7, and construct GL models of these sources.  The visibility-based lens modeling incorporates several sources of residual interferometric calibration uncertainty, allowing us to properly account for noise in the observations.  At least 70% of the sources are strongly lensed by FG galaxies (mu_870um>2), with a median magnification mu_870um=6.3, extending to mu_870um>30.  Compare the intrinsic size distribution of the SL sources to a similar number of unlensed DSFGs and find no significant differences in spite of a bias between the magnification and intrinsic source size.  This may indicate that the true size distribution of DSFGs is relatively narrow.  Use the source sizes to constrain the wavelength at which the dust optical depth is unity and find this wavelength to be correlated with the dust temperature.  This correlation leads to discrepancies in dust mass estimates of a factor of 2 compared to estimates using a single value for this wavelength.  Investigate the relationship between the [CII] line and the FIR luminosity and find the the same correlation between the [CII]L_FIR ratio and Sigma_FIR found for low-z SF galaxies applies to high-z galaxies and extend at least 2 orders of magnitude higher in Sigma_FIR.  This lends further credence to the claim that the compactness of the IR-emitting region is the controlling parameter in establishing the "[CII] deficit."

Day 1082

Thursday.  Friday.

1604.03934
Large-scale imprint of relativistic effects in the cosmic magnification
Duniya

Apart from the known WL effect, the cosmic magnification acquires relativistic corrections owing to: Doppler, ISW, time-delay and other (local) gravitational potential effects, respectively.  These corrections grow on very large scales and high redshifts z, which will be [within] reach of forthcoming surveys.  In this work, these relativistic corrections are investigated in the magnification angular power spectrum, using both (standard) non-interacting dark energy (DE), and interacting dark energy (IDE).  It is found that for non-interaction DE, the relativistic corrections can boost the magnification large-scale power by ~40% at z=3, and increases at lower z.  It is also found that the IDE effect is sensitive to the relativistic corrections in the magnification power spectrum, particularly at low z---which will be crucial for constraints on IDE.  Moreover, the results show that if relativistic corrections are not taken into account, this may lead to an incorrect estimate of the large-scale imprint of IDE in the cosmic magnification: including the relativistic corrections can enhance the true potential of the cosmic magnification as a cosmological probe.


1604.03937
Evidence for the alignment of quasar radio polarizations with large quasar group axes
Pelgrims, Hutsemékers

Recently, evidence has been presented for the polarization vectors from quasars to preferentially align with the axes of the large quasar groups (LQG) to which they belong.  This report was based on observations made at optical wavelengths for two large quasar groups at z~1.3.  The correlation suggests that the spin axes of quasars preferentially align with their surrounding large-scale structure that is assumed to be traced by the LQGs.  Here, consider a large sample of LQGs build from SDSS DR7 quasar catalog in 1.0<z<1.8.  For quasars embedded in this sample, collected radio polarization measurements with the goal to study possible correlations between quasar polarization vectors and the major axis of their host LQGs.  Assuming the radio polarization vector is perpendicular to the quasar spin axis, found that the quasar spin axis is preferentially parallel to the LQG major axis inside LQGs that have at least 20 members.  This result independently supports the observations at optical wavelengths.  Additionally find that when the richness of an LQG decreases, the quasar spin axis becomes preferentially perpendicular to the LQG major axis and that no correlation is detected for quasar groups with fewer than 10 members.


1604.03957
RESOLVE and ECO: the halo mass-dependent shape of galaxy stellar ad baryonic mass functions
Eckert, et al

Present galaxy stellar and baryonic (stars plus cold gas) mass functions (SMF and BMF) and their halo mass dependence for 2 volume-limited data sets.  The first, RESOLVE-B, coincides with the Stripe 82 footprint and is extremely complete down to baryonic mass Mbary~1e9.1 Msun, probing the gas-rich dwarf regime below Mbary~1e10 Msun.  The second, ECO, covers a ~40 times larger volume (containing RESOLVE-A) and is complete to Mbary~1e9.4 Msun.  To construct the SMF and BMF, implement a new "cross-bin sampling" technique with MC sampling from the full likelihood distributions of stellar or baryonic mass.  The SMFs exhibit the "plateau" feature staring below Mstar~1e10 Msun that has been described in prior work.  However, the BMF fills in this feature and rises as a straight power law below ~1e10 Msun, as gas-dominated galaxies become the majority of the population.  Nonetheless, the low-mass slope of the BMF is not as steep as that of the theoretical DM halo MF.  Moreover, assign group halo masses by abundance matching, finding that the SMF and BMF separated into 4 physically motivated halo mass regimes reveal complex structure underlying the simple shape of the overall MFs.  In particular, the satellite MFs are depressed below the central galaxy MF "humps" in groups with mass <1e13.5 Msun yet rise steeply in clusters.  The results suggest that satellite destruction and/or stripping are active from the point of nascent group formation.  Show that the key role of groups in shaping MFs enables reconstruction of a given survey's SMF or BMF based on its group halo mass distribution.

Day 1081

Monday.  Tuesday.  Wednesday.  Thursday.

1604.03109
Characterizing strong lensing galaxy clusters using the Millennium-XXL and MOKA simulations
Giocoli, et al

Investigate the SL statistics in galaxy clusters.  Extract DM haloes from Millennium sims, compute their Einstein radius distribution, and find a very good agreement with MC predictions produced with the MOKA code.  The distribution of the Einstein radii is well described by a log-normal distribution, with a considerable fraction of the largest systems boosted by different projection effects.  Discuss the importance of substructures and triaxiality in shaping the size of the critical lines for cluster size haloes.  Then model and interpret the different deviations, accounting for the presence of a BCG and 2 different stellar mass density profiles.  Present scaling relations between WL quantities and the size of the Einstein radii.  Finally, discuss how sensible is the distribution of the Einstein radii on parameters Omega_m-sigma8 finding that cosmologies with higher Omegam and sigma8 possess a large sample of SL clusters.  The Einstein radius distribution may help distinguish Planck13 and WMAP7 cosmology at 3 sigma.


1604.03131
Earth-mass haloes and the emergence of NFW density profiles
Angulo. Hahn, Ludlow, Bronoli

Report sim results from neutralino DM haloes: follow from their emergence at 1 earth mass to a final mass of a few percent solar.  Show that the density profiles of the first haloes are well described by a ~r^-1.5 power-law.  As haloes grow in mass, their density profiles evolve significantly.  In the central regions, they become shallower and reach on average ~r^-1, the asymptotic form of an NFW profile.  However, the profile of individual haloes can show non-monotonic density slopes, and be shallower than -1 in some cases.  Investigate the transformation of cusp power-law profiles using a series of non-cosmos sims of equal-mass mergers.  Contrary to previous findings, observe that temporal variations in the gravitational potential caused by mergers lead to a shallowing of the inner profiles, an effect which is stronger for shallower initial profiles and for mergers that involve a higher number of systems.  Depending on the merger details, the resulting profiles can be shallower or steeper than NFW in their inner regions.  Mergers have a much weaker effect when the initial profile is given by a broken power-law with an inner slope of -1 (such as NFW or Hernquist profiles).  This offers a plausible explanation for the emergence of NFW-like profiles in neutralino DM sims.  After their initial collapse, neutrialino DM haloes suffer copious major mergers, which progressively shallows the profile.  However, once an NFW-like profile is established, it appears stable against subsequent merging.  This suggests that halo profiles are not universal but rather a combination of (1) the physics of the formation of the micro haloes and (2) their early merger history, which are both set by the properties of the DM particle, as well as (3) the resilience of NFW-like profiles to perturbations.

Day 1080

Friday.

1604.01424
A 2.4% Determination of the local value of the Hubble constant
Rises, et al

Use WFC3 on HST to reduce the uncertainty in the local value of H0 from 3.3% to 2.4%.  Improvements come from observations of Cepheid variables in 10 new hosts of recent SNeIa, more than doubling the sample of SNeIa having a Cepheid-calibrated distance for a total of 18; these leverage with magnitude-redshift relation based on 300 SNeIa at z<0.15.  All 18 hosts and the megamaser system NGC4258 were observed with WFC3, thus nullifying cross-instruemtn zero point errors.  Other improvements include a 33% reduction in the systematic uncertainty in the maser distance to NGC4258, more Cepheids and a more robust distance to the LMC from late-type DEBs, HST observations of Cepheids in M31, and new HST-based trigonometric parallaxes for MW Cepheids.  Consider 4 geometric distance calibrations of Cepheids: (i) megamasers in NGC4258, (ii) 8 DEBs in the LMC, (iii) 15 MW Cepheids with parallaxes, and (iv) 2 DEBs in M31.  The H0 from each is 72.39±2.56, 71.93±2.70, 76.09±2.42, and 74.45±3.34 km/s/Mpc, respectively.  The best estimate of 73.03±1.79 km/s/Mpc combines the anchors NGC4258, MW and LMC, and includes systematic errors for a final uncertainty of 2.4%.  This value is 3.0 sigma higher than 67.3±0.7 km/s/Mpc predicted by LCDM with 3 neutrinos with a mass of 0.06 eV and the Planck data, but reduces to 1.9 sigma relative to the prediction of 69.3±0.7 km/s/Mpc with the combination of WMAP+ACT+SPT+BAO, suggesting systematic uncertainties in CMB measurements may play a role in the tension.  If the conflict between Planck and the H0 is taken at face value, one plausible explanation could involve an additional source of dark radiation in the early Universe in the range of Delta N_eff=0.4-1.  Anticipate signifiant improvements in H0 from upcoming parallax measurements.


1604.01769
Microlensing as a possible probe of event-horizon structure in quasars
Tomozeiu, Mohammed, Rabold, Saha, Wambsganss

In quasars which are lensed by galaxies, the point-like images sometimes show sharp and uncorrelated brightness variations (microlensing).  These brightness changes are associated with the innermost region of the quasar passing through a complicated pattern of caustics produced by the stars in the lensing galaxy.  In this paper, study whether the universal properties of optical caustics could enable extraction of shape information about the central engine of quasars.  Present a toy model with a precent-shaped source crossing a fold caustic. The silhouette of a black hole over an accretion disk tends to produce roughly crescent sources.  When a crescent-shaped source crosses a fold caustic, the resulting light curve is noticeably different form the case of a circular luminosity profile or Gaussian source.  With good enough monitoring data, the crescent parameters, apart from one degeneracy, can be recovered.


1604.01788
The Carnegie-Chicago Hubble Program.  I.  A new approach to the distance ladder using only distance indicators of population II
Beaton, et al

An ongoing program to obtain a 3% measurement of H0 using alternative methods to the traditional Cepheid distance scale.  Aim to establish a completely independent rout to H0 using RR Lyrae variables, the tip of the red giant branch (RGB), and SNeIa.  This alternative distance ladder can be applied to galaxies of any Hubble Type, of any inclination, and, utilizing old stars in low density environments, is robust to the degenerate effects of metallicity and interstellar extinction.  Given the relatively small number of SNeIa host galaxies with independently measured distances, these properties prove a great systematic advantage in the measurement of the Hubble constant via the distance ladder.  Initially, the accuracy of the value of the Hubble constant will be set by the 5 Galactic RR Lyrae calibrators with HST Fine-Guidance Sensor parallaxes.  With GAIA, bot the RR Lyrae zero point and TRGB method will be independently calibrated, the former with at least an order of magnitude more calibrators and the latter directly through parallax measurement of tip red giants.  As the first end-to-end "distance ladder" completely independent of both Cepheid variables and the LMC, this path to H0 will allow for the high precision comparison at each rung of the traditional distance ladder that is necessary to understand tensions between this and other routs to H0.


1604.01923
Galaxy and mass assembly (GAMA): accurate panchromatic photometry from Optical priors using LAMBDAR
Wright, Robotham, et al

Present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating match aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high res optical imaging.  The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions.  Describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of aperture to images with arbitrary resolution, local background estimation, aperture normalization, uncertainty determination and propagation, and object deblending.  Using simulated images, demonstrate that the program is able to recover accurate photometric measurements in both high-resolution, low-confusion, and low-resolution, high-confusion, regimes.  Apply the program to the 21-band photometric dataset from GAMA Panchromatic Data Release (PDR: Driver+2016), which contains imaging spanning the far-UV to the far-IR.  Compare photometry derived form LAMBDAR with that presented in Driver+2016, finding broad agreement between the datasets.  Nonetheless, demonstrate that the photometry from LAMBDAR is superior to that form the GAMA PDR, as determined by a reduction in the outlier rate and intrinsic scatter of colors in the LABMDA dataset.  Similarly find a decrease in the outlier rate of stellar masses and SFRs using LAMBDAR photometry.  Finally, note an exceptional increase in the number of UV and mid-IR sources able to be constrained, which is accompanied by a significant increase in the mid-IR colour-colour parameter-space able to be explored.

Day 1079

Thursday.

1604.01400
A 17-billion-solar-mass black hole in a group galaxy with a diffuse core
Thomas, Ma, McConnell, Greene, Blakeslee, Janish

Detection of highly luminous quasars z>6 suggest that BHs up to ten billion Msun already existed 13 billion years ago.  Two possible present-day dormant descendants of this population of active BHs have been found in the galaxies at the centers of the Leo and Coma galaxy clusters, which together form the central region of the Great Wall - the largest local structure of galaxies.  The most luminous galaxy clusters, however, are not confined to such high-density regions of the early Universe; yet dormant BHs of this high mass have not yet been found outside of modern-day rich clusters.  Report observations of the stellar velocity distribution in the galaxy NGC1600 - a relatively isolated elliptical galaxy near the center of a galaxy group at a distance of 64 Mpc from Earth.  Use orbit superposition models to determine that the BH at the center has a mass of 17 billion Msun.  The spatial distribution of stars near the centre is rather diffuse.  Find that the region of depleted stellar density in the cores of massive elliptical galaxies extends over the same radius as the gravitational sphere of influence of the central BH, and interpret this as the dynamical imprint of the BHs.

Day 1078

Wednesday.

1604.01050
Redshift weights for Baryon Acoustic Oscillations : application to mock galaxy catalogs
Zhu, Padmanabhan, White, Ross, Zhao

Large z surveys capable of measuring the BAO signal have proven to be a effective way of measuring the distance-redshift relation from BAO measurements without splitting the sample into redshift bins.  Building off the work in Zhu+2015, develop a technique to directly constrain the distance-redshift relation from BAO measurements without splitting the sample into redshift bins.  Parameterize the distance-redshift relation, relative to a fiducial model, as a quadratic expansion.  Measure its coefficients and reconstruct the distance-redshift relation from the expansion.  Apply the z weighting technique in Zhu+2015 to the clustering of galaxies from 1000 QuickPM (QPM) mock sims after reconstruction and achieve a 0.75% measurement of the angular diameter distance D_A at z=0.64 and the same precision for Hubble parameter H at z=0.29.  These QPM mock catalogs are designed to mimic the clustering and noise level of BOSS DR12.  Compress the correlation functions in the redshift direction onto a set of weighted correlation functions.  These estimators give unbiased D_A and H measurements at all redshifts within the range of the combined sample.  Demonstrate the effectiveness of redshift weighting in improving the distance and Hubble parameter estimates.  Instead of measuring at a single 'effective' redshift as in traditional analyses, report the D_A and H measurements at all redshifts.  The measured fractional error of D_A ranges from 1.53% at z=0.2 to 0.75% at z=0.64.  The fractional error of H ranges from 0.85% at z=0.29 to 2.45% at z=0.7.  The measurements are consistent with a Fisher forecast to within 10% to 20% depending on the pivot redshift.  Further show the results are robust against the choice of fiducial cosmologies, galaxy bias models, and RSD streaming parameters.


1604.01051
Photometric selection of a luminous red galaxy catalog with $z\geq0.55$
Núñez, Spergel, Ho

Present development of photometrically selected LRG catalog at z>0.55.  LRG candidates are selected using IR/optical color-color cuts, optimized using ROC curve analysis, with optical data from SDSS and IR data rom "unWISE" forced photometry derived from WISE.  The catalog contains 16M objects, selected over the full SDSS DR10 footprint.  The z distribution of the resulting catalogs is estimated using spec-z from DEEP2 and COSMOS.  Restfram U-B colors from DEEP2 are used to estimate LRG selection efficiency.  In DEEP2, the resulting catalog has average redshift z=0.65, with sigma=2.0 and average rest frame U-B=1.0, with sigma=0.27.  In COSMOS, the resulting catalog has average redshift z=0.60, with sigma=1.8.  Also for 35% contamination from bluer galaxies, however anticipate these to be massive galaxies in the targeted z range that will be equally cosmologically useful.  Only an estimated 6% of selected objects are bluer sources with z<0.55.  Stellar contamination is estimated to be 1.8%.

Day 1077

Tuesday.

1604.00394
Mass segregation in star clusters is not energy equipartition
Parker et al

Mass segregation in star clusters is often thought to indicate the onset of energy equipartition, where the most massive stars impart kinetic energy to the lower-mass stars and brown dwarfs/free floating planets.  The predicted net result of this is that the centrally concentrated massive stars should have significantly lower velocities thanfast-moving low-mass objects on the periphery of the cluster.  Search for energy equipartition in initially spatially and kinematically substructures N-body simulations of star clusters with N-1500 stars, evolved for 100 Myr.  In clusters that show significant mass segregation, find no differences in the proper motions or radial velocities as a function of mass.  The kinetic energies of all stars decrease as the clusters relax, but the kinetic energies of the most massive stars do not decrease faster than those of lower-mass stars.  These results suggest that dynamical mass segregation -- which is observed in many star clusters -- is not a signature of energy equipartition from 2-body relaxation.


1604.00435
Galaxy Zoo: Mergers - Dynamical models of interacting galaxies
Holincheck et al

With the use of a restricted 3-body simulation code and the help of Citizen Scientists, sample 1e5 points in parameter space for each system.  Demonstrate a successful recreation of the morphologies of 62 pairs of interacting galaxies through the review of more than 3 million simulations.  Examine the level of convergence and uniqueness of the dynamical properties of each system.  These simulations represent the largest collection of models of interacting galaxies to date, providing a valuable resource for the investigation of mergers.  This paper present the simulation parameters generated by the project, available online.  Though the best-fit model parameters are not an exact match to previously published models, the method for determining uncertainty measurements will aid future comparison between models.  The dynamical clocks from the models agree with previous results of the time since the onset of SF from star burst models in interacting systems and suggests that tidally induced star formation is triggered very soon after closest approach.


1604.00652
Galaxy redshifts form discrete optimization of correlation functions
Lee, Budavári, Basu

Propose a new method of constraining the redshifts of individual extragalactic sources based on their celestial coordinates.  Techniques from integer linear programming are utilized to optimize simultaneously for the angular 2-pt cross- and autocorrelation functions.  The novel formalism introduced here not only transforms the otherwise hopelessly expensive, brute-force combinatorial search into a linear system with integer constraints but is also readily implementable in off-the-shelf solvers.  Adopt Gurobi and use Python to dynamically build the cost function.  The preliminary results on simulated data show great promise for future applications to sky surveys by complementing and enhancing photometric redshift estimators. The approach is the first use of linear programming in astronomy.


1604.00988
Galaxy populations in massive galaxy clusters to z=1.1: color distrubiton, concentration, halo occupation number and red sequence fraction
Hennig Mohr, et al

Study the galaxy populations in 74 SZE selected clusters from SPT survey that have been imaged in SV phase of DES.  The sample extends up to z~1.1 with 4e14 Msun < M200 < 3e15 Msun.  Using the band containing the 4000 A break and its reward neighbor, study the color-magnitude distributions of cluster galaxies to ~m*+2 fining: (1) the intrinsic rest frame g-4 color width of the red sequence (RS) population is ~0.03 out to z~0.85 with a preference for an increase to ~0.07 at z=1 and (2) the prominence of the RS declines beyond z~0.6. The spatial distribution of cluster galaxies is well described by the NFW profile out to 4R200 with a concentration of c_g=3.59±0.2, 5.37±0.27 and 1.38±0.2 for the full, the RS and the blue non-RS populations, respectively, but with ~40% to 55% cluster to cluster variation and no statistically significant redshift or mass trends.  The number of galaxies within the viral region N200 exhibits a mass trend indicating that the number of galaxies per unit total mass is lower in the most massive clusters, and shows no significant redshift trend.  The RS fraction within R200 is (68±3)% at z=0.46, varies from ~55% at z=1 to ~80% at z=0.1, and exhibits intrinsic variation among clusters of ~14%.  Discuss a model that suggests the observed redshift trend in RS fraction favors a transformation timescale for infalling field galaxies to become RS galaxies of 2 to 3 Gyr.

Day 1076

Friday.  Monday.

1604.00005
The distortion of the cosmic microwave background spectrum due to intergalactic dust
Imara, Loeb

IR emission from intergalactic dust might compromise the ability of future experiments to detect subtle spectral distortions in the CMB from the early Universe.  Provide the first estimate of foreground contamination of the CMB signal due to diffuse dust emission in the IGM.  Use models of the extragalactic background light to calculate they intensity of IGM dust emission and find that emission by IGM dust at z<0.5 exceeds the sensitivity of planned Primordial Inflation Explorer (PIXIE) to CMB spectral distortions by 1-3 orders of magnitudes.  Place an upper limit on 0.23% on the contribution to the far-IR background from IGM dust emission.


1604.00006
Dynamical ejections of massive stars from your star clusters under diverse initial conditions
Oh, Kroupa

Study the effects of initial conditions (ICs) of star clusters and their massive star population on dynamical ejections of stars from star clusters up to an age of 3 Myr, particularly focusing on massive systems, using a large set of direct N-body calculations for moderately massive star clusters (Mecl=1e3.5  Msun).  Vary the ICs of the calculations such as the initial half-mass radius of the clusters, initial binary populations for massive stars and initial mass segregation.  Find that the initial density is the most influential parameter for the ejection fraction of the massive systems.  The clusters with an initial half-mass radius of 0.1 (0.3) pc can eject put to 50% (30%) of their O-star systems on average.  Most of the models show that the average ejection fraction decreases with decreasing stellar mass.  For clusters efficient at ejecting O stars, the mass function of the ejected stars is top-heavy compared to the given IMF, while the mass function of stars remaining in the cluster becomes slightly steeper (top-light) than the IMF.  The top-light mass functions of stars in 3Myr old clusters in the N-body models are in good agreement with the mean mass function of young intermediate mass clusters in M31 as found by Weisz et al.  Show that the multiplicity fraction of the ejected massive stars can be as high as 60%, that massive high-order multiple systems can be dynamically ejected, and that high-order multiples become common especially in the cluster.  Furthermore, binary populations of the ejected massive systems are discussed. When a large survey of the kinematics of the field massive stars becomes available, e.g. through Gaia, the results may be used to constan the birth configuration of massive stars in star clusters.  


1604.00034
The role of quenching time in the evolution of the mass-size relation of passive galaxies from the WISP survey
Zanella, et al

Do not find a significant trend in the distributions of the difference between the observed radius and the one predicted by the mass-size relation.  The relation between the galaxy age and its distance from the mass-size relation, if it exists, is rather shallow, wit ha slope alpha >~=-.6.  At face value, this finding suggests that multiple dry and/or wet minor mergers, rather than the appearance of newly quenched galaxies, are mainly responsible for the observed time evolution of the mass-size relation in passive galaxies.


1604.00271
Synergies between SALT and Herschel, Euclid & the SKA: strong gravitational lensing & galaxy evolution
Serjeant

GL has seen a surge of interest n the past few years.  The handful of SL systems known in the year 2000 has now been replaced with hundreds, thanks to innovative multi-wavelength selection, and there is an imminent prospect of thousands of lenses from Herschel and other sub-millimeter surveys.  Euclid and SKA promise tens or even hundreds of thousands.  GL is one of the very few probes capable of mapping DM halo distributions. Lensing also provides independent cosmo parameter estimates and enables the study of galaxy populations that are otherwise too faint for detained study.  SALT is extremely well placed to have an enormous impact with follow-up observations of FG lenses and BG sources from e.g. Herschel, the SPT, ACT, Euclid and SKA.  This paper reviews the prospects for high-impact SALT science and the many constraints of galaxy evolution want can result.


1604.00282
Strong gravitational lenses and multi-wavelength galaxy surveys with AKARI, Herschel, SPICA and Euclid
Serjeant

Submillimetre and millimeter-wave surveys with Herschel and SPT have revolutionized the discovery of SL systems.  Their follow-ups have been greatly facilitated by the multi-wavelength supplementary data in the survey fields.  The forthcoming Euclid optical/near-IR space telescope will also detected SL systems in large numbers, and orbital constraints are likely to require placing its deep survey at the North Ecliptic Pole (the natural deep field for a wide class of ground-based and space-based observations including AKARI, JWST and SPICA).  In this paper, review the current status of the multi-wavelength survey coverage in the NEP, and discuss the prospects for the detection of SL in forthcoming or proposed facilities such as Euclid, FIRSPEX and SPICA.