Day 341

Tuesday.

1211.5601
Blocking low-eccentricity EMRIs: A statistical direct-summation N-body study of the Schwarzschild barrier
Brem et al

Extreme-mass ratio inspiral (EMRI), the capture of a compact object by SMBH in a galactic nucleus, is the best way to map space and time around it.  "Schwarzschild barrier": stellar dynamics phase space complot [what is this word?] in phase space acting on low-eccentricity captures (rates decrease significantly by the presence of a blockade in the rate at which L change takes place).  Result of the impact of relativistic precession on to the stellar potential torques, and thus it affects the enhancement on lower-eccentricity EMRIs that one would expect from resonant relaxation.  Confirm and quantify the existence of this barrier with 2500 direct-summation N-body sims; use post-Newtonian and geodesic approximation for the relativistic orbits.  The existence of the barrier prevents low-eccentricity EMRIs from approaching the central MBH, but high-eccentricity EMRIs ignore the presence of the barrier, because they are driven by 2-body relaxation.  Since the rates are significantly affected in the case of low-eccentricity EMRIs, predict that a LISA-like observatory will predominantly detect high-e EMRIs.

1211.5603
Planets near mean-motion resonances
Petrovich, Malhotra, Tremaine

Multiple planets found by Kepler: planet pairs near first-order mean-motion resonances prefer orbits just outside the nominal resonance, while avoiding those just inside the resonance.  Simple dynamical model for planet formation where planets grow in mass at a prescribed rate without orbital migration or dissipation.  Develop an analytic version of this model for 2 planet systems in 2 limiting cases: the planet mass grows quickly or slowly relative to the characteristic resonant libration time.  In both cases the distribution of systems in period ratio develops a characteristic asymmetric peak-trough structure around the resonance, qualitatively similar to that observed in the Kepler sample.  Verify this result with numerical integrations of the restricted 3-body problem.  Show: for 3:2 resonance (where the observed peak-trough structure is strongest), the simple model is consistent with the observations for a range of mean planet masses 20-100 M_earth.  This mass range is higher than expected, by at least a factor of three, from the few Kepler planets with measured masses, but part of this discrepancy could be due to oversimplifcations in the dynamical model or uncertainties in the planetary mass-radius relation.

1211.5605
The WiggleZ dark energy survey: probing the epoch of radiation domination using large scale structure
Poole, Blake, et al

Find the turnover of MPS at k_0=0.016pm0.004 h/Mpc.

1211.5607
The colors of central and satellite galaxies in zCOSMOS out to z~0.8 and implications for quenching
Knobel, Lilly, et al

Examine the red fraction of central and satellite galaxies in zCOSMOS group catalog out to z~0.8, correcting for both the incompleteness in stellar mass and for the less than perfect purities of the central and satellite samples.  Show: at all masses and z, the fraction of satellite galaxies that have been quenched (i.e., are red), is systematically higher than that of centrals, as seen locally in the SDSS.  The satellite quenching efficiency, which is the probability that a satellite is quenched because it is a satellite rather than a central, is, as locally, independent of stellar mass.  Furthermore, the average value is about 0.5, which is also very similar to that seen in the SDSS.  Also construct the mass functions of blue and red centrals and satellites and show that these broadly follow the predictions of the Peng+2012 analysis of the SDSS groups.  Together, these results indicate that the effect of the group environment in quenching satellite galaxies was very similar when the Universe was about half its present age.

1211.5619
Correlating features in the primordial spectra
Achucarro, Gong (Jinn-Ouk!), Palma, Patil

Heavy fields coupled to the inflation reduce the speed of sound in the effective theory of the adiabatic mode each time the BG inflationary trajectory deviates from a geodesic; this can result in features in the primordial spectra.  Compute corresponding bispectrum and show that if a varying speed of sound induces features in the power spectrum, the change in the bispectrum is given by a simple formula involving the change in the PS and its derivatives.  In this manner, provide a uniquely discriminable signature of a varying sound speed for the adiabatic mode during inflation that indicates the influence of heavy fields.  Find that features in the bispectrum peak in the equilateral limit and, in particular, in the squeezed limit we find considerable enhancement entirely consistent with the single field consistency relation.  From the perspective of the underlying effective theory, results can be generalized to incorporate a wide variety of inflationary models where features are sourced by the time variation of BG quantities.

1211.5709
Magnetic white dwarf stars in the SDSS
Kepler, et al

Look for Zeeman splittings in H lines of WD atmosphere; about 4% of them were split, with fields from 1 MG to 733 MG.  

1211.5743
PHIBSS: molecular gas content and scaling relations in a~1-3 normal star forming galaxies
Tacconi, ... Genzel,... et al

High-z blue sequence CO 3-2 survey of molecular gas properties in normal SFGs near the cosmic SF peak.  52 CO detections in 2 redshift slices z~1.2 and 2.2, with log (M*/Msun)>10.4, and log(SFR/(Msun/yr))>1.5.  Include correction for the incomplete coverage of M*-SFR plane, infer average gas fractions of ~0.33 at z~1.2 and ~0.47 at z~2.2.  Gas fractions drop with stellar mass, in agreement with cosmological simulations including strong SF feedback.  Most of the z~1-3 SFGs are rotationally supported turbulent disks.  The sizes of CO and UV/optical emission are comparable.  The molecular gas-SF relation for the z=1-3 SFGs is near-linear, with a ~0.7 Gyrs gas depletion timescale; changes in depletion time are only a secondary effect.  Since this timescale is much less than the Hubble time in all SFGs between z~0 and 2, fresh gas must be supplied with a fairly high duty cycle over several billion years.  At given z and M*, gas fractions correlate strongly with the specific SFR.  The variation of specific SFR between z~0 and 3 is mainly controlled by the fraction of baryonic mass that resides in cold gas.

1211.5854
Feedback from high-mass X-ray binaries on the high redshift intergalactic medium : model spectra
Power, James, Combet, Wynn

Massive stars at z>6 plays a major role in cosmological reionization as luminous sources of UV photons.  Remnants of these stars can be equally important as x-ray luminous high-mass X-ray binaries (HMXBs).  Absorption cross section of neutral H decreases sharply with photon energy (propto inverse cube), X-rays can escape more freely than UV photons from SF regions in which they are produced, allowing HMXBs to make a potentially significant contribution to the ionizing X-ray background during reionization.  Explore the ionization power of HMXBs at z>6 using MC model for a coeval stellar population of MS stars and HMXBs.  Using the archetypal galactic HMXB Cygnus X-1 as template, propose a composite HMXB SED consisting of BB and power-law components, whose contributions depend on the accretion state of the system.  Determine the time-dependent ionizing power of a combined population of UV-luminous stars and X-ray luminous HMXBs, and deduce fitting formulae for the boost in the population's ionizing power arising from HMXBs; these fits allow for simple implementation of HMXB feedback in numerical simulations.  Based on this analysis, estimate the contribution of high-z HMXBs to the present-day soft X-ray BG, and show that it is a factor of ~100-1000 smaller than the observed limit.  Finally, discuss the implications of our results for the role of HMXBs in reionization and in high z galaxy formation.

1211.5966
Measuring the mass distribution of voids with stacked weak lensing
Higuchi, Oguri, Hamana

Study the prospects of measuring the DM distribution of voids with stacked WL.  Select voids from a large set of N-body simulations, and explore their lensing signals with the full ray-tracing simulations, including the effect of the large-scale structure along the LoS.  The lensing signals are compared with simple void model predictions to reconstruct the 3d mass distribution of voids.  Show that the stacked WL signals are detected at significant level (S/N >= 5) for a 5000 deg^2 survey area, for a wide range of void radii up to ~ 50 Mpc.  The error from the shape noise little affects lensing signals at large scale.  Also found that dense ridges around voids have a great impact on the WL signal, suggesting that proper modeling of the void density profile including surrounding ridges is essential for extracting the average total mass of voids.

1211.5376
Measuring dark matter profiles non-parametrically in dwarf spheroidals: an application to Draco
Jardel et al

Use stellar kinematics to map DM distribution, find it to be pretty cuspy for Draco, a dSph.  The profile for 20 < r < 700 pc well-fit by a power law with slope alpha=-1.0 pm 0.2, consistent with CDM simulations.  Despite its low baryon content, Draco lives in a massive halo.

Day 340

Monday.

1211.5140
Extended hot halos around isolated galaxies observed in the ROSAT All-sky survey
Anderson, Bregman, Dai

Stack 2k galaxies from the 2MASS very isolated galaxy catalog (2MVIG), as well as subsets of this sample based on galaxy morphology and K-band luminosity.  Detect X-ray emission at ~10 sigma for each subsample; average L_X within 50 kpc is 1e40 erg/s, although the early-type galaxies are more than twice as luminous as the late-type galaxies.  Use spatial analysis to find evidence for extended emission in 5 of the 7 subsamples (full, luminous, early-type, luminous late-type and luminous early-type).  About 1/2 of the total emission is extended, and about 1/3 of the extended emission comes from hot gas.  The average of hot gas mass is 4e9Msun in luminous galaxies, within 50 kpc, and the implied accretion rate is 0.4 Msun/yr.

1211.5146
The BOSS lyman-alpha forest sample from SDSS data release 9
Lee (KG), Bailey, et al

BOSS Lya from 54k quasar spectra with z_qso>2.15 suitable for Lya forest analysis.  This data set probes the IGM with absorption at 2.0<z<5.7 over an area of 3275 sq deg, and encompasses an approximate comoving voume of 20 (Gpc/h)^3.  Each spectrum flagged for bad pixels; correction for known biases in the pipeline estimated noise, masks for cores of damped Lya systems and corrections for their wings, and estimates of the unabsorbed continua so that the observed flux can be converted to a fractional transmission.  The continua are derived using a principal component fit to the quasar spectrum redwards of restframe Lya extrapolated into the forest region and normalized by a linear function to fit the expected evolution of the Lya forest mean-flux.  Estimated continuum errors are ~5% rms.  Discuss possible systematics arising from uncertain spectrophotometry and artifacts in the flux calibration; global corrections for the latter are provided.  Sample provides a convenient starting point for users to analyze clustering in BOSS Lya forest data; fiducial dataset that can be used to compare results from different analysis of BAO in Lya forest.  Full data available from DR9 website.

1211.5213
A robust measure of cosmic structure beyond the power-spectrum: cosmic filaments and the temperature of dark matter
Obreschkow et al

Use DM distribution phase info to get DM particle mass.

1211.5275
Excess ellipticity of hot and cold spots in the WMAP data?
Berntsen, Hansen

The ellipticity of hot and cold spots are perfectly consistent with simulated CMB maps based on concordance cosmology [seems like detector systematics would come into this?], unlike in the WMAP3 analysis.  

1211.5377
Gravitational waves and stalled satellites from massive galaxy mergers at z<1
McWilliams, Ostriker, Pretorius

Model for merger-driven evolution of the mass function for massive galaxies and their central SMBH at late times. . .. Calculate the stochastic GW signal from the resulting BH-binary mergers in the z<1 universe, and find that this population has a signal-to-noise ratio as much as 5x larger than previous estimates.  ...

1211.5589
Probing the bias of radio sources at high redshift
Passmoor ... Hoyle, et al

New methods to probe the bias of intermediate to high-z radio continuum sources for which no z information is available.  Obtain photo-z for matched radio sources from SDSS, then use the publicly available semi-empirical simulation of extragalactic radio continuum sources to infer the z distribution for all FIRST sources, and estimate the z distribution of unmatched sources by subtracting the matched distribution from the distribution of all sources.  Infer that the majority of unmatched sources are at higher redshifts than the optically matched sources and demonstrate how the angular scales of the angular two-point correlation function can be used to probe different z ranges.  Compare the angular clustering of radio sources with that expected for DM and estimate the bias of different samples.

Day 339

Sunday.  Catching up Thanksgiving week.

1211.4874

Kelvin-Helmholtz instabilities at the sloshing cold fronts in the Virgo cluster as a measure for the effective ICM viscosity

Roediger, Kraft, Ofrman, Nulsen, Churazov

Sloshing cold fronts (CFs) arise from minor merger triggered gas sloshing.  Their detailed structure depends on the properties of the ICM: hydrosims predict the CFs to be distorted by KH instabilities (KHIs), but aligned B-fields, viscosity, or thermal conduction can suppress the KHIs. Thus, observing the detailed structure of sloshing CFs can be used to constrain these ICM properties.  Both smooth and distorted sloshing CFs have been observed, indicating that the KHI is suppressed in some clusters, but not in all.  Need to address at least some sloshing clusters individually before drawing general conclusions about the ICM properties.  Present first detailed attempt to constrain the ICM properties in a specific cluster from the structure of its sloshing CF.  Proximity and brightness make the Virgo cluster and ideal target.  Combine observations and Virgo-specific hydrodynamical sloshing simulations.  Focus on a Spitzer-like temperature dependent viscosity as a mechanism to suppress the KHI, but discuss the alternative mechanisms in detail.  For viscosities >~ 10% of Spitzer values KHIs, CF are suppressed.  Describe in detail the observable signatures at low and high viscosities, i.e., in the presence or absence of KHIs.  Find indications for a low ICM viscosity in archival XMM-Newton data and demonstrate the detectability of the predicted features in deep Chandra observations.

1211.4875

The extensive age gradient of the Carina dwarf galaxy

Battaglia, Irwin, Tolstoy, de Boer, Mateo

The evolution of small systems such as dSph's is likely to have been a balance between external environmental effects and internal processes within their own relatively shallow potential wells.  Assessing how strong such environmental interactions may have been is therefore an important element in understanding the baryonic evolution of dSphs and their derived DM distribution.  Present results from a wide-area CTIO/MOSAIC II photometric survey of Carina dSph, reaching down to ~2 mags below the oldest MS turn-off (MSTO).  This dataset enables tracing of Carina structure in detail out to very large distances from its center, and as a function of stellar age.  Observe the precense of an extended structure made up primarily of ancient MSTO stars, at distances between 25-60 arcmin from Carina's center, confirming that Carina extends well beyond its nominal tidal radius.  The large number statistics of survey reveals features such as isophote twists and tails that were undetected in other shallower surveys.  Unambiguous signs of tidal disruption, other than Sagittarius dwarf. Demonstrate the presence of a negative age gradient in Carina from its MSTOs, and trace it out to very large distances from the center.  Signs of interaction with MW make it unclear whether the age gradient was already in place before Carina underwent tidal disruption.

1211.5025

On the shear estimation bias induced by the spatial variation of colour across galaxy profiles

Semboloni, Hoekstra, ... Joachimi, Kitching, Kuijken, ... Mellier, Miller, Rhodes, .. Schrabback, Velander et al

Spatial variation of the color of a galaxy may introduce a bias in the measurement of its shape if the PSF profile depends on wavelength.  Study how this bias depends on the properties of the PSF and the galaxies themselves.  The bias depends on the scales used to estimate the shape, which may be used to optimise methods to reduce the bias.  here we develop a general approach to quantify the bias.  Although applicable to any WL survey, focus on the implications for Euclid.  Based on study of synthetic galaxies, find that the bias is a few x 1e-3 for a typical galaxy observed by Euclid.  Consequently, it cannot be neglected and needs to be accounted for.  Demonstrate how one can do so using spatially resolved observations of galaxies in two filters.  Show that HST observations in the F606W and F814W filters allow modeling and reduce the bias by an order of magnitude, sufficient to meet Euclid's scientific requirements.  The precision of the correction is ultimately determined by the number of galaxies for which spatially-resolved observations in at least 2 filters are available.  Use results from the Millennium Simulation to demonstrate that archival HST data will be sufficient for the tomographic cosmic shear analysis with the Euclid dataset.  

1211.4864

THe universe at extreme scale: Multi-petaflop sky simulation on the BG/Q

To explore the 'dark universe' requires a corresponding extreme-scale simulation capability the HACC (Hybrid/Hardware accelerated cosmology code) framework has been designed to deliver this level of performance.  HACC attains unprecedented scalable performance: 14 PFlops at 70% of peak, and 90% parallel efficiency on 1M cores and equal number of MPI ranks, and a concurrency of 6.3 million.  Benchmark run with >3.6 trillion particles, significantly larger than any cosmo simulation yet performed.

1211.4579

He II optical depth and UV escape fraction of galaxies

Khaire, Srianand

Study the effect of H I ionizing photons escaping from high-z galaxies on He II ionizing UVB.  Show that, while these photons do not directly interact with He II ions, they play an important role through radiative transport in modifying the shape of He II ionizing part of UVB spectrum . Within the observed range of UV escape from galaxies, show the rapid increase in He II Lyman alpha effective optical depth at z~2.7 can be naturally explained without resorting to pre-overlap area of He II reionization.  A well measured He II Lyman alpha effective optical depth vs z can be used to constrain the z evolution of UV escape from high-z galaxies.  Study also stresses the importance of including galaxy contribution even in the fluctuating UV BG calculations.

1211.4585

Toward a direct measurement of the cosmic acceleration

Darling

Precise HI 21cm absorption line z observed in multiple epochs to directly constrain the secular redshift drift dz/dt_o or the cosmic acceleration dv/dt_o; use Green Bank telescope.  10 objects from 0.09<z<0.69 observed over 13.5 years show the rates.  Measurements are 3 orders of magnitude larger than the theoretically expected acceleration at z=0.5, but they demonstrate the lack of peculiar acceleration in absorption line systems and the long-term frequency stability of modern radio telescopes.  A comparison of UV metal absorption lines to the 21 cm line improves constraints on the cosmic variation of physical constants.  Linear evolution is consistent with no variation.  The cosmic acceleration could be directly measured in ~125 years using current telescopes, or in ~5 years using SKA, but systematic effects will arise at the 1cm/s/yr level.

1211.4590

The imminent detection of gravitational waves from massive black-hole binaries with pulsar timing arrays

McWilliams, Ostriker, Pretorius

Observations: massive balaxies double in mass and quintuple in size between z=1 and present, despite undergoing very little SF, suggesting that galaxy mergers drive the evolution.  Since these galaxies will contain SMBH, this suggests a larger BH merger rate, and tehrefore a larger gravitational-wave signal.  Calculate the merger-driven evolution of the mass function, and find taht merger rates are 10 to 30 times higher and gravitational waves are 3 to 5 times stronger than previously estimated, so that the gravitational-wave signal may already be detectable with existing data from pulsar timing arrays.  Also provide an explanation for the disagreement with past estimates that were based on DM halo simulations.

1211.4610

21-cm lensing and the cold spot in the cosmic microwave background

Kovetz, Kamionkowski

Test CMB large cold spot hypothesis, (i) extremely large void and (ii) cosmic texture, with WL of 21-cm fluctuations from EoR with SKA.  Void can be tested with SKA, texture requires prolonged observations at the highest frequencies that correspond to EoR, over the field of view containing the cold spot.

1211.4612

The ring nebula around the blue supergiant SBW1: pre-explosion snapshot of a SN 1987A twin

Smith (Nathan), ... Filippenko

[The double-polar ring, as also seen in SN 1987, in another star]  Suggest model: does not require a fast wind colliding with a previous red supergiant wind.  Observation also show diffuse emission filling the interior of the ring in H-alpha and thermal-IR emission: 190K dust with 1e-5 Msun.  Dense inner ring causes the two polar rings (model).

1211.4799

Origin of galactic cosmic rays

Blasi

From the energetic point of view, SNRs remain the most plausible sources of CRs: CRs are accelerated through diffusive shock acceleration in SNRs and propagate diffusively in the galaxy in an energy-dependent way.  Qualitative confirmation of the SNR acceleration scenario has recently been provided by gamma ray and X-ray observations.  Diffusive propagation in the Galaxy is probed observationally through measurement of the secondary to primary nuclei flux ratios.  There are some weak points in the paradigm, which suggest missing physical ingredients in the models: Predicted spectra of accelerated particles are systematically too hard compared to gamma-ray observations, and hard injection spectra indirectly imply a steep energy dependence of the diffusion coefficient in the galaxy, which in turn leads to anisotropy larger than the observed one.  Recent measurements of the flux of nuclei suggest that the spectra have a break at some rigidity that does not agree with acceleration and propagation.  

1211.4834

Comments on "A huge reservoir of ionized gas around the Milky Way: accounting for the missing mass?" (2012 ApJL, 756, 8) and "The warm-hot gaseous halo of the Milky Way" (arXiv1211.3137)

Wang, Yao

These papers are seriously flowed in many aspects (analysis, assumptions) as well as mis-reading and mis-interpreting earlier studies. Show examples of such flaws.

1211.4847

A simple fitting method (gfit) for galaxy shape measurement in weak lensing surveys

Gentile, Courbin, Meylan

A simple forward deconvolution method to measure galaxy shapes with PSF and noise.  2d elliptical Sersic profile fit to data, convolved with the PSF.  Apply to GREAT10; lowest additive bias and the second lowest multiplicative bias.  Fitting method, so will be affected by noise bias.  Competitive performances for a relatively low computing time.

1211.4979

Finding the first cosmic explosions I: pair-instability supernovae

Whalen , ... Holz, .. et al

Properties of Pop III stars: direct observations are still decades away, but can probe its properties via their SNe.  JWST can detect such SNe out to z>30; WFIRST in the all-sky survey out to z=15~20, and LSST and Pan-STARRS at z~7-8.  The discovery of these ancient explosions will probe the first stellar populations and reveal the existence of primitive galaxies that might not otherwise have been detected.

Day 338

Thursday.


1211.4583
A possible impact near the Milky Way of a former major merger in the local group
Fouquet et al

MW dwarf system has 2 'exceptional' features: Thick plane ("Vast Polar Structure") and the MCs (irregulars that almost never seen this close from a L* galaxy like the MW).  Simulation of M31 show that a former gas-rich major merger's tidal tail may have reached the MW.  Most of the MW dwarves (including the MCs) may have been formed within a tidal tail during the former merger in the local group.  Leads to a fair reproduction of the VPOS as well as to a simple explanation of the MCs proximate to the MW (accounts for both the weird features).  But, this scenario predicts DM-free MW dwarves, in contradiction with their intrinsically large velocity dispersions.  Requires further investigation.

1211.4584
The rate of WD-WD head-on collisions may be as high as the SNe Ia rate
Katz, Dong

As the title says.

1211.4345
Cosmic microwave background filters and the dark-flow measurement
Atrio-Barandela, Kashlinsky, Ebeling, Kocevski

[Oh wait, I think I pretended to read this one before, but I didn't understand it was about DM flow]  kSZ measurements identifies a bulk flow roughly aligned with CMB dipole and of magnitude 600-1000 km/s at 0.5-1 Gpc scale; [then talks about data filtering] no detection of large-scale flow indicates inadequate filtering.  Filter normalization gives results similar to their result.  Discrepancies come from cluster profiles.  

1211.4439
A multi-wavelength study of the gravitational lens COSMOS J095930+023427
Cao et al

z=0.89 lens, with LoS group lens at z=0.7.  Source redshift ~2.0.  Einstein radius of 0.79".  SIE and PIEMD mass analysis; total mass, DM fraction within Einstein radius,, and external shear due to a FG galaxy group are robust wrt the choice of parametric model and source redshift.  Measure luminous mass from photometric data; DM fraction between 0.71 to 0.79 depending on the unknown source z.  The non-null external shear found in lensing models supports the presence and structure of galaxy group at z~0.7, and an independent measurement of 0.5-2 keV X-ray luminosity within 20" around X-ray centroid provides a group mass of M=3-10*1e13 Msun, in good agreement with previous WL estimate.

1211.4480
Cosmology with photometrically-classified Type Ia supernovae from the SDSS-II supernova survey
Campbell, D'Andrea, Nichol, Sako, ... et al

752 photometrically classified SNIa from SDSS-II SN survey, supplemented by BOSS.  Host galaxy redshifts of 0.05<z<0.55; SNIa typing efficiency of 70.8% with 3.9% contamination.  Demonstrate that this contamination has no effect on the cosmology constraints; quantify and correct for selection effects (Malmquist bias) with simulations.  Fit to flat LCDM; omega_m=024pm0.07 (statistical errors only).    Competitive omega_m and omega_lambda from SNLS3.  w=-0.96pm0.1, omega_k=0pm0.03; competitive with spectro SNIa.  Lower redshift leverage of SDSS-II SN sample, but lack of spectroscopic confirmation.

1211.4585
Toward a direct measurement of the cosmic acceleration
Darling

HI 21cm absorption line redshifts observed in multiple epochs (13.5 years)

Day 337

Wednesday.

1211.4031
Effective conductance method for the primordial recombination spectrum
Ali-Haimoud

A fast way to compute the spectrum, separating the cosmology (cheap) from cosmology-independent part (expensive).  1e4 times faster.

1211.4128
A local bias approach to the clustering of discrete density peaks
Desjacques

Show: 2pt correlation function of maxima of homogeneous and isotropic Gaussian random field can be thought of (to 2nd order) as arising from a local bias expansion formulated in terms of rotationally invariant variables.  This expansion relies on a unique smoothing scale (Lagrangian radius of dark matter haloes).  Advantage: circumvents the difficult computation of joint probability distributions.  Demonstrate that the bias factors associated with these rotational invariants can be computed using a peak-BG spit argument.  Bias factors are orthogonal polynomials averaged over spatial locations that satisfy the peak constraint.  Asphericity in the peak profile contributes to the clustering at quadratic and higher order, with bias factors given by generalized Laguerre polynomials.  Useful to model the clustering of discrete tracers (eg peaks) with more realistic collapse prescriptions involving the tidal shear.

1211.4253
Hubble parameter measurement constraints on dark energy
Farooq, Mania, Ratra

21 H(z) points from past literature to constrain model parameters on time-evolving DE cosmologies.  Constraints now almost as restrictive as that from SNIa (Suzuki+ 2012).  Joint analysis of H(z), BAO and SNIa data favors a spatially-flat cosmological model by a cosmological constant, but does not exclude slowly-evolving DE.

1211.4308
On the scatter in the relation between stellar mass and halo mass: random or halo formation time dependent?
Wang, De Lucia, Weinmann

HOD fit of both stellar MF and correlation function of galaxies by definition; SAM built on the same DM halo merger trees than empirical model still have difficulties in reproducing the observational data simultaneously.  Compare relation between M* of galaxies and their host halo mass in the 3 models (1 HOD and 2 SAM); find that they are different.  Rescaled DLB07 SAM does ok, SAM model Guo11 still over-predicts the clustering of low-mass galaxies.  This indicates that the detail of how galaxies populate the scatter in the M*-M_halo relation does play an important role in determining the correlation functions of galaxies.  While the M* of galaxies in HOD (Wang) model depends only on halo mass and is randomly distributed within the scatter, galaxy M* depends also on the halo formation time in SAMs.  At fixed value of infall mass, galaxies that lie above the median M*-M_halo relation reside in haloes that formed earlier, while galaxies that lie below the median relation reside in haloes that formed later.  This effect much stronger in Guo11, which explains the over-clustering of low mass galaxies ing Guo11.  Results illustrate that the assumption of random scatter in the relation between stellar and halo mass as employed by current HOD an abundance matching models may be problematic in case a significant assembly bias exists in the real Universe.

1211.4345
Cosmic microwave background filters and the dark-flow measurement
Atrio-Barandela, Kashlinsky, Ebeling, Kocevski

Large-scale peculiar velocities from cumulative kSZ effect identified a bulk flow of galaxy clusters at 600-1000 km/s on scales of 0.5-1 Gpc, roughly aligned with the all-sky CMB dipole.  The signal originates from a residual dipole in the direction of galaxy clusters; amplitude increases with the X-ray luminosity of the clusters.  Data must be filtered to remove the primary CMB (increases S/N).  Filtering important to get signal.  Results from alternative filters consistent with measurement [x-ray?], when filters are normalized to the data.  The discrepancies can be traced to the assumptions on cluster profile and extent that reduce the efficiency of the filter and the possible existence of tSZ residual dipoles.  PLANCK maps will be important to probe the bulk flows as well as to remove spurious dipole signals and further identify the filtering schemes appropriate for this measurement.

1211.4356
Magnetic fields during high redshift structure formation
Schleicher et al

High-res cosmo sims of primordial haloes with 1e7 Msun; turbulent structures and complex morphologies.  Turbulence implies the efficient amplification of B-fields via the small-scale dynamo.  Field strengths of ~1e-5 G can be expected at number densities of ~5/cm^3.

Day 336

Tuesday.


1211.3741
The clustering of galaxies in the SDSS-III baryon oscillation spectroscopic survey: weighing the neutrino mass using the galaxy power spectrum of the CMASS sample
Zhao, Saito, Percival, Ross, ...

Measure neutrino mass using 3d galaxy power spectra of SDSS BOSS DR9 CMASS galaxy sample.  Combine with CMB, SN and other BAO data: Sum m_nu < 0.340 eV with flat LCDM, or <0.821 eV for a more general cosmological background.  N_eff = 4.308 or 4.032, respectively.  Effects of: galaxy power spectrum bias model, effect of z-space distortion, the cutoff scale of power spectrum, and the choice of additional data.  Impact of neutrinos with unknown masses on other cosmo parameter measurements investigated.  ... Other cosmo params constrained.

1211.3743
Global 21cm signal experiments: a designer's guide
Liu, Pritchard, Tegmark, Loeb

21cm: potentially a direct probe of EoR and Dark Ages.  Signal = purely spectral signature; have little angular sensitivity; difficult to distinguish from FG (galactic synchrotron radiation, much brighter).  Optimal FG removal (mathematical framework); complement spectra with angular information.  (1) with spectral-only methods, it is impossible to mitigate errors that arise from uncertainties in FG modeling, (2) FG contamination can be significantly reduced for experiments with fine angular resolution, (3) most of the statistical significance in a positive detection during the Dark Ages comes from a characteristic high-z trough in the 21cm brightness temperature; and (4) measurement errors decrease more rapidly with integration time for instruments with fine angular resolution.  An instrument with 5 degree beam can achieve highly significant detection (>5 sigma) of extended reionization scenarios after integrating for 500 hrs.  No angular resolution means no detection of gradual reionization.  Abrupt ionization histories can be detected at the level of 10-100's of sigma.  

1211.3752
Massive black hole seeds born via direct gas collapse in galaxy mergers: their properties, statistics and environment
Bonoli, Mayer, Callegari

Study the statistics and cosmic evolution of SMBH seeds formed during major mergers of gas-rich late-type galaxies with hydro-sims.  Envision a scenario in which a supermassive star can form at the center of galaxies that just experienced a major merger owing to a multi-scale powerful gas inflow, provided that such galaxies live in haloes with masses above 1e11 Msun, are gas-rich and disc-dominated, and do not already host a massive black hole.  Assume: ultimate collapse of the SM star leads to the rapid formation of BH of 1e5 Msun following a quasi-star stage.  Using a model for galaxy formation applied to the outputs of the Millennium Simulation, we show that the conditions required for this massive BH formation route to take place in the LCDM model are actually common at high z, and can be realized even at low redshift.  Most major mergers above z~4 in haloes with >1e11 Msun can lead to fromation of a massive seed and, at z~2, the fraction of favrouable mergers decreases to 1/2.  Find that even in the local universe a fraction (~20%) of major mergers in massive haloes still satisfy the conditions of our massive black hole formation route.  These late events take place in galaxies with a markedly low clustering amplitude, that have lived in isolation for most of their life, and that are experiencing a major merger for the first time.  We predict that massive black hole seeds from galaxy mergers can dominate the massive end of the mass function at z>4 and z~2 relative to lighter seeds formed at higher z (e.g. collapse of Pop III stars).  A fraction of these massive seeds could lie, soon after formation, above the MBH-MBulge relation.

1211.3771
The size and mass evolution of the massive galaxies over cosmic time
Trujillo

Passively evolving objects: which mechanism has made galaxies grow large in size without altering their stellar population properties dramatically?  Most likely minor mergers...  but: (1) insufficient number of satellites, and (2) the presence of a population of nearby massive compact galaxies with mixture of stellar properties is another piece of the puzzle that still does not nicely fit within a comprehensive scheme.

1211.3774
Modeling the distribution of Mg II absorbers around galaxies using background galaxies & quasars
Bordoloi, Lilly, Kacprzak, Churchill

Joint constraints on the distribution of MgIi absorption around galaxies: combine MgII absorption in stacked BG galaxy spectra and the distribution of host galaxies of strong MgII systems from the spectra of background quasars.  Present a suite of models that predict the dependence of MgII absorption on a galaxy's apparent inclination, impact parameter and azimuthal angle.  The variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the MgII absorption than the dependence on the galaxy's inclination.  Strong absorbers are asymmatrically distributed in azimuth around their host galaxies: located within 50 deg of the host galaxy's projected minor axis.  Simple bipolar component plus a spherical or disk component, or a single highly softened bipolar distribution, can well represent the azimuthal dependencies observed in both the datasets.  Simultaneously fitting both datasets to the composite model, bipolar cone is confined to 50 deg of the minor axis and contains 2/3 of the total MgII absorption.  The single softened cone model has an exponential fall off with azimuth with an exponential scale-length in opening angle of 45 deg.  Conclude that the distribution of MgII gas at low impact parameters is not the same as that found at high impact parameters.  MgII absorption within 40 kpc primarily arises from cool MgII gas entrained in winds.  Beyond 40 kpc, there is evidence for a more symmetric distribution, significantly different from that closer into the galaxies; a significant component appears aligned more with the disk and is possibly inflowing, perhaps as part of a galactic fountain or the inflow of material from further out in the system.

1211.3973
What determines the sizes of red early-type galaxies?
Lee, Kim, Ree, ...

Investigate the origin of size dispersions, after their M, L, z and morphologies are set.  Find: sizes of faint galaxies are affected more significantly by L, while for bright galaxies, by dynamical mass.  At fixed M and L, the sizes of low-mass gals are less sensitive to their colors, color gradients and axis ratios.  On the other hand, the sizes of intermediate-mass and high-mass galaxies significantly depends on color, gradients, and axis ratios: larger red E galaxies have bluer colors [?!], more negative color gradients (bluer outskirts) and smaller axis ratios.  Results indicate that the sizes of intermediate- and high-mass red early-type galaxies are significantly affected by their recent minor mergers or rotations, whereas the sizes of low-mass red early-type galaxies are affected by some other mechanisms.  Major dry mergers also seem to have influenced on the size growth of high-mass red early-type galaxies.

1211.3976
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic survey: the low redshift sample
Parejko, Sunayama, Padmanabhan, ... et al

Small scale clustering (0.5<r< 40 Mpc/h) of 78k massive (>1e11.3Msun) galaxies at 0.2<z<0.4 from BOSS; describe the sample selection, properties of galaxies, caveats for working with the data.  Calculate the real-and z-space 2-pt correlation functions of these galaxies, fit these measurements using HOD modeling within DM cosmo sims, and estimate the errors using mocks.  

Day 335

Monday.

1211.3415
Uncovering drivers of disk asembly: bulgeless galaxies and the stellar mass Tully-Fisher relation
Miller, Sullivan, Ellis

Assembly history of galaxies with rotating disks: examine the stellar mass TF relation over a wide range in z (Keck spectro-z sample) partitioned according to whether or not galaxies contain a prominent bulge (from HST images).  Find: bulgeless disk galaxies with z>0.8 present a significant offset from the local TF relation, whereas, at all z probed, those with significant bulges fall along the local relation.  Results support the suggestion that bulge growth may somehow expedite the maturing of disk galaxies onto the TF relation.  Discuss a variety of physical hypothesis that may explain this result in the context of kinematic observations of SF galaxies at z=0 and z>2.

1211.3417
An improved estimator for non-Gaussianity in cosmic microwave background observations
Smith, Grin, Kamionkowski

As the title says.  Standard estimators are constructed to be optimal in the Gaussian limit.  Apply a known technique to full-sky map.  As a result of the late time ISW effect, the performance of the improved estimator is degraded.  If the CMB maps are first cleaned of the ISW effect using a tracer of FG structure (eg galaxy survey or CMB WL), the new estimator does remove a majority of the excess variance, allowing a higher significance detection of fnl.

1211.3418
The mass-metallicity relation with the direct method on stacked spectra of SDSS galaxies
Andrews, Martini

The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution (cosmological gas inflow, metal production in stars, and gas outflow via galactic winds).  Measure metallicity of 200k SF galaxies from SDSS: stacked in bins of (1) M* and (2) both M* and SFR to get O III and O II lines for the "direct method" [?].  3 decades in stellar mass: log(M*/Msun)=7.4 to 10.5.  Mass-metallicity relation rises steeply at low mass (O/H~M*^1/2) until it turns over at M*=1e8.9Msun, and asymptotes to log(O/H)+12 = 8.8 at high mass.  Direct method has steeper slope, lower turnover mass, and a greater dependence on SFR then strong line mass-metallicity relations. SFR dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations.  [what's the significance of the mass-metallicity relation differences?!?]

1211.3420
The dark halo - spheroid conspiracy and the origin of elliptical galaxies
Remus, Burkert, Dolag, Johansson, Naab, Oser, Thomas

Dynamical modeling and SL data indicate that the total density profiles of early-type galaxies are close to isothermal (rho_tot ~ r^gamma, where gamma~-2).  Understand toe origin of this universal slope with simulated spheroids in isolated binary mergers with controlled initial conditions as well as the formation within the cosmological framework.  On average, gamma=-2.1 with a tendency towards steeper slopes for more compact, lower-mass ellipticals.  In the binary mergers, the amount of gas involved in the merger determines the steepness of the slope.  The amount of gas involved in the merger determines the steepness of the slope; agrees with cosmo sims where ellipticals with steeper slopes have a higher fraction of stars formed in-situ.  At higher z, the slopes of the ellipticals extracted from the cosmo sims are generally steeper.  Each gas-poor merger event evolves the slope towards gamma=-2; once this slope is reached, further merger events do not change the slope anymore.  Independent of their individual slopes or evolution scenarios, all ellipticals have flat intrinsic combined stellar and DM velocity dispersion profiles.  The variety of complex formation histories as present in cosmo sims, including major as well as minor merger events, is essential to generate the full range of observed density slopes seen for present day elliptical galaxies.

1211.3424
Stellar kinematics of z~2 galaxies and the inside-out growth of quiescent galaxies
van de Sande, Kriek, Franx, van Dokkum, Bezanson, ... Rix... et al

Investigate whether massive, quiescent galaxies were denser at z~2 than they are today.  Stellar kinematics from spectra in UV to NIR; dynamical mass meausrements of 5 quiescent massive (>1e11Msun) galaxies at z~2.  Find: stellar ages range from 0.5-2Gyr with no sign of on-going SF.  Measure velocity dispersions (300-450 km/s) and find that they are 1.6-2.1 times higher than those of galaxies in the SDSS at fixed mass.  Sizes are measured with GALFIT from HST image; dynamical masses correspond well to the SED-based M*, with dynamical masses that are ~15% higher.  Find M*/M_dyn may decrease slightly with time, which could reflect the increase of the DM fraction within an effective radius.  Combine different stellar kinematic studies from the literature, and examine the structural evolution from z~2 to z~0: we confirm that at fixed dynamical mass, the effective radius increases by a factor of ~2.8, and the velocity dispersion decreases by a factor of ~1.7 with time [if M_dyn = halo mass, then this means ... wait, what's happening to M*?  Is it correct to assume that M_dyn = M_halo?  Does this mean that the stars are more fluffier in the halo at later times?].  The mass density within one effective radius decreases by a factor of ~21, while within a fixed physical radius (1kpc) it decreases only mildly (~2.3).  [oh, I guess there is cosmological expansion.]  When allowed for an evolving mass limit by selecting a population of galaxies at fixed number density, a stronger size growth with time is found (~4), velocity dispersion decreases by a factor of ~1.4, and the mass density within 1kpc is consistent with no evolution.  This finding suggests that massive quiescent galaxies at z~2 grow in an inside-out matter, consistent with the expectations from minor mergers.

1211.3441
Quenching of SF in molecular outflow host NGC 1266
Alatalo, .. Graves, .. et al

AGN-driven molecular outflow in NGC 1266, potentially quenching all of its SF within the next 100 Myr.  No evidence of major interaction.  The molecular gas and the instantaneous SF tracers indicate that the current sites of SF are located in a hypercompact disk within 200 pc of the nucleus.  On the other hand, tracers of recent SF (H_beta and SPS analysis) show that the young stars are distributed throughout a larger area of the galaxy than current SF.  As the AGN at the center of the NGC 1266 continues to drive cold gas out of the galaxy, we expect SFR to decline as the SF is ultimately quenched.  Thus, NGC 1266 is in the midst of a key portion of its evolution; may want to keep a close eye on it.

1211.3663
CLASH: three strongly lensed images of a candidate z~11 galaxy
Coe, Zitrin, ... et al

As the title says.

Day 334

Sunday.

1211.3170
Population gradients and photometric metallicities in early- and transition-type dwarf galaxies: clues from the Sculptor group
Lianou, Grebel, Da Costa, Rejkuba, Jerjen, Koch

Focus on the resolved stellar populations of one early- and four transition-type dwarf galaxies with the aim to examine the potential presence of population gradients and place constraints on their mean metallicities.  HST images generate CMDs of resolved stellar populations to constrain range of ages and metallicities, and their spatial distribution.  (photometric metallicities too).  All studied dwarfs contain intermediate-age stars of ~1Gyr and older (AGB and red clump stars), while the transition-type dwarfs contain also stars younger than ~1Gyr (young MS and vertical red clump stars).  Spatial distribution of stars trace different evolutionary phases show a population gradient in all transition-type dwarfs.  [what kind of population gradient?!?]  ... Photo-metallicity not realizable due to degeneracies.  ...

1211.3199
The M_(black hole)-L_(spheroid) relation at low masses
Graham, Scott

For 72 galaixes, derive M_BH vs L_{host spheroid} relation for (i) subsample of 24 core-Sersic galaxies with partially depleted cores, and (ii) the remaining subsample of 48 Sersic galaxies. Near-linear relation M_BH ~ L(K_s)^1.1 for the core-Sersic spheroids (build in additive dry merger events), while ~L(K_s)^2.73 for the Sersic spheroids build from gas-rich processes.  After converting literature B-band disk galaxy mags into inclination- and dust-corrected bulge magnitudes, obtain a similar result.  Remains unknown whether barred and non-barred Sersic galaxies are offset from each other in the M_BH-L diagram.  Feedback results in a dramatically different scaling relation.  Introduce a new, quadratic cold-gas 'quasar' mode feeding equation for semi-aalytical models to reflect the quadratic mass growth of BHs in Sersic galaxies build admist gas-rich processes.  

1211.3206
Sunyaev-Zeldovich signal processing and temperature-velocity moment method for individual clusters
Chulba, Switzer, Nagai, Nelson

SZ observation of individual clusters can ask specific questions about the dynamical state of ICM.  In this paper, develop a new method that clearly shows the connection of SZ signal with the cluster model.  Relativistic temperature and kinematic corrections in the single-scattering approximation.  Illustrate how to apply method to different cluster models, highlighting parameter degeneracies and instrumental effects that are important for interpreting future high-res SZ data.  Shows: LoS temperature variations can introduce significant biases in the derived SZ temperature and peculiar velocity.  Furthermore discuss how the position of the SZ null is affected by the cluster's temperature and velocity structure. SZ signal around the null alone is rather insensitive to different cluster models, and that high frequency channels add a large leverage in this regard.  Also apply method to recent high sensitivity SZ data of the Bullet cluster, showing how the results can be linked to LoS variations in the electron temperature.  Tools developed as part of SZpack should be useful for analyzing high-resolution SZ data and computing SZ maps from simulated clusters.

1211.3245
Improved photometric redshifts via enhanced estimates of system response, galaxy templates, and magnitude priors
Schmidt, Thorman

Photo-z's depend critically on accurate photometry.  Describe the improvements to the photometric calibration and the photo-z estimate in DLS from correcting 3 of the inputs to the photo-z calculation: the system response as a function of wavelength, the SED templates, and template prior probabilities as a function of magnitude.  Model the system response with a physical model of the MOSAIC camera's CD, which corrects a 0.1 mag discrepancy in the colors of type M2 and later stars relative to the SDSS z-band photometry.  Provide new x-band response for MOSAIC (before its recent detector upgrade).  Improved inputs lead to a 20% reduction in photo-z scatter and a reduction of the bias by a factor of more than two.  This paper serves as both a photo-z data release description for DLS and a guild for testing the quality of photometry and resulting photo-z's generally.

1211.3249
Less is more: How cosmic voids can shed light on dark energy
Bos, Weygaert, Ruwen, Dolag, Pettorino

How the shape of cosmic voids can be used to distinguish between different models of DE using galaxy positions.  [3 page paper on proceedings]

1211.3337
Rise and fall of radio halos in simulated merging galaxy clusters
Donnert, Dolag, Brunetti, Cassano

Show in sim: reacceleration of CRe has the potential to reproduce key observables of radio haloes.  (Clusters evolve being radio loud or radio quiet, depending on their evolutionary stage during the merger.)

1211.3358
Bias from gas inhomogeneities in the pressure profiles as measured from X-ray and SZ observations
Khedekar .. Kravtsov, .. Nagai, ... Sunyaev et al

As the title says.  Unrelaxed clusters display larger scatter.  Bias remain +/- 20% within 0.8R_500 for all clusters.

1211.3399
An examination of the optical substructure of galaxy clusters hosting radio sources
Wing, Blanton (Elizabeth, not Mike)

FIRST radio survey and SDSS optical counterparts; radio sources within these clusters driven by AGN, and cluster samples include clusters with bent, straight, double-lobed radio sources. Also included a single-radio-component comparison sample.  Examine these galaxy clusters for evidence of optical substructure, testing the possibility that bent double-lobed radio sources are formed as a result of large-scale cluster mergers.  Use a suite of substructure analysis tools to determine the location and extent of substructure visible in the optical distribution of cluster galaxies, and compare the rates of substructure in clusters with different types of radio sources.  Find: no preference for significant substructure in clusters hosting bent double-lobed radio sources compared to those with other types of radio sources.

1211.3401
The effect of particl noise in N-body simulations of gravitational lensing
Rau, Vegetti, White (SDM)

Density field only becomes smooth on scales beyond a few times the local mean interparticle separation.  Present analytic expressions to quantify the Poisson noise and study the scaling with the particle number of the simulation and the Lagrangian smoothing size.  Quantify the smallest resolved substructure that is significant compared to the noise: result is roughly independent of the SL property.  Simple scaling relates the smallest resolved substructures in a simulation with the resolution of the N-body simulation.

1211.3411
Quenching star formation in cluster galaxies
Taranu, et al

SF quenching in rich clusters: library of subhalo orbits drawn from LCDM cosmological N-body simulations of 4 rich clusters.  The orbits are combined with models of SF followed by quenching in the cluster environment to predict colors and spectroscopic lines indices of satellite galaxies.  Simple models with only halo mass-dependent quenching and without environmental (cluster-dependent) quenching fail to reproduce the observed cluster-centrioc colour and absorption linestrength gradients.  Models in which SF is instantly quenched at the virial radius also fail to match the observations.  Better matches to the data are achieved by more complicated bulge-disc models in which the bulge stellar populations depend only on the galaxy subhalo mass while the disc quenching depends on the cluster environment.  In the most successful models quenching begins at pericentre, operating on an exponential timescale of 2-3 Gyr, with the shorter timescale being a better match to disc colors as a function of cluster-centric radius and the longer being a better fit to the radial dependence of stellar absorption line indices.  The models thus imply that the environments of rich clusters must impact SFR of infalling galaxies on relatively long timescales - several times longer than a typical halo spends within the virial radius of a cluster.  This scenario favours gentler quenching mechanisms such as slow strangulation" over more rapid ram-pressure stripping.