Day 478

Wednesday.


1307.7136
The long lives of giant clumps and the birth of outflows in gas-rich galaxies at high redshift
Bournaud, ... Dekel, ... Teyssier, et al

SF disk galaxies at high z are often subject to violent disk instability, characterized by giant clumps whose fate is yet to be understood.  The main question: whether the clumps disrupt within their dynamical timescale (<50Myr), like molecular clouds in today's galaxies, or whether they survive stellar feedback for more than a disk orbital time (~300 Myr) in which case they can migrate inward and help build the central bulge.  Present 3.5-7pc resolution AMR simulations of high-z disks including photo-ionization, radiation pressure, and SNe feedback.  Modeling of radiation pressure determines the mass loading and initial velocity of winds from basic physical principles.  Find that the giant clumps produce steady outflow rates comparable to and sometimes somewhat larger than their SFR, with velocities largely sufficient to escape galaxy.  The clumps also lose mass, especially old stars, by tidal stripping, and the stellar populations contained in the clumps hence remain relatively young (<=200Myr), as observed.  The clumps survive gaseous outflows and stellar loss, because they are wandering in gas-rich turbulent disks from which they can re-accrete gas at high rates compensating for outflows and tidal stripping, overall keeping realistic and self-regulated gaseous and stellar masses.  Our simulations produce gaseous outflows with velocities, densities and mass loading consistent with observations, and at the same time suggest that the giant clumps survive for hundreds of Myr and complete their migration to the center of high-z galaxies, without rapid dispersion and reformation of clumps.

1307.7147
A theory of grain clustering in turbulence: the origin and nature of large density fluctuations
Hopkins

Propose a theory for density fluctuations of aerodynamic grains embedded in a turbulent, gravitating gas disk.  The theory combines calculations for the average behavior of grains encountering a single turbulent eddy, with a hierarchical description of the eddy velocity statistics.  Show that this makes analytic predictions for a wide range of quantities, including: the distribution of volume-average grain densities, the PS and correlation functions of grain density fluctuations, and the maximum volume density of grains reached.  For each, predict how these scales as a function of grain stopping/friction time (t_stop), spatial scale, grain-to-gas mass ratio, strength of the turbulence (alpha), and detailed disk properties (orbital frequency, sound speed).  Test these against numerical simulations and find good agreement over a huge [is he allowed to say "huge"?  :D] parameter space.  Results from 'turbulent concentration' simulations and laboratory experiments are also predicted as a special case.  Predict that vortices on a wide range of scales act to disperse and concentrate grains hierarchically (even if the gas is incompressible).  For small grains this is most efficient in eddies with turnover time comparable to the stopping time.  But for large grains, shear and gravity are important and lead to a broad range of eddy scales driving fluctuations, with most power on the largest scales.  The grain density distribution is driven to a log-Poisson shape, with fluctuations for large grains up to >1000 times the mean density.  Predict much smaller grains will also experience large fluctuations, but on small scales (not resolved in most simulations).  Provide simple analytic expressions for the important predictions, and discuss implications for planetesimal formation, grain growth, and the structure of turbulence.

1307.7157
The generalized scaling relations for X-ray galaxy clusters: the most powerful mass proxy
Ettori

Discuss application to observational data of generalized scaling relations (gSR).  Extend the formalism of gSR in the self-similar model for X-ray galaxy clusters, showing that for a generic relation M_tot~L^a M_g^b T^c, where L, M_g and T are the gas luminosity, mass and temperature, respectively, the values of the slopes lay in the plane 4*a + 3*b + 2*c = 3.  Using published dataset, show that some projections of the gSR are the most efficient relations, holding among observed physical X-ray quantities, to recover the cluster mass.  This conclusion is based on the evidence that they provide the lowest chi^2, the lowest total scatter and the lowest intrinsic scatter among the studied scaling laws on both galaxy group and cluster mass scales.  By the application of the gSR, the intrinsic scatter is reduced in all the cases down to a relative error on M_tot below 16 %.  The best-fit relations are: M_tot~M_g^a T^{1.5-1.5a}, with a~0.4 and M_to L^a T^{1.5-2a}, with a~0.15.  As a byproduct of this study, provide the estimates of the gravitating mass at Delta=500 for 120 objects, 114 of which are unique entries.  The typical relative error in the mass provided from the gSR only (i.e., not propagating any uncertainty associated with the observed quantities) ranges between 3-5% on cluster scale and is about 10% for galaxy groups.  With respect to the hydrostatic values used to calibrate the gSR, the masses are recovered with deviations in the order of 10% due to the different mix of relaxed/disturbed objects present in the considered samples.  In the extreme case of a gSR calibrated with relaxed systems, the hydrostatic mass in disturbed objects is over-estimated by about 20%.

1307.7707
The densest galaxy
Strader, ... Conroy, et al

Ultra-compact dwarf around the Virgo elliptical galaxy NGC 4649 (M60), termed M60-UCD1.  With a dynamical mass of 2e8 Msun but a half-light radius of only ~24 pc, This UCD is more massive than any ultra-compact dwarfs of comparable size, and is arguably the densest galaxy known in the local universe.  Has a 2-component structure well-fit by a sum of Sersic functions, with an elliptical, compact inner component (n~3.3, r_h=14pc) and a round, exponential, extended (r_h=49pc) outer component.  Chandra data reveal a variable central X-ray source with L_X~1e38 erg/s that could be an active galactic nucleus associated with a massive BH or a low-mass X-ray binary.  Analysis of optical spectroscopy shows the object to be old (~>10 Gyr) and of solar metallicity, with elevated [Mg/Fe] and strongly enhanced [N/Fe] that indicates light element self-enrichment; such self-enrichment may be generically present in dense stellar systems.  The velocity dispersion (~70 km/s) and resulting dynamical M/L_V=4.9pm0.7 are consistent with expectations for an old, metal-rich stellar population with a Kroupa IMF.  The presence of a massive BH or a mild increase in low-mass stars or stellar remnants is therefore also consistent with this M/L_V.  The stellar density of the galaxy is so high that no dynamical signature of DM is expected.  However, the properties of this UCD suggest an origin in the tidal stripping of a nucleated galaxy with M_B~-18 to -19.

1307.7715
nu-LCDM: neutrinos reconcile Planck with the local universe
Wyman, Rudd, Vanderveld, Hu

Two-part tension with 6-parameter flat LCDM: (1) the Planck satellite suggests a higher normalization of matter perturbations than local measurements of galaxy clusters.  (2) the expansion rate of the Universe today, H_0, derived from local distance-redshift measurements is significantly higher than that inferred using the acoustic scale in galaxy surveys and the Planck data as a standard ruler.  The adidtion of a sterile neutrino species changes the acoustic scale and brings the two into agreement; adding mass to the active neutrinos or to a sterile neutrino can suppress the growth of structure, bringing the cluster data into concordance as well.  For the fiducial dataset combination, with statistical errors for clusters, a model with a massive sterile neutrino shows 3.5 sigma evidence for a non-zero mass and an even stronger rejection of the minimal model.  A model with massive active neutrinos and a massless sterile neutrino is similarly preferred.  An eV-scale sterile neutrino mass --- suggested by short baseline and reactor anomalies --- is well within the allowed range.

1307.7735
The tenth data release of the Sloan digital sky survey: first spectroscopic data from the SDSS-III Apache point observatory galactic evolution experiment
Ahn, et al

SDSS DR10 released.  APOGEE, BOSS spectra included.  APOGEE is NIR R~22,500 300-fiber spectrograph covering 1.514-1.696 microns; studies the chemical abundances and radial velocities of 100k red giant star candidates in the bulge, bar, disk and halo of MW.  DR10 includes 178k spectra of 57,454 stars, each typically observed 3 or more times, from APOGEE.  Derived quantities from these spectra (radial velocities, effective temperatures, surface gravities, and metallicities) are also included.  DR10 also doubles the number of BOSS spectra over DR9.  DR10 includes a total of 1.5M BOSS spectra (927k galaxy spectra, 182k quasar spectra, and 159k stellar spectra), selected over 6373 square degrees.

1307.8062
Optimising spectroscopic and photometric galaxy surveys: same-sky benefits for dark energy and modified gravity
Kirk, Lahav, Bridle, Jouvel, Abdalla, Frieman

Combine (i) WL with photo-z, and (ii) galaxy clustering and RSD with spectroscopic redshifts.  Combining surveys greatly improves their power to measure both DE and modified gravity.  An independent, non-overlapping combination sees a DE FoM >4x larger than that produced by either survey alone.  The synergies between the surveys are strongest for MG, where their constraints are orthogonal, producing a non-overlapping joint FoM nearly 2 orders of magnitude larger than either alone.  Projected angular PS formalism makes it easy to model the cross-correlation observable when the surveys overlap on the sky, producing a joint data vector and full covariance matrix.  Calculate a same-sky improvement factor, from the inclusion of these cross-correaltions, relative to non-overlapping surveys.  Find nearly a factor of 4 for DE and more than a factor of 2 for MG.  THe exact forecast FoM and same-sky benefits can be radically affected by a range of forecasts assumption, which is explored methodically in a sensitivity analysis.  Show that fiducial assumptions produce robust results which give a good average picture of the science return from combining photometric and spectroscopic surveys.

Day 477

Tuesday.
1307.6869
A Herschel study of D/H in Water in the Jupiter-Family comet 45P/Honda-Mrkos-Pajdusakova and Prospects for D/H measurements with CCAT
Lis et al

No HDO emission detected; confirm that a diversity of D/H ratios exists in the comet population.

1307.6916
Luhman 16AB: a remarkable, variable L/T transition binary 2 pc from the Sun
Burgasser et al

Luhman (2013) has reported the discovery of a brown dwarf binary system only 2.01+/-0.15 pc from the Sun.  The binary is well-resolved with a projected separation of 1.5", spectroscopic confirmation of late-L and early T-dwarfs.  Exhibits "flux reversal" (T dwarf brighter over 0.9-1.3 um but fainter at other wavelengths) and significant (10%) short-period (~4.9 hr) photometric variability with at complex light curve.  These observations suggest spatial variations in condensate cloud structure, known to evolve substantially across the L/T transition.  Report results from a multi-site monitoring campaign aimed at probing the spectral and temporal properties of this source.  Focusing on spectroscopic observations, report the first detections of NIR spectral variability, detailed analysis of K I lines that confirm differences in condensate opacity between the components, and preliminary determinations of radial and rotational velocities based on high-res NIR spectroscopy.

1307.6994
Gravitational redshift profiles in the $f(R)$ and symmetron models
Grönke, Llinares, Mota

The characteristic feature of both models is the screening mechanism that hides the fifth force in dense environments recovering general relativity.  Use N-body sims Isis which includes scalar fields to analyse deviation from LCDM.  Find: deviation is highly dependent on the halo mass due to screening.  Enhancement of gravitational signal by up to 50% for halos with masses 1e13-15 Msun/h.  The characteristic mass range where the fifth force is most active varies with the model parameters.  Usual assumption: presence of a fifth force leads to a deeper potential well, and thus, a stronger gravitational redshift.  Find that in cases in which only the central regions of the haloes are screened, there could also be a weaker gravitational redshift.

1307.7095
What Planck does not tell us about inflation
Elliston et al

Planck has not found the non-Gaussianity that would have necessitated consideration of inflationary models beyond the simplest canonical single field scenarios.  What does this imply for more general models, in particular, multi-field inflation?  Revisit 4 ways in which 2-field scenarios can behave differently from single field models: two-field slow-roll dynamics, curvaton-type behavior, inflation ending on an inhomogeneous hypersurface and modulated reheating.  Study the constraints that Planck data puts on these classes of behaviour, focusing on the latter two which have been least studied in the recent literature.  Show that these latter classes are almost equivalent, and extend their previous analysis by accounting for arbitrary evolution of the isocurvature mode which, in particular, places important limits on the Gaussian curvature of the reheating hypersurface.  In general, however, find that Planck bispectrum results only constrain certain regions of parameter space, conclude that inflation sourced by more than one scalar field remains an important possibility.

Day 476

Monday.

1307.6859
Lyman-alpha heating of inhomogeneous high-redshift intergalactic medium
Oklopcic, Hirata

IGM before reionization consists mostly of neutral H gas.  Ly-a photons produced by early stars resonantly scatter off H atoms, causing energy exchange between the radiation field and the gas.  This interaction results in moderate heating of the gas due to the recoil of the atoms upon scattering, which is of great interest for future studies of the pre-reionzation IGM in the HI 21 cm line.  Investigate the effect of the Ly-a heating in the IGM with linear density, temperature and velocity perturbations.  Perturbations smaller than the diffusion length of photons could be damped due to heat conduction by Ly-a photons.  The scale at which damping occurs and the strength of this effect depend on various properties of the gas, the flux of Ly-a photons and the way in which photon frequencies are redistribtued upon scattering.  To find the relevant length scale and the extent to which Ly-a heating affects perturbations, calculate the gas heating rates by numerically solving linearized Boltzmann equations in which scattering is treated by the Fokker-Planck approximation.  Find that (i) perturbations add a small correction to the gas heating rate, and (ii) the damping of temperature perturbations occurs at scales with comoving wavenumber K>1d4 Mpc^-1, which are much smaller than the Jeans scale and thus unlikely to substantially affect the observed 21 cm signal.

Day 475

Saturday.

1307.6559

The optical green valley vs mid-IR canyon in compact groups

Walker ... Zabuldoff, et al

Compact groups of galaxies provide conditions similar to those experienced by galaxies in the earlier universe [why?].  Recent work on compact groups has led to the discovery of a dearth of mid-IR transition galaxies (MIRTGs) in IRAC (3.6-8.0 micron) color space, as well as at intermediate sSFRs.   But find that in compact groups these MIR transition galaxies in the MIR dearth have already transitioned to the optical (i.e., [g-r]) red sequence.  Investigate the optical CMD of 99 compact groups containing 348 galaxies and compare the optical CMD with MIR color space for compact group galaxies.  Utilizing redshifts available from SDSS, identify new galaxies members for 6 groups.  By combining optical and MIR data, obtain information on both the dust and the stellar populations in compact group galaxies.  Also compare with more isolated galaxies and galaxies in the Coma cluster, reveal (similarly to clusters) compact groups are dominated by optically red galaxies.  Find that compact group transition galaxies [at what redshift range are they?] lie on the optical red sequence, LVL+SINGS MIR transition galaxies span the range of optical colors.  The dearth of IMR transition galaxies in compact groups may be due to a lack of moderately SFing low mass galaxies; the relative lack of these galaxies could be due to their relatively small gravitational potential wells.  This makes them more susceptible to this dynamic environment, thus causing them to more easily lose gas or be accreted by larger members.

1307.6563

The specific frequency and the globular cluster formation efficiency in Milgromian dynamiacs

Wu, Kroupa

There appears to be a universal specific GC formation efficiency eta which relates the total mass of GCs to the virial mass of host DM haloes M_vir (recent studies).  Drive specific frequency [?] and specific GC formation efficiency eta derived as a function of M_vir in Milgromian dynamics (MOND).  In MOND, for galaxies with M_vir <=1e12 Msun, eta decreases with the increase of M_vir, while for massive galaxies eta increases with the increase of M_vir.  (If you assume DM exists, you would incorrectly infer a universal constant fraction between mass of the GC system and a "false" DM halo of the baryonic galaxy.)

1307.6565

The preferentially magnified active nucleus in IRAS F10214+4724 - 

I., Lens model and spatially resolved radio emission, 

II. spatially resolved cold molecular gas, 

III. VLBI observations of the radio core

Deane, ... Marshall et al

I. Lensing model suggests magnifications of 15-20, smaller than mu=50-100 often used for this lensed ULIRG system.

II. Observation of cold (CO (1-0)) molecular gas in a lensed ULIRG at z=2.3 with an obscured active nucleus.  The galaxy is spatially and spectrally well-resolved in the CO (1-0) emission line.  Counter image detected at 3 sigma.  SED resolved, see linear arrangement (tentatively a rotating disk).  Predict a distortion of the CO SLED (spectral line energy distribution) where higher order J lines that may be partially excited by AGN heating will be preferentially lensed owing to their smaller solid angles and closer proximity to the AGN and therefore the cusp of the caustic.  Comparison with other lensing inversion results shows that the narrow line regions and AGN radio core are preferentially lensed by a factor ~3 and 11 respectively, relative to the (cool) molecular gas emission.  This distorts the global continuum emission SED and suggests caution in unsophisticated uses of IRAS F102114+4724 as an archetype of high-z ULRIG.  Present tentative evidence for an extended, low excitation cold gas component that implies that the total molecular gas mass in this galaxy is a factor of >2x greater than that calculated using spatially unresolved CO observations.

III. Lensing allows effective angular resolution of 50 pc at z=2.3.  Estimate quasar bolometric luminosity from a number of independent techniques; find evidence that the AGN may be close to Compton-thick, with an intrinsic bolometric luminosity of 1e11.34 L_sun.  Make SMBH mass estimate and find 1e8.36 Msun, suggesting a low BH accretion rate.  Find evidence for M_BH/M_spheroid ratio that is 1-2 orders of magnitude larger than that of SMGs at z~2.  At face value, suggests that this system has undergone a different evolutionary path compared to SMGs at the same epoch.  A primary result of this work is the demonstration that emission regions of differing size and position can undergo significantly different magnification boosts (>1 dex) and therefore distort the high-z view of gravitationally lensed galaxies.

1307.6575

Cosmic ray acceleration in young supernova remnants

Schure, Bell

Investigate appearance of B-field amplification resulting from CR escape current in the context of SNe remnant shock waves.  The current is inversely proportional to the maximum energy of CRs, and is a strong function of the shock velocity.  Depending on the evolution of the shock wave (drastically different for different circumstellar environments), the maximum energy of CRs as required to generate enough current to trigger the "non-resonant hybrid instability" [what is that?] that confines the CRs follows a different evolution and reaches different values.  Find that the best candidates to accelerate CRs to ~few PeV energies are young remnants in a dense environment, such as a red supergiant wind, as may be applicable to Cass A.  Also find that for a typical BG B-field strength of 5 microG the instability is quenched in about 1000 years, making SN1006 just at the border of candidates for CR acceleration to high energies.

1307.6588

Metal-poor, cool gas in the circumgalactic medium of a z=2.4 star-forming galaxy: direct evidence for cold accretion?

Crighton, Hennawi, Prochaska

Current galaxy formation paradigm: high-z galaxies are predominantly fuelled by accretion of cool, metal-poor gas from IGM.  Hydro sims predict that this material should be observable in absorption against BG sightlines within a galaxy's virial radius as optically thick lyman-lymit systems (LLSs) with low metallicities.  Report the discovery of exactly such a strong metal-poor absorber at an impact parameter R_perp = 58 kpc from a SF galaxy at z=2.44.  Besides strong neutral hydrogen [N(HI)=1e19.5 cm^-2], detect neutral deuterium and oxygen, allowing a precise measurement of the metallicity: log10(Z/Zsolar)=-2.0, or 7-15e-3 solar.  Furthermore, the narrow deuterium linewidth requires a cool temperature <20,000 K.  Given the striking similarities between this system and the predictions of simulations, argue that it represents the direct detection of a high redshift cold-accretion stream.  The low metallicity gas cloud is a single component of an absorption system exhibiting a complex velocity, ionization, and enrichment structure.  Two other components have metallicities >0.1 solar, 10x larger than the metal-poor component.  Conclude that the photoionized CGM of this galaxy is highly inhomogeneous: the majority of the gas is in a cool, metal-poor and predominantly neutral phase, but the majority of the metals are in a highly-ionized phase exhibiting weak neutral hydrogen absorption but strong metal absorption.  If such inhomogeneity is common, then high-resolution spectra and detailed ionization modeling are critical to accurately appraise the distribution of metals in the high-z CGM.

1307.6643

The pre-merger impact velocity of the binary cluster A1750 from X-ray, lensing and hydrodynamical simulations

Molnar, Chiu, Broadhurst, Stadel

Study initial velocity conditions of merging cluster pairs (as the IC affects the final collision velocity, which seems to be too large in cases of Bullet cluster or similar cluster collisions).  Use Chandra data confirming a significant increase in the projected X-ray temperature between the two cluster centers in A1750 consistent with expectations for a merging cluster.  Model this system with a self-consistent hydrodynamical simulation of DM and gas using the FLASH code.  Simulations reproduce well the X-ray data, and the measured redshift difference between the two clusters in the phase before the first core passage viewed at an intermediate projection angle.  The deprojected initial relative velocity derived using this model is 1460 km/s which is considerably higher than the predicted mean impact velocity for simulated massive haloes derived by recent LCDM cosmological simulations [!], but it is within the allowed range.  Simulations demonstrate that such systems can be identified using a multi-wavelength approach and numerical simulations, for which the statistical distribution of relative impact velocities may provide a definitive examination of a broad range of DM scenarios.  

1307.6815

Planck intermediate results. XIV. Dust emission at millimetre wavelengths in the galactic plane

Planck Collaboration

Planck HFI data combined with ancillary radio data to study the emissivity index of the interstellar dust emission in the frequency range 3-0.8 mm in the Galactic plane.  Analyse the region l=20-44 deg, and |b| <= 4 deg where the free-free emission can be estimated from radio recombination line data.  Fit the spectra at each sky pixel with a modified blackbody model and two spectral indices, beta_mm and beta_FIR, below and above 353 GHz respectively.  Find that beta_mm is smaller than beta_FIR and detect a correlation between this low frequency power-law index and the dust optical depth at 353 GHz, tau_353.  beta_mm increases from about 1.53 in the more diffuse regions of the Galactic disk, |b|=3-4 deg and and tau_353~5e-5, to about 1.65 in the densest regions with an optical depth of more than one order of magnitude higher.  Associate this correlation with an evolution of the dust emissivity related to the fraction of molecular gas among the line of sight.  This translates into beta_mm~1.53 for a medium which is mostly atomic and beta_mm~1.65 when the medium is dominated by molecular gas.  Find that the both the 2-level system model and the emission by ferromagnetic particles can explain the results if spatial variations of the component of physical processes responsible for the flattening of the dust emission are allowed.  The results improve the understanding of the physics of interstellar dust, and lead towards a complete model of the dust spectrum from FIR to millimeter wavelengths.  

Day 474

Friday.

1307.6553
The dependence of galactic outflows on the proeprties and orientation of zCOSMOS galaxies at z~1
Bordoloi, Lilly, ..., Kneib, LeFevre, et al

Analysis of cool outflowing gas around galaxies, traced by MgII absorption lines in the co-added spectra of a sample of 486 zCOSMOS galaxies at 1<z<1.5.  These galaxies span a range of stellar masses 9.45<log(M*/Msun)<10.7 and SFR 0.14<log(SFR/Msun/yr)<2.35.  Identify the cool outflowing component in the MgII absorption and find that the equivalent width of the outflowing component increases with stellar mass.  The outflow equivalent width also increases steadily with the increasing SFR of the galaxies.  At similar stellar masses, the blue galaxies exhibit a significantly higher outflow EW as compared to red galaxies.  The outflow EW is higher for the face-on systems as compared to edge-on ones, indicating that for the disk galaxies, the outflowing gas is primarily bipolar in geometry.  Galaxies typically exhibit outflow velocities ranging from -200 km/s to -300 km/s and on average the face-on galaxies exhibit higher outflow velocity as compared to the edge-on ones.  Galaxies with irregular morphologies exhibit outflow EW as well as outflow velocities comparable to face on disk galaxies.  These galaxies exhibit minimum mass outflow rates > 5-7 Msun/yr and a mass loading factor /eta = dMout/ dt /SFR comparable to the SFRs of the galaxies.

Day 473

Thursday.

1307.5847
Evidence for Ubiquitous, high-EW nebular emission in z~7 galaxies: towards a clean measurement of the specific star formation rate using a sample of bright, magnified galaxies
Smit, ... Moustakas, Umetsu, Zitrin, Coe, Gonzalez, Bartelmann, Benitez, Broadhusrt, et al


Nebular line emission has significant impact on the rest-frame optical fluxes of z~5-7 galaxies observed with Spitzer.  The line emission makes z~5-7 galaxies appear more massive, with lower sSFRs.  But corrections for thie line emission have been very difficult to perform reliably due to huge uncertainties on the overall strength of such emission at z>~5.5.  Present the most direct observational evidence yet for ubiquitous high-EW [OIII]+Hbeta line emission in Lyman-break galaxies at z~7, while also presenting a strategy for an improved measurement of the sSFR at z~7.  Accomplish this through the selection of bright galaxies in the narrow redshift window z~6.6-7.0 where the IRAC 4.5 micron flux provides a clean measurement of the stellar continuum light. Observed 4.5 micron fluxes in this window contrast with the 3.6 micron fluxes which are contaminated by the prominent [OIII]+Hbeta lines.  To ensure a high S/N for the IRAC flux measurements, consider only the brightest (H_160<26 mag) magnified galaxies identified in CLASH and other programs targeting galaxy clusters.  Remarkably, the mean rest-frame optical color for the bright 7-source sample is very blue, [3.6]-[4.5]=-0.9pm0.3.  Such blue colors cannot be explained by the stellar continuum light and require that the rest-fram EW of [OIII]+Hbeta be greater than 637 Angstroms for the average source [blue = contaminated].  The bluest four sources from the 7-source sample require and even more extreme EW of 1582 Angstroms.  The derived lower limit for the mean [OIII]+Hbeta EW could underestimate the true EW by ~2x based on a simple modeling of the redshift distribution of the sources.  Can also set a robust lower limit of >~4 Gyr^-1 on the sSFR based on the mean SED of the 7-source sample.

1307.5854
The environment of bright QSOs at z~6: star forming galaxies and X-ray emission
Costa, Sijacki, Trenti, Haehnelt

Employ cosmo hydro-sims to investigate models in which the SMBHs powering luminous z~6 QSOs grow from massive seeds.  Simulate at high res 18 fields sampling regions with densities ranging from the mean cosmic density all the way to the highest sigma peaks in the Millennium sim volume.  Only in the most massive haloes, BHs can grow to masses up t o 1e9 Msun by z~6 without invoking super-Eddington accretion.  Accretion onto the most massive BHs becomes limited by thermal AGN feedback by z~9-8 with further BH growth proceeding in short Eddington limited bursts.  Modeling suggest that current flux-limited surveys of QSOs at high z preferentially detect objects at their peak luminosity and therefore miss a substantial population of QSOs powered by similarly massive BHs but with low accretion rates.  To test whether the required host halo masses are consistent with the observed galaxy environment of z~6 QSOs, produce a realistic rest-frame UV images of simulated galaxies.  Without strong stellar feedback, sims predict numbers of bright galaxies larger than observed by 10x or more.  SNe-driven galactic winds reduce the predicted numbers to a level consistent with observations indicating that stellar feedback was already very efficient at high z.  Further investigated the effect of thermal AGN feedback on the surrounding gas.  Adopted AGN feedback prescription drives mostly energy-driven highly anisotropic outflows with gas speeds of >1000 km/s to distances of >=10 kpc consistent with observations.  The spatially extended thermal X-ray emission around bright QSOs powered by these outflows can exceed by large factors the emission expected without AGN feedback and is an important diagnostic of the mechanism whereby AGN feedback energy couples to surrounding gas.

1307.5909
Empirical constraints for the magnitude and composition of galactic winds
Zahid, ... Vogelsberger, Hernquiest, Dave, et al

Galactic winds are a key physical mechanism for understanding galaxy formation and evolution, yet empirical and theoretical constraints for the character of winds are limited and discrepant.  Recent empirical models find that local SF galaxies have a deficit of oxygen that scales with galaxy stellar mass [more M*, less O outflow?  ...that sounds right.  deeper potential, less SNe outflow].  The oxygen deficit provides unique empirical constraints on the magnitude of mass loss, composition of outflowing material and metal reaccretion onto galaxies.  Formulate the oxygen deficit constraints, so they may be easily implemented into theoretical models of galaxy evolution.  Parameterize an effective metal loading factor which combines the uncertainties of metal outflows and metal reaccretion into a single function of galaxy virial velocity.  Determine the effective metal loading factor by forward-fitting the oxygen deficit.  The effective metal loading factor we derive has important implications for the implementation of mass loss in models of galaxy evolution.

1307.5988
No evidence for planetary influence on solar activity
Cameron, Schüssler

Abreu+ (2012) proposed a long-term modulation of solar activity through tidal effects exerted by the planets.  This claim is based upon a comparison of pseudo-periodicities derived from records of cosmogenic isotopes [what are these?] with those arising from planetary torques on an ellipsoidally deformed Sun.  Examined the statistical significance of the reported similarity of the periods: the tests carried out were repeated with artificial records of solar activity in the form of white or red noise.  The tests were corrected for errors in the noise definition as well as in the apodization and filtering of the random series.  The corrected tests provide probabilities for chance coincidence that are higher than nose claimed by Abreu+(2012) by about 3 and 8 order of magnitude for white and red noise, respectively.  For an unbiased choice of the width of the frequency bins used for the test (a constant multiple of the frequency resolution) the probabilities increase by another two orders of magnitude to 7.5% for red noise and 22% for white noise.  The apparent agreement between the periodicities in records of cosmogenic isotopes as proxies for solar activity and planetary torques is statistically insignificant.  There is no evidence for a planetary influence on solar activity.

1307.6002
The biasing of baryons on the cluster mass function and cosmological parameter estimation
Martizzi, Mohammed, Teyssier, Moore

The DM halo MF will be measured to high precision by ongoing and next generation surveys.  It is crucial to determine which are the theoretical uncertainties that need to be taken into account when comparing the observed halo MF (HMF) to the predictions of theoretical cosmological models and numerical simulations.  In this paper, study the effect of baryonic processes on the HMF in the galaxy cluster mass range, using a catalogue of 153 high resolution cosmological hydrodynamical sims performed with the AMR code ramses.  Use the results of our simulations within a simple analytical model to gauge the effects of baryon physics on the HMF.  Find: neglect of AGN feedback leads to a significant boost in the cluster MF similar to that reported by others.  However, including AGN feedback not only gives rise to systems that are similar to observed, but they also reverse the global baryonic effects on the clusters.  The resulting MF is closer to the unmodified DM HMF but still contains a mass dependent bias at the 5-10% level.  Then explore how these effects are within the noise for current survey volumes, but forthcoming and planned large surveys will be highly biased by these processes.

1307.6091
A small survey of the magnetic fields of planet-host stars
Fares et al

The comparison shows that these giant planet-host stars tend to have similar B-field topologies to stars without detected hot-Jupiters.

1307.6210
Dwarf galaxy planes: the discovery of symmetric structures in the Local Group
Pawlowski, Kroupa, Jerjen

Both major galaxies [Andromeda and MW] in the LG are surrounded by thin planes of mostly co-orbiting satellite galaxies, the vast polar structure (VPOS) around the MW and Great Plane of Andromeda (GPoA) around M31.  Summarize the current knowledge concerning these structures and compare their relative orientations and properties in a common coordinate system.  The existence of coherent satellite structures motivates an investigation of the distribution of the more distant non-satellite galaxies in the LG.  This results in the discovery of two planes (with diameters of 1-2 Mpc) which contain almost all nearby non-statellite galaxies.  The two LG planes are surprisingly symmetric, inclined by only 20 deg relative to the galactic disc of M31, similarly thin (h~60 kpc) and have near-to-identical offsets from the MW and M31.  They are inclined relative to each other by 35 deg.  Comparing the plane orientations with each other and with additional features indicates an intimate connection between the VPOS and the GPoA.  They are both polar to the MW, have similar orbital directions and are inclined by ~45 deg relative to each other.  The Magellanic Stream approximately aligns with the VPOS and the GPoA.  The alignment with other features such as the Supergalactic Plane and the over-density in hypervelocity stars are discussed as well. End with a summary of proposed scenarios trying to explain the LG galaxy structures as either originating from cosmological structures or from tidal debris of a past galaxy encounter.  There currently exists no full detailed model which satisfactorily explain the existence of the thin symmetric LG planes.

1307.6212
Astropy: a community Python package for Astronomy
The Astropy Collaboration

Present the v0.2 public version of the open-source and community-developed Python package.  Provides core astronomy-related functionality to the community, including support for domain-specific file formats such as FITS fils, VO tables, and common ASCII table formats, unit and physical quantity conversions, physical constants specific to astronomy, celestial coordinate and time transformation, WCS support, generalized containers for representing gridded as well as tabular data, and a framework for cosmological transformations and conversions.  Significant functionality is under active development, such as a model fitting framework, VO client and server tools, and aperture and PSF photometry tools.  The core development team is actively making additions and enhancements to the current code base, and everyone is encouraged to participate in the development of future Astropy versions.

1307.6518
The VIMOS VLT Depp Survey: the redshift distribution N(z) of magnitude-limited samples down to iAB=24.75 and KsAB=22
Le Fevre et al

Study provides a comprehensive galaxy number counts N(z) from galaxies with spectroscopic redshifts over a large redshift domain 0<z<5, a solid basis for the measurement of volume-complete quantities.  Magnitude-selected surveys identify a higher number of galaxies at z>2 than in color-color selected samples [by ratio, in absolute numbers?  probably absolute number], and use the magnitude-selected VVDS to emphasize the large uncertainties associated to other surveys using color or color-color selected samples.  Results further demonstrate that SAMs on DM sims have yet to find the right balance of physical processes and time-scales to properly reproduce a fundamental galaxy population property like the observed N(z).

Day 472

Wednesday.
1307.5324
A search for fast optical transients in the Pan-STARRS1 medium-deep survey: M Dwarf Flares, Asteroids, Limits on Extragalactic rates, and implications for LSST
Berger, ... et al

Present a search for fast optical transients (~0.5 hr - 1 day) using repeated observations of the Pan-STARRS1 MDS fields.  Consecutive g/r-band observations, 16.5 min in each filter, by requiring detections in both bands, with non-detections on preceding and subsequent nights.  Identify 19 transients <22.5 mag (S/N>10).  Of these, 11 exhibit quiescent counterparts in the deep PS1/MDS templates identified as M4-M9 dwarfs.  The remaining 8 transients exhibit a range of properties indicative of main-belt asteroids near the stationary point of their orbits.  With identifications for all 19 transients, place an upper limit of R_FOT(0.5hr)<0.12 deg^-2 /day (95% CL) on the sky-projected rate of extragalactic fast transients at <22.5 mag, a factor of 30-50 times lower than previous limits; the limit for a timescale of ~day is R_FOT<2.4e-3 deg^-2 /day.  To convert these sky-projected rates to volumetric rates, explore the expected peak luminosities of fast optical transients powered by various mechanisms, and find that non-relativistic events are limited to M~-10 mag (M~-14 mag) for a timescale of ~0.5 hr (~day), while relativistic sources (GRBs, etc) can reach much larger luminosities.  The resulting volumetric rates are <13 (-10mag), <0.05(`14mag) and <1e-6 Mpc^-3 /yr (-24 mag), significantly above the nova, SNe, and GRB rates, respectively, indicating that much larger surveys are required to provide meaningful constraints.  Motivated by the results of the search, discuss strategies for identifying fast optical transients in the LSST main survey, and reach the optimistic conclusion that the veil of FG contaminants can be lifted with the survey data, without the need for expensive follow-up observations.
1307.5326
The M-sigma relation in simulations of isolated and merging disk galaxies with kinetic or thermal AGN feedback
Barai, Viel, Murante, Gaspari, Borgani

Two modes of coupling the feedback energy from a central AGN to the neighboring gas in galaxy simulations: kinetic - velocity boost, and thermal - heating.  Formulate kinetic feedback models for energy-driven wind (EDW) and momentum-driven wind (MDW), using two free parameters: feedback efficiency epsilon_f, and AGN wind velocity v_w.  New algorithm in SPH code GADGET-3 to prevent the expansion of a hole in the gas distribution around the BH.  Perform simulations of isolated evolution and merger of disk galaxies, of MW mass as well as lower and higher masses.  Find that in the isolated galaxy BH kinetic feedback generates intermittent bipolar jet-like gas outflows.  Infer that current prescriptions for BH subgrid physics in galaxy simulations can grow the BH to observed values even in an isolated disk galaxy.  The BH growth is enhanced in a galaxy merger.  Comparing the [M_BH-sigma_star] relation obtained in simulations with observational data, conclude that it is possible to find parameter sets for a fit in all the models, except for the case with MDW feedback in a galaxy merger, in which the BH is always too massive.  The BH thermal feedback implementation of Springel, DiMatteo & Hernquiest (2005) within the multiphase SF model is found to have negligible impact on gas properties; and the effect claimed in all previous studies is attributed to gas depletion around the BH by the creation of an artificial hole.  The BH mass accretion rate in simulations exhibit heavy fluctuations.  The SFR is quenched with feedback by removal of gas.  The CGM gas at galactocentric distances (20-100)/h kpc are found to give the best metallicity observational diagnostic to distinguish between BH models.  

1307.5374
Solar activity during two millennia as estimated from annual tree rings
Muraki et al

As the title says.  Solar maximum and minimum global effect was 0.17 pm 0.01K, but at 40N/S, maximum effect of 0.5K.  Look for trees with this latitude: find two cycles (12 and 25 years) during the Maunder minimum in the annual growth rate.  Evidence of solar activity found in all samples.  Discovered a correlation between Swiss glacier fluctuation and the growth rate of the Yaku tree ring.

1307.5395
Dual haloes and formation of early-type galaxies
Park, Lee

Present a determination of the 2d shape parameters of the blue and red globular cluster systems (GCSs) in a large number of elliptical galaxies and lenticular galaxies (ETGs).  Use a  homogeneous data set of the globular clusters in 23 ETGs from HST.  The position angles of both blue and red GCSs show a correlation with those of the stellar light distribution, showing that the major axes of the GCSs are well aligned with those of their host galaxies.  However, the shapes of the red GCSs show a tight correlation with the stellar light distribution as well as with the rotation property of their host galaxies, while the shapes of the blue GCSs do much less.  These provide clear geometric evidence that the origins of the blue and red globular clusters are distinct and that ETGs may have dual haloes: a blue (metal-poor) halo and a red (metal-rich) halo.  These two haloes show significant differences in metallicity, structure, and kinematics, indicating that they are formed in two distinguishable ways.  The red halos might have formed via dissipational processes with rotation, while the blue haloes are through accretion.

1307.5637
ASTROSAT: some key science prospects
Paul

ASTROSAT is a satellite designed for Optical/UV and a broad X-ray energy range.  With 4 X-ray instruments and a pair of UV-Optical telescopes, ASTROSAT will provide unprecendented opportunity for simultaneous multi-wavelength observations, of highly variable sources (X-ray binaries and AGN).  Largest effective area in the hard X-ray compared to all previous X-ray missions, will enable high time resolution X-ray measurements in the 2-80 keV band with moderate energy resolution.  Here, give a brief summary of the payload characteristics of ASTROSAT, and discuss the main science.  Possibility of aitding gravitational wave experiments.

1307.5639
A sub-parsec resolution simulation of the Milky Way: global structure of the ISM and properties of molecular clouds
Renaud, .. Dekel, et al

Resolution of 0.05pc, hydro-sim, with a self-consistent description of the galaxy comprising live stellar and DM dynamics.  Model: SF and stellar feedback through photo-ionization, radiative pressure and SNe blasts.  Resolution fo the simulation allows to probe the structure of the ISM down to the formation sites of individual stars, at subparsec resolution for a few cloud lifetimes, and at 0.05 pc for about a cloud crossing time.  IN the full galactic context, turbulence cascade and gravitation from the kpc scales are de facto included in smaller structures like molecular clouds, without having to add them artificially.  In this first paper of a series, present the global structures of the ISM.  In particular, the formation of a bar influences the dynamics of the central ~100 pc by creating resonances that regulate the fueling of the central black hole.  At larger radii, the spiral arms host the formation of regularly spaced clouds: beads on a strong and spurs from gravitational and KH instabilities, respectively.  These instabilities pump turbulent energy in the gas, generally in the supersonic regime.  Because of asymmetric drift due to increased velocity dispersion of young stars compared to gas, and to galactic rotation, the SNe explode outside of their dense gaseous nursery, which diminishes the effect of stellar feedback on the structure of clouds.  The evolution of gas clouds is thus mostly due to fragmentation and gas consumption, regulated mainly by supersonic turbulence, while feedback plays a less important role.

1307.5830
Detection of B-mode polarization in the cosmic microwave background with data from the south pole telescope
Hanson, Hooever, et al

Gravitational lensing of the CMB generates a curl pattern in the observed polarization.  This "B-mode" signal provides a measure of the projected mass distribution over the entire observable Universe and also acts as a contaminant for the measurement of primordial gravity-wave signals.  In this letter, present the first detection of gravitational lensing B modes, using first-season data from the polarization-sensitive receiver on the SPTpol.  Construct a template for the lensing B-mode signal by combining E-mode polarization measured by SPTpol with estimates of the lensing potential from a Herschel-SPIRE map of the cosmic IR background.  Compare this template to the B-modes measured directly by SPTpol, finding a non-zero correlation at 7.7 sigma significance.  The correlation has an amplitude and scale-dependence consistent with theoretical expectations, is robust with respect to analysis choices, and constitutes the first measurement of a powerful cosmological observable.

1307.5842
The same frequency of planets inside and outside open clusters of stars
Meibom, et al

Most stars and their planets form in open clusters.  Over 95% of such clusters have stellar densities too low (<100 stars/parsec^3) to withstand internal and external dynamical stress and fall apart within a few 100 million years.  Older open clusters have survived by virtue of being richer and denser in stars (1000 to 10k per cubic parsec) when they formed.  Such clusters represent a stellar environment very different from the birthplace of the Sun and other planet-hosting field stars.  So far more than 800 planets have been found around Sun-like stars in the field.  THe field planets are usually the size of Neptune or smaller.  In contrast, only four planets have been found orbiting stars in open clusters, all with masses similar to or greater than that of Jupiter.  Report observations of the transits of 2 Sun-like stars by planets smaller than Neptune in the billion-year-old open cluster NGC6811.  This demonstrates that small planets can form and survive in a dense cluster environment, and implies that the frequency and properties of planets in open clusters are consistent with those of planets around field stars in the Galaxy.

Day 471

Tuesday.

1307.5107
How are the brightest group galaxies statistically special?
Shen, Yang, Mo, van den Bosch, More

Statistical properties of BGGs using SDSS DR7.  Test whether BGGs and other bright members of groups are consistent with an ordered population among the total population of group galaxies.  Find that the luminosity distributions of BGGs do not follow the predictions from the order statistics (OS).  The average luminosities of BGGs are systematically brighter than OS predictions.  On the other hand, by properly taking into account the brightening effect of the BGGs, the luminosity distributions of the second brightest galaxies are in excellent agreement with the expectations of OS.  The brightening of BGGs relative to the OS expectation is consistent with a scenario that the BGGs on average have over-grown about 20% masses relative to the other member galaxies.  The growth (Delta M) is not stochastic but correlated with the magnitude gap (G_1,2) between the brightest and the second brightest galaxy.  The growth (Delta M) is larger for the groups having more prominent BGGs and contributes on average about 30%  of the final G_1,2 of the groups of galaxies.

1307.5176
Constraining primordial black-hole bombs through spectral distortions of the cosmic microwave background
Pani, Loeb

Consider the imprint of superradian instabilities of nonevaporating primordial BHs (PBHs) on the spectrum of CMB.  In the radiation dominated era, PBHs are surrounded by a roughly homogeneous cosmic plasma which endows photons with an effective mass through the plasma frequency.  In this setting, spinning PBHs are unstable to a spontaneous spindown through the well-known "BH bomb" mechanism.  At linear level, the photon density is trapped by the effective photon mass and grows exponentially in time due to superradiance.  As the plasma density declines due to cosmic expansion, the associated energy around PBHs is released and dissipated in the CMB.  Evaluate the resulting spectral distortions of the CMB in 1e3 < z < 2e6.  Derive upper limits on the fraction of DM that can be associated with spinning PBHs in the mass range 1e-8 Msun < M < 0.2 Msun.  For maximally-spnning PBHs, limits are much tighter than those derived from microlensing or other methods.  Future data from the proposed PIXIE mission could improve limits by several orders of magnitude.

Day 470

Monday.

1307.5065
Semi-analytic galaxy formation in f(R)-gravity cosmologies
Fontanot, Puchwein, Springel, Bianchi

The f(R)-gravity models imply the existence of a 'fifth-force', which is however locally suppressed, preserving the successes of GR on solar system scales.  Employ high-res numerical sims of f(R)-gravity models coupled with SAM for galaxy formation to obtain detailed predictions for the evolution of galaxy properties.  Show that DM haloes in f(R)-gravity models are characterized by a modified virial scaling with respect to the LCDM scenario, reflecting a higher DM velocity dispersion at a given mass.  This effect is taken into account in the SAM by an appropriate modification of the mass-temperature relation.  Find that the statistical properties predicted for galaxies (such as the stellar mass function and the cosmic SFR) in f(R)-gravity show generally only very small differences relative to LCDM, smaller than the dispersion between the results of different SAM models, which can be viewed as a measure of their systematic uncertainty.  Also demonstrate that galaxy bias is nto able to disentangle between f(R)-gravity and the standard cosmological scenario.  However, f(R)-gravity imprints modifications in the linear growth rate of cosmic structures at large scale, which can be recovered from the statistical properties of large galaxy samples.

1307.5066
Giga-z: a 100,000 object superconducting spectrophotometer for LSST follow-up
Marsden, Mazin, O'Brien, Hirata

Simulate the performance of a new type of instrument: SuperMOS (Superconducting Multi-Object spectrograph), that uses Microwave Kinetic Inductance Detectors (MKIDs).  MKIDs, a new detector technology, feature good QE in the UVOIR, can count individual photons with microsecond timing accuracy and, like X-ray calorimeters, determine their energy to several percent.  The performance of Giga-z, a SuperMOS designed for wide field imaging follow-up observations, is evaluated using simulated observations of the COSMOS mock catalog with an array of 100,000 R_{423 nm} = E/Delta E = 30 MKID pixels.  Compare results against a simultaneous simulation of LSST observations.  In 3 years on a dedicated 4m-class telescope, Giga-z could observe ~2 billion galaxies, yielding a low resolution SED spanning 350-1350 nm for each; 1000x the number measured with any currently proposed LSST spectroscopic follow-up, at a fraction of the cost and time.  Giga-z would provide redshifts for galaxies up t o z~6 with magnitudes m_i < 25, with accuracy sigma_{Delta z/(1+z)}=0.03 for the whole sample, and 0.007 for a select subset.  Also find catastrophic failure rates and biases that are consistently lower than for LSST. The added constraint on DE parameters for WL+CMB by Giga-z using the FoMSWG default model is equivalent to multiplying the LSST Fisher matrix by a factor of alpha=1.27 (w_p), 1.53 (w_a), or 1.98 (Delta gamma).  This is equivalent to multiplying both the LSST coverage area and the training sets by alpha, and reducing all systematics by a factor of 1/sqrt(alpha), advantages that are robust to even more extreme models of IA.

1307.5067
Moving objects in the Hubble Ultra Deep Field
Kilic, Giannias, von Hippel

Compare 2004 UDF to the 128-orbit 2012 UDF; find 12 sources brighter than I=27 mag that display >3 sigma proper motions.  Do not find any proper motion objects fainter than this magnitude limit.  Combining optical and NIR photometry, model the SED of each point source using stellar templates and WD models.  For I<27 mag, identify 23 stars with K0-M6 spectral types and two faint blue objects that are clearly old-thick disk white dwarfs.  Measure a thick disk [of the MW, I presume] WD space density of 0.1-1.7 e-3 per cubic parsec from these two objects.  There are no halo WDs in the UDF down to I=27 mag.  Combining the HDF N, S, and the UDF data, do not see any evidence for DM in the form of faint halo WDs, and the observed population of WDs can be explained with the standard Galactic models.

1307.5083
Cosmic variance of the spectral index from mode coupling
Bramante, Kumar, Nelson, Shandera

Demonstrate that local, scale-dependent non-Gaussianity can generate cosmic variance uncertainty in the observed spectral index of primordial curvature perturbations.  In a universe much larger than the current Hubble volume, locally unobservable long wavelength modes can induce a scale-dependence in the PS of typical subvolumes, so that the observed spectral index varies at a cosmologically significant level (Delta ns ~ O(0.04)).  Similarly, show that the observed bispectrum can have an induced scale dependence that varies about the global shape.  If tensor modes are coupled to long wavelength modes of a second field, the locally observed tensor power and spectral index can also vary.  All of these effects, which can be introduced in models where the observed non-G is consistent with bounds from the Planck satellite, loosen the constraints that observations place on the parameters of theories of inflation with mode coupling.  Suggest observational constraints that future measurements could aim for to close this window of cosmic variance uncertainty.

Day 469

Saturday.

1307.4876
Weighting neutrinos in $f(R)$ gravity
He

Constrain the neutrino properties in f(R) gravity using the latest observations from CMB and BAO measurements.  First constrain separately the total mass of neutrinos and N_eff respectively; then constrain them simultaneously.  Find Sum m_nu < 0.462 eV at 95% CL for the combination of Planck, WMAP, BAO, ACT and SPT.  Also find N_eff-3.32+0.54-0.51 at 95% CL for the same data set.  When constraining N_eff and Sum m_nu simultaneously, the constraint is weaker.

1307.4985
Cosmological fast radio bursts from binary neutron star mergers
Totani

Fast radio bursts (FRBs) at cosmological distances recently discovered, whose duration is ~milliseconds.  Argue that the observed short duration is difficult to explain by giant flares of soft gamma-ray repeaters, though their event rate and energetics are consistent with FRBs.  Discuss NS-NS mergers as a possible origin of FRBs.  Considering uncertainties and cosmological rate evolution, the FRB rate is consistent with the plausible rate estimate of NS-NS mergers, while a large fraction of NS-NS mergers must produce observable FRBs.  A likely radiation mechanism is coherent radio emission like radio pulsars, by magnetic breaking when magnetic dipoles of neutron stars are synchronized to binary rotation [what does this mean?] at the time of coalescence.  B-fields of the standard strength (1e12 G) can explain the observed FRB fluxes, if the conversion efficiency from magnetic breaking energy loss to radio emission is similar to that of isolated radio pulsars.  Since FRBs tell us the exact time of mergers, correlated search [correlated search of what?] would significantly improve the effective sensitivity of gravitational wave detectors.

1307.4995
Primordial black holes in non-Gaussian regimes
Young, Byrnes

Primordial black holes (PBHs) can form in the early Universe from the collapse of rare, large density fluctuations.  They have never been observed, but this fact is enough to constrain the amplitude of fluctuations on very small scales which cannot be otherwise probed.  Because PBHs form only in very rare large fluctuations, the number of PBHs formed is extremely sensitive to changes in the shape of the tail of the fluctuation distribution - which depends on the amount of non-Gaussianity present.  First study how local non-Gaussianity of arbitrary size up to fifth order affects the abundance and constraints from PBHs, finding that they depend strongly on even small amounts of non-Gaussianity and the upper bound on the allowed amplitude of the PS can vary by several orders of magnitude.  The sign of the non-linearity parameters (f_NL, g_NL, etc) are particularly important.  Also study the abundance and constraints from PBHs in the curvaton scenario, in which case the complete NL probability distribution is known, and find that truncating to any given order (i.e., to order f_NL or g_NL, etc) does not give accurate results.

1307.5035
Preparing for an explosion: hydrodynamic instabilities and turbulence in presupernovae
Smith, Arnett

Both observations and direct numerical simulations are discordant with predictions of conventional stellar evolution cores for the latest stages of a massive star's life prior to core collapse.  Suggest that the problem lies in the treatment of turbulent convection in these codes, which ignores finite amplitude fluctuations in velocity and temperature, and their NL interaction with nuclear burning.  The hydrodynamic instabilities that may arise prompt us to discuss a number of far-reaching implications for the fates of massive stars.  In particular, explore connections to enhanced presupernova mass loss, unsteady nuclear burning and consequent eruptions, swelling of the stellar radius that may trigger violent interactions with a companion star, and potential modifications to the core structure that could dramatically impact calculations of the core-collpase mechanism itself.  These modifications may be of fundamental importance to the interpretation of young core-collapse supernova remnants.  They may also make possible the development of an early warning system for the detection of impending core collapse.

1307.5051
The effects of local primordial non-guassianity on the formation and evolution of galaxies
Zhao, Li, Shandera, Jeong

Numerical modeling of the NG signals from different inflation models is essential to correctly interpret current and near future data from large-scale structure surveys.  In this study, use high-resolution cosmo hydro sims to investigate the effects of primordial NG on the formation and evolution of galaxies from the cosmic dawn to the present day.  Focusing on the local type primordial NG, find that it may affect the formation history of stars and BHs in galaxies, and their distribution.  Compared to the Gaussian case, large non-G potential with f_NL>1e3 leads to earlier collapse of the first structures, more massive galaxies especially at high redshifts, stronger clustering of galaxies, and higher halo bias.  However, for smaller NG with f_NL<1e2, the effect is significantly weaker.  Observations of the distribution and properties of high-z, rare objects such as the first galaxies and quasars may provide further constraints on the primordial NG.

Day 468

Friday.

1307.4758
Stars were born in significantly denser regions in the early Universe
Shirazi, Brinchmann, Rahmati

The density of the warm ionized gas in high-z galaxies is known to be higher than what is typical in local galaxies on similar scales.  At the same time, the mean global properties of the high- and low-redshift galaxies are quite different.  Present a detailed differential analysis of the ionization parameters of 14 star forming galaxies at redshift 2.6-3.4, compiled from the literature.  For each of those high-z galaxies, construct a comparison sample of low-z galaxies closely matched in specific SFR and stellar mass, thus ensuring that their global physical conditions are similar to the high-z galaxy.  Find that the median log [OII] 3727/[OIII] 5007 line ratio of the high-z galaxies is 0.5 dex higher than their local counterparts.  Construct a new calibration between the [OII] 3727 / [OIII] 5007 emission line ratio and ionization parameter to estimate the difference between the ionization parameters in the high and low-redshift samples.  Using this, show that the typical density of the warm ionized gas in SF regions decreases by a median factor of 8 from z~3.3 to z~0 at fixed mass and sSFR.  Show that metallicity differences can not explain the observed density differences.  Because the high- and low-z samples are comparable in size, infer that the relationship between SFR density and gas density must have been significantly less efficient at z~2-3 than what is observed in nearby galaxies with similar levels of SF activity.

1307.4759
The LS2S Galaxy-scale Lens sample.  IV.  The dependence of the total mass density profile of early-type galaxies on redshift, stellar mass, and size
Sonnenfeld, Treu, .. Suyu, Marshall, ... et al

Optical and NIR spectroscopy of 36 secure SL and 17 candidates as part of SL2S survey.  The deflectors are massive early-type galaxies in 0.2<z<0.8, while the lensed sources are 1<z<3.5.  Combine data with photometric and lensing measurements presented in paper III and with lenses from SLACS and LSD surveys to investigate the cosmic evolution of the internal structure of massive early-type galaxies over half the age of the universe.  Study the dependence of the slope of the total mass density profile gamma' (rho(r) ~ r^{-gamma'}) on M*, size, and redshift.  Find that two parameters are sufficient to determine gamma' with less than 6% residual scatter.  At fixed redshift, gamma' depends solely on the surface stellar mass density: d gamma'/ d Sigma* = 0.38 pm 0.07.  At fixed M* and R_eff, gamma' depends on redshift: galaxies at lower z have steeper slopes (d gamma' / d z = -0.31).  However, the mean redshift evolution of gamma' for an individual galaxy is consistent with zero d gamma' / dz = -0.10pm0.12.  This result is obtained by combining the measured dependencies of gamma' on z, M*, R_eff with the evolution of the R_eff-M* taken from the literature, and is broadly consistent with current models of the formation and evolution of massive early-type galaxies.  Detailed quantitative comparisons of our results with theory will provide qualitatively new information on the detailed physical processes at work.

1307.4762
Modelling the nucleosynthetic properties of carbon-enhanced metal-poor RR Lyrae stars
Stancliffe, Kennedy, Lau, Beers

Certain C-enhanced metal-poor stars likely obtained their composition via pollution from some of the earliest generations of AGB stars and as such provide important clues to early Universe nucleosynthesis.  Recently, Kinman+ discovered that the highly C- and Ba-enriched metal-poor star SDSS J1707+58 is in fact an RR Lyrae pulsator.  This gives an object in a definite evolutionary state where the effects of dilution of material during the MS are minimised owing to the object having passed through first dredge-up.  Perform detailed stellar modeling of putative progenitor systems in which ..  accreted material from AGB stars in the mass range 1-2 Msun.  Investigate how the surface abundances are affected by the inclusion of mechanisms like thermohaline mixing and gravitational settling.  Able to find a reasonable fit to the C and Na abundances of the star, suggesting accretion of around 0.1 Msun from a 2 Msun companion, but the Sr and Ba abundances remain problematic and this object may have experienced something other than a standard s process.  More success in fitting the abundances of the mildly C-enriched, metal-poor RR Lyrae pulsator TY Gru, which suggest received 0.1 Msun of material from a companion of around 1 Msun.

1307.4764
The SL2S galaxy-scale lens sample. III. Lens models, surface photometry and stellar masses for the final sample
Sonnenfeld, Gavazzi, Suyu, Treu, Marshall

HST imaging data and CHFT NIR images for the final sample of 56 galaxy-scale lenses in the CFHTLS as part of the SL in the Legacy survey (SL2S) project.  The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies.  Lens modeling is performed on the HST images (or CFHT when HST not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid.  Based on the analysis of systematic uncertainties and comparison with inference based on different methods, estimate that the Einstein Radii are accurate to ~3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does.  Lens modeling with ground-based images, however, when successful, yields Einstein radius measurements that are competitive with spaced-based images.  Information from the lens models is used together with spectroscopic information from the companion paper IV to classify the systems, resulting in a final sample of 39 confirmed (grade-A) lenses and 17 promising candidates.  The redshifts of the main deflector span a range 0.3 < z<0.8, providing and excellent sample for the study of the cosmic evolution of the mass distribution of early-type galaxies over the second half of the history of the Universe.

Day 467

Thursday.

1307.4398
Constraints on neutrino density and velocity isocurvature modes from WMAP-9 data
Savelainen et al

WMAP9 and other CMB data to constraint cosmological models where the primordial perturbations have both an adiabatic and a (possibly correlated) neutrino density (NDI), neutrino velocity (NVI), or cold dark matter density (CDI) isocurvature component.  For NDI and CDI use both a phenomenological approach, where primordial perturbations are parameterized in terms of amplitudes at two scales, and a slow-roll two-field inflation approach, where slow-roll parameters are used as primary parameters.  For NVI use only the phenomenological approach, since it is difficult to imagine a connection with inflation.  Find that in the NDI and NVI cases, larger isocurvature fractions are allowed than in the corresponding models with CDI.  For uncorrelated perturbations, the upper limit to the primordial NDI (NVI) fraction is 24% (20%) at k=0.002 /Mpc and 28% (15%) at k=0.01 /Mpc.  For maximally correlated (anticorrelated) perturbations, the upper limit to the NDI fraction is 0.3% (0.9%).  The nonadiabatic contribution to the CMB temperature variance can be as large as 10% (-13%) for the NDI (NVI) modes.  Bayesian model comparison favors pure adiabatic initial mode over the mixed primordial adiabatic and NDI, NVI, or CDI perturbations.  At the best, the betting odds for a mixed model (uncorrelated NDI) are 1:3.4 compared to the pure adiabatic model.  For the phenomenological generally correlated mixed models the odds are about 1:100, whereas the slow-roll approach leads to 1:13 (NDI) and 1:51 (CDI).

1307.4399
Joint likelihood function of cluster number counts and weak lensing power spectrum
Takada, Spergel

A coherent over- or under-density contrast across a finite survey volume causes an upward- or downward- fluctuation in the number of haloes.  This fluctuation in halo number adds a significant covariant scatter in the observed amplitudes of WL PS at NL, small scales.  Because of this covariance, the amount of information that can be extracted from a measurement of theWL PS is significantly smaller than naive estimates.  In this paper, show that by measuring both the number counts of clusters and the PS in the same survey region, can mitigate this loss of information and significantly enhance the scientific return from the upcoming surveys.  First, using the halo model approach, derive the joint likelihood function of the halo number counts and the WL PS, taking into account the super-sample covariance effect on the two observables.  Show that the analytical model matches the distributions measured from 1000 realizations for a LCDM model.  Then develop a method of combining the observed number counts of massive haloes with a measurement of the WL PS, in order to suppress or correct for the super-sample variance effect.  Adding the observed number counts of massive haloes with M>1e14 Ms/h can significantly improve the information content of WL PS, almost recovering the Gaussian information of the initial density field up to l_max~1000.  When combined with the halo number counts for M > 3 or 1e14 Ms/h, the improvement is up to a factor of 1.4 or 2 at angular modes of l_max~1000-2000, equivalent to a 2x or 4x larger survey volume, compared to the PS measurement without the Gaussianization method.  The improvements are larger for surveys with higher number densities of galaxies.
1307.4402
zCOSMOS 20k: satellite galaxies are the main drivers of environmental effects in the galaxy population at least to z~0.7
Kovac, Lilly, ... et al

Explore the role of environment in the evolution of galaxies over 0.1<z<0.7 using the final zCOSMOS-bright data set.  Using the red fraction of galaxies as a proxy for the quenched population, find that the fraction of red galaxies increases with the environmental overdensity and with the stellar mass, consistent with previous works.  As at lower redshift, the red fraction appears to be separable in mass and environment, suggesting the action of two processes: mass and environmental quenching.  The parameters describing these appear to be essentially the same at z~0.7 as locally.  Explore the relation between red fraction, mass and environment also for the central and satellite galaxies separately, paying close attention to the effects of impurities in the central-satellite classification and using carefully constructed samples matched in stellar mass.  There is little evidence for a dependence of the red fraction of centrals on overdensity.  Satellites are consistently redder at all overdensities, and the satellite quenching efficiency increases with overdensity at 0.1<z<0.4.  This is less marked at higher redshift, but both are nevertheless consistent with the equivalent local measurements.  At a given stellar mass, the fraction of galaxies that are satellites also increases with the over density.  At a given overdensity and mass, the obtained relation between the environmental quenching and the satellite fraction agrees well with the satellite quenching efficiency, demonstrating that the environmental quenching in the overall population is consistent with being entirely produced through the satellite quenching processes at least up to z=0.7.  However, despite the unprecedented size of high-z samples, the associated statistical uncertainties are still significant and these statements should be understood as approximations to physical reality, rather than physically exact.

Day 466

Wednesday.

1307.4075
Establishing a relation between mass and spin of stellar mass black holes
Banerjee, Mukhopadhyay

SMBHs (stellar mass BHs), forming by the core collapse of very massive, rapidly rotating stars, are expected to exhibit a high density accretion disk around them developed from the spinning mantle of the collapsing star.  A wide class of such disks, due to their high density and temperature, are effective emitters of neutrinos and hence called neutrino cooled disks.  Tracking the physics relating the observed (neutrino) luminosity to the mass, spin of BHs and the accretion rate M_dot of such disks, establish a correlation between the spin and mass of SMBHs at their formation stage.  Show that spinning BHs are more massive than non-spinning BHs for a given M_dot.  However, slowly spinning BHs can turn out to be more massive than spinning BHs if M_dot at their formation stage was higher compared to faster spinning BHs.

1307.3285
Modeling Baryon Acoustic Oscillations with perturbation theory and stochastic halo biasing
Kitaura, Yepes, Prada

Investigate the generation of mock halo catalogs based on perturbations theory and NL stochastic biasing with the PATCHY-code.  Use Augmented Langrangian Perturbation Theory (ALPT) to generate a DM density field on a mesh starting from Gaussian fluctuations.  ALPT is based on a combination of second order LPT (2LPT) on large scales and the spherical collapse model on smaller scales.  Account for the systematic deviation of perturbative approaches from N-body simulations together with halo biasing adopting an exponential bias [what is an exponential bias?].  Then account for stochastic biasing by defining three regimes: a low, an intermediate and a high density regime, using a Poisson distribution in the intermediate regime and the negative binomial distribution including an additional parameter to model over-dispersion in the high density regime.  Since this study focuses on massive haloes, suppress the generation of haloes in the low density regime.  The various NL biasing parameters, stochastic biasing parameter and density thresholds are calibrated with the large BigMultiDark N-body sim to match the PS of the corresponding halo population.  Model effectively includes only 4 parameters, as they are additionally constrained by the number density.  Mock catalogs show PS which are compatible with N-body sims within about 2% up to k~1h/Mpc at z=0.577 for a sample of haloes with the typical BOSS CMASS galaxy density.  The corresponding correlation functions are compatible down to a few Mpc.  Also find that neglecting over-dispersion in high density regions produces PS with deviations of 10% at k~0.4 h/Mpc.  These results indicate the need to account for an accurate statistical description of the galaxy clustering for precise studies of large scale surveys.  

1307.3686
Solar neutrino analysis for Super-Kamiokande
Sekiya, for Super-K Collaboration

Super-Kamiokande-IV started taking data in September of 2008, and with upgraded electronics and improvements to water system dynamics, calibration and analysis techniques, a clear solar neutrino signal could be extracted at recoil electron kinetic energies as low as 3.5 MeV.  SK-IV extracted solar neutrino flux between 3.5 and 19.5 MeV as 2.36e6 cm^-2 s^-1.  The SK combined recoil electron energy spectrum favors distortions predicted by standard neutrino flavor oscillation parameters over a flat suppression at 1 sigma level.  A maximum likelihood fit to the amplitude of the expected solar zenith angle variation of the elastic neutrino-electron scattering rate in SK, results in a day/night asymmetry of -3.2%.  THe 2.7 sigma significance of non-zero asymmetry is the first indication of the regeneration of electron type solar neutrinos as they travel through Earth's matter.  A fit to all solar neutrino data and KamLAND yeidls sin^2 theta_12=0.304, sin^2 theta_13=0.031, and Delta m^2_21=7.45e-5 eV^2.

1307.4000
Filtergraph: an interactive web application for visualization of astronomy datasets
Burger et al

As the title says.

1307.4079
Colour gradients of high-redshift early-type galaxies from hydrodynamical monolithic models
Tortora et al

Analyze the evolution of color gradients predicted by hydro models of early type galaxies (ETGs) in Pipino+(2008), which reproduce the chemical abundance pattern and the metallicity gradients of local ETGs.  Convert the SF and metal content into colors by means of stellar population synthesis model and investigate the role of different physical ingredients, as the initial gas distribution and content, and eps_SF, the normalization of SFR.  From the comparison with high z data, a full agreement with optical rest-frame observations at z<1 s found, for models with low eps_SF, whereas some discrepancies emerge at 1<z<2, despite the models reproducing quite well the data scatter at these redshifts [scatter of what?].  To reconcile the prediction of these high eps_SF systems with the shallower color gradients observed at lower z, suggest intervention of 1-2 dry mergers.  Suggest that future studies should explore the impact of wet galaxy mergings, interactions with environment, dust content  and a variation of the IMF from the galactic centers to the peripheries.

1307.4081
Is there a metallicity ceiling to form carbon stars? - A novel technique reveals a scarcity ofC stars in the inner M31 disk
Boyer, ... Dalcanton, et al

Use medium-band NIR WFC3 photometry with model NIR spectra of AGB stars to develop a new tool for efficiently distinguishing C-type AGB stars from oxygen-rich (M-type)AGB stars in galaxies at the edge of and outside the Local Group.  Present the results of a test of this method on a region of the inner disk of M31, where lack of C stars found, contrary to the findings of previous C star searches in other regions of M31.  Find only 1 candidate C star (+ 6 maybes) resulting in an extremely low ratio of C to M stars (C/M=3.3e-4) that is 1-2 orders of magnitude lower than other C/M estimates in M31.  THe low C/M ratio is likely due to the high metallicity in this region which impedes stars from achieving C/O>1 in their atmospheres.  These observations provide stringent constraints [to] evolutionary models of metal-rich AGB stars and suggest that there is a metallicity threshold above which M stars are unable to make the transition to C stars, dramatically affecting AGB mass loss and dust production and, consequently, the observed global properties of metal-rich galaxies.

1307.4089
Keck-I MOSFIRE spectroscopy of the z~12 candidate galaxy UDFj-39546284
Capak et al

A z~12 H-band dropout galaxy candidate: Find a 2.2 sigma peak with a line that can indicate 2<z<3.5 or a luminous galaxy at z~12 (flux was lower than expected).  Also search for low-z emission lines in 10 other 7<z<10 z, Y, and J-dropout candidates in mask, and find no significant detections.

1307.4177
Direct model fitting to combine dithered ACS images
Mahmoudian, Wucknitz

Combined sub-pixel dithered images can produce high-quality images, their use as input to forward-modelling techniques in gravitational lensing is still not optimal, because the residual artifacts still affect the modeling results in unpredictable ways.  In this paper, argue for an overall modeling approach that takes into account the dithering and the lensing without the intermediate product of a combined image.  Introduce an alternative approach to combine dithered images by direct model fitting with a least-squares approach including a regularization constraint.  Present tests with simulated and real data that show the quality of the results.  The additional effects of gravitational lensing and the convolution with an instrumental PSF can be included in a natural way, avoiding the possible systematic errors of previous procedures.

1307.4181
A test of the Suyama-Yamagushi inequality from weak lensing
Grassi, et al

Investigate the WL signature of primordial non-Gaussianities of the local type by constraining the magnitude of the weak convergence bi- and trispectra expected for the EUCLID WL survey.  Starting from expressions for the weak convergence spectra, bispectra and trispectra, whose relative magnitudes is investigated as a function of scale, compute their respective signal to noise ratios by relating the polyspectra's amplitude to their Gaussian covariance using a Monte-Carlo technique for carrying out the configuration space integrations.  In computing the Fisher-matrix on the non-Gaussianity parameters f_nl, g_nl and tau_nl with a very similar technique, derive Bayesian evidences for a violation of the Suyama-Yamaguchi relation tau_nl>=(6 f_nl/5)^2 as a function of the true f_nl and tau_nl-values and show that the relation can be probed down to levels of f_nl~100 and tau_nl~1e5.  IN a related study, ,derive analytical expressions for the probability density that the SY-relation is exactly fulfilled, as required by models in which any one field generates the perturbations.  Conclude with an outlook on the levels of non-Gaussianity that cna be probed with tomographic lensing surveys.

1307.4220
How well can cold-dark-matter substructures account for the observed lensing flux-ratio anomalies?
Xu, Sluse, Gao, Wang, Frenk, Mao, Schneider

Lensing flux-ratio anomalies are most likely caused by gravitational lensing by small-scale DM structures.  These anomalies offer the prospect of testing a fundamental prediction of the CDM cosmological model: the existence of numerous substructures that are too small to host visible galaxies.  Previous studies found that the number of subhalos in the six high-resolution simulations of CDM galactic haloes of the Aquarius project is not sufficient to account for the observed frequency of flux ratio anomalies seen in selected quasars from the CLASS survey.  These studies were limited by the small number of haloes used, their narrow range of masses (1-2e12 Msun), and the small range of lens ellipticities considered.  Address these shortcomings by investigating the lensing properties of a large sample of haloes with a wide range of masses in two sets of high resolution simulations of cosmological volumes and comparing them to a currently best available sample of radio quasars.  Find that, as expected, substructures do not change the flux-ratio probability distribution of image pairs and triples with large separations, but they have a significant effect on the distribution at small separations.  For such systems, CDM substructures can account for a substantial fraction of the observed flux-ratio anomalies.  For large close-pair separation systems, the discrepancies existing between the observed flux ratios and predictions from smooth halo models are attributed to simplifications inherent in these models which do not take account of fine details in the lens mass distributions.