Day 711

Tuesday.

1407.7030
Star formation at $4<z<6$ from the Spitzer large area survey with Hyper-Suprime-Cam (SPLASH)
Steinhardt, et al

Estimate the masses and SFRs of 3396 M*>1e10Msun SF galaxies at 4<z<6 with a substantial population up to M*>1e11.5Msun.  Find that the strong correlation between stellar mass and SFR seen at lower z (the "main sequence" of SF galaxies) extends to z~6.  The observed relation and scatter is consistent wit ha continued increase in SFR at fixed mass in line with extrapolations from lower-redshift observations. It is difficult to explain this continued correlation, especially for the most massive systems, unless the most massive galaxies are forming stars near their Eddington-limited rate from their first collapse.  Furthermore, find no evidence for moderate quenching at higher masses, indicating quenching either has not occurred prior to z~6 or else occurs rapidly, so that few galaxies are visible in transition between SF and quenched.

1407.7032
Planet Formation Imager (PFI): introduction and technical considerations
Monnier, et al

The aim of the PFI project is to develop the roadmap for the construction of a new near-/mid-IR interferometric facility that will be optimized to unmask all the major stages of planet formation, from initial dust coagulation, gap formation, evolution of transition disks, mass accretion onto planetary embryos, and eventual disk dispersal.  High resolution imaging at a range of wavelengths will give a glimpse and enable a robust theoretical framework for predicting planetary system architectures around a range of stars surrounded by disks with a diversity of initial conditions   Only long-baseline interferometry can provide the needed angular resolution and wavelength coverage to reach these goals.  PFI will be able to detect the emission of the cooling, newly-formed planets themselves over the first 100 Myrs, opening up both spectral investigations and also providing a vibrant look into the early dynamical histories of planetary architectures.  Introduce the PFI project and give initial thoughts on possible facility architectures and technical advances that will be needed to meet the challenging top-level science requirements.

1407.7039
Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy
van de Voort, Quataert, Hopkins, Keres, Faucher-Giguere

Using cosmological zoom-in simulations of MW-mass galaxy, quantify the stellar abundances of neutron-rich r-process nuclei.  The galaxy is enriched with r-process elements by binary NS mergers and with Fe and other metals by SNe.  These calculations include key hydrodynamic mixing processes not present in standard semi-analytic chemical evolution models, such as galactic winds and hydrodynamic flows associated with structure formation.  Explore a range of models for the rate and delay time of NS mergers, intended to roughly bracket the wide range of models consisted wit current observational constraints.  Show that NS mergers can produce [r-process/Fe] abundance ratios and scatter that appear reasonably consistent with observational constraints.  At low metallicity, [Fe/H]<-2, predict there is a wide range of stellar r-process abundance ratios, with both super solar and subsloar abundances.  Low-metallicit stars or stars that are outliers in their r-process abundance rations are, on average, formed at high z and located at large galactocentric radius.  Because NS mergers are rare, results are not fully converged wrt resolution, particularly at low metallicity.  However, the uncertain rate and delay time distribution of NS mergers introduces an uncertainty in the r-process abundances comparable to that due to finite numerical resolution.  Overall, results are consistent with NS mergers being the source of most of the r-process nuclei in the Universe.

1407.7040
The EAGLE project: simulating the volition and assembly of galaxies and their environments
Schaye, .. Bower, .. White, ..  Navarro, .. et al

Introduce the Virgo Consortium's EAGLE project, a suite of hydro sims that follow the formation of galaxies and black holes in representative volumes.  Limitations due to resolution discussed.  Major improvement is the treatment of feedback from massive stars and AGN in which thermal energy is injected into the gas without the need to turn off cooling or hydrodynamical forces, allowing winds to develop without predetermined speed or mass loading factors.  Because the feedback efficiencies cannot be predicted from first principles, calibrate them to the z~0 galaxy stellar MF and the amplitude of the galaxy-central BH mass relation, also taking galaxies sizes into account.  The observed galaxy MF is reproduced to <0.2 dex over the full mass range, 1e8<M*/Msun<1e11, a level of agreement close to that attained by semi-analytic models, and unprecedented for hydrodynamical simulations.  Compare results to a representative set of low-z observables not considered in the calibrations, and find good agreement with the observed galaxy sSFRs, passive fractions, TF relation, total stellar luminosities of galaxy clusters, and column density distributions of intergalactic CIV and OVI.  While the mass-metallicity relations for gas and stars are consistent with observations for M*>1e9 Msun, they are insufficiently steep at lower masses.  The gas fractions and temperatures are too high for clusters of galaxies, but for groups there discrepancies can be resolved by adopting a higher heating temperature in the sub grid prescription for AGN feedback.  EAGLE constitutes a valuable new resources for studies of galaxy formation.

1407.7129
Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams to an extended titled ring, disk and bulge
Danovich, Dekel, Hahn, Ceverino, Primack

Study the buildup of angular momentum (AM) in high-z galaxies using zoom-in hydro-cosmo sims.  The disk AM originates in a few co-planar streams of cold gas and merging galaxies tracing filaments of the cosmic web and undergo 4 phases of evolution.  In phase I, outside the halo virial radius (Rv), the elongated streams gain AM by tidal torques with a specific AM (sAM) ~1.7 times that of the DM due to gas' higher quadrupole moment.  This AM is expressed as stream impact parameters, from ~0.3 Rv to occasional counter rotation.  In phase II, in the outer halo, while the incoming DM mixes with the existing halo of lower sAM to a spin lambda_dm~0.04, the cold streams transport the AM to the inner halo such that their spin in the halo is ~3 lambda_dm.  In phase III, near pericenter, the streams dissipate and form a non-uniform, rotating ring extending to ~0.3 Rv and tilted relative to the inner disc.  Torques exerted partly by the disc make the gas ring lose AM, spiral in, and settle into the disc within one orbit.  The ring is observable with 30% probability as a damped Lyman-alpha absorber.  In phase IV, within the disc, torques associated with violent disc instability drive AM out and baryons into a central bulge, while outflows remove low-spin gas.  Despite the different AM histories of gas and DM, the spin of the disc is only moderately smaller that that of the DM halo.

1407.7316
Measurement of galaxy clustering at z~7.2 and the evolution of galaxy bias from 3.8<z<8 in the XDF, GOODS-S and GOODS-N
Barone-Nugent, ... Oesch, ... van Dokkum, et al

N=743 LBG candidates at z>6.5 at a mean redshift of z=7.2 from various surveys.  Detect a clear clustering signal in the angular correlation function (ACF) at ~4sigma, corresponding to a real-space correlation length r_0=6.7pm1 cMpc/h.  The derived galaxy bias b=8.6pm1 is that of DM haloes of M=1e11 Msun at z=7.2, and highlights that galaxies below the current detection limit (M_AB~-17.7) are expected in lower mass haloes (M~1e8-10.5 Msun).  Compute the ACF of LBGs at z~3.8-5.9 in the same surveys.  A trend of increasing bias is found from z=3.8 (b~3.0) to z=7.2 (b~8.6), broadly consistent with galaxies at fixed luminosity being hosted in DM haloes of similar mass at 4<z<6, followed by a slight rise in halos masses at z~7 (~2 sigma confidence).  Separating the data at the median luminosity of the z=7.2 sample (M_UV=-19.4) shows higher clustering at z=5.9 for bright galaxies (b=6.2) compared to faint galaxies (b=2.7) implying a constant M/L ratio dlogM/dlogL~1.2p1.8m0.5.  A similar trend is present n the z=7.2 sample with larger uncertainty.  Finally, bias measurements allow us to investigate the fraction of DM haloes hosting UV-bright galaxies (the duty-cycle).  At z=7.2 values near unity are preferred, which may be explained by the shortened halo assembly time at high-redshift.

1407.7335
The SAMI galaxy survey: instrument specification and target selection
Bryant, et al

Integral-field spectrograph survey of 3400 galaxies in the GAMA region.

1407.7364
On the local variation of the Hubble constant
Odderskov, Hannestad, Haugbølle

From N-body sims: the expected variance in measurements of H0 is far too small to explain the current discrepancy between the low value of H0 inferred from measurements of CMB and Type Ia SNe.