Day 518

Sunday.

13096636
Extreme galaxies during reionization: testing ISM and disk models
Muñoz, Furlanetto

Test the ability of equilibrium galactic disk and one-zone interstellar medium models to describe the physical and emission properties of a sample of quasar hosts, submillimeter galaxies, and Lyman-alpha emitters during the epoch of cosmic reionization at z>~6.  Find that the size, line widths, SFRs BH accretion rates, gas masses and temperatures, and the relationships between these properties are well-described by this model.  In particular, the quasars in the sample are hosted by haloes with masses of ~1e12-13 Msun and require an inflow velocity of gas toward the disk center of v_in=sqrt(2) beta sigma with beta~0.1 --- somewhat higher if quasar outflows are significant --- where sigma is the halo velocity dispersion.  Also provide approximate fitting formulae to the results for comparison with future observations.  However, fiducial model underestimates the [CII] line emission from the systems in the sample by an order of magnitude or more.  Explore two variants to this model and find that the requisite flux can be produced if either the SF efficiency of molecular clouds is higher or the depletion of metals onto dust at fixed metallicity is lower at higher redshift than expected from standard models.  Models also predict a higher median density in molecular clouds than found in fits to observations resulting from turbulent fragmentation in molecular clouds leading to a more thermalized CO(6-5) line and a higher CO(6-5)/CO(1-0) ratio than determined observationally.  While this issue is left unresolved in detail, suggest that either clouds smaller than the local Jeans mass or a support mechanism other than turbulence could result in a lower turbulent Mach number and more subthermal CO(6-5) emission.


1309.6638
Tight correlations between massive galaxy structural properties and dynamics: the mass fundamental plane was in place by z~2
Bezanson, van Dokkum, van de Sande, Franx, Leja, Kriek

The FP is an empirical relation between the size, surface brightness, and velocity dispersion of early-type galaxies.  This relation has been studied extensively for early-type galaxies in the local universe to constrain galaxy formation mechanisms.  The evolution of the zeropoint of this plane has been extended to high z to study the luminosity evolution of massive galaxies, under the assumption of structural homology.  In this work, assess this assumption by replacing surface brightness with stellar mass density and present the evolution of the "mass FP" for massive, quiescent galaxies since z~2.  By accounting for stellar populations, thereby isolate and trace structural and dynamical evolution.  Despite the observed dramatic evolution in the sizes and morphologies of massive galaxies since z~3, find that quiescent galaxies lie on the mass FP out to z~2.  In contrast with ~1.4 dex evolution in the luminosity FP, average residuals from the z~0 mass FP are less than ~0.15 dex since z~2.  Assuming the Hyde & Bernardi (2009) mass FP slope, find that this minimal offset scales as (1+z)^-0.095pm0.043.  This result lends credence to previous studies that derived luminosity evolution from the FP.  Therefore, despite their compact sizes and suggestions that massive galaxies are more disk-like at z~2, the relationship between their dynamics and structural properties are consistent with local early-type galaxies.  Finally, find no strong evidence for a tilt of the mass FP relative to the virial plane, but emphasize the need for full models including selection biases to fully investigate this issue.

1309.6641
A halo bias function measured deeply into voids without stochasticity
Neyrinck, Aragon-Calvo, Jeong, Wang

Study the relationship between DM haloes and matter in the MIP N-body simulation ensemble, which allows precision measurements of this relationship, even deeply into voids.  What enables this is a lack of discreteness, stochasticity, and exclusion, achieved by averaging over hundreds of possible sets of initial small-scale modes, while holding fixed large-scale modes that give the cosmic web.  Find (i) that DM-halo formation is greatly suppressed in voids; there is an exponential downturn at low densities in the otherwise power-law matter-to-halo density bias function.  Thus the rarity of haloes in voids is akin to the rarity of the largest clusters, and their abundance is quite sensitive to cosmological parameters.  The exponential downturn appears both in an excursion-set model, and in a new model in which fluctuations evolve in voids as in an open universe with an effective Omega_m proportional to a large-scale density.  Also find that (ii) haloes typically populate the average halo-density filed in a super-Poisson way, i.e., with a variance exceeding the mean; and (iii) the rank-order-Gaussianized halo and DM fields are impressively similar in Fourier space.  Compare both their PS and cross-correlation, supporting the conclusion that one is roughly a strictly-increasing mapping of the other.