Monday.
1310.1079
The dwarfs beyond: the stellar-to-halo mass relation for a new sample of intermediate redshift low mass galaxies
Miller, Ellis, Newman, Benson
Discrepancy in observation and LCDM prediction of abundance and kinematics of local dwarf galaxies: rely heavily on assumption that the local dwarf and satellite galaxies form a representative distribution in terms of their stellar-to-halo mass ratios. To address this question, present new, deep DEIMOS spectroscopy for 82 low mass (1e7-9 Msun [is this stellar mass?]) SF galaxies at 0.2<z<1. For 50 % of these, able to determine resolved rotation curves using nebular emission lines and hence construct the stellar mass TF relation to masses as low as 1e7 Msun. Using scaling relations determined from WL data, convert this to a stellar-to-halo mass relation for comparison with abundance matching predictions. Find a discrepancy between the propagated predictions from simulations compared to observations, and suggest possible reasons for this, as well as future tests that will be more effective. [does low-mass SF 0.2<z<1 galaxy represent something similar to local dwarf and satellite galaxies?]
1310.1080
Olivine-dominated asteroids: mineralogy and origin
Sanchez et al
Olivine-dominated asteroids: a rare type of objects formed either in nebular processes or through magmatic differentiation. At least 100 parent bodies in the main belt experienced partial or complete melting and differentiation before being disrupted. But only a few olivine-dominated asteroids (representative of the mantle of disrupted differentiated bodies) are known to exist. Due to the paucity of these objects in the main belt, their origin and evolution have been a matter of great debate. Present a detailed mineralogical analysis of 12 olivine-dominated asteroids. Within the sample, distinguish two classes, "pure-olivine asteroids" and "olivine-rich asteroids". In pure-olivine asteroids the chemistry found to range from Fo49 to Fo70 [?], consistent with the values measured for brachinites and R chondrites. In Olivine-rich asteroids, determine their olivine and low-Ca pyroxene abundance using a new set of spectral calibrations derived from the analysis of R chondrites spectra. Found that the olivine abundance for these asteroids varies from 0.68 to 0.93, while the fraction of low-Ca pyroxene to total pyroxene ranges from 0.6 to 0.9. A search for dynamical connections between the olivine-dominated asteroids and asteroid families found no genetic link (of the type core-mantel-crust) between these objects.
1310.1086
The fast route to modified gravitational growth
Baker, Ferreira, Skordis
Observing growth rate of LSS == testing gravity on cosmological scales. Consider linear order deviations from GR, show that corrections to the growth rate, f, can be expressed as an integral over a "source" term, weighted by a theory-independent 'response kernel'. This leads to an efficient and accurate 'plug-and-play' expression for generating growth rates in alternative gravity theories, bypassing lengthy theory-specific computations. Use this approach to explicitly show that f is sensitive to a degenerate combination of modified expansion and modified clustering effects. Hence the growth rate, when used in isolation, is not a straightforward diagnostic of modified gravity.
1310.1093
PRIMUS: galaxy clustering as a function of luminosity and color at 0.2<z<1
Skibba, .. Coil, .. Cool, Eisenstein, et al
Measurements of luminosity and color-dependence of galaxy clustering at 0.2<z<1.0 in PRIMUS. Quantify the clustering with the z-space and projected 2-pt correlation functions, xi(rp,pi) and wp(rp), using volume-limited samples constructed from a parent sample of >130k galaxies with robust z in 7 independent fields covering 9 sq deg. Quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes. Find that red galaxies have stronger small-scale (0.1<rp<1 Mpc/h) clustering and steeper correlation functions compared to blue galaxies, as well as strong color dependent clustering within the red sequence alone. Interpret measured clustering trends in terms of galaxy bias and obtain values between b_gal=0.9-2.5, quantifying how galaxies are biased tracers of DM depending on their luminosity and color. Also interpret the color dependence with mock catalogs, and find that the clustering of blue galaxies is nearly constant with color, while redder galaxies have stronger clustering in the one-halo term due to a higher satellite galaxy fraction. In addition, measure the evolution of the clustering strength and bias, and do not detect statistically significant departures from passive evolution. Argue that the luminosity- and color-environment (or halo mass) relations of galaxies have not significantly evolved since z=1. Finally, using jackknife subsampling methods, find that sampling fluctuations are important and that the COSMOS field is generally an outlier, due to having more overdense structures than other fields; find that 'cosmic variance' can be a significant source of uncertainty for high-z clustering measurements.
1310.1099
Hot galactic winds constrained by the X-ray luminosities of galaxies
Zhang, Thompson, Murray, Quataert
Galactic superwinds may be driven by very hot outflows generated by overlapping SNe with the host galaxy, and the cold gas seen in absorption may be accelerated by the ram pressure of this hot wind. Use the CC85 wind model and the observed correlation between X-ray luminosities of galaxies and their SFRs to constrain the mass loss rates (dot{M}_hot) across a wide range of SFRs, from dwarf starbursts to ULIRGs. Show that for fixed thermalization efficiency and mass loading rate [?], the X-ray luminosity of the hot wind scales as L_X~SFR^2, significantly steeper than is observed for SF galaxies: L_X~SFR. Using this difference, constrain the mass-loading and thermalization efficiency of hot galactic winds. For reasonable values of the thermalization efficiency (<~1) and for SFR >~ 10 Msun/yr, find that dot{M}_hot/SFR<~1, significantly lower than required by integrated constraints on the efficiency of stellar feedback in galaxies, and potentially too low to explain observations of winds from rapidly SF galaxies. In addition, highlight the fact that heavily mass-loaded winds cannot be described by the adiabatic CC85 model because they become strongly radiative.
1310.1106
The clustering of galaxies in the SDSS-III DR10 baryon oscillation spectroscopic survey: no detectable colour dependence of distance scale or growth rate measurements
Ross, ... Percival, ... Eisenstein, ... Ho, ... et al
Study the clustering of galaxies as a function of their color from DR10 BOSS. 123k galaxies with 0.43<z<0.7 into a "Blue" sample and 132k into a "Red" sample based on k+e corrected (to z=0.55) r-i colors and i band magnitudes. The samples are chosen to each contain more than 100k galaxies, have similar z distributions, and maximize the difference in clustering amplitude. The Red sample has a 40% larger bias than the Blue (b_red/ b_blue = 1.39 pm 0.04), implying the Red galaxies occupy DM haloes with an average mass that is 0.5 log Msun greater. Spherically averaged measurements of the correlation function, xi_0, and the power spectrum are used to locate the position of the BAO feature of both samples. Using xi_0, obtain distance scales, relative to LCDM cosmology, of 1.10pm0.027 for the Red sample and 1005 pm 0.031 for the Blue. After applying reconstruction, these measurements improve to 1.013 pm 0.020 for the Red sample and 1.008 pm 0.026 for the Blue. For each sample, measurements of xi_0 and the second multipole moment, xi_2, of the anisotropic correlation function are used to determine the rate of structure growth, parameterized by f\sigma_8. Find f\sigma_8,_Red = 0.511pm0.083, f\sigma_8,_Blue = 0.509pm0.085, and f\sigma_8,Cross=0.423pm0.061 (from the cross-correlation between the Red and Blue samples). Us the covariance between the bias and growth measurements obtained from each sample and their cross-correlation to produce an optimally-combined measurement of f\sigma_8,comb = 0.443 pm 0.055. In no instance is significant differences in distance scale or structure growth measurement detected from the Blue and Red samples.
1310.1238
A few cosmological implications of tensor nonlocalities
Ferreira, Maroto
Consider nonlocal gravity theories that include tensor nonlocalities. Show that in the cosmological context, the tensor nonlocalities, unlike scalar ones, generically give rise to growing modes. An explicit example with quadratic curvature terms is studied in detail. Possible consequences for recent nonlocal cosmological models proposed in the literature are also discussed.
1310.1245
Cosmic Topology: twenty years after
Luminet
As the title implies.
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