1212.3327
CFHTLenS tomographic weak lensing: quantifying accurate redshift distributions
Benjamin, Van Waerbeke, Heymans, Kilbinger, Erben, Hildebrandt, Hoekstra, Kitching, Mellier, Miller, Rowe, Schrabback, ... Kuijken, Semboloni, et al
CFHTLenS: u*g'r'i'z' photometry: redshift probability distribution function summed over galaxies provides an accurate representation of the galaxy redshift distribution accounting for random and catastrophic errors for galaxies with best fitting photometric z_p<1.3. Present cosmological constraints using tomographic WL by LSS. Use 2 broad z bins 0.5<z_p<=0.85 and 0.85<z_p<=1.3 free of intrinsic alignment contamination, and measure the shear correlation function on angular scales in the range ~1-40 arcmin. Show that the problematic z scaling of the signal does not affect th CFHTLenS data [why?]. For a flat LCDM model and Omega_m=0.27 (fixed), find the sigma_8=0.771 pm 0.041. When combined with WMAP7, BOSS, and a prior on the Hubble constant from the HST distance ladder, find that CFHTLenS improves the precision of the fully marginalised parameter estimates by an average factor of 1.5-2. Combining results with the above probes, find Omega_m=0.2762pm0.0074 and sigma_8=0.802 pm 0.013.
1212.3331
Remarkable spectral variability on the spin period of the accreting white dwarf in V455 And
Bloemen, et al
Spin-resolved spectroscopy of accreting WD binary: suggested spin period of 67s, one of the fastest spinning WDs known. Study spectral variability on the spin period; 2s integration times. Strong coherent signals detected in time series, leads to a robust determination of the spin period of the WD (67.619 pm 0.002 sec). Folding the spectra on the WD spin period uncovered very complex emission line variations in H_gamma, He I and He II. Attribute the observed spin sphase dependence of the emission line shape to the presence of magnetically controlled accretion onto the WD via accretion curtains, consistent with an intermediate polar type system. No specific model that can quantitatively explain the complex velocity variations detected. The orbital variations in the spectral lines indicate that the accretion disc of V455 And is rather structureless, contrary to the disk of the prototype of the intermediate polars, DQ Her. This work demonstrates the potential of electron multiplying CCDs to observe faint targets at high cadence, as readout noise would make such a study impossible with conventional CCDs.
1212.3332
MegaMorph - multi-wavelength measurement of galaxy structure: complete S\'ersic profile information from modern surveys
Häußler, ... Nichol, et al
Find: fitting galaxy light profiles with multi-wavelength data increases the stability and accuracy of the measured parameters, and hence produces more complete and meaningful multi-wavelength photometry than has been available previously. The improvement is particularly significant for magnitudes in low S/N bands and for structural parameters like half-light radius re and Sersic index n for which a prior is used by constraining these parameters to a polynomial as a function of wavelength. This allows the fitting routines to push the magnitude of galaxies for which sensible values can be derived to fainter limits The technique utilises a smooth transition of galaxy parameters with wavelength, creating more physically meaningful transitions than single-band fitting and allows accurate interpolation between passbands, perfect for derivation of rest-frame values.
1212.3336
The 70 month Swift-BAT All-sky hard X-ray survey
Baumgartner et al
1171 hard X-ray sources in the 14-195 keV band down to 5 sigma, associated with 1210 counterparts. Down to flux level of 1.0e-11 erg/s/cm2 over 50% of the sky, and 1.3e-11 ergs/s/cm2 over 90% of the sky. The majority of new sources i the 70-mo survey continue to be AGN, with >700 i the 70 mo survey catalog. Also make available 8-channel spectra and monthly-sampled lightcurves for each object detected in the survey at the Swift-BAT 70 mo website.
[*]1212.3338
CFHTLenS: Combined probe cosmological model comparison using 2d weak gravitational lensing
Kilbinger, Fu, Heymans, Benjamin, Erben, ... Hoekstra, Hildebrandt, Kitching, Mellier... et al
Cosmological constraints from 2d WL by LSS in CFHTLenS over 154 sq. deg in 5 optical bands. 4.2 million galaxies between 0.2<z<1.3, compute the 2d cosmic shear correlation function over angular scales from 0.8 to 350 arcmin. Use NL models of DM PS, constrain cosmological parameters by exploring the parameter space with Population MC sampling. Bets constraints from lensing alone are obtained for the small-scale density-fluctuations amplitude sigma_8 scaled with the total matter density Omega_m. For a flat LCDM model, obtain sigma_8(Omega_m/0.27)^0.6 = 0.79 pm 0.03. Combine the CFHTLenS with WMAP7, BOSS and HST Hubble distance-ladder constant prior to get joint constraints. For a flat LCDM model, find Omega_m=0.283 pm 0.010 and sigma_8=0.813pm0.014. In the case of a curved wCDM universe, obtain Omega_m = 0.27 pm 0.03, sigma_8=0.83pm0.04, w_0=-1.1pm0.15, and Omega_K=0.006 pm 0.006. Calculate the Bayesian evidence to compare flat and curved LCDM and DE CDM models. From the combination of all four probes, find models with curvature to be at moderately disfavoured with respect to the flat case. A simple DE model is indistinguishable from LCDM. Results therefore do not necessitate any deviations from the standard cosmological model.
[*]CFHTLenS: testing the laws of gravity with tomographic weak lensing and redshift space distortions
Simpson, Heymans, Parkinson, Blake, Kilbinger,... et al
WL and galaxy peculiar velocities provide complementary probes of GR, and in combination allow us to test modified theories of gravity in a unique way. Combine WiggleZ and 6dFGS with CFHTLenS. For scale-independent modifications to the metric potentials which evolve linearly with the effective DE density, find present-day cosmological deviations in the Newtonian potential and curvature potential from the prediction of GR to be Delta Psi/ Psi = 0.05 pm 0.25 and Delta Phi / Phi = -0.05 pm 0.3 respectively (1 sigma).
1212.3342
Deviation of stellar orbits from test particle trajectories around Sgr A* due to tides and winds
Psaltis, Li, Loeb
Effects of stellar winds are, in general, negligible. On the other hand, the most eccentric orbits (e>0.96) for which an optical interferometer, such as GRAVITY, will detect orbital plane precession due to frame dragging, the tidal dissipation of orbital energy occurs at timescales comparable to the timescale of precession due to the quadrupole moment of the BH. This non-conservative effect is a potential source of systematic uncertainty in testing the no-hair theorem with stellar orbits.
1212.3408
The dependence of tidal stripping efficiency on the satellite and host galaxy morphology
Chang, Maccio', Kang
Find that the host morphology and the orbital parameters have an effect on determining the mass removal, but they are of secondary importance with respect to satellite morphology; satellite morphology has a very strong effect on the efficiency of stellar stripping; should be taken into account in modeling galaxy formation and evolution.
1212.3438
Can we measure the slopes of density profiles in dwarf spheroidal galaxies?
Kowalzyk et al
The masses withing half-light radii obtained by Wolf+ are over(under)estimated by up to a factor of two when the LoS is along the longest (shortest) axis of the stellar component. Divide the initial stellar distribution into an inner and outer population and trace their evolution in time. The two populations retain different density profiles even after a faew Gyr. Measure the half-light radii and velocity dispersions of the stars in the 2 populations along different lines of sight and use them to estimate the slope of the mass distribution in the dwarfs following the method proposed by Walker & Penarrubia. The inferred slopes are systematically over- or underestimated, depending on the LoS. When the dwarf is seen along the longest axis of the stellar component, a significantly shallower density profile is inferred than the real one measured from the simulations. Since most dSphs are non-spherical and their orientation with respect to our LoS is unknown, the method can be reliably applied only to a large sample of dwarfs when these systematic errors are expected to be diminished.
1212.3514
Cosmological structure formation with augmented Lagrangian perturbation theory
Kitaura, Heß
For long range, use second order LPT (contains a tidal nonlocal and nonlinear term). For short therm, use spherical collapse approximation. Use a Gaussian filter with a smoothing radius r_S to separate between both regimes. This method improves previous approximations at all scales, showing ~25% and ~75% higher correlation than 2LPT with the N-body solution at k=1 and 2 h/Mpc, respectively. Conduct a parameter study to determine the optimal range of smoothing radii and find that the maximum correlation is achieved with r_S=4-5 h/Mpc. This structure formation approach could be used for setting up IC for N-body sims, generating mock galaxy catalogs, perform cosmic web analysis, or for reconstructions of the primordial density fluctuations.
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