1305.7231
Modelling element abundances in semi-analytic models of galaxy formation
Yates, Henriques, Thomas, Kauffmann, Johansson, White
Update Munich SAM (L-GALAXIES) for chemical evolution treatment. Include: delayed enrichment from stellar winds, SNe-II and SNe-Ia, as well as metallicity-dependent yields and a reformulation of the associated supernova feedback. Two different sets of SN-II yields and 3 different SN-Ia delay-time distributions (DTDs) are considered, and eleven heavy elements (including O, Mg and Fe) are self-consistently tracked. Compare the results of this new implementation with data on a) local, SF galaxies, b) MW disk G dwarfs, and c) local, elliptical galaxies. Find that the z=0 gas-phase mass-metallicity relation is very well reproduced for all forms of DTD considered, as is the [Fe/H] distribution in the MW disc. The [O/Fe] distribution in the MW disc is best reproduced when using a DTD with <= 50% of SNIa exploding within ~400 Myrs. Positive slopes in the mass-[alpha/Fe] relations of local ellipticals are also obtained when using a DTD with such a minor 'prompt' component. Alternatively, metal-rich winds that drive light alpha elements directly out into the circumgalactic medium also produce positive slopes for all forms of DTD and SN-II yields considered. Overall, find that the best model for matching the wide range of observational data considered here should include a power-law SNIa DTD, SN-II yields that take account of prior mass loss through stellar winds, and some direct ejection of light alpha elements out of galaxies.
1305.7457
Testing modified gravity with Planck: the case of coupled dark energy
Pettorino
Explore the possibility that DE is dynamical and gravitational attraction between DM particles is effectively different from the standard one in GR: this is the case of coupled DE models, where DM particles feel the presence of a 5th force, larger than gravity by a factor beta^2. Investigate constraints on the strength of the coupling beta in view of Planck data. SHow that a non-zero coupling is compatible with data and find a likelihood peak at beta=0.036 pm 0.016. This peak comes mostly from the small difference between the Hubble parameter determined with CMB measurements and the one coming from astrophysics measurements. Show how Planck data can be used to provide information on dynamical DE and modified gravity, allowing to test the strength of an effective fifth force between DM particles with precision smaller than 2%.
1306.0005
Estimating the large-scale angular power spectrum in the presence of systematics: a case study of Sloan digital sky survey quasars
Leistedt, Peiris, Mortlock, Benoit-Levy, Pontzen
Angular power spectrum is powerful, but current surveys cover limited portions of the sky, and are contaminated by systematics that jeopardize the interpretation of measured PS. Provide a framework for obtaining unbiased estimates of the angular power spectra of large-scale structure surveys at the largest scales using quadratic estimators. Test with CMASS mock catalogues; consider DR6 photometric quasar catalog, known to include significant stellar contamination and systematic uncertainties. Focusing on the sample of UVX sources, show that the excess clustering power present on the largest-scales can be largely mitigated by making use of improved sky masks and projecting out the modes corresponding to the principal systematics. [what are the principal systematics?] Find that the sample of objects with photos 1.3<z_p<2.2 exhibits no evidence of contamination when using the most conservative mask and mode projection. This indicates that any residual systematics are well within the statistical uncertainties. Conclude that, with this approach, this sample can be used for cosmological studies.
1306.0009
Focusing on warm dark matter with lensed high-redshift galaxies
Paucci, Mesinger, Haiman
Use high-z galaxy counts, detected by SL (such as in CLASH), to put constraint on WDM. Lower limit on WDM particle mass; future HST frontier fields can significantly tighten these constraints.
1306.0015
Weak lensing detection of intra-cluster filaments with ground based data
Maturi, Merten
Constraining the DM content of the "cosmic web" (the filamentary LSS) turns out to be difficult. Direct detection via GL is difficult; present two methods: (1) a linear matched filter that aims at the detection of the smooth mass component of filaments. Optimized to perform a shear decomposition that follows the anisotropic component of the lensing signal. Contamination signal arising from the central massive cluster is controlled in a natural way. The filament 1 sigma detection is of about kappa~0.01-0.005 according to the filter's template width and length, enabling the detection of structures out of reach with other approaches. (2) Detect the clumpy components of filaments (complementary to (1)); determined by the number density of sub-clump identifications in an area enclosing the potential filament, as it was found within the observed field with the filter approach. Test both methods against Mock observations based on realistic N-body simulations of filamentary structure and prove the feasibility of detecting filaments with ground-based data.
1306.0534
Using cross-correlations to calibrate lensing source redshift distributions: improving cosmological constraints from upcoming weak lensing surveys
de Putter, Dore, Das
Lensing source redshift distribution can in principle be calibrated using X-correlations between galaxy number density in lensing source sample and an overlapping spectroscopic sample. Study in detail to what extent this cross-correlation method can mitigate loss of cosmological information in WL surveys, combined with a CMB prior, due to lack of knowledge of the source distribution. Consider a scenario where photo-z are available, and find that, unless the photoz distribution p(z_ph|z) is calibrated very accurately a priori (bias and scatter known to ~0.002 for e.g., Euclid), the additional constraint on p(z_ph|z) from the X-correlation technique to a large extent restores the cosmological information originally lost due to the uncertainty in dn/dz(z). Considering only the gain in photo-z accuracy and not the additional cosmological information, enhancements of the DE FoM of up to a factor of 3 (23) can be achieved for SuMIRe (Subaru measurement of images and redshifts: HSC + Prime focus spectrograph z survey)-like (Euclid-like) combination of lensing and redshift surveys. However, the success of the method is strongly sensitive to the knowledge of the galaxy bias evolution in the source sample. If this bias is modeled by a free parameter in each of a large number of redshift bins, find that a prior of order 0.01 is needed on b_i sqrt(Delta z) in each redshift slice to optimize the gains from the X-correlation method (to approach the cosmology constraints attainable if the bias were known exactly). [nice paper, Roland.]
1306.0559
Observing the next galactic supernova
Adams, Kochanek, Beacom, Vagins, Stanek
As the title says, but on core collapse supernova (ccSNe). ~100% that the next Galactic SN will be detectable in NIR, and ~92% probability that the progenitor is already in 2MASS. Most ccSNe ~98% will be observable in optical, but ~43% will lack progenitor observation due to survey sensitivity and confusion. If neutrino from SN detected to ~3deg resolution, a modestly priced IR camera can probably detect the shock breakout radiation pulse even in daytime. Find : shock breakouts from failed ccSNe of red supergiants may be more observable than those of successful SNe.
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