Day 579

Friday.

1401.3334
Galaxy Zoo: an independent look at the evolution of the bar fraction over the last eight billion years from HST-COSMOS
Melvin, … Nichol, … etal

z evolution of 2380 disk galaxies in COSMOS from Galaxy Zoo: find overall bar fraction decreases by a factor of two, from 22% at z=0.4 (4.2 Gyr) to 11% at z=1.0 (7.8 Gyr), not redshift dependent biases.  Decrease in mass most prominent in the highest mass bin; lower mass show a more modest evolution.  Include sample of 98 red disc galaxies---they have high bar fraction (45%) and are missing from other COSMOS samples which used SED fitting or colors to identify high redshift disks.  Results consistent with a picture in which the evolution of massive disc galaxies begins to be affected by slow (secular) internal process at z~1.  Discuss possible connections of the decrease in bar fraction to the redshift, including the growth of stable disc galaxies, mass evolution of the gas content in disc galaxies, as well as the mass dependent effects of tidal interactions.

1401.3352
Type Ia supernova Hubble residuals and host-galaxy properties
Kim et al

Simulations possibly capturing features of SNIa diversity arising from progenitor stellar evolution.

1401.3356
Hubble space telescope/advanced camera for surveys confirmation of the dark substructure in A520
Jee, Hoekstra, Mahdavi, Babul

ACS imageing, 109 source galaxies per sq. arcmin. [!]  Remove CTI and PSF.  Confirm that a substantial amount of dark mass is present between two luminous sub clusters.  Dark matter centroid coincides with X-ray emission peak; M/L = 813pm80 Msun/Lrun; A520 can be sued to establish a lower limit of the self-interacitng cross-section of DM.

1401.3694
Cosmology with Doppler Lensing
Bacon et al

Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities.  Objects falling into an over density appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts [?].  How to utilize as a probe in cosmology with forthcoming surveys.  Present cosmo sims of Doppler and gravitational lensing effects based on Millennium simulation.  Show that Doppler lensing can be detected around stacked voids or unvirialized over-densities.  New PS and correlation functions are proposed which are designed to be sensitive to Doppler lensing.  Consider impact of gravitational lensing and intrinsic size correlations on these quantities.  Compute the correlation functions and forecast the error for realistic forthcoming surveys, providing predictions for constraints on cosmological parameters.  Finally, demonstrate how to make 3-d potential maps of large volumes of the Universe using Doppler lensing.

1401.3742
Constraining dark energy through the stability of cosmic structures
Pavlidou, etal

For a general DE EoS, estimate the maximum possible radius of massive structures that are not destabilized by the acceleration of the cosmological expansion.  A comparison with known stable structures constrains the equation of state.  The robustness of the constrain can be enhanced through the accumulation of additional astrophysical data and a better understanding of the dynamics of bound cosmic structures.