Day 787

Monday.

1411.3717
Synthetic galaxy images and spectra from the Illustrious simulation
Torrey et al

Method for generating a catalog of 7k synthetic images and 40k integrated spectra of z=0 galaxies from Illustris Sim.  Mock data products produced by using stellar population synthesis models to assign SED to each star particle in the galaxies.  The resulting synthetic images and integrated SEDs therefore properly reflect the spatial distribution, stellar metallicity distribution, and SFH of the galaxies.  From the synthetic data products, it is possible to produce monochromatic or color-composite images, perform SED fitting, classify morphology determine galaxy structural properties, and evaluate the impacts of galaxy viewing angle.  The main contribution of this paper is to describe the production, format and composition of the image catalog that makes up the Illustris Sim Observatory. As a demonstration of this resource, derive galactic stellar mass estimates by applying the SED fitting code FAST to the synthetic galaxy products, and compare the derived stellar masses against the true stellar masses from sim.  Find from this idealized experiment that systematic biases exist in the photometrically derived stellar mass values that can be reduced by using a fixed metallicity in conjunction with a minimum galaxy age restriction.
1411.3725
Cosmological leverage from the matter power spectrum in the presence of baryon and nonlinear effects
Bielefeld, Huterer, Linder

Take into account uncertainties from ML density fluctuations, (scale dependent) galaxy bias, and baryonic effects.  Allowing for substantially model independent uncertainties through separate fit parameters in each wavenumber bin that also allow for z evolution, quantify strong gains in DE and nu mass leverage with increasing maximum wavenumber, despite marginalizing over numerous (up to 125) extra fit parameters.  The leverage is due to not only an increased number of modes but, more significantly, breaking of degeneracies beyond the linear regime.

1411.3729
The stability of stellar disks in Milky-Way sized dark matter haloes
Yurin, Springel

Improved methodology to insert live stellar disks into high-res DM sims of MW-sized halos, allowing investigation of the fate of thin stellar disks in the tumultuous environment of CDM structures.  Study a set of 8 different halos, drawn from Aquarius simulation project, in which stellar disks are adiabatically grown with a prescribed structure, and then allowed to self-consistently evolve.  The initial velocity distribution is set-up in very good equilibrium with the help of the GALIC code.  Find that the residual triaxiality of the halos leads to significant disk tumbling, qualitative confirming earlier work.  Show that the disk turning motion is unaffected by structural properties of the galaxies such as the presence or absence of a bulge or bar.  In typical MW-sized DM halos, expect an average turning of the disks by about 40 degrees between z=1 and 0, over the course of 6 Gyr.  Also investigate the impact of the disks on substructures, and conversely, the disk heating rate caused by the DM halo substructures.  The presence of disks reduces the central sub halo abundance by about a factor of 2, due to an increase evaporation rate by gravitational shocks from disk passages.  Find that substructures are important for heating the outer parts of stellar disks but do not appear to significantly affect their inner parts.