Day 778

Tuesday.

1411.0032
Modeling the transfer function for the Dark Energy Survey
Chang, Busha, Wechsler, Refregier, Amara, Rykoff, ... et al

Present a forward-modelling simulation framework designed to model the data products from the DES.  This forward-model process can be thought of as a transfer function - a mapping from cosmo and astro signals to the final data products used by the scientists.  Using output from the cosmo simulations (the Blind Cosmology Challenge), generate simulated images (the Ultra Fast Image Simulator, Berge+2013) and catalogs representative of the DES data.  In this work, simulate the 244 sq deg coda images and catalogs in 5 bands for the DES Science Verification (SV) data.  The simulation output is compared with the corresponding data to show that major characteristics of the images and catalogs can be captured.  Also point out several directions of future improvements.  Two practical examples, star/galaxy classification and proximity effects on object detection, are then used to demonstrate how one can use the simulations to address systematics issues in data analysis.  With clear understanding of the simplifications in the model, show that one can use the simulations side-by-side with data products to interpret the measurements.  This forward doodling approach is generally applicable for other upcoming and future surveys.  It provides a powerful tool for systematics studies which is sufficiently realistic and highly controllable.

1411.0115
Review article: cosmology with cosmic shear observations
Kilbinger

By measuring galaxy shape correlations, can study the properties and evolution of structure on large scales as well as the geometry of the Universe.  Cosmic shear is a powerful probe into the nature of DM and the origin of the current accelerated expansion of the Universe.  Over the last years, cosmic shear has evolved into a reliable and robust cosmological probe, providing measurements of the expansion history of the Universe and the growth of its structure.  Review here the principles of weak gravitational lensing and show how cosmic shear is interpreted in a cosmological context.  Then give an overview of WL measurements, and present the main observational cosmic-shear results since it was discovered 15 years ago, as well as the implications for cosmology.  Then conclude with an outlook on the various future surveys and missions, for which cosmic shear is one of the main science drivers, and discuss promising new weak cosmological lensing techniques for future observations.

1411.0200
Recent stellar mass assembly of low-mass star-forming galaxies at redshifts 0.3 < z < 0.9
Rodrigues-Munoz et al

The median SFH of LMSFGs at intermediate redshifts appears to form 90% of the median stellar mass inferred for the sample in the 0.5-1.8Gyr immediately preceding the observation.  These results suggest a recent stellar mass assembly for LMSFGs, consistent with the cosmological downsizing trends.  Find similar median SFH timescales for the more massive secondary sample.

1411.0313
Wide-Field InfraRed Survey Telescope (WFIRST) Mission and Synergies with LISA and LIGO-Virgo
Gehrels, Spergel

WFIRST is a NASA space mission in study for launch in 2024, with 2.4m telescope, wide-field IR instrument operating in the 0.7-2.0 um range and an exoplanet imaging coronagraph instrument operating in the 400-1000nm range.  The observatory will perform galaxy surveys over thousands of square degrees to J=27 AB for DE WL and BAO measurements and will monitor a few square degrees for DE SN Ia studies.  It will perform microlensing observations of the galactic bulge for an exoplanet census and direct imaging observations of nearby exoplanets with a pathfinder coronagraph.  The mission will have a robust and well-funded guest observer program for 25% of the observing time.  WFIRST will be a powerful tool for time domain astronomy and for coordinated observations with gravitational wave experiments. Gravitational wave events produced by mergers of a nearby binary NS (LIGO-Virgo) or extragalactic SMBH binaries (LISA) will produce electromagnetic radiation that WFIRST can observe.

1411.0399
The proper motion of the galactic center pulsar relative to Sagittarius A*
Bower et al

Using VLBA data, measure proper motion of the pulsar PSR J1745-2900 relative to the galactic center massive BH, Sgr A*.  Projected separation of 0.097 pc from Sgr A*, transverse velocity of 236km/s at 22 deg East of North.  Given the unknown radial velocity, this transverse velocity measurement does not conclusively prove that the pulsar is bound to Sgr A*, but the probability of chance alignment is very small.  Velocity and position is consistent with a bound orbit originating in the clockwise disk of massive stars orbiting Sgr A* and a natal velocity kick of <~500 km/s.  An origin among the isotropic stellar cluster is possible but less probable.  If the pulsar remains radio-bright, multi-year astrometry of PSR can detect its acceleration and determine the full 3d orbit.  Also demonstrate the PSR exhibits the same angular broadening as Sgr A* over a wavelength range of 3.6 cm to 0.7 cm, further confirming that the two sources share the same interstellar scattering properties.  Finally, place the first limits on the presence of a wavelength-dependent shift in the position of Sgr A*, i.e., the core shift, one of the expected properties of optically-thick jet emission.  Results for PSR support the hypothesis that Galactic Center pulsars will originate from the stellar disk and deepens the mystery regarding the small number of detected Galactic Center pulsars.

1411.0649
A proto-cluster at z=2.45
Diener, Lilly, ... Capak, Ilbert, McCracken, et al

Spectroscopic confirmation of a z=2.45 proto-cluster, overdensity of 10, 1.4 Mpc (physical) projected radius, and within delta nu = pm 700 km/s along the LoS.  Structure has made the turn-around, but not assembled yet.  Compare with Millennium sims show that analogous structures evolve into 1e14-15 Msun/h type DM haloes by z=0.  Complete census reveals that they are widely spread over areas with diameter of 3-20 Mpc.  This suggests that the optical selection of such proto-clusters can result in a rich diversity regarding their z=0 descendants.  Also searched for signs of environmental differentiation in this proto-cluster.  See a weak trend for more massive and more quiescent galaxies in the proto-cluster, but it is not statistically significant.