Day 317

Thursday.

1210.6354
Lensing noise in mm-wave galaxy cluster surveys
Hezaveh, ... Holder, et al

How lensing by clusters can affect dusty SF galaxies (DSFGs) and CMB, and implications for SZ cluster surveys.  At the location of galaxy clusters, GL modifies PDF of BG flux of DSFG as well as the CMB.  Find that in a 150 GHz survey, lensing of DSFGs leads to both a slight increase (~10%) in detected cluster number counts (due to a a ~50% increase in the variance of the DSFG background, and hence an Eddington bias), as well as to a rare (occurring in ~2% of clusters) "filling-in" of SZ cluster signals by bright strongly lensed background sources.  Lensing of the CMB leads to a ~55% reduction in CMB power at the location of massive galaxy clusters in a spatially-matched single-frequency filter, leading to a net decrease in detected cluster number counts.  Find: increase in DSFG power and decrease in CMB power due to lensing at cluster locations largely cancel, such that the net effect on cluster number counts for current SZ surveys is sub-dominant to Poisson errors.

1210.6446
Precise measurement of the radial baryon acoustic oscillation scales in galaxy redshift surveys
Sanchez et al

Using radial scale of BAO in deep galaxy surveys.  Method: empirical parameterization of the radial 2pt correlation function, which provides a robust and precise extraction of the sound horizon scale.  Moreover, it uses data from galaxy surveys that is fully cosmology independent and therefore, unbiased.  A study of the main systematic errors and the validation of the method in simulations also presented, showing the measurement is limited only by cosmic variance.  Study full information contained in BAO, obtaining the combination of radial and angular determinations is a sensitive probe of cosmological parameters, able to set constraints on DE w/o combining with any other probe.

1210.6563
Replacing standard galaxy profiles with mixtures of gaussians
Hogg, Lang

Exponential, deVaucouleurs, and Sersic profiles: simple and successful models of 2d images of galaxies.  Numerical issues: pixel rendering and convolution (or correlation) of the models with the PSF, which are slow, and easy to get slightly wrong at small radii.  These models can be approximated to arbitrary accuracy with a mixture (linear superposition) of 2d Gaussians (MoGs), which are fast to render and fast to affine-transform [dilation, rotation, translation, reflection.  things that preserve straight lines.  "affinity" transformation].  A MoG model for pixel-convolved PSF: the convolved, affine-transformed galaxy models are themselves MoGs, and very fast to compute, integrate, and render precisely.  Present worked examples that can be directly used in image fitting.  MoG profiles can be swapped in to replace the standard models in any image-fitting code.  Sped up model fitting by order of magnitude; make any code faster at essentially no cost in precision.

1210.6362
Identifying elusive electromagnetic counterparts to gravitational wave mergers:an end-to-end simulation
Nissanke et al

NS-NS binary mergers can be detected out to 400/750 Mpc distance with 3/5 detector GW networks.  NS-BH mergers can be detected a factor of 1.5 further out.  Localization uncertainty for NS-BH mergers are 50-170 sq deg (or 6-65 sq deg) for 3 (5) GW network detectors.  Quantify fractions of optical counterparts detectable by different size telescopes.  Present 5 case studies to illustrate diversity of challenges in secure identification of EM counterpart at low and high galactic latitudes.  

1210.6368
Our astrochemical heritage
Caselli, Ceccarelli

Chemical composition of meteorites, comets and other small bodies of the solar system, potentially linked to the first phases of SS formation.  Observed chemical composition in the pre-stellar core, protostellar envelope and protostellar envelope and protoplanetary disk phases, including the processes that lead to them.  Draw together pieces from the idfferent objects and phases to understand whether and how much we inherited chemically from the time of the Sun's birth.