Day 567

Friday.

1312.2458
Magnification of photometric LRGs by foreground LRGs and clusters in SDSS
Bauer, Gaztañaga, Martí, Miquel

Measure the mass profiles of spectroscopic LRGs and galaxy clusters by measuring WL magnification of photometric LRGs in their BG.  Measure the change in detected galaxy counts as well as the increased average galaxy flux behind the lenses.  In addition, measure the average change in source color due to extinction by dust in the lenses.  By simultaneously fitting these 3 probes, constrain the mass profiles and dust-to-mass ratios of the lenses in six bins of lens richness. For each richness bin, fit an NFW halo mass, BCG mass, second halo term, and dust-to-mass ratio, and marginalize over uncertainties in the lensing sensitivities alpha_{c,m}.  Measure a mass-richness relation consistent with previous measurements of the catalogs, and limits on the dust-to-mass ratio in the lenses in agreement with expectations.  Explore the effects of including the (low S/N) flux magnification and reddening measurements in the analysis compared to using only the counts magnification data; the additional probes significantly improve the agreement between the measured mass-richness relation and previous results.
1312.2462
Constraints on the CMB temperature evolution using multi-band measurements of the Sunyaev Zel'dovich effect with the South Pole Telescope
Saro et al

The adiabatic evolution of the temperature of the CMB is a key prediction of standard cosmology.  Study deviations from the expected adiabatic evolution of the CMB temperature from T(z) = T_0(1+z)^(1-alpha) using measurements of the spectrum of the SZ effect with SPT.  Present a method for using the ratio of the SZ signal at 95 and 150 GHz in the SPT data to constrain the temperature of the CMB.  Demonstrate that this approach provides unbiased results using mock observations of clusters from a new set of hydro-sims.  Apply this method to a sample of 158 SPT-selected clusters, spanning 0.05<z<1.35, and measure alpha=0.017pm0.03, consistent with the standard model prediction of alpha=0.  In combination with other published results, constrain alpha=0.011pm0.016, an improvement of ~20% over published constraints.  This measurement also provides a strong constraint on the effective equation of state in models of decaying DE w+eff = -0.987pm0.016.

1312.2464
Stellar spectral signatures in high-redshift galaxies
Leitherer

Stellar emission and absorption lines are routinely observed in galaxies at z up to 5 with spectrographs on 8-10m class telescopes.  While the overall spectra are well understood and have been successfully modeled using empirical and theoretical libraries, some challenges remain.  Three issue are discussed: determining abundances using stellar and interstellar spectral lines, understanding the origin of the strong, stellar He II 1640 line, and gauging the influence of stellar Lyman-alpha on the combined stellar+nebular profile.  All three issues can be tackled with recently created theoretical stellar libraries for hot stars which take into account the radiation-hydrodynamics of stellar winds.

1312.2513
Strong neutrino cooling by cycles of electron capture and $/beta^-$ decay in neutron star crusts
Schatz et al

* Urca process: In astroparticle physics, an Urca process is a reaction which emits a neutrino and which is assumed to take part in cooling processes in NS and WDs.  Process was first discussed by Gamow and Schoenberg in a casino named Cassino de Urca.

The temperature in the crust of an accreting NS, which comprises its outermost kilometer, is set by heating from nuclear reactions at large densities, neutrino cooling, and heat transport from the interior.  The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope.  Here, report that cycles of electron capture and its inverse, beta- decay, involving neutron-rich nuclei at a typical depth of about 150m, cool the outer NS crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust.  This Urca mechanism has been studied in the context of WDs and SNIa, but hitherto was not considered in NS, because previous models computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth.  This thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating.  The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear super bursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the NS surface.