Day 477

Tuesday.
1307.6869
A Herschel study of D/H in Water in the Jupiter-Family comet 45P/Honda-Mrkos-Pajdusakova and Prospects for D/H measurements with CCAT
Lis et al

No HDO emission detected; confirm that a diversity of D/H ratios exists in the comet population.

1307.6916
Luhman 16AB: a remarkable, variable L/T transition binary 2 pc from the Sun
Burgasser et al

Luhman (2013) has reported the discovery of a brown dwarf binary system only 2.01+/-0.15 pc from the Sun.  The binary is well-resolved with a projected separation of 1.5", spectroscopic confirmation of late-L and early T-dwarfs.  Exhibits "flux reversal" (T dwarf brighter over 0.9-1.3 um but fainter at other wavelengths) and significant (10%) short-period (~4.9 hr) photometric variability with at complex light curve.  These observations suggest spatial variations in condensate cloud structure, known to evolve substantially across the L/T transition.  Report results from a multi-site monitoring campaign aimed at probing the spectral and temporal properties of this source.  Focusing on spectroscopic observations, report the first detections of NIR spectral variability, detailed analysis of K I lines that confirm differences in condensate opacity between the components, and preliminary determinations of radial and rotational velocities based on high-res NIR spectroscopy.

1307.6994
Gravitational redshift profiles in the $f(R)$ and symmetron models
Grönke, Llinares, Mota

The characteristic feature of both models is the screening mechanism that hides the fifth force in dense environments recovering general relativity.  Use N-body sims Isis which includes scalar fields to analyse deviation from LCDM.  Find: deviation is highly dependent on the halo mass due to screening.  Enhancement of gravitational signal by up to 50% for halos with masses 1e13-15 Msun/h.  The characteristic mass range where the fifth force is most active varies with the model parameters.  Usual assumption: presence of a fifth force leads to a deeper potential well, and thus, a stronger gravitational redshift.  Find that in cases in which only the central regions of the haloes are screened, there could also be a weaker gravitational redshift.

1307.7095
What Planck does not tell us about inflation
Elliston et al

Planck has not found the non-Gaussianity that would have necessitated consideration of inflationary models beyond the simplest canonical single field scenarios.  What does this imply for more general models, in particular, multi-field inflation?  Revisit 4 ways in which 2-field scenarios can behave differently from single field models: two-field slow-roll dynamics, curvaton-type behavior, inflation ending on an inhomogeneous hypersurface and modulated reheating.  Study the constraints that Planck data puts on these classes of behaviour, focusing on the latter two which have been least studied in the recent literature.  Show that these latter classes are almost equivalent, and extend their previous analysis by accounting for arbitrary evolution of the isocurvature mode which, in particular, places important limits on the Gaussian curvature of the reheating hypersurface.  In general, however, find that Planck bispectrum results only constrain certain regions of parameter space, conclude that inflation sourced by more than one scalar field remains an important possibility.