Day 564

Wednesday.

1312.2009
Spectra as windows into exoplanet atmospheres
Burrows

Planet's atmosphere necessary to understand: the planet itself, its formation, structure, evolution and habitability.  Spectra would be great, but very far for exoplanets.  Give a personal perspective on exoplanet theory and remote sensing via photometry and low-res spectroscopy.  Highlight the limitations in knowledge of compositions, thermal profiles, effects of stellar irradiation, focusing on transiting giant planets.  Recent past of exoplanet atmospheric research has been not to constrain planet properties for all time, but to train a new generation of scientists that is fast establishing a solid future foundation for a robust science of exoplanets.

1312.2013
The MICE grand challenge light cone simulation II: halo and galaxy catalogues
Crocce et al

Present end-to-end simulation from MICE-GC run.  Introduce halo and galaxy catalogues built on it, both in wide (5000 sq deg) and deep (z<1.4) light-cone in several redshift snap shots.  FoF halos resolved down to 1e11 Msun/h, allowed modeling galaxies down to faint luminosities (M_r<-18.9).  Used a new hybrid HOD and abundance matching technique for galaxy assignment.  The catalogue includes SEDs of all galaxies from which multi-band photometric galaxy surveys are modeled.  Describe a variety of applications for halo and galaxy clustering statistics.  Discuss how mass resolution effects can bias the large scale 2pt clustering amplitude of poorly resolved haloes at the <~5% level, and their 3pt correlation function.  Find a characteristic scale dependent bias of <~6% across the BAO feature for halos well above M* ~1e12 Msun/h and for LRG like galaxies.  For haloes well below M* the scale dependence at 100 Mpc/h is <~2%.  Lastly discuss the validity of the large-scale Kaiser limit across redshift and departures from it towards NL scales, in particular due to the motion of satellite galaxies.  Make the current version of light-cone halo and galaxy catalogue (MICECATv1.0) publicly available on http://cosmohub.pic.es, to help develop and exploit the new generation of astronomical surveys.

1312.2025
Using dimers to measure biosignatures and atmospheric pressure for terrestrial exoplanets
Misra, Meadows, Claire, Crisp

Present new method to probe atmospheric pressure on Earthlike planets using (O2-O2) dimers in the near-IR.  Show that dimer features possibly the most readily detectable biosignatures for Earthlike atmospheres, may even be more detectable in transit transmission with JWST.  Absorption by dimers changes more rapidly with pressure and density than that of monomers, and can therefore provide additional information about atmospheric pressures.  By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet.  This method is demonstrated using the O2 A band and the 1.06 um dimer feature, either in transmission or reflected spectra.  It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bars, and for O2 volume mixing ratios above 50% of Earth's present day level.  Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 um, and is therefore potentially applicable, although challenging, to near-term planet characterization mission such as JWST.  Performed detectability studies for JWST transit transmission spectroscopy and find the the 1.06 um and 1.27 um dimer features could be detectable (SNR>3) for an Earth-analog orbiting an M5V star at distance of 5 pc.  The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet, and serve as biosignatures for oxygenic photosynthesis.  Calculated the required SNRs to detect and characterize O2 monomer and dimer features in reflected spectra and find that SNRs greater than 10 at a spectral resolving power of R=100 would be required.

1312.2101
PkANN - II. A non-linear matter power spectrum interpolator developed using artificial neural networks
Agarwal, Abdalla, Feldman, Lahav, Thomas

Introduce PkANN, SW package for interpolating the NL matter PS, constructed using ANNs.  Previously, using Halofit to calculate matter power spectrum, demonstrated that ANNs can make extremely quick and accurate predictions of the PS.  Using a suite of 6380 N-body sims spanning 580 cosmologies, train ANNs to predict the PS over the cosmological parameter space spanning 3sigma CL around the concordance cosmology.  Present with a set of cosmological parameters (Omh2, Obh2, ns, w, sigma8, Sum m_nu and redshift z), the trained ANN interpolates the PS for z<~2 at sub% accuracy for modes up to k<0.8 h/Mpc.  PkANN is after than computationally expensive N-body sims, yet provides a worst-case error <1% fit to the NL matter PS deduced through N-body sims.  The overall precision of PkANN is set by the accuracy of the N-body sims, at 5% level for cosmological models with Sum m_nu<0.5 eV for all redshifts z<=2.  For models with Sum m_nu>0.5 eV, predictions are expected to be at 5(10)% level for redshifts z>1 (z<=1).  The PkANN interpolator publicly available at http://zuserver2.star.ucl.ac.uk/~fba/PkANN.