Day 604

Tuesday.

1403.1870
Planets on the edge
Valsecchi, Rasio

Hot Jupiters formed through circularization of high-eccentricity orbits should be found at orbital separations a exceeding twice that of their Roche limit a_R.  Nevertheless, about a dozen giant planet have not been found well within this limit (a_R<a<2a_R), with one coming as close as 1.2 a_R.  In this Letter, show that orbital decay (starting beyond 2a_R) driven by tidal dissipation in the star can naturally explain these objects.  For a few systems, this explanation requires the linear reduction in convective tidal dissipation, but rules out the quadratic prescription.  Additionally, find that WASP-19-type systems could potentially provide empirical support to Zahn's 1966 prescription through high precision transit timing measurements of their orbital decay rate.

1403.1873
The bias of DLAs at z~2.3: evidence for very strong stellar feedback in shallow potential wells
Barnes, Haehnelt

Discuss the recent BOSS measurement of a rather high bias factor for the host galaxies/haloes of Damped Lya Absorbers (DLAs), in the context of the previous modeling of the physical properties of DLAs within the LCDM paradigm.  Joint modeling of the column density distribution, the velocity width distribution of associated low ionization metal absorption, and the bias parameter suggests that DLAs are hosted by galaxies with dark matter halo masses in the range 10.5< log Mv<13, with a rather sharp cutoff at the lower mass end, corresponding to viral velocities of ~90 km/s.  The observed properties of DLAs appear to suggest very efficient (stellar) feedback in haloes with masses/virial velocities below the cutoff and a large retained baryon fraction (>35%) in haloes above the cutoff.

1403.1874
Radiation feedback in ULIRGS: are photons movers and shakers?
Davids, Jiang, Stone, Murray

Use variable Eddington tensor (VET) radiation hydro code to perform 2d sims to study the impact of radiation forces on atmospheres composed of dust and gas.  Setup closely follows that of Krumholz & Thompson, assuming that dust and gas are well-coupled and that the radiation field is characterized by BBs with T>~80 K, as might be found in ULIRGs.  In agreement with previous work, find that Rayleigh-Taylor instabilities develop in radiation supported atmospheres, leading to inhomogeneities that limit momentum exchange between radiation and dusty gas, and eventually providing a near balance of the radiation and gravitational forces.  However, the evolution of the velocity and spatial distribution of the gas differs significantly from previous work, which utilized a less accurate flux-limited diffusion (FLD) method.  The VET simulations show continuous net acceleration of the gas, with no steady-state reached by the end of the simulation.  In contrast, FLD results show lithe net acceleration of the gas and settle into a quasi-steady, turbulent state with low velocity dispersion.  The discrepancies result primarily from the inability of FLD to properly model the variation of the radiation field around structures that are less than a few optical depths across.  Conclude that radiation feedback remains a viable mechanism for driving high-Mach number turbulence.  Discuss implications for observed systems and global numerical simulations of feedback, but more realistic setups are needed to make robust observational predictions and assess the prospect of launching outflows with radiation.

1403.1875
The SDSS-2MASS-WISE ten dimensional stellar color locus
Davenport, Ivezic, Becker, … et al

As the title says.  >1M stars with r-band extinction <0.125, 10 photometric colors.  Use this locus to measure the dust extinction curve relative to the r-band; consistent with previous measurements.  The WISE band extinction coefficients are larger than predicted by standard extinction models.  Find variations in the extinction curve in H, Ks, and WISE bandpasses in 13 lines of sight.  Relative extinction decreases towards Galactic anti-center, in agreement with prior studies.  Relative extinction increases with Galactic latitude, in contrast to previous observations.  This indicates a universal MIR extinction law does not exist due to variations in dust grain size and chemistry with Galactocsntric position.  A preliminary search for outliers due to warm circumstellar dust is also presented, using stars with high S/N in the W3 band.  Find 199 such outliers, identified by excess emission in Ks-W3.  Inspection of SDSS images for these outliers reveals a large number of contaminants due to nearby galaxies.  Six sources appear to be genuine dust candidates, yielding a fraction of systems with IR excess of 0.12 pm 0.05%.  

1403.2181
The expansion rate of the intermediate universe in light of Planck
Verde, Protopapas, Jiminez

Use cosmology-independent measurements of the expansion history in 0.1<z<1.2 and compare them with CMB-derived expansion history predictions.  The motivation is to investigate if the tension between the local (cosmology independent) Hubble constant H0 value and the Planck-derived H0 is also present at other redshifts.  Conclude that there is no tension between Planck and cosmology independent-meausrements of the Hubble parameter H(z) at 0.1<z<1.2 for the LCDM model (odds of tension are only 1:15, statistically not significant).  Considering extensions of the LCDM model worsens the odds, thus favoring the simpler model over its extensions.  On the other hand the H(z) data are also not in tension with the local H0 measurements but the combination of all 3 data-sets shows a highly significant tension (1:400).  Thus the new data deepen the mystery of the mismatch between Planck and local H0 measurements, and cannot univocally determine whether it is an effect localized at a particular redshift.  Find that, assuming the NGC4258 maser distance as the correct anchor for H0, brings the odds to comfortable values.  Further, using only the expansion history measurements, constrain within the LCDM model, H0=68.5pm3.5 and Omega_m=0.32pm0.05 without relying on any CMB prior.  Also address the question of how smooth the expansion history of the universe is given the cosmology independent data and conclude that there is no evidence for deviations from smoothness on the expansion history, neither variations with time in the value of the EoS of DE.

1402.7077
The phase space and stellar populations of cluster galaxies at z~1: simultaneous constraints on the location and timescale of satellite quenching
Muzzin et al

Investigate the velocity vs. position phase space of z~1 cluster galaxies using a set of 424 spectroscopic redshifts in 9 clusters drawn from the GCLASS survey.  Dividing the galaxy population into 3 categories: quiescent, SF, and post starburst, find that these populations have distinct distributions in phase space.  Most striking are the post starburst galaxies, which are commonly found at small cluster centric radii with high cluster centric velocities, and appear to trace a coherent "ring" in phases space.  Using several zoom simulations of cluster, show that the coherent distribution of the poststarbursts can be reasonably well-reproduced using a simple quenching scenario.  Specifically, the phase space is best reproduced if satellite quenching occurs on a rapid timescale (0.1<tau_Q<0.5 Gyr) after galaxies make their first passage of R~0.5 R_2000, a process that takes a total time of ~1 Gyr after first infall.  Compare this quenching timescale to the timescale implied by the stellar populations of the poststarburst galaxies and find that the poststarburst spectra are well-fit by a rapid quenching (tau_Q=0.4 Gyr) of a typical SF galaxy.  The similarity between the quenching timescales derived rom these independent indicators is a strong consistency check of the quenching model.  Given that the model implies satellite quenching is rapid, and occurs well within R_200 this would suggest that ram-pressure stripping of either the hot or cold gas component of galaxies are the most plausible candidates for the physical mechanism.  The high cold gas consumption rates at z~1 make it difficult to determine if hot or cold gas stripping is dominant; however, measurements of the z evolution of the satellite quenching timescale and location may be capable of distinguishing between the two.