Day 1145

Thursday.

1608.08626
The afterglow and early-type  host galaxy of the short GRB 150101B at z=0.1343
Fong et al

Present the discovery of the X-ray nd optical afterglows of the short-duration GRB 150101B, pinpointing the event to an early-type host galaxy at z=0.1343±0.0030.  This makes GRB 150101B the most nearby short GRB with an early-type host galaxy discovered to date.  Citing the spectral energy distribution of the host galaxy results in an inferred stellar mass of ~7e10 Msun, stellar population age of ~2-2.5 Gyr, and SFR of <0.4 Msun/yr.  The host of GRB 150101B is one of the largest and most luminous short GRB host galaxies, with a B-band luminosity of ~4.3L* and half-light radius of ~8 kpc.  GRB 150101B is located at a projected stance of 7.35±0.07 kpc from its host center, and lies on a faint region of its host rest-frame optical light.  Its location, combined with the lack of associated supernova, is consistent with a NS-NS/NS-BH merger progenitor.  From modeling the evolution of the broad-band afterglow, calculate isotropic-equivalent gamma-ray and kinetic energies of ~1.3e49 erg and ~(6-14)e51 erg, respectively, a circumburst density of ~(0.8-4)e-5 cm^-3, and a jet opening angle of >9 deg.  Using observations extending to ~30 days, place upper limits of <(2-4)e41 erg/s on associated kilonova emission.  Compare searches following previous short GRBs to existing kilo nova models, and demonstrate the difficulty of performing effective kilonva searches from cosmological short GRBs using current ground-based facilities.  Show that at the Advanced LIGO/VIRGO horizon distance of 200 Mpc, searches reaching depths of ~23-24 AB mag are necessary to probe a meaningful range of kilonava models.


1608.08629
Confronting semi-analytic galaxy models with galaxy-matter correlations observed by CFHTLenS
Saghiha, Simon, Schneider, Hilbert

Testing predictions of semi-analytic models of galaxy evolution against observations help to understand the complex processes that shape galaxies. Compare predictions from the Garching and Duram models implemented on the Millennium Run with observations of GGL and G3L for various galaxy samples with stellar masses in the range 0.5<(M*/1e10 Msun)<32 and photometric redshift range 0.2<z<0.6 in CFHTLenS.  Find that the predicted GGL and G3L signals are in qualitative agreement with CFHTLenS data.  Quantitatively, the models succeed in reproducing the observed signals in the highest stellar mass bin 16<M*/1e10 Msun<32 but show different degrees of tensions from the other stellar mass samples.  The Durham model is strongly excluded on a 95% confidence level by the observations as it largely over-predicts the amplitudes of GGL and G3L signals, probably owing to a larger number of satellite galaxies in massive haloes.


1608.08959
On the origin of Earth's Moon
Barr

The Giant Impact is currently accepted as the leading theory for the formation of Earth's Moon.  Successful scenarios for lunar origin should be able to explain the chemical composition of the Moon (volatile content and stable isotope ratios), the Moon's initial thermal state, ad the system's bulk physical and dynamical properties.  Hydrocode simulations of the formation of the Moon have long been able to match the bulk properties, but recent, more detailed work on the evolution of the protolunar disk has yielded great insight into the origin of the Moon's chemistry, and its early thermal history.  Here, show that the community has constructed the elements of an end-to-end theory for lunar origin that matches the overwhelming majority of observational constraints.  In spite of the great progress made in recent years, new samples of the Moon, clarification of processes in the impact-generated disk, and a broader exploration of impact parameter space could yield even more insights into this fundamental and uniquely challenging geophysical problem.