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.

Day 1144

Wednesday.

1608.08218
The origin of scatter in the stellar mass - halo mass relation of central galaxies in the EAGLE simulation
Matthew, Schaye, et al

Use the hydrosim EAGLE to study the magnitude and origin of the scatter in the stellar mass - halo mass relation for central galaxies.  Separate cause and effect by correlating stellar masses in the baryonic sim with halo properties in a matched DM only (DMO) sim.  The scatter in stellar mass increases with redshift and decreases with halo mass.  At z=0.1 it declines from 0.25 dex at M_200_DMO~1e11 Msun to 0.12 dex at M_200_DMO~1e13 Msun, but the trend is weak above 1e12 Msun.  For M200_DMO<1e12.5 Msun up to 0.04 dex of the scatter is due to scatter in the halo concentration.  At fixed halo mass, a larger stellar mass corresponds to a more concentrated halo.  This is likely because higher concentrations imply earlier formation times and hence more time for accretion and star formation, and/or because feedback is less efficient in haloes with higher binding energies.  The maximum circular velocity, V_max_DMO, and binding energy are therefore more fundamental properties than halo mass, meaning that they are more accurate predictors of stellar mass, and so provide fitting formulae for their relations with stellar mass.  However, concentration alone cannot explain the total scatter in the M_star - M200_DMO relation, and it does not explain the scatter in M_star - V_max_DMO.  Halo spin, sphericity, triaxiality, substructure and environment are also not responsible for the remaining scatter, which thus could be due to more complex halo properties or non-linear/stochastic baryonic effects.


1608.08603
VIS: the visible imager for Euclid
Cropper, et al

Euclid-VIS is the large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled for launch in 2020.  Together with the NIR imaging within the NISP instrument, it forms the basis of the WL measurements of Euclid.  VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5 deg2.  By combining 4 exposures with a total of 2260 sec, VIS will reach to deeper than mAB=24.5 (10sigma) for sources with extent ~0.3 arcsec.  The image sampling is 0.1 arcsec.  VIS will provide deep imaging with a tightly controlled and stable PSF over a wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5 billion galaxies to high levels of accuracy, from which the cosmo parameters will be measured.  In addition, VIS will also provide a legacy dataset with an unprecedented combination of spatial resolution, depth and area covering most of the extra-Galactic sky.  Here, present the results of the study carried out by the Euclid Consortium during the period up to the Critical Design Review.  

Day 1143

Tuesday.

1608.07581
Cross-correlating Planck tSZ with RCSLenS weak lensing: implications for cosmology and AGN feedback
Hojjati, et al

Present measurements of the spatial mapping between (hot) baryons and the total matter in the Universe, via the cross-correlation between the tSZ map from Planck and the WL maps from RCSLenS.  The cross-correlations are performed on the map level where all the sources (including diffuse intergalactic gas) contribute to the signal.  Consider two configuration-space correlation function estimators, xi^{y-kappa} and xi^{y-gamma_t}, and a Fourier space estimator, C^{y-kappa}_ell, in the analysis.  Detect a significant correlation out to 3 degrees of angular separation on the sky.  Based on statistical noise only, report 13 sigma and 17 sigma detections of the cross-correlation using the configuration-space y-kappa and y-gamma_t estimators, respectively.  Including a heuristic estimate of the sampling variance yields a detection significance of 6 sigma and 8 sigma, respectively.  A similar level of detection is obtained from the Fourier-space estimator, C^{y-kappa}_ell.  As each estimator probes different dynamical ranges, their combination improves the significance of the deletion.  Compare the measurements with predictions from the cosmos-OWLS suite of cosmo hydrodynamical sims, where different galactic feedback models are implemented.  Find that a model with considerable AGN feedback that removes large quantities of hot gas from galaxy groups and WMAP-7yr best-fit cosmological parameters provides the best match to the measurements.  All baryonic models in the context of a Planck cosmology over-predict the observed signal.  Similar cosmo conclusions are drawn when a halo model with the observed 'universal' pressure profile is employed.

Day 1142

Monday.

1608.05446

Precise clustering and density evolution of redMaPPer galaxy clusters versus MXXL simulation
Jimena, Broadhurst, et al

Construct a large, redshift complete sample of distant galaxy clusters by correlating SDSS DR12 redshifts with clusters identified with redMaPPer algorithm.  The spectroscopic completeness is 97% for ~7000 clusters within the redMaPPer selection limit, z<0.325, so that the cluster correlation functions are much more precise than earlier work and not suppressed by photometric redshifts.  Derive an accurate power-law mass-richness relation from the observed abundance with respect to the mass function from Millennium XXL (MXXL) sims, adjusted to the Planck weighted cosmology.  The number density of clusters is found to decline by 20% over the range 0.1<z<0.3, in good agreement with the evolution predicted by MXXL.  The projected 3d correlation function scales with richness, lambda, rising from r0=14Mpc/h at lambda~25, to r0=22Mpc/h at lambda~60, with a gradient that matches MXXL when applying the mass-richness relation, whereas the observed amplitude of the correlation function at <z>=0.24 exceeds the MXXL prediction by 20% at the ~2.5 sigma level.  This tension cannot be blamed on spurious, randomly located clusters as this would reduce the correlation amplitude.  Full consistency between the correlation function and the abundances is achievable for the pre-Planck values of sigma8=0.9, Omega_m=0.25, and h=0.73, matching the improved distance ladder estimate of the Hubble constant.



1608.06942
Geometric corroboration of the earliest lensed galaxy at z~10.8 from robust free-form modeling
Chan, Broadhurst, Lim, Diego, Zitrin, Coe, Ford

A multiply-lensed galaxy, MACS0647-JD, with a probably photometric redshift of z~10.7±0.5 is claimed to constitute one of the very earliest known galaxies, formed well before reionization was completed.  However, spectral evidence that MACS0647-JD lies at high redshift has proven invisible and so see any independent lensing used "geometric redshift" derived from the angles between the 3 lensed images of MACS0647-JD, using the free-form mass model (WSLAP+) for the lensing cluster MACSJ0647.7+7015 (at z=0.591).  The lens model uses the 9 sets of multiple images, including those of MACS0647-JD< identified by the CLASH survey towards this cluster.  Convincingly exclude the low redshift regime of z<3, for which convoluted critical curves are generated by the method, as the solution bends to accommodate the wide angles of MACS0647-JD for this low redshift.  Instead, a best fit to all sets of lensed galaxy positions and redshifts provides a geometric redshift of z~10.8±0.4 for MACS0647-JD, strongly supporting the higher photometric redshift solution.  Importantly, find a tight linear relation between the relative brightnesses of all 9 sets of multiply lensed images and their relative magnifications as predicted by the model.  This agreement provides a benchmark for the quality of the lens model, and establishes the robustness of the free-form lensing method for measuring model-independent geometric source distances and for deriving objective central cluster mass distributions.  After correcting for its magnification the luminosity of MACS0647-JD remains relatively high at M_UV=-19.4, which is within a factor of a few in flux of some surprisingly luminous z~10-11 candidates discovered recently in Hubble black field surveys.


1608.07345
Prospects for characterizing the atmosphere of Proxima Centauri b
Kreidberg, Loeb

The newly detected Earth-mass planet in the habitable zone of Proxima Centauri could potentially host life -- if it has an atmosphere that supports surface liquid water.  Show that thermal phase curve observations with JWST from 5-12 microns can be used to test the existence of such an atmosphere.  Predicts the thermal variation for the bare rock versus a planet with 35% heat redistribution to the nightside and show that a JWST phase curve measurement can distinguish between these cases at 5 sigma confidence.  Also consider the case of an Earth-like atmosphere, and find that the ozone 9.8 micron band could be detected with longer integration times (a few months).  Conclude that JWST observations have the potential to put the first constraints on the possibility of life around the nearest star to the Solar System.

Day 1141

Friday.

1608.06938
The impact of baryonic physics on the sub halo mass function and implications for gravitational lensing
Despali, Vegetti

Investigate the impact of baryonic physics on the sub halo population by analyzing the results of 2 recent hydrosims (EAGLE and Illustris) which have very similar configuration but a different model of baryonic physics.  Concentrate on haloes with a mass between 1e12.5 and 14 Msun/h and 0.2<z<0.5, comparing with observational results and subhalo detections in early-type galaxy lenses.  Compare the number and the spatial distribution of sub haloes in the fully hydro runs and in their DM only counterparts, focusing on the differences between the 2 simulations.  Find that the presence of baryons reduces the number of sub haloes, especially at the low mass end (<1e10 Msun/h), by different amounts depending on the model.  The variations in the sub halo mass function are strongly dependent on those in the halo mass function, which is shifted by the effect of stellar and AGN feedback: a lower number of low mass haloes available for accretion in the first place; then additional differences can be attributed to the action of baryonic physics inside the halo.  Finally, search for analogues of the observed lenses (SLACS) in the simulations, doing a selection in velocity dispersion and dynamical properties.  Use the selected galaxies to quantify detection expectations based on the sub halo populations in the different simulations, calculating the detection probability and the predicted values for the DM fraction in sub haloes f_DM and the slope of the mass function alpha.

Day 1140

Thursday.

1608.03074
The Venus Hypothesis
Cartwright

Current models indicate that Venus may have been habitable.  Complex life may have evolved on the highly irradiated Venus, and transferred to Earth on asteroids.  This model fits the pattern of pulses of highly developed life appearing, diversifying and going extinct with astonishing rapidity through the Cambrian and Ordovician periods, and also explains the extraordinary genetic variety which appeared over this period.


1608.00706
Was Venus the first habitable world of our Solar System?
Way, et al

Present-day Venus is an inhospitable place with surface temperatures approaching 750K and an atmosphere over 90 times as thick as present day Earth's.  Billions of years ago the picture may have been very different.  Create a suite of 3D climate simulations using topographic data from the Magellan mission, solar spectral irradiance estimates for 2.9 and 0.715 billion years ago, present day Venus orbital parameters, and ocean volume consistent with current theory and measurements, and an atmospheric composition estimate for early Venus.  Using these parameters, find that such a world could have had moderate temperatures if Venus had a rotation period slower than about 16 Earth days, despite and incident solar flux 46-70% higher than model Earth receives.  At its current rotation period of 243 days, Venus's climate could have remained habitable until at least 715 million years ago if it hosted a shallow primordial ocean.  These results demonstrate the vital role that rotation and topography play in understanding the climatic history of exoplanetary Venus-like worlds being discovered in the present epoch.


Nature
A terrestrial planet candidate in a temperate orbit around Proxima Centauri
Anglada-Escudé, et al

At a distance of 1.295 pc, the red dwarf Proxima Centauri (alpha Centauri , GL 551, HIP 70890 or simply Proxima) is the Sun's coolest stellar neighbor and one of the best-studied low-mass stars.  It has an effective temperature of only around 3050 K, a luminosity of 0.15% of that of the Sun, a measured radius of 14% of the radius of the Sun and a mass of about 12% of the mass of the Sun.  Although Proxima is considered a moderately active star, its rotation period is about 83 days and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun.  Report observations that reveal the presence of a small planet wit ha minimum mass of about 1.3 M_Earth orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 AU.  Its equilibrium temperature is within the range where water could be liquid on its surface.


1608.06672
MOST observations of our Nearest Neighbor: flares on Proxima Centauri
Davenport et al

Present a study of white light flares from the active M5.5 dwarf Proxima Centauri using the Canadian micro satellite MOST.  Using 37.6 days of monitoring data from 2014 and 2015, detected 66 individual flare events, the largest number of white light flares observed to date on Proxima Cen.  Flare energies on the sample range from 1e29-31.5 ergs, with complex, multi-peaked structure found in 22% of these events. The flare rate is lower than that of other classic flare stars of similar spectral type, such as UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth.  Proxima Cen does have an unusually high flare rate given the slow reported rotation period, however.  Extending the observed power-law occurrence distribution down to 1e28 erg, show that flares with flux amplitudes of 0.5% occur 63 time per day, while super flares with energies of 1e33 erg occur ~8 times per year.  Small flares may therefore pose a great difficulty in searches for transits from the recently announced 1.27 M_earth Proxima b, while frequent large flares could have significant impact on the stellar atmosphere.

Day 1139

Monday.  Tuesday.  Wednesday.

1608.04736
Blending bias impacts the host halo masses derived from a cross-correlation analysis of bright sub-millimetre galaxies
Cowley, Lacey, Baugh, Cole, et al

Placing bright sub-millimetre galaxies (SMGs) within the broader context of galaxy formation and evolution requires accurate measurements of their clustering, which can constrain the masses of their host DM halos.  Recent work has shown that the clustering measurements of these galaxies may be affected by a 'blending bias,' which results in the angular correlation function of the sources extracted from single-dish imaging surveys being boosted relative to that of the underlying galaxies.  This is due to confusion introduced by the coarse angular resolution of the single-dish telescope and could lead to the inferred halo masses being significantly overestimated.  Investigate the extent to which this bias affects the measurement of the correlation function of SMBs when it is derived via a cross-correlation with a more abundant galaxy population.  Find that the blending bias is essentially the same as in the auto-correlation case and conclude that the best way to reduce its effects is to calculate the angular correlation function using SMGs in narrow redshift bins.  Blending bias causes the inferred host halo masses of the SMBs to be overestimated by a factor of ~6 when a redshift interval of delta z = 3 is used.  However, this reduces to a factor of ~2 for delta z = 0.5.  The broadening of photo-z probability distributions with increasing redshift can therefore impart a mild halo 'downsizing' effect onto the inferred host halo masses, though this trend is not as strong as seen in recent observational studies.


1608.06494
Evolution and statistics of non-sphericity of dark matter haloes from cosmological N-body simulation
Suto, Kitayama, Nishimichi, Sasaki, Suto

Revisit the non-sphericity of cluster-mass scale halos from cosmo N-body sim on the basis of triaxial modeling.  In order to understand the difference between the sim results and the conventional ellipsoidal collapse model (EC), first consider the evolution of individual simulated halos.  The major difference between EC and the simulation becomes appreciable after the turn-around epoch.  Moreover, it is sensitive to the individual evolution history of each halo.  Despite such strong dependence on individual halos, the resulting non sphericity of halos exhibits weak but robust mass dependence in a statistical fashion; massive halos are more spherical up to the turn-around, but gradually become less spherical by z=0.  This is clearly inconsistent with the EC prediction; massive halos are usually more spherical.  In addition, at z=0, inner regions of he halos are less spherical than outer regions, i.e., the density distribution inside the halos is highly inhomogeneous and therefore not self-similar.  Since most of previous fitting formulae for the PDF of axis ratio of triaxial ellipsoids have been constructed under the self-similarity assumption, they are not accurate.  Computing the PDF of projected axis ratio a1/a2 directly from the sim data without the self-similarity assumption finds that it is very sensitive to this assumption.  The latter needs to be carefully taken into account in direct comparison with observations, and therefore provide and empirical fitting formulas for the PDF of a1/a2.  The preliminary analysis suggests that the derived PDF of a1/a2 roughly agrees with the current WL observations.  More importantly, the present results will be useful in future exploration of the non-sphericity of clusters in X-ray and optical observations.

Day 1138

Friday.

1608.05086
Testing galaxy formation models with galaxy stellar mass functions
Lim, Mo, Lan, Ménard

Compare predictions of a number of empirical models and numerical sims of galaxy formation to the conditional stellar mass functions (CSMF) of galaxies in groups of different masses obtained recently by Lan+ to test how well different models accommodate the data.  Among all the models considered, only the model of Lu+ can match the observational data; all other models fail to reproduce the faint-end upturn seen in the observations.  The CSMFs are used to update the halo-based empirical model of Lu+, and the model parameters obtained are very similar to those inferred by Lu+ from a completely different set of observational constraints.  The observational data clearly prefer a model in which SF in low-mass haloes changes behavior at a characteristic redshift z_c~2.  There is also tentative evidence that this characteristic z depends on environments, becoming z_c~4 in regions that eventually evolve into rich clusters of galaxies.  The constrained model is used to understand how galaxies form and evolve in DM haloes, and to make predictions for other statistical properties of the galaxy population, such as the stellar mass functions of galaxies at high z, the SF and stellar mass assembly histories in DM haloes.  A comparison of the model predictions with those of other empirical models shows that different models can make vastly different predictions, even though all of them are tuned to match the observed stellar mass functions of galaxies.


1608.05191
The spherical Brazil Nut Effect and its significance to asteroids
Perera et al

Many asteroids are likely rubble-piles that are a collection of smaller objects held together by gravity and possibly cohesion.  These asteroids are seismically shaken by impacts, which leads to excitation of their constituent particles.  As a result, it has been suggested that their surfaces and sub-surface interiors may be governed by a size sorting mechanism known as the Brazil Nut Effect.  Study the behavior of a model asteroid that is a spherical, self-gravitating aggregate with a binary size-distribution of particles under the action of applied seismic shaking.  Find that above a seismic threshold, larger particles rise to the surface when friction is present, in agreement with previous studies that focussed on a cylindrical and rectangular box configurations.  Unlike previous works, also find that size sorting takes place even with zero friction, though the presence of friction does aid the sorting process above the seismic threshold.  Additionally find that while strong size sorting can take place near the surface, the innermost regions remain unsorted under even the most vigorous shaking.


1608.05284
The interaction of relativistic spacecrafts with the interstellar medium
Hoang, Lazarian, Burkhart, Loeb

For a spacecraft speed nu=0.2c [speed capable of reaching the nearest star system alpha Centauri in about 20 years], find that dust bombardment can erode a surface layer of ~0.5 mm thickness after the spacecraft has swept a column density of N_H~3e17 cm-2, assuming the standard gas-to-dust ratio of the ISM.  Dust bombardment also damages the spacecraft surface by modifying the material structure through melting.  Calculate the equilibrium surface temperature due to collisional heating by gas atoms as well as the temperature profile as a function of depth into the spacecraft.  The quantitative result suggest methods for damage control, and highlight possibilities for shielding strategies and protection of the spacecraft.

Day 1137

Wednesday.  Thursday.

1608.04753
The awakening of a classical nova from hibernation
Mroz, et al

Cataclysmic variable stars (CVs) are close binary systems consisting of a white dwarf (primary) that is accreting matter from a low-mass companion star (secondary).  From time to time such systems undergo large-amplitude brightening.  The most spectacular eruptions, over 1e4 times in brightness, occurring classical novae and are caused by a thermonuclear runaway on the surface of the WD.  Such eruptions are thought to recur on timescales of 1e4-1e6 [yrs].  In between, the system's properties depend primarily on the mass-transfer rate: if it is lower than 1e-9 Msun/yr, the accretion becomes unstable and the matter is dumped onto the WD during quasi-periodic dwarf nova outbursts.  The hibernation hypothesis predicts that nova eruptions strongly affect the mass-transfer rate, keeping it high for centuries after the event.  Subsequently, the mass-transfer rate should significantly decrease for 1e3-1e6 years, staring the hibernation phase.  After that the nova awakes again - with accretion returning to the pre-eruption level and leading to a new nova explosion.  The hibernation model predicts cyclical evolution of CVs through phases of high and low mass-transfer.  The theory gained some support from the discovery of ancient nova shells around war novae Z Cam and AT Cnc, but direct evidence for considerable mass-transfer changes prior, during and after nova eruptions has not hitherto been found.  Report long-term observations of the classical nova V1213 en (Nova Cen 2009) covering its pre- and post-eruption phases.  Within the 6 years before the explosion, the system revealed dwarf nova outbursts indicative of a low mass-transfer rate.  The post-nova is 2 orders of magnitude brighter than the pre-nova at minimum light with no trace of dwarf nova behavior, implying that the mass-transfer rate increased considerably as a result of the nova explosion.

Day 1136

Tuesday.

1608.03892
Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation
Lofthouse, Kaviraj, Conselice, Mortlock, Hartley

Investigate the contribution of major mergers (mass ratios > 1:5) to stellar mass growth and morphological transformations around the epoch of peak cosmic star formation (z~2).  Visually classify a complete sample of massive (M>1e10 Msun) galaxies at this epoch, drawn from the CANDELS survey, into late-type galaxies, major mergers, spheroids and disturbed spheroids which show morphological disturbances.  Given recent sim work, which indicates that recent (<0.3-0.4 Gyr) major-merger remnants exhibit clear tidal features in such images, use the fraction of disturbed spheroids to probe the role of major mergers in driving morphological transformations.  The percentage of blue spheroids (i.e. with ongoing star formation) that show morphological disturbances is only 21±4%, indicating that major mergers are not the dominant mechanism for spheroid creation at z~2 --- other processes, such as minor mergers or cold accretion are likely to be the main drivers of this process.  Also use the rest-frame U-band luminosity as a proxy for star formation to show that only a small fraction of the star formation budget (~3%) is triggered by major mergers.  Take together, the results show that major mergers are not significant drivers of galaxy evolution at z~2.


1608.03926
The Moon as a recorder of nearby supernovae
Crawford

The lunar geological record is expected to contain a rich record of the galactic environment of the Solar System, including records of nearby (i.e. less than a few tens of parsecs) SN explosions.  This record will be composed of 2 principal components: (i) cosmogenic nuclei produced within, as well as radiation damage to, surface materials caused by increases in the galactic CR flux resulting from nearby SNe; and (ii) the direct collection of SN ejecta, likely enriched in a range of unusual and diagsnotic isotopes, on the lunar surface.  Both aspects of this potentially very valuable astrophysical archive will be best preserved in currently buried, but nevertheless near-surface, layers that were directly exposed to the space environment at known times in the past and for known durations. Suitable geological formation certainly exist on the Moon, but accessing them will require a greatly expanded program of lunar exploration.

Day 1135

Monday.

1608.03743
The insight into the dark side.  I.  The pitfalls of the dark halo parameters estimation
Saburova, Kasparov, Katkov

[...] Pseudoisotehermal, Burkert and NFW dark halo parameters for mass modeling of the rotation curves.  Use two variants of models in which the M/L ratios of disk and bulge were (1) taken as free parameters, (2) fixed in a narrow range according to the models of stellar populations.  Show that, due to the degeneracy between the central densities and the radial scales of the dark haloes, there are considerable uncertainties of their concentration estimates.  It is also impossible to draw any firm conclusion about universality of the dark halo column density based on mass-modeling of even with a high quality rotation curve.  The problem is not solved by fixing the density of baryonic matter.  In contrast, the estimates of dark halo mass within optical radius are much more reliable.  Demonstrate that one can evaluate successfully the halo mass using the pure best-fitting method without any restrictions on the M/L ratio.


1608.03891
Could Cirrus clouds have warmed early Mars?
Ramirez, Kasting

The presence of the ancient valley networks on Mars indicates that the climate at 3.8 Ga was warm enough to allow substantial liquid water to flow on the martian surface for extended periods of time.  However, the mechanism for producing this warming continues to be debated.  One hypothesis is that Mars could have been kept warm by global cirrus cloud decks in a CO2-H2O atmosphere containing at least 0.25 bar of CO2 (Urata+Toon, 2013).  Initial warming from some other process, e.g., impacts, would be required to make this model work.  Those result were generated using the CAM 3D global climate model.  The calculations indicate that cirrus cloud decks could have produced global mean surface temerpatures above freezing, but only if cirrus cloud cover approaches ~70-100% and if other cloud properties (e.g., height, optical depth, particle size) are chosen favorably.  However, at more realistic cirrus cloud fractions, or if cloud parameters are not optimal, cirrus clouds do not provide the necessary warming, suggesting that other greenhouse mechanisms are needed.

Day 1134

Thursday.  Friday.

1608.03074
The Venus Hypothesis
Cartwright

Current models indicate that Venus may have been habitable.  Complex life may have evolved on the highly irradiated Venus, and transferred to Earth on asteroids.  This model files the pattern of pulses of highly developed life appearing, diversifying and going extinct with astonishing rapidity through the Cambrian and Ordovician periods, and also explains the extraordinary genetic variety which appeared over this period.


1608.03169
CMB Lensing beyond the power spectrum: cosmological constraints from the one-point PDF and peak counts
Liu, Hill, Sherwin, Petri, Böhm, Haiman

Unprecedentedly precies CMB data are expected from ongoing and near-future CMB Stage-III and IV surveys, which will yield reconstructed CMB lensing maps with effective resolution approaching several arc minutes.  The small-scale CMB lensing fluctuations receive non-negligible contributions from nonlinear structure in the late-time density field.  These fluctuations are not fully characterized by traditional 2pt statistics, such as the power spectrum.  Here, use N-body ray-tracing simulations of CMB lensing maps to examine two higher-order statistics: the lensing convergence one-point PDF and peak counts.  Show that these statistics contain significant information not captured by the 2pt function, and provide specific forecasts for the ongoing Stage-III AdvACT experiment.  Considering only the temperature-based reconstruction estimator, forecast 30 sigma (PDF) and 10 sigma (peaks) detentions of these statistics with AdvACT.  The simulation pipeline fully accounts for the non-Gaussianity of the lensing reconstruction noise, which is significant and cannot be neglected.  Combining the power spectrum PDF, and peak counts for AdvACT will tighten cosmo constraints in the Omega_m-sigma8 plane by ~30%, compared to using the power spectrum alone.


1608.03279
The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
Bañados, et al

Luminous quasars at z>5.6 can be studied in detail with the current generation of telescopes and provide us with unique information on the first gigayear of the universe.  Thus far these studies have been statistically limited by the number of quasars known at these redshifts.  Such quasars are rare and therefore wide-field surveys are required to identify them and multi wavelength data are needed to separate them efficiently from their main contaminants, the far more numerous cool dwarfs.  In this paper, update and extend the selection for z~6 quasars presented in Banados+2014 using the PS1 survey.  Present the PS1 distant quasar sample, which currently consists of 124 quasars in 5.6<z<6.7 that satisfy the selection criteria.  77 of these quasars have been discovered with PS1, and 63 of them are newly identified in this paper.  Present composite spectra of the PS1 distant quasar sample.  This sample spans a factor of ~20 in luminosity and shows a variety of emission line properties.  The number of quasars at z>5.6 presented in this work almost double the quasars previously known at these redshifts, marking a transition phase from studies of individual sources to statistical studies of the high-z quasar population, which was impossible with earlier, smaller samples.  

Day 1133

Wednesday.

1608.02668
The 2-degree field lensing survey: design and clustering measurements
Blake, et al

Present 2dFLenS, a new galaxy redshift survey performed at the Anglo-Australian Telescope.  2dFLenS is the first wide-area spectroscopic survey specifically targeting the area mapped by deep-imaging gravitational lensing fields, in this case the KiDS survey.  2dFLenS obtained 70,079 redshifts in the range z<0.9 over an area of 731 sq deg, and is designed to extend the datasets available for testing gravitational physics and promote the development of relevant algorithms for joint imaging and spectroscopic analysis.  The redshift sample consists first of 40,531 LRGs, which enable analyses of g-g lensing, redshift-space distortion, and the overlapping source redshift distribution by cross-correlation.  An additional 28,269 redshifts form a magnitude-limited (r<19.5) nearly-complete sub-sample, allowing direct source classification and photometric-redshift calibration.  In this paper, describe the motivation, target selection, spectroscopic observations, and clustering analysis of 2dFLenS.  Use power spectrum multipole measurements to fit the z-space distortion parameter of the LRG sample in 2 redshift ranges 0.15<z<0.43 and 0.43<z<0.7 as beta=0.49±0.15 and beta=0.26±0.09, respectively.  These values are consistent with those obtained from LRGs in BOSS.  2dFLenS data products will be released via http://2dflens.swin.edu.au.

Day 1132

Tuesday.

1608.02308
Supernovae and single-year anomalies in the atmospheric radiocarbon record
Dee, Pope, Miles, Manning, Miyake

Single-year spikes in radiocarbon production are caused by intense bursts of radiation from space.  See emit both high-energy particle and EM radiation, but it is the latter that is most likely to strike the atmosphere all at once and cause a surge in 14C production.  In the 1990s, it was claimed that the SN in 1006 CE produced exactly this effect.  With the 14C spikes in the years 775 and 994 CE now attributed to extreme solar events, attention has returned to the question of whether historical SNe are indeed detectable using annual 14C measurements.  Here, combine new and existing measurements over 6 documented and putative SNe, and conclude that no such astrophysical event has yet left a distinct imprint on the past atmospheric 14C record.


1608.02408
The lunar Askaryan technique with the Square Kilometer Array
James, et al

The lunar Askaryan technique is a method to study the highest-energy cosmic rays, and their predicted counterparts, the ultra-high-energy neutrinos.  By observing the Moon with a radio telescope, and searching for the characteristic nanosecond-scale Askaryan pulses emitted when a high-energy particle interacts in the outer layers of the Moon, the visible lunar surface can be used as a detection area.  Several previous experiments, at Parkes, Goldstone, Kalyazin, Westerbork, and ATCA, Lovell, LOVAR, and the VLA, have developed the necessary techniques to search for these pulses, but existing instruments have lacked the necessary sensitivity to detect the know flux of cosmic rays from such a distance.  This will change with the advent of SKA.  SKA will be the world's most powerful radio telescope.  To be built in southern Africa, Australia and New Zealand during the next decade, it will have an unsurpassed sensitivity over the key 100 MHz to few-GHz band.  Introduce a planned experiment to use the SKA to observe the highest-energy CRs and, potentially, neutrons.  The estimated event rate will be presented, along with the predicted energy and directional resolution.  Prospects for directional studies with phase 1 of the SKA will be discussed, as well the major technical challenges to be overcome to make full use of this powerful instrument.  Finally, show how phase 2 of the SKA could provide a vast increase in the number of detected CRs at the highest energies, and this to provide new insight into their spectrum and origin.

Day 1131

Monday.

1608.01838
Inference from the small scales of cosmic shear with current and future Dark Energy Survey data
MacCrann, et al

Cosmic shear is sensitive to fluctuations in the cosmological matter density field, including on small physical scales, where matter clustering is affected by baryonic physics in galaxies and galaxy clusters, such as SF, SNe feedback and AGN feedback.  While muddying any cosmological information that is contained in small scale cosmic shear measurements, this does mean that cosmic shear has the potential to constrain baryonic physics and galaxy formation.  Perform an analysis of the DES SV cosmic shear measurements, now extended to smaller scales, and using the Mead+2015 halo model to account for baryonic feedback.  While the SV data has limited statistical power, demonstrate using a simulated likelihood analysis that the final DES data will have the statistical power to differential among baryonic feedback scenarios.  Also explore some of the difficulties in interpreting the small scales in cosmic shear measurements, presenting estimates of the size of several other systematic effects that make inference from small scales difficult, including uncertainty in the modeling of intrinsic alignment on nonlinear scales, 'lensing bias', and shape measurement selection effects.  For the latter two, make use of novel image simulations.  While future cosmic shear datasets have the statistical power to constrain baryonic feedback scenarios, there are several systematic effects that require improved treatments, in order to make robust conclusions about baryonic feedback.