Day 1508

Tuesday.

1811.12940

Binary black hole population properties inferred from the first and second observing runs of Advanced LIGO and Advanced Virgo

The LIGO Scientific Collaboration, The Virgo Collaboration

Present results on the mass, spin, and redshift distributions of the ten binary black hole mergers detected in Advanced LIGO's and Advanced Virgo's first and second observing runs.  Constrain properties of the binary black hole (BBH) mass spectrum using models with a range of parameterizations of the BBH mass and spin distributions.  Find that the mass distribution of the more massive black hole in each binary is well approximated by models with almost no BHs larger than 45 Msun, and a power law index of alpha=....  Also show that BBHs are unlikely to be composed of BHs with large spins aligned to the orbital angular momentum.  Modeling the evolution of the BBH merger rate with redshift, show that it is increasing with redshift with credibility ....  Marginalizing over uncertainties in the BBH population, find robust estimates of the BBH merger rate density of R=...  As the BBH catalog grows in future observing runs, expect that uncertainties in the population model parameters will shrink, potentially providing insights into the formation of black holes via supernovae, binary interactions of massive stars, stellar cluster dynamics, and the formation history of BHs across cosmic time.

1812.00346

Influence of gravity waves on the climatology of high-altitude Martian carbon dioxide ice clouds

Yigit, et al

CO2 ice clouds have been routinely observed in the middle atmosphere of Mars.  However, there are still uncertainties concerning physical mechanisms that control their altitude, geographical, and seasonal distributions.  Using the Max Planck Institute Martian General Circulaion Model (MPI-MGCM), incorporating a state-of-the-art whole atmosphere subgrid-scale gravity wave parameterization, demonstrate that internal gravity waves generated by lower atmospheric weather processes have wide reaching impact on the Martian climate.  Globally, gas cool the upper atmosphere of Mars by ~10% and facilitate high-altitude CO2 ice cloud formation.  CO2 ice cloud seasonal variations in the mesosphere and the mesopause region appreciably coincide with the spatio-temporal variations of GW effects, providing insight into the observed distribution of clouds.  The results suggest that GW propagation and dissipation constitute a necessary physical mechanism for CO2 ice cloud formation in the Martian upper atmosphere during all seasons.

1812.00514

LSST observing strategy white paper: LSST Observations of WFIRST Deep Fields

Foley, Koekeloer, Spergel, et al

WFIRST is expected to launch i the mid-2020s.  With its wide-field near-IR camera, it will survey the sky to unprecedented detail.  As part of normal operations and as the result of multiple expected dedicated surveys, WFIRST will produce several relatively wide-field (tens of square degrees) deep (limiting magnitude of 28 or fainter) fields.  In particular, a planned SN survey is expected to image 3 deep fields in the LSST footprint roughly every 5 days over 2 years.  Stacking all data, this river will produce, over all WFIRST SN fields in the LSST footprint, ~12-25 deg2 and ~5-15 deg^2 regions to depths of 28 mag and 29 mag, respectively.  Suggest LSST undertake mini-surveys that will match the WFIRST cadence and simultaneously observe the SN survey fields during the 2yr WFIRST SN survey, achieving a stacked depth similar to that of the WFIRST data.  Also suggest additional observations of these same regions throughout the LSST survey to get deep images earlier, have long-term monitoring in the fields, and produce deeper images overall.  These fields will provide a legacy for cosmology, extragalactic, and transient/variable science.


1812.00607
Simultaneous LSST nd Euclid observations - advantages for Solar System Objects
Snodrass, et al

The ESA Euclid mission is a space telescope that will survey ~15000 sq deg of the sky, primarily to study the distant universe (constraining cosmological parameters through the lensing of galaxies).  It is also expected to observe ~150,000 Solar System Objects (SSOs), primarily in poorly understood high inclination populations, as it will mostly avoid ±15 degrees from the ecliptic plane.  With a launch data of 2022 and a 6 year survey, Euclid and LSST will operate at the same time, and have complementary capabilities.  Propose a LSST mini-survey to coordinate quasi-simultaneous observations between these two powerful observatories, when possible, with the primary aim of greatly improving the orbits of SSOs discovered by these facilities.  As Euclid will operate from a halo orbit around the Sun-Earth L2 Lagrangian point, there will be significant parallax between observations from Earth and Euclid (0.01 AU).  This means that simultaneous observations will give an independent distance measurement to SSOs, giving additional constraints on orbits compared to single Euclid visits.


1812.00638
Neutrino properties and the cosmological tensions in the $\Lambda$LCDM model
Gariazzo

Review the current status of the constraints on the neutrino properties from cosmological measurements, with a particular focus on their mass and effective number.  Also discuss the existing tensions within the context of the LCDM model, including the discrepancies on the Hubble parameter and on the matter fluctuations at small scales, and how neutrinos could help to alleviate the aforementioned problems.


1812.00861
Accurately computing weak lensing convergence
Koksbang, Clarkson

WL will play an important role in future cosmo surveys, including Euclid and SKA.  Sufficiently accurate theoretical predictions are important for correctly interpreting these surveys and hence for extracting correct cosmological parameter estimations.  Quantify for the first time in a relativistic setting how many post-Born and lens-lens coupling correction are required for sub-percent accuracy of the theoretical WL convergence and distance-z relation for z<2 (the primary WL range for Euclid and SKA).  Do this by randomly ray-tracing through a fully relativistic exact solution of the Einstein Field Equations which consists of randomly picked mass-compensated under-densities of realistic amplitudes.  Find that one needs to include lens-lens coupling terms and post-Born corrections at least up to second and 3rd order respectively for sub-percent accuracy of the convergence and angular diameter distance d_A.  Find that, out of the random lines of sight studied, post-Born corrections can be as large as 70% of the total correction to the area distance.  Also provide a simplified operator formalism for calculating the leading corrections to these quantities to arbitrary order.