BOSS DR12 survey: Clustering of galaxies and Dark Matter Haloes
Sergio Rodriguez, UAM, Madrid and Cal. Berkeley
BOSS SDSS-III is the largest redshift survey for the large scale structure and a powerful sample for the study of the low redshift Baryonic Acoustic Oscillations. We combine the features of the survey, such as, geometry, angular incompleteness and stellar mass incompleteness, with the BigMultiDark cosmological simulation to do a study of the distribution of galaxies in the dark matter halos. Using this large N-Body simulation and the halo abundance matching technique, we found a remarkably good agreement with the 2-point and 3-point statistics of the data.
Evolving Perspectives on the Atmosphere and Climate of Mars
Dr. Richard Zurek, JPL
Abstract: The planet Mars has both fascinated and tantalized humankind since the invention of the telescope and now well into the age of exploration from space. The first of three waves of space missions to Mars were flyby spacecraft that returned images of a heavily cratered planet with a thin atmosphere, suggesting Mars was more like the Moon than an older Earth. However, Mariner 9, the first spacecraft to orbit another planet, found vast channel and valley networks carved into its surface, as well as towering volcanoes, suggesting that ancient Mars was once much more Earth-like. Subsequent missions have landed on the planet and new orbiters have probed the planet at ever increasing spatial resolution and spectral coverage. As a result of the latest round of space exploration, Mars is revealed to be a complex, diverse planet— one whose climate has changed dramatically over time from an ancient atmosphere where water was active on its surface to a drier, thinner atmosphere shaped by periodic ice ages, to the present atmosphere where dynamic change continues today.
Dr. Zurek is the Chief Scientist in the Mars Program Office, Project Scientist, MRO.
Exploring Impact Heating of the Early Martian Climate
Kathryn Steakley, NMSU
ABSTRACT: Geological evidence implies that Mars may have had a more warm and wet environment during the late Noachian / early Hesperian era (3.5–3.8 billion years ago), but climate models struggle to reproduce such warm conditions. Prior studies with one-dimensional atmospheric models indicate that the water and energy from impacts could provide enough greenhouse warming to raise temperatures above the freezing point of liquid water for many years. We will use the NASA Ames Research Center Mars GCM to characterize potential atmospheric changes induced by impactors ranging in diameter from 50 m to 100 km on a range of early Mars surface pressure scenarios (10-mbar, 100-mbar, 300-mbar, 1-bar, 2-bar, 3-bar). Our objectives are 1) to examine the temperature behavior of the early Martian climate following impacts and determine if environmental conditions on its surface could support liquid water for extended periods of time, and 2) to quantify precipitation rates and examine rainfall patterns on a simulated early Martian surface following impacts and determine if this mechanism is possibly responsible for the formation of observed river valley networks on Mars. Examining climate conditions after impacts with a GCM will allow us to test a potential mechanism for heating the early Martian atmosphere, constrain the magnitude and temporal duration of these potential heating events, and provide insight regarding the availability of liquid water on early Mars which is relevant to its past habitability.
New Tools for Galactic Archaeology from the Milky Way
Gail Zasowski, John Hopkins University
One of the critical components for understanding galaxy evolution is understanding the Milky Way Galaxy itself — its detailed structure and chemodynamical properties, as well as fundamental stellar physics, which we can only study in great detail locally. This field is currently undergoing a dramatic expansion towards the kinds of large-scale statistical analyses long used by the extragalactic and other communities, thanks in part to an enormous influx of data from space- and ground-based surveys. I will describe the Milky Way and Local Group in the context of general galaxy evolution and highlight some recent developments in Galactic astrophysics that take advantage of these big data sets and analysis techniques. In particular, I will focus on two diverse approaches: one to characterize the distribution and dynamics of the carbon-rich, dusty diffuse ISM, and one to map the resolved bulk stellar properties of the inner disk and bulge. The rapid progress in these areas promises to continue, with the arrival of data sets from missions like SDSS, Gaia, LSST, and WFIRST.
Giant Planet Shielding of the Inner Solar System Revisited: Blending Celestial Mechanics with Advanced Computation
Dr. William Newman, UCLA
The Earth has sustained during the last billion years as many as five catastrophic collisions with asteroids and comets which led to widespread species extinctions. Our own atmosphere was literally blown away 4.5 billion years ago by a collision with a Mars-sized impactor. However, collisions with comets originating in the outer solar system accreted much of the present-day atmosphere. Relatively advanced life on our planet is the beneficiary of a number of impact events during Earth’s history which built our atmosphere without destroying a large fraction of terrestrial life. Using very high precision Monte Carlo integration methods to explore the orbital evolution over hundreds of millions of years followed by the application of celestial mechanical techniques, the presentation will explain directly how Earth was shielded by the combined influence of Jupiter and Saturn, assuring that only 1 in 100,000 potential collisions with the Earth will materialize.