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|Thu, Oct 15|
Univ. of Wyoming
"Through Curving Wherewhen: Quasar Cosmology with SDSS-IV"
Quasars are actively accreting black holes, with masses of more than a billion suns, at the hearts of distant galaxies. Because quasars are the most luminous long-lived phenomena in cosmic history, they can be used to observe gigantic volumes of the Universe at redshifts back to almost the dawn of time. As part of the fourth iteration of the Sloan Digital Sky Survey (SDSS-IV) the extended Baryon Oscillation Spectroscopic Survey (eBOSS) will identify over half-a-million new quasars over a wide range of redshifts close to the faint limits of the SDSS imaging. I will characterize the eBOSS quasar sample based on data from the Sloan Extended QUasar, ELG and LRG Survey (SEQUELS), a ~300 square degree precursor survey near the North Galactic Cap. I will outline my group's recent work on using CMB lensing maps to directly "weigh" the environments around quasars, and will discuss the prospects of eBOSS for characterizing the masses of the dark matter halos that host quasars. Over the next 5 years, eBOSS will use the most voluminous maps ever made, etched in quasar-light, to probe dark matter, dark energy and the evolution of galaxies throughout cosmic history.
|Thu, Oct 22|
"Tending the Fire: Growing Blacks Holes through Galaxy Mergers and Gas Accretion"
|Thu, Oct 29|
"The detection and characterization of transiting exoplanets and their population"
|Thu, Nov 05|
UC Santa Cruz
"New Insights into Astrophysical Turbulence"
Turbulence influences the properties of astrophysical fluids on a wide range of scales, from protoplanetary disks to the outskirts of galaxy clusters, and governs the critical process of star formation in galaxies like the Milky Way. While the theory of incompressible, subsonic turbulence benefits from a rich history spanning more than half a decade, the theory of supersonic turbulence in astrophysical contexts remains work in progress. Aided by large-scale numerical simulations, much of the theoretical success in modeling supersonic isothermal turbulence involves a coarse description of its statistical properties. After reviewing the theory of turbulence and its relevance for astronomical observations, I will present a fundamentally new framework for thinking about supersonic turbulence that focuses on describing the properties of shocked, dense regions. This new approach benefits from a direct connection with the astrophysics of star formation, and makesverifiable predictions for the structure of star forming clouds. I will conclude by discussing new computational methods engineered to tackle problems like supersonic turbulence in astrophysical contexts.
|Thu, Nov 12|
Western Washington Univ
"Radii, rotation, and relaxation: stellar populations and kinematics of young open clusters"
Young clusters are a primary site of Milky Way star formation, and an important dynamic and radiative environment for planet formation. Measurements of the properties of young clusters (e.g., velocity dispersions and star formation histories) and the stars forming within them (e.g, rotation rates and radii) provide the opportunity to test theoretical models of stellar evolution and cluster formation (and dissolution). I will begin with an overview of results from the Infrared Survey of Young Nebulous Clusters (IN-SYNC), an SDSS-III ancillary program using the APOGEE multi-object infrared spectrograph to characterize the kinematics and stellar properties of young stars in the Perseus and Orion molecular clouds. These observations have revealed the dynamical effects of gas expulsion on the internal kinematics of young clusters, and place a new upper limit on the duration of star formation events within these regions. I will also present results from recent wide-field multi-epoch photometric monitoring programs targeting nearby open clusters. These surveys reveal anomalies in the assumed colors and rotational evolution of low-mass stars, and have uncovered new eclipsing binaries that provide tests for stellar evolution models of unprecedented precision.
|Thu, Nov 19|
|Keivan Guadalupe Stassun|
Vanderbilt and Fisk
"Advances in Stellar Astrophysics, Star Formation, and Exoplanet Science with Large Surveys"
Large surveys, such as the Sloan Digital Sky Survey and the upcoming Large Synoptic Survey Telescope, are revolutionizing many areas of astrophysics. I present some recent discoveries that highlight the diversity of advances enabled by large surveys of stars and exoplanet systems, including: (1) that the most and least tightly bound binary star systems likely have a common dynamical origin, (2) that the properties of low-mass stars and of benchmark eclipsing binary systems can be corrupted through the effects of magnetic activity and of tertiary bodies, and (3) that the "flickering" of stars, due to the granulation of their surfaces, reveals the true physical properties of exoplanets. I close with some thoughts on the role of human visualization for discovery with big data (joint Astronomy/Physics Colloquium).
|Thu, Dec 03|
"Compact Binary Studies with PTF, ZTF, and Beyond"
Optical transient surveys such as the Palomar Transient Factory (PTF) are generating datasets of steadily increasing value for studying photometric variability. I will describe our ongoing efforts to identify and characterize compact binaries using PTF data. I will focus on our search for Fermi-identified "spiders." These eclipsing binary millisecond pulsars may be the evolutionary link between accreting Low-Mass X-ray Binaries and isolated millisecond pulsars. Beginning in 2017, the Zwicky Transient Facility (ZTF) survey will provide more an order of magnitude improvement in survey speed relative to PTF. I will summarize ZTF's design, scientific motivation, and development to date. ZTF will produce a remarkable variability dataset with more than 250 epochs per field each year over the entire Northern Hemisphere sky.
|Thu, Dec 10|
Univ. of Alaska