Events Archive

Gravity Group Seminar, Avery Broderick (Perimeter Institute), "Images on the horizon: A view of black holes from the Event Horizon Telescope"
Fri, Nov 20, 2015, 11:30 am1:00 pm

Supermassive black holes, located at the centers of galaxies, are at once an extreme consequence of general relativity and the sites of energetic processes that shape the cosmos. Nevertheless, their extraordinarily compact nature has prohibited the direct study of the key gravitational and astrophysical features underlying their nature and…

Gravity Group Seminar, Bill Jones (Princeton), "SuperBIT: Cosmology & Astrophysics with a wide-field, sub-arcsecond imager on the Super Pressure Balloon platform"
Fri, Nov 13, 2015, 12:00 pm1:00 pm

Abstract | Ed Young is in Antarctica on a recovery mission for Spider. I'll give an update on the plan. Then I'll describe our plans for doing cosmology and astrophysics with SuperBIT, a new wide-field sub-arcsecond imager operating over 100 nights in the space-like environment provided by the Super Pressure Balloon Platform…

Gravity Group Seminar, Laura Sales (UC Riverside), "Dwarf galaxies and their satellites as extreme probes of LCDM"
Fri, Oct 30, 2015, 12:00 pm1:00 pm

Dwarf galaxies are extremely diverse in their morphology, from rotationally-supported star-forming disks to gas-free spheroidal stellar systems with no star-formation and negligible rotation. We use cosmological hydrodynamical simulations to show that environment plays a significant role on the assembly history, star formation and globular…

Special Cosmology Seminar, Katerina Chatziioannou (Montana State University)
Mon, Oct 26, 2015, 1:30 pm3:00 pm
Title: Studying the Universe using Gravitational Waves from Compact Binaries Abstract: The second generation era of ground-based gravitational wave detectors has just begun. Years of instrument upgrades have led to unprecedented sensitivity and the first direct detection of gravitational waves should be imminent. Compact binaries of neutron…
Gravity Group Lunch Seminar, Tessa Baker (Oxford, UPENN), "A Parameter Space for Gravity"
Fri, Oct 23, 2015, 12:00 pm1:30 pm

Abstract | From satellites orbiting about the Earth to the large-scale structure of the universe, all astrophysical systems are dominated by gravitational forces. In theory, this should make it easy for us to test General Relativity (GR) and its many proposed extensions. In practice, a synthesis of all our constraints on…

Gravity Group Seminar, "Nitty Gritty Talks on CMB Experiments"
Fri, Oct 16, 2015, 12:00 pm1:30 pm

Presented by, Christine Pappas, Patty Ho, Yaqiong Li, Stevie Bergman, and Anne Gambrel. Five short talks on different aspects of the instruments and analyses for Advanced ACTPol and SPIDER, putting each into context.

Gravity Group Seminar, Thomas Essinger-Hileman "CLASS: The Cosmology Large Angular Scale Surveyor"
Fri, Oct 9, 2015, 12:00 pm1:30 pm

The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravitational-wave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array of four telescopes operating from a high-altitude site in the Atacama Desert in Chile. CLASS will survey 70…

Gravity Group Seminar, Anna Ijjas "An Introduction to Anamorphic Cosmology"
Fri, Oct 2, 2015, 12:00 pm1:30 pm
Abstract: I will present a novel approach to explain the smoothness and flatness of the universe on large scales and the generation of a nearly scale-invariant spectrum of adiabatic density perturbations.

Gravity Group Seminar, Bhuvnesh Jain "Lensing measurements of galaxies and voids"
Fri, Sep 25, 2015, 12:00 pm1:30 pm

Abstract: I will show weak lensing results from the Sloan Digital Sky Survey and the Dark Energy Survey. From Sloan data we use new methods to measure the mass distributon and clustering of cosmic voids and filaments. We also measure the ellipticity of galaxy and cluster halos and relate it to the light. These new measurements of voids and…

Gravity Group Lunch Seminar, Neal Dalal, "Backsplash in dark matter halos" & "Probing dark matter substructure using dusty galaxies"
Fri, Apr 24, 2015, 12:00 pm1:30 pm

Talk 1 Title: Backsplash in dark matter halos Abstract: Recent work has shown that halos in cosmological N-body simulations exhibit a pronounced feature in their density profiles at large radii. I will explain the origin of this newly discovered feature, and describe how it could be used as a ruler to probe cosmology. Talk 2 Title: Probing…

Gravity Group Lunch Seminar, Kent Yagi, "I-Love-Q and Follicly Challenged Neutron Stars"
Fri, Apr 10, 2015, 12:00 pm1:30 pm

Neutron stars offer us an excellent testbed to probe nuclear physics and strong-field gravity. Unlike the well-studied mass-radius relation for neutron stars that depends strongly on their internal structure, I first report unexpected universal relations that we found among the moment of inertia, tidal Love number and quadrupole moment ("I…

Special Cosmology Seminar, Daniel Eisenstein, "Baryon Acoustic Oscillations: A Robust and Precise Route to the Cosmological Distance Scale"
Wed, Mar 4, 2015, 4:00 pm6:00 pm
I will discuss how the acoustic oscillations that propagate in the photon-baryon fluid during the first million years of the Universe provide a robust method for measuring the cosmological distance scale. The distance that the sound can travel can be computed to high precision and creates a signature in the late-time clustering of matter that…
Gravity Group Lunch Seminar, Sam Gralla "QED Plasma and Magnetars"
Fri, Feb 27, 2015, 12:00 pm1:30 pm

Magnetars are surrounded by diffuse relativistic plasma in magnetic field strengths well above the quantum electrodynamic (QED) critical value. We derive equations of ``quantum force-free electrodynamics'' for this plasma using an effective field theory approach where electron field fluctuations are integrated out of the QED action. We argue…

Gravity Group Lunch Seminar, Zoltan Haiman, "Electromagnetic Emission from Compact Supermassive Black Hole Binaries"
Fri, Feb 20, 2015, 12:00 pm1:30 pm

In this talk, I will discuss possible characteristics of electromagnetic (EM) emission from supermassive black hole (SMBH) binaries. In particular, any detectable EM emission is likely to be time-variable, and contain unique spectral signatures, which should aid identifying SMHB binaries. I will discuss recent hydrodynamical simulations, which…