Events Archive

Gravity Group Seminar | October 04, 2019
Fri, Oct 4, 2019, 12:00 pm12:00 pm
Gravity Group Seminar, Charles Romero | UPenn "High resolution SZ observations of galaxy clusters"
Tue, Jun 4, 2019, 2:00 pm2:00 pm

The Sunyaev-Zel'dovich (SZ) effect was first proposed in 1970, but it took until the 1990s before SZ observations became possible without enormous effort. However, the resolution of these observations were always above an arcminute, and thus SZ measurements were primarily sought for determining global properties of the…

Gravity Group Seminar, Simons Observatory | Instrument Overview
Fri, May 31, 2019, 12:00 pm12:00 pm

Details to come...

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Joint Thunch / Gravity Group Seminar, Kris Pardo | Princeton "Implications for the Stochastic Gravitational Wave Background from a Massive Quasar-binary"
Thu, Apr 25, 2019, 12:30 pm12:30 pm

Implications for the Stochastic Gravitational Wave Background from a Massive Quasar-binary The collective inspirals of very close-separation supermassive black holes (SMBHs) are expected to produce a stochastic gravitational wave background (GWB) at nHz frequencies, which is accessible to pulsar timing arrays. However, we have…

Gravity Group Lunch Seminar, Colin Hill | IAS/CCA "Extragalactic Foreground Biases in Primordial non-Gaussianity Measurements from the CMB"
Fri, Apr 19, 2019, 12:00 pm12:00 pm

Abstract: The cosmic microwave background (CMB) temperature bispectrum is currently the most precise tool for constraining non-Gaussianity (NG) in the primordial curvature perturbations.  The Planck temperature data tightly constrain the amplitude of local-type NG, as could be generated in (e.g.) multi-field inflation: f_NL^loc = 2.5 +/- 5.7. …

Gravity Group Lunch Seminar, Xue (Sherry) Song and Joseph van der List | Princeton
Fri, Mar 15, 2019, 12:00 pm12:00 pm

Xue (Sherry) Song and Joseph van der List will lead our first journal club discussion of the academic year. The focus will be on attempts to resolve the inconsistency between local and cosmological measurements of the Hubble constant (H_0): Joseph will discuss "Model…

Gravity Group Lunch Seminar, Max Abitbol | Oxford "Foregrounds of CMB B-modes and spectral distortions"
Fri, Mar 8, 2019, 12:00 pm12:00 pm

I will discuss topics related to foregrounds of two different CMB science cases. For the first part, I will introduce an expansion to foreground SED parameterizations in terms of moments of the parameter distributions. I will then discuss a power spectrum based foreground cleaning algorithm for the Simons Observatory B-mode analysis pipeline…

Gravity Group Lunch Seminar, Jo Dunkley | Princeton "Science forecasts for the Simons Observatory"
Fri, Mar 1, 2019, 12:00 pm12:00 pm

The Simons Observatory (SO) is a new CMB experiment being built in the Atacama Desert in Chile (with many contributions from Princeton) due to begin observations in the early 2020s. We will describe SO's science goals: to characterize the primordial perturbations and look for primordial gravitational waves, to measure the mass of neutrino…

Gravity Group Lunch Seminar, Steve Benton | Princeton "Spider, SuperBIT, Taurus, and Cosmology from the Stratosphere"
Fri, Feb 22, 2019, 12:00 pm12:00 pm

As cosmological measurements increase in precision, foregrounds are increasingly problematic. One foreground that's possible to reduce is Earth's atmosphere. I will talk about experiments that use stratospheric balloons to achieve higher sensitivity and lower systematic errors than are possible on the ground, and at much lower cost than in…

Gravity Group Lunch Seminar, Susan Clark | IAS "The magnetic interstellar medium and the polarized dust foreground"
Fri, Feb 15, 2019, 12:00 pm12:00 pm

The interstellar medium (ISM) is multi-phase, turbulent, and magnetic. This makes the ISM an ideal laboratory for studying the multi-scale physics of star formation and galactic evolution. This also makes the ISM a formidable foreground for cosmology experiments, such as the search for inflationary gravitational wave B-mode polarization in the…

Gravity Group Lunch Seminar, Jean-Loup Puget, IAS (Orsay) and ENS (Paris) "Planck 2018"
Fri, Feb 8, 2019, 12:00 pm12:00 pm

The Planck collaboration is in the process of delivering the "Planck results 2018" papers and data. The improvement of the map making will be described together with a new set of maps with some improvements for polarization at large scales. The consequences for the cosmological parameters are driven by a new determination of the reionization…

Gravity Group Lunch Seminar, Paul Steinhardt (Princeton) "Introduction to Bouncing Cosmology"
Fri, Dec 7, 2018, 12:00 pm12:00 pm

This talk will be an elementary introduction to cosmological theories that replace the big bang with a smooth, classical transition from contraction to expansion in order to address many of the fundamental problems of cosmology.

Sign up here by 2pm tomorrow, Thursday

Gravity Group Lunch Seminar, Adri Duivenvoorden (Stockholm University) "CMB B-modes: optical systematics and novel non-Gaussianity"
Fri, Nov 9, 2018, 12:00 pm12:00 pm

One of the main goals of modern observational cosmology is to constrain or detect a stochastic background of primordial gravitational waves. Realizing this goal will rely on highly accurate measurements of the B-mode signature in the cosmic microwave background (CMB). I will give a brief overview of a particular dedicated B-mode experiment: the…

Gravity Group Lunch Seminar, Rachael Beaton (Princeton) "An Update on an Alternate Route to the Hubble Constant via the Distance Ladder"
Fri, Oct 19, 2018, 12:00 pm12:00 pm

The tension between measurements of the Hubble constant (H0) as determined from the "local" and "distant" Universe persists. The Carnegie-Chicago Hubble Program was designed to provide a calibration of the Type Ia Supernovae (SNe Ia) completely independent of the Leavitt Law for Cepheid variables. Our use of distances determined via the tip of…

Gravity Group Lunch Seminar, Brandon Hensley (Princeton) "Dust Polarization and the Quest for Primordial B-Modes"
Fri, Oct 12, 2018, 12:00 pm12:00 pm

In even the cleanest regions of the sky, polarized emission from our Galaxy is a limiting contaminant for the detection of primordial gravitational waves via a B-mode polarization signature in the Cosmic Microwave Background (CMB). In this talk, I will first review the physics of dust polarization and present models of the physical properties…

Gravity Group Lunch Seminar, Mathew Madhavacheril (Princeton) "kSZ cosmology without the optical depth degeneracy"
Fri, Sep 28, 2018, 12:00 pm12:00 pm

We show how kSZ tomography measures a bispectrum containing a cosmological power spectrum of the velocity field and an astrophysical power spectrum of the electron density. While these are degenerate up to an overall amplitude, scale-dependent effects on large scales are much better constrained by the inclusion of kSZ on top of galaxy…

Gravity Group Lunch Seminar: Hans Bantilan (QMUL), "Non-Spherically Symmetric Collapse in Asymptotically AdS Spacetimes"
Fri, Sep 21, 2018, 12:00 pm12:00 pm

The main purpose of this talk is to describe, by way of a concrete example, how the field of numerical relativity contributes to our understanding of asymptotically AdS spacetimes. I will begin by motivating these studies in terms of gauge/gravity duality, heavy ion physics, and gravitational collapse. I will then describe in detail results…

Special Gravity Group Seminar, Satoru Takakura (IPMU) "Ice clouds -- probable 1/f noise source in POLARBEAR"
Fri, Jun 22, 2018, 12:00 pm12:00 pm

The B-mode polarization, a parity-odd component of polarization anisotropies on the cosmic microwave background (CMB), is a unique probe of primordial gravitational waves from the cosmic inflation. One of the challenges for the measurement is mitigation of the low-frequency noise, also called the 1/f noise, which…

Gravity Group Lunch Seminar, Justin Ripley (Princeton) "Black holes and modified gravity"
Fri, May 18, 2018, 12:00 pm12:00 pm

We motivate the study of modified gravity theories and the role these modifications may play in addressing open questions about the formation and structure of black holes.

We discuss theoretical challenges in studying modified gravity theories and outline current work on a numerical study of gravitational collapse and black hole…

Gravity Group Lunch Seminar, Vera Gluscevic (IAS) "Cornering Dark Matter"
Fri, Apr 6, 2018, 12:00 pm12:00 pm

On galactic scales, structure is gravitationally held by dark matter, while stars and  gas present merely an “icing on the cake.” In spite of their dominance over the matter budget in the universe, particle constituents of dark matter have eluded detection and characterization to the present day. This talk will focus on a variety of promising…