Events Archive

Gravity Group Lunch Seminar, David Spergel (CCA, NYC) "The Search for Dark Energy and NASA’s WFIRST mission"
Fri, Mar 30, 2018, 12:00 pm12:00 pm

Over the last twenty years, there has been growing evidence that our universe is dominated by dark energy.  The nature of this dark energy remains a mystery. Is it the signature of the breakdown of general relativity or vacuum energy associated with quantum gravity?  I will review the current observations and note…

Gravity Group Lunch Seminar, Cynthia Chiang (U. KwaZulu-Natal, SA), "Illuminating the Dark Universe with Radio Observations" Jadwin A10
Wed, Jan 31, 2018, 12:30 pm12:30 pm

Observations of redshifted 21-cm emission of neutral hydrogen are a rapidly growing area of cosmology research.  Measurements across a wide range of radio frequencies allow us to access redshifts that encompass a vast comoving volume, spanning both cosmic dawn and the formation of large-scale structure.  I will describe two new experiments,…

Gravity Group Lunch Seminar, Sherry Song and Yaqiong Li (Princeton University), Jadwin 102
Fri, Jan 26, 2018, 12:00 pm12:00 pm

Xue (Sherry) Song, Princeton University
"Journal Club Discussion of Watts et al. (2018) [CLASS Collaboration]"

The paper is available at .

Yaqiong Li, Princeton University
"The Microwave SQUID…

Gravity Group Lunch Seminar, Steve Choi (Princeton University) "Precision Cosmology with Advanced ACTPol" (102 Jadwin Hall)
Fri, Jan 19, 2018, 12:00 pm12:00 pm

The Advanced ACTPol upgrade on the Atacama Cosmology Telescope aims to improve the measurement of the cosmic microwave background anisotropies and polarization, using four new dichroic detector arrays fabricated on 150-mm silicon wafers. In 2016, the Atacama Cosmology Telescope began mapping approximately half the sky with increased sensitivity…

Gravity Group Lunch Seminar, Kevin Crowley (Princeton University), "Transition-Edge Sensors for CMB Polarimetry"
Fri, Dec 15, 2017, 12:00 pm12:00 pm

Studies of the anisotropies in the Cosmic Microwave Background (CMB) are now focused on recovering primordial signals from polarization patterns on the sky. The demand for instruments with greater raw sensitivity is being met by scaling the density of telescope focal planes up to thousands, and tens of thousands, of detectors. Transition-edge…

Gravity Group Lunch Seminar, Adrian Price-Whelan (Princeton University), "Improving Gaia parallaxes with data driven models, and other Gaia miscellany"
Fri, Oct 27, 2017, 12:00 pm12:00 pm

The Gaia mission will deliver astrometry for >1 billion stars in the Milky Way.For distant or faint sources -- i.e. most sources -- the astrometry alone willbe low signal-to-noise, so inferred distances or tangential velocities will be noisy. However, Gaia also measures colors and low-resolution spectroscopy for these stars: stars live on a…

Astroplasmas / Gravity Group Joint Seminar, Brian Metzger (Columbia University), "The Multi-Messenger Picture of a Neutron Star Merger"
Fri, Oct 20, 2017, 12:30 pm12:30 pm

On August 17 the LIGO/Virgo gravitational wave observatories detected the first binary neutron star merger event (GW170817), a discovery followed by the most ambitious electromagnetic (EM) follow-up campaign ever conducted.  A gamma-ray burst (GRB) of short duration and very low luminosity was discovered by the Fermi and INTEGRAL satellites…

Gravity Group Lunch Seminar, Heather McCarrick (Columbia University), "KIDs for CMB Polarimetry"
Fri, Oct 13, 2017, 12:00 pm12:00 pm

I will talk about the development of kinetic inductance detectors (KIDs) optimized for cosmic microwave background (CMB) polarization studies. We have designed, fabricated, and tested arrays of dual-polarization lumped-element KIDs (LEKIDs). The arrays are mounted in 64-element modules where each element contains a conical horn and two…

Gravity Group Lunch Seminar, Nick Jennings (University of Oxford), "Searches for ALPs with Current and Future X-ray Satellites"
Fri, Sep 29, 2017, 12:00 pm12:00 pm

Galaxy clusters represent excellent laboratories to search for Axion-Like Particles (ALPs). They contain magnetic fields which can induce quasi-sinusoidal oscillations in the X-ray spectra of AGNs situated in or behind them. Ultra-deep Chandra observations of the Perseus cluster contain over 5e5 counts from the central NGC1275 AGN, and…

Gravity Group Lunch Seminar, Srini Raghunathan (University of Melbourne, AU), "Measuring masses of galaxy clusters using CMB-cluster lensing"
Fri, Sep 22, 2017, 12:00 pm12:00 pm

Galaxy clusters are the largest gravitationally bound objects in the Universe and are excellent cosmological probes. Their power as cosmological probes, however, is currently limited by the systematics involved in the measurement of their mass. In this talk, I will discuss the method to estimate their masses using the weak-gravitational lensing…

Gravity Group Seminar, Brenna Flaugher (Fermilab)
Fri, Jun 9, 2017, 12:00 pm12:00 pm

TITLE: The Dark Energy Survey 

ABSTRACT: The Dark Energy Survey Collaboration built the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera for the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile. DECam was installed on the telescope in 2012 and is being used to carry out a 5 year,…

Gravity Group Seminar, Neil Cornish (Montana Sate University)
Fri, Jun 2, 2017, 12:00 pm12:00 pm

“Gravitational Wave Astronomy - What’s next?”

The detection by LIGO of gravitational waves from the merger of two black holes marks the end of a half-century long quest, and the beginning of a new branch of astronomy. A tremendous amount has already been learned from the first few detection's, both in terms of fundamental physics and…

Gravity Group Seminar, Benjamin A. Mazin (UCSB)
Fri, May 5, 2017, 12:00 pm12:00 pm

TITLE Microwave Kinetic Inductance Detectors for High Contrast Imaging

ABSTRACT Microwave Kinetic Inductance Detectors, or MKIDs, are superconducting detector arrays that can measure the energy and arrival time of individual optical through near-IR photons without read noise or dark current. I will report on the promising…

Gravity Group Seminar, Chiara Mingarelli (Max Planck)
Fri, Apr 28, 2017, 12:00 pm12:00 pm

Insights into Supermassive Black Hole Mergers, Stalling and Demographics with Pulsar Timing Arrays

Galaxy mergers are a standard aspect of galaxy formation and evolution, and likely all large galaxies contain central supermassive black holes (SMBH). Here I discuss a new bottom-up approach to identifying…

Gravity Group Seminar, Cristobal Sifon (Princeton University) "Weak lensing masses of galaxies in galaxy clusters, from LRGs to UDGs"
Fri, Apr 21, 2017, 11:50 am11:50 am

We present a direct measurement of the masses of subhalos hosting galaxies in massive, low-redshift galaxy clusters using weak gravitational lensing. We constrain the average subhalo mass as a function of stellar mass to probe the total-to-stellar mass relation of satellite galaxies and discuss our results in the context of the…

Gravity Group Seminar, Kimmy Wu (UC Berkeley) Adam Anderson (Fermilab, University of Chicago)
Wed, Apr 12, 2017, 2:30 pm2:30 pm

Speaker 1: Kimmy Wu, UC Berkeley

"CMB Polarization B-mode Delensing with SPTpol and Herschel"

Inflation generically predicts a background of primordial gravitational waves, which generate a primordial B-mode component in the polarization of the cosmic microwave background (CMB). The measurement of such B-mode signature will…

Gravity Group Seminar, Simon Foreman (CITA)
Fri, Apr 7, 2017, 12:00 pm12:00 pm

Cosmic shear as a probe of galaxy formation physics

The precision of current and future cosmological observations at Megaparsec scales demands a detailed understanding of the effects of baryonic processes on the clustering of matter at these scales. In this talk, I will explore how to use measurements of…

Gravity Group Seminar, Will Coulton (Princeton University) "Cosmology and astrophysics from the bispectrum"
Fri, Mar 31, 2017, 12:00 pm12:00 pm

Cosmology and astrophysics from the bispectrum

The three point function of the cosmic microwave background (CMB) is an ideal place to study CMB secondary sources as there is no noise bias and CMB secondaries are the dominant contribution. In this talk I will discuss my work measuring the bispectrum from…

Gravity Group Seminar, Jon Gudmundsson (NORDITA & Stockholm University, Sweden)
Fri, Mar 17, 2017, 12:00 pm12:00 pm

The planets in our solar system provide a valuable calibration source for experiments designed to probe the cosmic microwave background (CMB). 
In this talk, I will describe how the Planck satellite used Mars, Jupiter, Saturn, Uranus, and Neptune to characterize its spatial (beam) and spectral response functions. I will also discuss how…

Gravity Group Lunch Seminar, Ed Young | Justin Ripley, (Princeton University)
Fri, Mar 10, 2017, 12:00 pm12:00 pm

We will have two half-hour talks (in the order below) instead of the "usual" one-hour presentation.

SPEAKER:  Ed Young (Princeton University) "Deprojection: Application to the SPIDER data"
In this talk, I'll introduce the basics of deprojection, then discuss its implementation in the SPIDER analysis pipeline…