Imperial College London

Professor Andrew H Jaffe

Faculty of Natural SciencesDepartment of Physics

Professor of Astrophysics and Cosmology
 
 
 
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Contact

 

+44 (0)20 7594 7526a.jaffe Website

 
 
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Assistant

 

Miss Louise Hayward +44 (0)20 7594 7679

 
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Location

 

1018BBlackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

284 results found

Jaffe A, 1996, H 0 and Odds on Cosmology, The Astrophysical Journal, Vol: 471, Pages: 24-29, ISSN: 0004-637X

JOURNAL ARTICLE

Jaffe AH, Kaiser N, 1995, Likelihood Analysis of Large-Scale Flows, The Astrophysical Journal, Vol: 455, Pages: 26-26, ISSN: 0004-637X

JOURNAL ARTICLE

Jaffe AH, 1994, Quasilinear evolution of compensated cosmological perturbations: The nonlinear σ model, Physical Review D, Vol: 49, Pages: 3893-3909, ISSN: 0556-2821

JOURNAL ARTICLE

Jaffe AH, Stebbins A, Frieman JA, 1994, Minimal microwave anisotrophy from perturbations induced at late times, The Astrophysical Journal, Vol: 420, Pages: 9-9, ISSN: 0004-637X

JOURNAL ARTICLE

Frieman JA, Jaffe AH, 1992, Cosmological constraints on pseudo Nambu-Goldstone bosons, Physical Review D, Vol: 45, Pages: 2674-2684, ISSN: 0556-2821

JOURNAL ARTICLE

Prather M, Jaffe AH, 1990, Global impact of the Antarctic ozone hole: Chemical propagation, Journal of Geophysical Research, Vol: 95, Pages: 3473-3473, ISSN: 0148-0227

JOURNAL ARTICLE

Guenther DB, Jaffe A, Demarque P, 1989, The standard solar model - Composition, opacities, and seismology, The Astrophysical Journal, Vol: 345, Pages: 1022-1022, ISSN: 0004-637X

JOURNAL ARTICLE

Collaboration TEBEX, Aboobaker AM, Ade P, Araujo D, Aubin F, Baccigalupi C, Bao C, Chapman D, Didier J, Dobbs M, Geach C, Grainger W, Hanany S, Helson K, Hillbrand S, Hubmayr J, Jaffe A, Johnson B, Jones T, Klein J, Korotkov A, Lee A, Levinson L, Limon M, MacDermid K, Matsumura T, Miller AD, Milligan M, Raach K, Reichborn-Kjennerud B, Sagiv I, Savini G, Spencer L, Tucker C, Tucker GS, Westbrook B, Young K, Zilic Ket al., The EBEX Balloon Borne Experiment - Optics, Receiver, and Polarimetry

The E and B Experiment (EBEX) was a long-duration balloon-borne cosmicmicrowave background polarimeter that flew over Antarctica in 2013. We describethe experiment's optical system, receiver, and polarimetric approach, andreport on their in-flight performance. EBEX had three frequency bands centeredon 150, 250, and 410 GHz. To make efficient use of limited mass and space wedesigned a 115 cm$^{2}$sr high throughput optical system that had two ambienttemperature mirrors and four anti-reflection coated polyethylene lenses perfocal plane. All frequency bands shared the same optical train. Polarimetry wasachieved with a continuously rotating achromatic half-wave plate (AHWP) thatwas levitated with a superconducting magnetic bearing (SMB). Rotation stabilitywas 0.45 % over a period of 10 hours, and angular position accuracy was 0.01degrees. This is the first use of a SMB in astrophysics. The measuredmodulation efficiency was above 90 % for all bands. To our knowledge the 109 %fractional bandwidth of the AHWP was the broadest implemented to date. Thereceiver that contained one lens and the AHWP at a temperature of 4 K, thepolarizing grid and other lenses at 1 K, and the two focal planes at 0.25 Kperformed according to specifications giving focal plane temperature stabilitywith fluctuation power spectrum that had $1/f$ knee at 2 mHz. EBEX was thefirst balloon-borne instrument to implement technologies characteristic ofmodern CMB polarimeters including high throughput optical systems, and largearrays of transition edge sensor bolometric detectors with mutiplexed readouts.

JOURNAL ARTICLE

Didier J, Miller AD, Araujo D, Aubin F, Geach C, Johnson B, Korotkov A, Raach K, Westbrook B, Young K, Aboobaker AM, Ade P, Baccigalupi C, Bao C, Chapman D, Dobbs M, Grainger W, Hanany S, Helson K, Hillbrand S, Hubmayr J, Jaffe A, Jones T, Klein J, Lee A, Levinson L, Limon M, MacDermid K, Milligan M, Moncelsi L, Pascale E, Reichborn-Kjennerud B, Sagiv I, Tucker C, Tucker GS, Zilic Ket al., Intensity-Coupled-Polarization in Instruments with a Continuously Rotating Half-Wave Plate

We discuss a systematic effect associated with measuring the polarization ofthe Cosmic Microwave Background (CMB) with a continuously rotating Half-WavePlate (HWP) using data from the E and B Experiment (EBEX). EBEX was aballoon-borne telescope designed to measure the polarization of the CMB as wellas that from Galactic dust. We show that EBEX measured excess polarizationcoupled to intensity, and provide a model for the origin of this polarizationinvolving detector non-linearity in the presence of a continuously rotatingHWP. We provide a map-based method to remove the excess polarization, showing81 (92) \% of the excess polarization was removed on the CMB in the 150(250)~GHz datasets. Characterization and mitigation of this effect is importantfor future experiments aiming to measure the CMB B-modes on large angularscales using a HWP.

JOURNAL ARTICLE

Heavens A, Alsing J, Jaffe A, Hoffmann T, Kiessling A, Wandelt Bet al., Bayesian hierarchical modelling of weak lensing - the golden goal

To accomplish correct Bayesian inference from weak lensing shear datarequires a complete statistical description of the data. The natural frameworkto do this is a Bayesian Hierarchical Model, which divides the chain ofreasoning into component steps. Starting with a catalogue of shear estimates intomographic bins, we build a model that allows us to sample simultaneously fromthe the underlying tomographic shear fields and the relevant power spectra(E-mode, B-mode, and E-B, for auto- and cross-power spectra). The proceduredeals easily with masked data and intrinsic alignments. Using Gibbs samplingand messenger fields, we show with simulated data that the large (over67000-)dimensional parameter space can be efficiently sampled and the fulljoint posterior probability density function for the parameters can feasibly beobtained. The method correctly recovers the underlying shear fields and all ofthe power spectra, including at levels well below the shot noise.

WORKING PAPER

Hotinli SC, Frazer J, Jaffe AH, Meyers J, Price LC, Tarrant ERMet al., Predictions After Many-field Reheating

We study the sensitivity of cosmological observables to the reheating phasefollowing inflation driven by many scalar fields. We describe a method whichallows semi-analytic treatment of the impact of perturbative reheating oncosmological perturbations using the sudden decay approximation. Focusing on$\calN$-quadratic inflation, we show how the scalar spectral index andtensor-to-scalar ratio are affected by the rates at which the scalar fieldsdecay into radiation. We find that for certain choices of decay rates,reheating following multiple-field inflation can have a significant impact onthe prediction of cosmological observables.

JOURNAL ARTICLE

Sellentin E, Jaffe AH, Heavens AF, On the use of the Edgeworth expansion in cosmology I: how to foresee and evade its pitfalls

Non-linear gravitational collapse introduces non-Gaussian statistics into thematter fields of the late Universe. As the large-scale structure is the targetof current and future observational campaigns, one would ideally like to havethe full probability density function of these non-Gaussian fields. The onlyviable way we see to achieve this analytically, at least approximately and inthe near future, is via the Edgeworth expansion. We hence rederive thisexpansion for Fourier modes of non-Gaussian fields and then continue by puttingit into a wider statistical context than previously done. We show that in itsoriginal form, the Edgeworth expansion only works if the non-Gaussian signal isaveraged away. This is counterproductive, since we target theparameter-dependent non-Gaussianities as a signal of interest. We hence alterthe analysis at the decisive step and now provide a roadmap towards acontrolled and unadulterated analysis of non-Gaussianities in structureformation (with the Edgeworth expansion). Our central result is that, althoughthe Edgeworth expansion has pathological properties, these can be predicted andavoided in a careful manner. We also show that, despite the non-Gaussianitycoupling all modes, the Edgeworth series may be applied to any desired subsetof modes, since this is equivalent (to the level of the approximation) tomarginalising over the exlcuded modes. In this first paper of a series, werestrict ourselves to the sampling properties of the Edgeworth expansion,i.e.~how faithfully it reproduces the distribution of non-Gaussian data. Afollow-up paper will detail its Bayesian use, when parameters are to beinferred.

JOURNAL ARTICLE

Suzuki A, Arnold K, Edwards J, Engargiola G, Ghribi A, Holzapfel W, Lee AT, Meng XF, Myers MJ, O'Brient R, Quealy E, Rebeiz G, Richards P, Rosen D, Siritanasak Pet al., Multi-chroic dual-polarization bolometric detectors for studies of the Cosmic Microwave Background

We are developing multi-chroic antenna-coupled TES detectors for CMBpolarimetry. Multi-chroic detectors increase the mapping speed per focal planearea and provide greater discrimination of polarized galactic foregrounds withno increase in weight or cryogenic cost. In each pixel, a silicon lens-coupleddual polarized sinuous antenna collects light over a two-octave frequency band.The antenna couples the broadband millimeter wave signal into microstriptransmission lines, and on-chip filter banks split the broadband signal intoseveral frequency bands. Separate TES bolometers detect the power in eachfrequency band and linear polarization. We will describe the design andperformance of these devices and present optical data taken with prototypepixels. Our measurements show beams with percent level ellipticity, percentlevel cross-polarization leakage, and partitioned bands using banks of 2, 3,and 7 filters. We will also describe the development of broadbandanti-reflection coatings for the high dielectric constant lens. The broadbandanti-reflection coating has approximately 100 percent bandwidth and nodetectable loss at cryogenic temperature. Finally, we will describe an upgradefor the POLARBEAR CMB experiment and installation for the LITEBird CMBsatellite experiment both of which have focal planes with kilo-pixel of thesedetectors to achieve unprecedented mapping speed.

JOURNAL ARTICLE

Thompson MA, Serjeant S, Jenness T, Scott D, Ashdown M, Brunt C, Butner H, Chapin E, Chrysostomou AC, Clark JS, Clements D, Collett JL, Coppin K, Coulson IM, Dent WRF, Economou F, Evans A, Friberg P, Fuller GA, Gibb AG, Greaves J, Hatchell J, Holland WS, Hudson M, Ivison RJ, Jaffe A, Joncas G, Jones HRA, Knapen JH, Leech J, Mann R, Matthews HE, Moore TJT, Mortier A, Negrello M, Nutter D, Pestalozzi MP, Pope A, Richer J, Shipman R, Urquhart JS, Vaccari M, Waerbeke LV, Viti S, Weferling B, White GJ, Wouterloot J, Zhu Met al., The SCUBA-2 "All-Sky" Survey

The sub-millimetre wavelength regime is perhaps the most poorly explored overlarge areas of the sky, despite the considerable effort that has been expendedin making deep maps over small regions. As a consequence the properties of thesub-millimetre sky as a whole, and of rare bright objects in particular,remains largely unknown. Here we describe a forthcoming survey (the SCUBA-2``All-Sky'' Survey, or SASSy) designed to address this issue by making alarge-area map of approximately one-fifth of the sky visible from the JCMT(4800 square degrees) down to a 1 sigma noise level of 30 mJy/beam. This mapforms the pilot for a much larger survey, which will potentially map theremaining sky visible from the JCMT, with the region also visible to ALMA as apriority. SASSy has been awarded 500 hours for the 4800 square degree pilotphase and will commence after the commissioning of SCUBA-2, expected in early2008.

JOURNAL ARTICLE

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