1,035 research outputs found
Could the next generation of cosmology experiments exclude supergravity?
Gravitinos are expected to be produced in any local supersymmetric model.
Using their abundance prediction as a function of the reheating energy scale,
it is argued that the next generation of Cosmic Microwave Background
experiments could exclude supergravity or strongly favor "thermal-like"
inflation models if B mode polarized radiation were detected. Galactic
cosmic--ray production by evaporating primordial black holes is also
investigated as a way of constraining the Hubble mass at the end of inflation.
Subsequent limits on the gravitino mass and on the related grand unification
parameters are derived.Comment: 8 pages, 5 figures, published version with minor changes, results
unchange
CMB Polarization Systematics Due to Beam Asymmetry: Impact on Inflationary Science
CMB polarization provides a unique window into cosmological inflation; the
amplitude of the B-mode polarization from last scattering is uniquely sensitive
to the energetics of inflation. However, numerous systematic effects arising
from optical imperfections can contaminate the observed B-mode power spectrum.
In particular, systematic effects due to the coupling of the underlying
temperature and polarization fields with elliptical or otherwise asymmetric
beams yield spurious systematic signals. This paper presents a non-perturbative
analytic calculation of some of these signals. We show that results previously
derived in real space can be generalized, formally, by including infinitely
many higher-order corrections to the leading order effects. These corrections
can be summed and represented as analytic functions when a fully Fourier-space
approach is adopted from the outset. The formalism and results presented in
this paper were created to determine the susceptibility of CMB polarization
probes of the primary gravitational wave signal but can be easily extended to
the analysis of gravitational lensing of the CMB.Comment: 14 pages, 11 figures, 6 tables. Minor corrections included to match
published versio
ARCHEOPS : Measurement of the CMB power spectrum on small and large angular scales and first detection of polarization of the submillimetre diffuse galactic dust emission
POKER: Estimating the power spectrum of diffuse emission with complex masks and at high angular resolution
We describe the implementation of an angular power spectrum estimator in the
flat sky approximation. POKER (P. Of k EstimatoR) is based on the MASTER
algorithm developped by Hivon and collaborators in the context of CMB
anisotropy. It works entirely in discrete space and can be applied to arbitrary
high angular resolution maps. It is therefore particularly suitable for current
and future infrared to sub-mm observations of diffuse emission, whether
Galactic or cosmological.Comment: Astronomy and Astrophysics, in pres
CMB Polarization Systematics Due to Beam Asymmetry: Impact on Inflationary Science
CMB polarization provides a unique window into cosmological inflation; the
amplitude of the B-mode polarization from last scattering is uniquely sensitive
to the energetics of inflation. However, numerous systematic effects arising
from optical imperfections can contaminate the observed B-mode power spectrum.
In particular, systematic effects due to the coupling of the underlying
temperature and polarization fields with elliptical or otherwise asymmetric
beams yield spurious systematic signals. This paper presents a non-perturbative
analytic calculation of some of these signals. We show that results previously
derived in real space can be generalized, formally, by including infinitely
many higher-order corrections to the leading order effects. These corrections
can be summed and represented as analytic functions when a fully Fourier-space
approach is adopted from the outset. The formalism and results presented in
this paper were created to determine the susceptibility of CMB polarization
probes of the primary gravitational wave signal but can be easily extended to
the analysis of gravitational lensing of the CMB.Comment: 14 pages, 11 figures, 6 tables. Minor corrections included to match
published versio
Submillimetre point sources from the Archeops experiment: Very Cold Clumps in the Galactic Plane
Archeops is a balloon-borne experiment, mainly designed to measure the Cosmic
Microwave Background (CMB) temperature anisotropies at high angular resolution
(~ 12 arcminutes). By-products of the mission are shallow sensitivity maps over
a large fraction of the sky (about 30 %) in the millimetre and submillimetre
range at 143, 217, 353 and 545 GHz. From these maps, we produce a catalog of
bright submillimetre point sources. We present in this paper the processing and
analysis of the Archeops point sources. Redundancy across detectors is the key
factor allowing to sort out glitches from genuine point sources in the 20
independent maps. We look at the properties of the most reliable point sources,
totalling 304. Fluxes range from 1 to 10,000 Jy (at the frequencies covering
143 to 545 GHz). All sources are either planets (2) or of galactic origin.
Longitude range is from 75 to 198 degrees. Some of the sources are associated
with well-known Lynds Nebulae and HII compact regions in the galactic plane. A
large fraction of the sources have an IRAS counterpart. Except for Jupiter,
Saturn, the Crab and Cas A, all sources show a dust-emission-like modified
blackbody emission spectrum. Temperatures cover a range from 7 to 27 K. For the
coldest sources (T<10 K), a steep nu^beta emissivity law is found with a
surprising beta ~ 3 to 4. An inverse relationship between T and beta is
observed. The number density of sources at 353 GHz with flux brighter than 100
Jy is of the order of 1 per degree of Galactic longitude. These sources will
provide a strong check for the calibration of the Planck HFI focal plane
geometry as a complement to planets. These very cold sources observed by
Archeops should be prime targets for mapping observations by the Akari and
Herschel space missions and ground--based observatories.Comment: Version matching the published article (English improved). Published
in Astron. Astrophys, 21 pages, 13 figures, 4 tables Full article (with
complete tables) can be retrieved at
http://www.archeops.org/Archeops_Publicatio
Bi-layer Kinetic Inductance Detectors for space observations between 80-120 GHz
We have developed Lumped Element Kinetic Inductance Detectors (LEKID)
sensitive in the frequency band from 80 to 120~GHz. In this work, we take
advantage of the so-called proximity effect to reduce the superconducting gap
of Aluminium, otherwise strongly suppressing the LEKID response for frequencies
smaller than 100~GHz. We have designed, produced and optically tested various
fully multiplexed arrays based on multi-layers combinations of Aluminium (Al)
and Titanium (Ti). Their sensitivities have been measured using a dedicated
closed-circle 100 mK dilution cryostat and a sky simulator allowing to
reproduce realistic observation conditions. The spectral response has been
characterised with a Martin-Puplett interferometer up to THz frequencies, and
with a resolution of 3~GHz. We demonstrate that Ti-Al LEKID can reach an
optical sensitivity of about ~ (best pixel), or
~ when averaged over the whole array. The optical
background was set to roughly 0.4~pW per pixel, typical for future space
observatories in this particular band. The performance is close to a
sensitivity of twice the CMB photon noise limit at 100~GHz which drove the
design of the Planck HFI instrument. This figure remains the baseline for the
next generation of millimetre-wave space satellites.Comment: 7 pages, 9 figures, submitted to A&
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