557 research outputs found
Using BBN in cosmological parameter extraction from CMB: a forecast for Planck
Data from future high-precision Cosmic Microwave Background (CMB)
measurements will be sensitive to the primordial Helium abundance . At the
same time, this parameter can be predicted from Big Bang Nucleosynthesis (BBN)
as a function of the baryon and radiation densities, as well as a neutrino
chemical potential. We suggest to use this information to impose a
self-consistent BBN prior on and determine its impact on parameter
inference from simulated Planck data. We find that this approach can
significantly improve bounds on cosmological parameters compared to an analysis
which treats as a free parameter, if the neutrino chemical potential is
taken to vanish. We demonstrate that fixing the Helium fraction to an arbitrary
value can seriously bias parameter estimates. Under the assumption of
degenerate BBN (i.e., letting the neutrino chemical potential vary), the
BBN prior's constraining power is somewhat weakened, but nevertheless allows us
to constrain with an accuracy that rivals bounds inferred from present
data on light element abundances.Comment: 14 pages, 4 figures; v2: minor changes, matches published versio
Axions and saxions from the primordial supersymmetric plasma and extra radiation signatures
We calculate the rate for thermal production of axions and saxions via
scattering of quarks, gluons, squarks, and gluinos in the primordial
supersymmetric plasma. Systematic field theoretical methods such as hard
thermal loop resummation are applied to obtain a finite result in a
gauge-invariant way that is consistent to leading order in the strong gauge
coupling. We calculate the thermally produced yield and the decoupling
temperature for both axions and saxions. For the generic case in which saxion
decays into axions are possible, the emitted axions can constitute extra
radiation already prior to big bang nucleosynthesis and well thereafter. We
update associated limits imposed by recent studies of the primordial helium-4
abundance and by precision cosmology of the cosmic microwave background and
large scale structure. We show that the trend towards extra radiation seen in
those studies can be explained by late decays of thermal saxions into axions
and that upcoming Planck results will probe supersymmetric axion models with
unprecedented sensitivity.Comment: 16 pages, 7 figures; v2: references added, minor clarifying
additions, matches published versio
Integrating remote sensing, geographic information system and fuzzy logic: an index to evaluate the natural potential for livestock ranching in the Pantanal.
Abstract: In this study, an index natural potential for livestock ranching (NPLR) at ranch level in the Pantanal wetland was obtained using landscape indicators combined with fuzzy inference process. Four landscape indicators related with livestock production were selected by an expertise group. The application of this approach was illustrated through a pilot ranch located in the NhecolĂąndia sub-region, Pantanal, MS. Remote Sensing (RS) and Geographic Information System (GIS) technologies were used to map the vegetation types and aquatic habitats (landscapes types) in this ranch. Landscape type?s composition metrics were obtained using the ArcGis 9 and were used to estimate the four indicators selected by expertise: forest cover proportion (FC); landscape productive value (LPV); diversity of aquatic habitats (DAH) and flooding degree (FD). Fuzzy inference process involving definitions of membership functions, fuzzy set operations and inference rule were run and validated with the participation of core stakeholders. Different scenarios also were simulated in batch and validated with the participation of stakeholders. Both procedures were performed by Webfuzzy software. The NPLR index value found in the pilot ranch was as expected by both expertise and stakeholders. Fuzzy logic combined with landscape metric seems to be suitable for the definition of the natural potential of ranches to produce livestock in the Pantanal.Geopantanal 2012
High resolution SZ observations at the IRAM 30-m telescope with NIKA
High resolution observations of the thermal Sunyaev-Zel'dovich (tSZ) effect
are necessary to allow the use of clusters of galaxies as a probe for large
scale structures at high redshifts. With its high resolution and dual-band
capability at millimeter wavelengths, the NIKA camera can play a significant
role in this context. NIKA is based on newly developed Kinetic Inductance
Detectors (KIDs) and operates at the IRAM 30m telescope, Pico Veleta, Spain. In
this paper, we give the status of the NIKA camera, focussing on the KID
technology. We then present observations of three galaxy clusters: RX
J1347.5-1145 as a demonstrator of the NIKA capabilities and the recent
observations of CL J1226.9+3332 (z = 0.89) and MACS J0717.5+3745 (z = 0.55). We
also discuss prospects for the final NIKA2 camera, which will have a 6.5
arcminute field of view with about 5000 detectors in two bands at 150 and 260
GHz
Detection of the tSZ effect with the NIKA camera
We present the first detection of the thermal Sunyaev-Zel'dovich (tSZ) effect
from a cluster of galaxies performed with a KIDs (Kinetic Inductance Detectors)
based instrument. The tSZ effect is a distortion of the black body CMB (Cosmic
Microwave Background) spectrum produced by the inverse Compton interaction of
CMB photons with the hot electrons of the ionized intra-cluster medium. The
massive, intermediate redshift cluster RX J1347.5-1145 has been observed using
NIKA (New IRAM KIDs arrays), a dual-band (140 and 240 GHz) mm-wave imaging
camera, which exploits two arrays of hundreds of KIDs: the resonant frequencies
of the superconducting resonators are shifted by mm-wave photons absorption.
This tSZ cluster observation demonstrates the potential of the next generation
NIKA2 instrument, being developed for the 30m telescope of IRAM, at Pico Veleta
(Spain). NIKA2 will have 1000 detectors at 140GHz and 2x2000 detectors at
240GHz, providing in that band also a measurement of the linear polarization.
NIKA2 will be commissioned in 2015.Comment: SF2A Proceedings 201
Non-parametric deprojection of NIKA SZ observations: Pressure distribution in the Planck-discovered cluster PSZ1 G045.85+57.71
The determination of the thermodynamic properties of clusters of galaxies at
intermediate and high redshift can bring new insights into the formation of
large-scale structures. It is essential for a robust calibration of the
mass-observable scaling relations and their scatter, which are key ingredients
for precise cosmology using cluster statistics. Here we illustrate an
application of high resolution arcsec) thermal Sunyaev-Zel'dovich (tSZ)
observations by probing the intracluster medium (ICM) of the \planck-discovered
galaxy cluster \psz\ at redshift , using tSZ data obtained with the
NIKA camera, which is a dual-band (150 and 260~GHz) instrument operated at the
IRAM 30-meter telescope. We deproject jointly NIKA and \planck\ data to extract
the electronic pressure distribution from the cluster core () to its outskirts () non-parametrically for the
first time at intermediate redshift. The constraints on the resulting pressure
profile allow us to reduce the relative uncertainty on the integrated Compton
parameter by a factor of two compared to the \planck\ value. Combining the tSZ
data and the deprojected electronic density profile from \xmm\ allows us to
undertake a hydrostatic mass analysis, for which we study the impact of a
spherical model assumption on the total mass estimate. We also investigate the
radial temperature and entropy distributions. These data indicate that \psz\ is
a massive ( M) cool-core cluster.
This work is part of a pilot study aiming at optimizing the treatment of the
NIKA2 tSZ large program dedicated to the follow-up of SZ-discovered clusters at
intermediate and high redshifts. (abridged)Comment: 16 pages, 10 figure
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