550 research outputs found

    1405: EROS-II status report

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    Study of a Strategy for Parallax Microlensing Detection Towards the Magellanic Clouds

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    In this article, we have investigated the possibility to distinguish between different galactic models through the microlensing parallax studies. We show that a systematic search for parallax effects can be done using the currently running alert systems and complementary photometric telescopes, to distinguish between different lens distance distributions. We have considered two galactic dark compact objects distributions, with total optical depths corresponding to the EROS current upper limits. These models correspond to two extreme hypothesis on a three component galactic structure made of a thin disc, a thick disc, and a spherically symmetric halo. Our study shows that for sub-solar mass lenses, an exposure of 8×1078\times 10^7 star×\timesyr toward LMC should allow to distinguish between these two extreme models. In addition the self-lensing hypothesis (lensing by LMC objects) can efficiently be tested through the method proposed here.Comment: 10 pages, 12 eps figures. To be published in A&A (accepted version). Minor changes: - Discussion added on the differential velocity of the thick galactic disk with respect to the thin disk. - Quality and lisibility of figures improved. - Typo errors correcte

    Possible use of the dedicated MARLY one meter telescope for intensive supernovae studies

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    The EROS2 microlensing search will end at the end of 2002. Apart of this microlensing search, EROS has discovered ~70 supernovae during 8 periods partially dedicated to a SN search. In this document, we investigated a new way of using the EROS telescope (The MARLY) after this date, as a dedicated nearby supernovae photometer. The performance of a set-up with two cameras allowing to simultaneously perform BVRI and U photometry have been estimated. Each year, of order of 100 type Ia supernovae at z ~0.05 should be photometrically followed-up during 80 days with a precision of 2% in BVRI and ~3,5% in U.Comment: You can find the full resolution of this report at http://www.lal.in2p3.fr/presentation/bibliotheque/publications/ publicationsLAL01.html/LAL0171.p

    Agnostic cosmology in the CAMEL framework

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    Cosmological parameter estimation is traditionally performed in the Bayesian context. By adopting an "agnostic" statistical point of view, we show the interest of confronting the Bayesian results to a frequentist approach based on profile-likelihoods. To this purpose, we have developed the Cosmological Analysis with a Minuit Exploration of the Likelihood ("CAMEL") software. Written from scratch in pure C++, emphasis was put in building a clean and carefully-designed project where new data and/or cosmological computations can be easily included. CAMEL incorporates the latest cosmological likelihoods and gives access from the very same input file to several estimation methods: (i) A high quality Maximum Likelihood Estimate (a.k.a "best fit") using MINUIT ; (ii) profile likelihoods, (iii) a new implementation of an Adaptive Metropolis MCMC algorithm that relieves the burden of reconstructing the proposal distribution. We present here those various statistical techniques and roll out a full use-case that can then used as a tutorial. We revisit the Λ\LambdaCDM parameters determination with the latest Planck data and give results with both methodologies. Furthermore, by comparing the Bayesian and frequentist approaches, we discuss a "likelihood volume effect" that affects the optical reionization depth when analyzing the high multipoles part of the Planck data. The software, used in several Planck data analyzes, is available from http://camel.in2p3.fr. Using it does not require advanced C++ skills.Comment: Typeset in Authorea. Online version available at: https://www.authorea.com/users/90225/articles/104431/_show_articl

    Relieving tensions related to the lensing of CMB temperature power spectra

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    The angular power spectra of the cosmic microwave background (CMB) temperature anisotropies reconstructed from Planck data seem to present too much gravitational lensing distortion. This is quantified by the control parameter ALA_L that should be compatible with unity for a standard cosmology. With the Class Boltzmann solver and the profile-likelihood method, for this parameter we measure a 2.6σ\sigma shift from 1 using the Planck public likelihoods. We show that, owing to strong correlations with the reionization optical depth τ\tau and the primordial perturbation amplitude AsA_s, a 2σ\sim2\sigma tension on τ\tau also appears between the results obtained with the low (30\ell\leq 30) and high (30<250030<\ell\lesssim 2500) multipoles likelihoods. With Hillipop, another high-\ell likelihood built from Planck data, this difference is lowered to 1.3σ1.3\sigma. In this case, the ALA_L value is still in disagreement with unity by 2.2σ2.2\sigma, suggesting a non-trivial effect of the correlations between cosmological and nuisance parameters. To better constrain the nuisance foregrounds parameters, we include the very high \ell measurements of the Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) experiments and obtain AL=1.03±0.08A_L = 1.03 \pm 0.08. The Hillipop+ACT+SPT likelihood estimate of the optical depth is τ=0.052±0.035,\tau=0.052\pm{0.035,} which is now fully compatible with the low \ell likelihood determination. After showing the robustness of our results with various combinations, we investigate the reasons for this improvement that results from a better determination of the whole set of foregrounds parameters. We finally provide estimates of the Λ\LambdaCDM parameters with our combined CMB data likelihood.Comment: accepted by A&

    About the connection between the CC_{\ell} power spectrum of the Cosmic Microwave Background and the Γm\Gamma_{m} Fourier spectrum of rings on the sky

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    In this article we present and study a scaling law of the mΓmm\Gamma_m CMB Fourier spectrum on rings which allows us (i) to combine spectra corresponding to different colatitude angles (e.g. several detectors at the focal plane of a telescope), and (ii) to recover the ClC_l power spectrum once the Γm\Gamma_m coefficients have been measured. This recovery is performed numerically below the 1% level for colatitudes Θ>80\Theta> 80^\circ degrees. In addition, taking advantage of the smoothness of the ClC_l and of the Γm\Gamma_m, we provide analytical expressions which allow to recover one of the spectrum at the 1% level, the other one being known.Comment: 8 pages, 8 figure

    HFI L2 DPC destripping and mapmaking modules

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    PoS(CMB2006)049International audienceThe data processing of the data from the High Frequency Instrument (HFI) of the Planck mission will use several modules. Destriping is expected to play a central role in the mapmaking stage. This paper outlines two existing HFI l2 DPC destriping modules together with estimations of their performances. MOKAPIX is a temperature data destriping tool based on scanning redundancies on the sky. We have developped another modules, BOGOPIX , based on the same philosophy, to perform simultaneously destriping and relative intercalibration

    A new host for a new Rossomyrmex minuchae population

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    Social parasites usually rely on chemical cues (cuticular hydrocarbons) to successfully invade and coexist with their hosts. Most ants that are obligate social parasites (slave-makers) can parasitize several related host species with different levels of chemical similarity although there are few exceptions where there is only a single host species. An example of the latter is Rossomyrmex minuchae, which was known to be only associated with Proformica longiseta. However, a recent discovery of a new R. minuchae population revealed that it can parasitize P. nasuta, a species with a separate distribution to P. longiseta. Chemical analyses of cuticular hydrocarbons show local adaptation of the parasite to its host in this new population, being more similar to P. nasuta than to other R. minuchae populations. In addition, genetic analyses evidence differences from the other known populations, from which it split 1.21 Mya during glacial and interglacial periods of the Pleistocene and remained separated to the present day. This historical genetic isolation and the chemical differences found between parasite populations may evidence a speciation process and support the local host–parasite coevolutionM Silvestre and FM Azcárate received administrative and fnancial support from the Spanish Ministry of Economy and Competitiveness (Project CGL2014-53789-R). Sierra de Guadarrama National Park provided the permits for the sampling (ref 10/101642.9/16). This work was also partially funded by the University of Jaén through the “Plan Operativo de Apoyo a la Investigación 2021-2022

    Comparison of absolute gain photometric calibration between Planck/HFI and Herschel/SPIRE at 545 and 857 GHz

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    We compare the absolute gain photometric calibration of the Planck/HFI and Herschel/SPIRE instruments on diffuse emission. The absolute calibration of HFI and SPIRE each relies on planet flux measurements and comparison with theoretical far-infrared emission models of planetary atmospheres. We measure the photometric cross calibration between the instruments at two overlapping bands, 545 GHz / 500 μ\mum and 857 GHz / 350 μ\mum. The SPIRE maps used have been processed in the Herschel Interactive Processing Environment (Version 12) and the HFI data are from the 2015 Public Data Release 2. For our study we used 15 large fields observed with SPIRE, which cover a total of about 120 deg^2. We have selected these fields carefully to provide high signal-to-noise ratio, avoid residual systematics in the SPIRE maps, and span a wide range of surface brightness. The HFI maps are bandpass-corrected to match the emission observed by the SPIRE bandpasses. The SPIRE maps are convolved to match the HFI beam and put on a common pixel grid. We measure the cross-calibration relative gain between the instruments using two methods in each field, pixel-to-pixel correlation and angular power spectrum measurements. The SPIRE / HFI relative gains are 1.047 (±\pm 0.0069) and 1.003 (±\pm 0.0080) at 545 and 857 GHz, respectively, indicating very good agreement between the instruments. These relative gains deviate from unity by much less than the uncertainty of the absolute extended emission calibration, which is about 6.4% and 9.5% for HFI and SPIRE, respectively, but the deviations are comparable to the values 1.4% and 5.5% for HFI and SPIRE if the uncertainty from models of the common calibrator can be discounted. Of the 5.5% uncertainty for SPIRE, 4% arises from the uncertainty of the effective beam solid angle, which impacts the adopted SPIRE point source to extended source unit conversion factor (Abridged)Comment: 13 pages, 10 figures; Incorporates revisions in response to referee comments; cross calibration factors unchange

    Iterative destriping and photometric calibration for Planck-HFI, polarized, multi-detector map-making

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    We present an iterative scheme designed to recover calibrated I, Q, and U maps from Planck-HFI data using the orbital dipole due to the satellite motion with respect to the Solar System frame. It combines a map reconstruction, based on a destriping technique, juxtaposed with an absolute calibration algorithm. We evaluate systematic and statistical uncertainties incurred during both these steps with the help of realistic, Planck-like simulations containing CMB, foreground components and instrumental noise, and assess the accuracy of the sky map reconstruction by considering the maps of the residuals and their spectra. In particular, we discuss destriping residuals for polarization sensitive detectors similar to those of Planck-HFI under different noise hypotheses and show that these residuals are negligible (for intensity maps) or smaller than the white noise level (for Q and U Stokes maps), for l > 50. We also demonstrate that the combined level of residuals of this scheme remains comparable to those of the destriping-only case except at very low l where residuals from the calibration appear. For all the considered noise hypotheses, the relative calibration precision is on the order of a few 10e-4, with a systematic bias of the same order of magnitude.Comment: 18 pages, 21 figures. Match published versio
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