We present the Planck Sky Model (PSM), a parametric model for generating all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and ...polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H ii regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modelling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared background. The PSM enables the production of random realisations of the sky emission, constrained to match observational data within their uncertainties. It is implemented in a software package that is regularly updated with incoming information from observations. The model is expected to serve as a useful tool for optimising planned microwave and sub-millimetre surveys and testing data processing and analysis pipelines. It is, in particular, used to develop and validate data analysis pipelines within the Planck collaboration. A version of the software that can be used for simulating the observations for a variety of experiments is made available on a dedicated website.
Inflation is the leading theory of the first instant of the universe. Inflation, which postulates that the universe underwent a period of rapid expansion an instant after its birth, provides ...convincing explanation for cosmological observations. Recent advancements in detector technology have opened opportunities to explore primordial gravitational waves generated by the inflation through “B-mode” (divergent-free) polarization pattern embedded in the cosmic microwave background anisotropies. If detected, these signals would provide strong evidence for inflation, point to the correct model for inflation, and open a window to physics at ultra-high energies. LiteBIRD is a satellite mission with a goal of detecting degree-and-larger-angular-scale B-mode polarization. LiteBIRD will observe at the second Lagrange point with a 400 mm diameter telescope and 2622 detectors. It will survey the entire sky with 15 frequency bands from 40 to 400 GHz to measure and subtract foregrounds. The US LiteBIRD team is proposing to deliver sub-Kelvin instruments that include detectors and readout electronics. A lenslet-coupled sinuous antenna array will cover low-frequency bands (40–235 GHz) with four frequency arrangements of trichroic pixels. An orthomode-transducer-coupled corrugated horn array will cover high-frequency bands (280–402 GHz) with three types of single frequency detectors. The detectors will be made with transition edge sensor (TES) bolometers cooled to a 100 milli-Kelvin base temperature by an adiabatic demagnetization refrigerator. The TES bolometers will be read out using digital frequency multiplexing with Superconducting QUantum Interference Device (SQUID) amplifiers. Up to 78 bolometers will be multiplexed with a single SQUID amplifier. We report on the sub-Kelvin instrument design and ongoing developments for the LiteBIRD mission.
Planck intermediate results Aghanim, N; Ashdown, M; Aumont, J ...
Astronomy and astrophysics (Berlin),
12/2016, Letnik:
596
Journal Article
Recenzirano
Odprti dostop
Parity-violating extensions of the standard electromagnetic theory cause in vacuo rotation of the plane of polarization of propagating photons. This effect, also known as cosmic birefringence, has an ...impact on the cosmic microwave background (CMB) anisotropy angular power spectra, producing non-vanishing T-B and E-B correlations that are otherwise null when parity is a symmetry. Here we present new constraints on an isotropic rotation, parametrized by the angle alpha, derived from Planck 2015 CMB polarization data. To increase the robustness of our analyses, we employ two complementary approaches, in harmonic space and in map space, the latter based on a peak stacking technique. The two approaches provide estimates for alpha that are in agreement within statistical uncertainties and are very stable against several consistency tests.Considering the T-B and E-B information jointly, we find alpha=0degrees.31 + or - 0degrees.05 (stat.) + or - 0degrees.28 (syst.) from alpha = 0degrees.35 + or - 0degrees.05 (stat.) + or - 0degrees.28 (syst.) from the stacking approach. These constraints are compatible with no parity violation and are dominated by the systematic uncertainty in the orientation of Planck's polarization-sensitive bolometers.
Planck intermediate results Ade, P A R; Aghanim, N; Arnaud, M ...
Astronomy and astrophysics (Berlin),
02/2013, Letnik:
550
Journal Article
Recenzirano
Odprti dostop
Taking advantage of the all-sky coverage and broad frequency range of the Planck satellite, we study the Sunyaev-Zeldovich (SZ) and pressure profiles of 62 nearby massive clusters detected at high ...significance in the 14-month nominal survey. Careful reconstruction of the SZ signal indicates that most clusters are individually detected at least out to R sub(500). By stacking the radial profiles, we have statistically detected the radial SZ signal out to 3 R sub(500), i.e., at a density contrast of about 50-100, though the dispersion about the mean profile dominates the statistical errors across the whole radial range. Our measurement is fully consistent with previous Planck results on integrated SZ fluxes, further strengthening the agreement between SZ and X-ray measurements inside R sub(500). Correcting for the effects of the Planck beam, we have calculated the corresponding pressure profiles. This new constraint from SZ measurements is consistent with the X-ray constraints from XMM-Newton in the region in which the profiles overlap (i.e., 0.1-1 R sub(500)), and is in fairly good agreement with theoretical predictions within the expected dispersion. At larger radii the average pressure profile is slightly flatter than most predictions from numerical simulations. Combining the SZ and X-ray observed profiles into a joint fit to a generalised pressure profile gives best-fit parameters P sub(0), c sub(500), gamma , alpha , beta = 6.41, 1.81, 0.31, 1.33, 4.13. Using a reasonable hypothesis for the gas temperature in the cluster outskirts we reconstruct from our stacked pressure profile the gas mass fraction profile out to 3 R sub(500). Within the temperature driven uncertainties, our Planck constraints are compatible with the cosmic baryon fraction and expected gas fraction in halos.
Planck intermediate results Ade, P A R; Aghanim, N; Arnaud, M ...
Astronomy and astrophysics (Berlin),
08/2015, Letnik:
580
Journal Article
Recenzirano
Odprti dostop
Any variation in the fundamental physical constants, more particularly in the fine structure constant, alpha, or in the mass of the electron, m sub(e), affects the recombination history of the ...Universe and cause an imprint on the cosmic microwave background angular power spectra. We show that the Planck data allow one to improve the constraint on the time variation of the fine structure constant at redshift z ~ 10 super(3) by about a factor of 5 compared to WMAP data, as well as to break the degeneracy with the Hubble constant, H sub(0). In addition to alpha, we can set a constraint on the variation in the mass of the electron, m sub(e), and in the simultaneous variation of the two constants. We examine in detail the degeneracies between fundamental constants and the cosmological parameters, in order to compare the limits obtained from Planck and WMAP and to determine the constraining power gained by including other cosmological probes. We conclude that independent time variations of the fine structure constant and of the mass of the electron are constrained by Planck to Deltaalpha/alpha = (3.6 + or - 3.7) x 10 super(-3) and Deltam sub(e)/m sub(e) = (4 + or - 11) x 10 super(-3) at the 68% confidence level. We also investigate the possibility of a spatial variation of the fine structure constant. The relative amplitude of a dipolar spatial variation in a (corresponding to a gradient across our Hubble volume) is constrained to be deltaalpha/alpha = (-2.4 + or - 3.7) x 10 super(-2).
Planck intermediate results Akrami, Y.; Ashdown, M.; Aumont, J. ...
Astronomy and astrophysics (Berlin),
12/2020, Letnik:
644
Journal Article
Recenzirano
Odprti dostop
The largest temperature anisotropy in the cosmic microwave background (CMB) is the dipole, which has been measured with increasing accuracy for more than three decades, particularly with the
Planck
...satellite. The simplest interpretation of the dipole is that it is due to our motion with respect to the rest frame of the CMB. Since current CMB experiments infer temperature anisotropies from angular intensity variations, the dipole modulates the temperature anisotropies with the same frequency dependence as the thermal Sunyaev-Zeldovich (tSZ) effect. We present the first, and significant, detection of this signal in the tSZ maps and find that it is consistent with direct measurements of the CMB dipole, as expected. The signal contributes power in the tSZ maps, which is modulated in a quadrupolar pattern, and we estimate its contribution to the tSZ bispectrum, noting that it contributes negligible noise to the bispectrum at relevant scales.
Context. CMB experiments aiming at a precise measurement of the CMB polarization, such as the Planck satellite, need a strong polarized absolute calibrator on the sky to accurately set the detectors ...polarization angle and the cross-polarization leakage. As the most intense polarized source in the microwave sky at angular scales of few arcminutes, the Crab nebula will be used for this purpose. Aims. Our goal was to measure the Crab nebula polarization characteristics at 90 GHz with unprecedented precision. Methods. The observations were carried out with the IRAM 30 m telescope employing the correlation polarimeter XPOL and using two orthogonally polarized receivers. Results. We processed the Stokes I, Q, and U maps from our observations in order to compute the polarization angle and linear polarization fraction. The first is almost constant in the region of maximum emission in polarization with a mean value of αSky = 152.1±0.3° in equatorial coordinates, and the second is found to reach a maximum of Π = 30% for the most polarized pixels. We find that a CMB experiment having a 5 arcmin circular beam will see a mean polarization angle of αSky = 149.9±0.2° and a mean polarization fraction of Π = 8.8±0.2%.
Planck intermediate results Ade, P A R; Aghanim, N; Arnaud, M ...
Astronomy and astrophysics (Berlin),
09/2013, Letnik:
557
Journal Article
Recenzirano
Odprti dostop
We present the scaling relation between Sunyaev-Zeldovich (SZ) signal and stellar mass for almost 260,000 locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey (SDSS). These ...are predominantly the central galaxies of their dark matter halos. We calibrate the stellar-to-halo mass conversion using realistic mock catalogues based on the Millennium Simulation. Applying a multi-frequency matched filter to the Planck data for each LBG, and averaging the results in bins of stellar mass, we measure the mean SZ signal down to M* ~ 2 x 10 super(11) M+ in circle, with a clear indication of signal at even lower stellar mass. We derive the scaling relation between SZ signal and halo mass by assigning halo properties from our mock catalogues to the real LBGs and simulating the Planck observation process. This relation shows no evidence for deviation from a power law over a halo mass range extending from rich clusters down to M sub(500) ~ 2 x 10 super(13) M+ in circle, and there is a clear indication of signal down to M sub(500) ~ 4 x 10 super(12) M+ in circle. Planck's SZ detections in such low-mass halos imply that about a quarter of all baryons have now been seen in the form of hot halo gas, and that this gas must be less concentrated than the dark matter in such halos in order to remain consistent with X-ray observations. At the high-mass end, the measured SZ signal is 20 % lower than found from observations of X-ray clusters, a difference consistent with the magnitude of Malmquist bias effects that were previously estimated for the X-ray sample.
Planck intermediate results Ade, P A R; Aghanim, N; Arnaud, M ...
Astronomy and astrophysics (Berlin),
06/2013, Letnik:
554
Journal Article
Recenzirano
Odprti dostop
Using precise full-sky observations from Planck, and applying several methods of component separation, we identify and characterise the emission from the Galactic "haze" at microwave wavelengths. The ...haze is a distinct component of diffuse Galactic emission, roughly centered on the Galactic centre, and extends to b ~ 35?50degrees in Galactic latitude and I / I ~ 15?20degrees in longitude. By combining the Planck data with observations from the Wilkinson Microwave Anisotropy Probe, we were able to determine the spectrum of this emission to high accuracy, unhindered by the strong systematic biases present in previous analyses. The derived spectrum is consistent with power-law emission with a spectral index of ?2.56 + or - 0.05, thus excluding free-free emission as the source and instead favouring hard-spectrum synchrotron radiation from an electron population with a spectrum (number density per energy) dN/dE proportional, variant E- super(2.1). At Galactic latitudes b < 30degrees, the microwave haze morphology is consistent with that of the Fermi gamma-ray "haze" or "bubbles", while at b ~ ?50degrees we have identified an edge in the microwave haze that is spatially coincident with the edge in the gamma-ray bubbles. Taken together, this indicates that we have a multi-wavelength view of a distinct component of our Galaxy. Given both the very hard spectrum and the extended nature of the emission, it is highly unlikely that the haze electrons result from supernova shocks in the Galactic disk. Instead, a new astrophysical mechanism for cosmic-ray acceleration in the inner Galaxy is implied.
Aims. Archeops is a balloon-borne experiment, mainly designed to measure the Cosmic Microwave Background (CMB) temperature anisotropies at high angular resolution (~12 arcmin). 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. Methods. We present in this paper the processing and analysis of the Archeops point sources. Redundancy across detectors is the key factor allowing us to distinguish glitches from genuine point sources in the 20 independent maps. Results. 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. The longitude range is from 75 to 198 degrees. Some of the sources are associated with the 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 β ~ 3 to 4. An inverse relationship between T and β 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.
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