53 research outputs found
DustPedia: Multiwavelength photometry and imagery of 875 nearby galaxies in 42 ultraviolet-microwave bands
Aims. The DustPedia project is capitalising on the legacy of the Herschel Space Observatory, using cutting-edge modelling techniques to study dust in the 875 DustPedia galaxies – representing the vast majority of extended galaxies within 3000 km s-1 that were observed by Herschel. This work requires a database of multiwavelength imagery and photometry that greatly exceeds the scope (in terms of wavelength coverage and number of galaxies) of any previous local-Universe survey.
Methods. We constructed a database containing our own custom Herschel reductions, along with standardised archival observations from GALEX, SDSS, DSS, 2MASS, WISE, Spitzer, and Planck. Using these data, we performed consistent aperture-matched photometry, which we combined with external supplementary photometry from IRAS and Planck.
Results. We present our multiwavelength imagery and photometry across 42 UV-microwave bands for the 875 DustPedia galaxies. Our aperture-matched photometry, combined with the external supplementary photometry, represents a total of 21 857 photometric measurements. A typical DustPedia galaxy has multiwavelength photometry spanning 25 bands. We also present the Comprehensive & Adaptable Aperture Photometry Routine (CAAPR), the pipeline we developed to carry out our aperture-matched photometry. CAAPR is designed to produce consistent photometry for the enormous range of galaxy and observation types in our data. In particular, CAAPR is able to determine robust cross-compatible uncertainties, thanks to a novel method for reliably extrapolating the aperture noise for observations that cover a very limited amount of background. Our rich database of imagery and photometry is being made available to the community
Planck 2013 results X. Energetic particle effects: characterization, removal, and simulation
This paper presents the detection, interpretation and removal of the signal
resulting from interactions of high energy particles with the Planck High
Frequency Instrument (HFI). These interactions fall into two categories,
heating the 0.1 K bolometer plate and glitches in each detector time stream.
Glitch shapes are not simple single pole exponential decays and fall into a
three families. The glitch shape for each family has been characterized
empirically in flight data and removed from the detector time streams. The
spectrum of the count rate/unit energy is computed for each family and a
correspondence to where on the detector the particle hit is made. Most of the
detected glitches are from galactic protons incident on the Si die frame
supporting the micromachined bolometric detectors. At HFI, the particle flux is
~ 5 per square cm and per second and is dominated by protons incident on the
spacecraft with an energy >39 MeV, leading to a rate of typically one event per
second and per detector. Different categories of glitches have different
signature in timestreams. Two of the glitch types have a low amplitude
component that decays over nearly 1 second. This component produces an excess
noise if not properly removed from the time ordered data. We have used a glitch
detection and subtraction method based on the joint fit of population
templates. The application of this novel glitch removal method removes excess
noise from glitches. Using realistic simulations, we find this method does not
introduce signal bias.Comment: 23 pages; v2: author list complete
Planck 2013 results. III. LFI systematic uncertainties
We present the current estimate of instrumental and systematic effect
uncertainties for the Planck-Low Frequency Instrument relevant to the first
release of the Planck cosmological results. We give an overview of the main
effects and of the tools and methods applied to assess residuals in maps and
power spectra. We also present an overall budget of known systematic effect
uncertainties, which are dominated sidelobe straylight pick-up and imperfect
calibration. However, even these two effects are at least two orders of
magnitude weaker than the cosmic microwave background (CMB) fluctuations as
measured in terms of the angular temperature power spectrum. A residual signal
above the noise level is present in the multipole range , most notably
at 30 GHz, and is likely caused by residual Galactic straylight contamination.
Current analysis aims to further reduce the level of spurious signals in the
data and to improve the systematic effects modelling, in particular with
respect to straylight and calibration uncertainties.Comment: Accepted for publication by A&
Planck 2013 results. VI. High Frequency Instrument data processing
We describe the processing of the 531 billion raw data samples from the High Frequency Instrument (hereafter HFI), which we performed to produce six temperature maps from the first 473 days of Planck-HFI survey data. These maps provide an accurate rendition of the sky emission at 100, 143, 217, 353, 545, and 857 GHz with an angular resolution ranging from 9.7 to 4.6 arcmin. The detector noise per (effective) beam solid angle is respectively, 10, 6, 12 and 39 microKelvin in HFI four lowest frequency channel (100--353 GHz) and 13 and 14 kJy/sr for the 545 and 857 GHz channels. Using the 143 GHz channel as a reference, these two high frequency channels are intercalibrated within 5% and the 353 GHz relative calibration is at the percent level. The 100 and 217 GHz channels, which together with the 143 GHz channel determine the high-multipole part of the CMB power spectrum (50 < l <2500), are intercalibrated at better than 0.2 %
Planck 2015 results. VI. LFI mapmaking
This paper describes the mapmaking procedure applied to Planck Low Frequency Instrument (LFI) data. The mapmaking step takes as input the calibrated timelines and pointing information. The main products are sky maps of I, Q, and U Stokes components. For the first time, we present polarization maps at LFI frequencies. The mapmaking algorithm is based on a destriping technique, which is enhanced with a noise prior. The Galactic region is masked to reduce errors arising from bandpass mismatch and high signal gradients. We apply horn-uniform radiometer weights to reduce the effects of beam-shape mismatch. The algorithm is the same as used for the 2013 release, apart from small changes in parameter settings. We validate the procedure through simulations. Special emphasis is put on the control of systematics, which is particularly important for accurate polarization analysis. We also produce low-resolution versions of the maps and corresponding noise covariance matrices. These serve as input in later analysis steps and parameter estimation. The noise covariance matrices are validated through noise Monte Carlo simulations. The residual noise in the map products is characterized through analysis of half-ring maps, noise covariance matrices, and simulations
Planck 2015 results. V. LFI calibration
We present a description of the pipeline used to calibrate the Planck Low Frequency Instrument (LFI) timelines into thermodynamic temperatures for the Planck 2015 data release, covering four years of uninterrupted operations. As in the 2013 data release, our calibrator is provided by the spin-synchronous modulation of the cosmic microwave background dipole, but we now use the orbital component, rather than adopting the Wilkinson Microwave Anisotropy Probe (WMAP) solar dipole. This allows our 2015 LFI analysis to provide an independent Solar dipole estimate, which is in excellent agreement with that of HFI and within 1σ (0.3% in amplitude) of the WMAP value. This 0.3% shift in the peak-to-peak dipole temperature from WMAP and a general overhaul of the iterative calibration code increases the overall level of the LFI maps by 0.45% (30 GHz), 0.64% (44 GHz), and 0.82% (70 GHz) in temperature with respect to the 2013 Planck data release, thus reducing the discrepancy with the power spectrum measured by WMAP. We estimate that the LFI calibration uncertainty is now at the level of 0.20% for the 70 GHz map, 0.26% for the 44 GHz map, and 0.35% for the 30 GHz map. We provide a detailed description of the impact of all the changes implemented in the calibration since the previous data release
Planck 2013 results. IX. HFI spectral response
The Planck High Frequency Instrument (HFI) spectral response was determined
through a series of ground based tests conducted with the HFI focal plane in a
cryogenic environment prior to launch. The main goal of the spectral
transmission tests was to measure the relative spectral response (including
out-of-band signal rejection) of all HFI detectors. This was determined by
measuring the output of a continuously scanned Fourier transform spectrometer
coupled with all HFI detectors. As there is no on-board spectrometer within
HFI, the ground-based spectral response experiments provide the definitive data
set for the relative spectral calibration of the HFI. The spectral response of
the HFI is used in Planck data analysis and component separation, this includes
extraction of CO emission observed within Planck bands, dust emission,
Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI
spectral response data have also been used to provide unit conversion and
colour correction analysis tools. Verifications of the HFI spectral response
data are provided through comparisons with photometric HFI flight data. This
validation includes use of HFI zodiacal emission observations to demonstrate
out-of-band spectral signal rejection better than 10^8. The accuracy of the HFI
relative spectral response data is verified through comparison with
complementary flight-data based unit conversion coefficients and colour
correction coefficients. These coefficients include those based upon HFI
observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is
observed between the ground-based spectral characterization of HFI and
corresponding in-flight observations, within the quoted uncertainty of each;
explanations are provided for any discrepancies.Comment: 27 pages, 28 figures, one of the papers associated with the 2013
Planck data releas
Planck 2015 results. XXVII. The second Planck catalogue of Sunyaev-Zeldovich sources
We present the all-sky Planck catalogue of Sunyaev-Zeldovich (SZ) sources detected from the 29 month full-mission data. The catalogue (PSZ2) is the largest SZ-selected sample of galaxy clusters yet produced and the deepest systematic all-sky surveyof galaxy clusters. It contains 1653 detections, of which 1203 are confirmed clusters with identified counterparts in external data sets, and is the first SZ-selected cluster survey containing >103 confirmed clusters. We present a detailed analysis of the survey selection function in terms of its completeness and statistical reliability, placing a lower limit of 83% on the purity. Using simulations, we find that the estimates of the SZ strength parameter Y5R500are robust to pressure-profile variation and beam systematics, but accurate conversion to Y500 requires the use of prior information on the cluster extent. We describe the multi-wavelength search for counterparts in ancillary data, which makes use of radio, microwave, infra-red, optical, and X-ray data sets, and which places emphasis on the robustness of the counterpart match. We discuss the physical properties of the new sample and identify a population of low-redshift X-ray under-luminous clusters revealed by SZ selection. These objects appear in optical and SZ surveys with consistent properties for their mass, but are almost absent from ROSAT X-ray selected samples
Planck 2013 results. XX. Cosmology from Sunyaev-Zeldovich cluster counts
We present constraints on cosmological parameters using number counts as a
function of redshift for a sub-sample of 189 galaxy clusters from the Planck SZ
(PSZ) catalogue. The PSZ is selected through the signature of the
Sunyaev--Zeldovich (SZ) effect, and the sub-sample used here has a
signal-to-noise threshold of seven, with each object confirmed as a cluster and
all but one with a redshift estimate. We discuss the completeness of the sample
and our construction of a likelihood analysis. Using a relation between mass
and SZ signal calibrated to X-ray measurements, we derive constraints
on the power spectrum amplitude and matter density parameter
in a flat CDM model. We test the robustness of
our estimates and find that possible biases in the -- relation and the
halo mass function are larger than the statistical uncertainties from the
cluster sample. Assuming the X-ray determined mass to be biased low relative to
the true mass by between zero and 30%, motivated by comparison of the observed
mass scaling relations to those from a set of numerical simulations, we find
that , , and
. The value of
is degenerate with the mass bias; if the latter is fixed to a value
of 20% we find and a
tighter one-dimensional range . We find that the larger
values of and preferred by Planck's
measurements of the primary CMB anisotropies can be accommodated by a mass bias
of about 40%. Alternatively, consistency with the primary CMB constraints can
be achieved by inclusion of processes that suppress power on small scales
relative to the CDM model, such as a component of massive neutrinos
(abridged).Comment: 20 pages, accepted for publication by A&
Planck 2015 results. XX. Constraints on inflation
We present the implications for cosmic inflation of the Planck measurements of the cosmic microwave background (CMB) anisotropies in both temperature and polarization based on the full Planck survey. The Planck full mission temperature data and a first release of polarization data on large angular scales measure the spectral index of curvature perturbations to be n s = 0.968 ± 0.006 and tightly constrain its scale dependence to dn s /dlnk = −0.003 ± 0.007 when combined with the Planck lensing likelihood. When the high-ℓ polarization data is included, the results are consistent and uncertainties are reduced. The upper bound on the tensor-to-scalar ratio is r 0.002 <0.11 (95% CL), consistent with the B-mode polarization constraint r<0.12 (95% CL) obtained from a joint BICEP2/Keck Array and Planck analysis. These results imply that V(ϕ)∝ϕ 2 and natural inflation are now disfavoured compared to models predicting a smaller tensor-to-scalar ratio, such as R 2 inflation. Three independent methods reconstructing the primordial power spectrum are investigated. The Planck data are consistent with adiabatic primordial perturbations. We investigate inflationary models producing an anisotropic modulation of the primordial curvature power spectrum as well as generalized models of inflation not governed by a scalar field with a canonical kinetic term. The 2015 results are consistent with the 2013 analysis based on the nominal mission data
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