Abstract The Tenerife Microwave Spectrometer (TMS) is a ground-based radio-spectrometer that will take absolute measurements of the sky between 10–20 GHz. To ensure the sensitivity and immunity to ...systematic errors of these measurements, TMS includes an internal calibration system optimised for the TMS band, and cooled down to 4 K. It consists of an Aluminium core, composed of a baseplate and a bed of pyramidal elements coated with an absorber material and a metallic shield. The absorber coating is made of a commercial resin ECCOSORB CR/MF 117. To achieve the high stability (± 1 mK/h), temperature homogeneity (thermal gradients Δ T ≤ 25 mK), and emissivity ( e ≥ 0.999) requirements of the reference unit, careful consideration has been given to the RF and thermal properties of the materials, as well as their geometry. In summary, this paper presents a comprehensive account of the design, characterisation, and test results of the TMS reference system.
We study the thermal (tSZ) and kinetic Sunyaev–Zel'dovich (kSZ) effect associated with superclusters of galaxies using the MareNostrum (MNU) universe smoothed particle hydrodynamics (SPH) simulation. ...In particular, we consider superclusters with characteristics (total mass, overdensity and number density of cluster members) similar to those of the Corona Borealis Supercluster (CrB-SC). This paper has been motivated by the detection at 33 GHz of a strong temperature decrement in the cosmic microwave background towards the core of this supercluster (Génova-Santos et al.). Multifrequency observations with Very Small Array (VSA) and Millimetre & Infrared Testa Grigia Observatory (MITO) suggest the existence of a tSZ effect component in the spectrum of this cold spot, with a Comptonization parameter value of y= 7.8+4.4−5.3× 10−6 (Battistelli et al.), which would account for roughly 25 per cent of the total observed decrement. From the SPH simulation, we identify nine (50 h−1 Mpc)3 regions containing superclusters similar to CrB-SC, obtain the associated SZ maps and calculate the probability of finding such SZ signals arising from hot gas within the supercluster. Our results show that the warm/hot intergalactic medium (WHIM) lying in the intercluster regions within the supercluster produces a tSZ effect much smaller than the observed value by MITO/VSA. Neither can, summing the contribution of small clusters and galaxy groups (M < 5 × 1013 h−1 M⊙) in the region, explain the amplitude of the SZ signal. Our synthetic maps show peak y-values significantly below the observations. Less than 0.3 per cent are compatible at the lower end of the 1σ level, even when considering privileged orientations in which the filamentary structures are aligned along the line of sight (LOS). When we take into account the actual posterior distribution from the observations, the probability that WHIM can cause a tSZ signal like the one observed in the CrB-SC is <1 per cent, rising up to a 3.2 per cent when the contribution of small clusters and galaxy groups is included. If the simulations provide a suitable description of the gas physics, then we must conclude that the tSZ component of the CrB spot most probably arises from an unknown galaxy cluster along the LOS. On the other hand, the simulations also show that the kSZ signal associated with the supercluster cannot provide an explanation for the remaining 75 per cent of the observed cold spot in CrB.
A brief description of the methodology of construction, contents and usage of the Planck Early Release Compact Source Catalogue (ERCSC), including the Early Cold Cores (ECC) and the Early ...Sunyaev-Zeldovich (ESZ) cluster catalogue is provided. The catalogue is based on data that consist of mapping the entire sky once and 60% of the sky a second time by Planck, thereby comprising the first high sensitivity radio/submillimetre observations of the entire sky. Four source detection algorithms were run as part of the ERCSC pipeline. A Monte-Carlo algorithm based on the injection and extraction of artificial sources into the Planck maps was implemented to select reliable sources among all extracted candidates such that the cumulative reliability of the catalogue is ≥90%. There is no requirement on completeness for the ERCSC. As a result of the Monte-Carlo assessment of reliability of sources from the different techniques, an implementation of the PowellSnakes source extraction technique was used at the five frequencies between 30 and 143GHz while the SExtractor technique was used between 217 and 857GHz. The 10σ photometric flux density limit of the catalogue at |b| > 30° is 0.49, 1.0, 0.67, 0.5, 0.33, 0.28, 0.25, 0.47 and 0.82 Jy at each of the nine frequencies between 30 and 857GHz. Sources which are up to a factor of ~2 fainter than this limit, and which are present in “clean” regions of the Galaxy where the sky background due to emission from the interstellar medium is low, are included in the ERCSC if they meet the high reliability criterion. The Planck ERCSC sources have known associations to stars with dust shells, stellar cores, radio galaxies, blazars, infrared luminous galaxies and Galactic interstellar medium features. A significant fraction of unclassified sources are also present in the catalogs. In addition, two early release catalogs that contain 915 cold molecular cloud core candidates and 189 SZ cluster candidates that have been generated using multifrequency algorithms are presented. The entire source list, with more than 15000 unique sources, is ripe for follow-up characterisation with Herschel, ATCA, VLA, SOFIA, ALMA and other ground-based observing facilities.
ABSTRACT
Map-making is an important step for the data analysis of cosmic microwave background (CMB) experiments. It consists of converting the data, which are typically a long, complex, and noisy ...collection of measurements, into a map, which is an image of the observed sky. We present in this paper a new map-making code named picasso (Polarization and Intensity CArtographer for Scanned Sky Observations), which was implemented to construct intensity and polarization maps from the Multi Frequency Instrument (MFI) of the QUIJOTE (Q-U-I Joint TEnerife) CMB polarization experiment. picasso is based on the destriping algorithm, and is suited to address specific issues of ground-based microwave observations, with a technique that allows the fit of a template function in the time domain, during the map-making step. This paper describes the picasso code, validating it with simulations and assessing its performance. For this purpose, we produced realistic simulations of the QUIJOTE-MFI survey of the northern sky (approximately ∼20 000 deg2), and analysed the reconstructed maps with picasso, using real and harmonic space statistics. We show that, for this sky area, picasso is able to reconstruct, with high fidelity, the injected signal, recovering all the scales with ℓ > 10 in TT, EE, and BB. The signal error is better than 0.001 per cent at 20 < ℓ < 200. Finally, we validated some of the methods that will be applied to the real wide-survey data, like the detection of the CMB anisotropies via cross-correlation analyses. Despite that the implementation of picasso is specific for QUIJOTE-MFI data, it could be adapted to other experiments.
Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus ...molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around −7% and +13%, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by the contribution of the J = 2 → 1 and J = 1 → 0 12CO and 13CO emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index β, and the dust optical depth at 250 μm τ250. The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16 − 17 K in the diffuse regions to 13 − 14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T − β anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and Hi data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 μm per hydrogen atom τ250/NH. We report an increase of τ250/NH by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.
ABSTRACT
Anomalous Microwave Emission (AME) is a significant component of Galactic diffuse emission in the frequency range 10–$60\, \mathrm{GHz}$ and a new window into the properties of ...sub-nanometre-sized grains in the interstellar medium. We investigate the morphology of AME in the ≈10○ diameter λ Orionis ring by combining intensity data from the QUIJOTE experiment at 11, 13, 17, and $19\, \mathrm{GHz}$ and the C-Band All Sky Survey (C-BASS) at $4.76\, \mathrm{GHz}$, together with 19 ancillary data sets between 1.42 and $3000\, \mathrm{GHz}$. Maps of physical parameters at 1○ resolution are produced through Markov chain Monte Carlo (MCMC) fits of spectral energy distributions (SEDs), approximating the AME component with a lognormal distribution. AME is detected in excess of $20\, \sigma$ at degree-scales around the entirety of the ring along photodissociation regions (PDRs), with three primary bright regions containing dark clouds. A radial decrease is observed in the AME peak frequency from $\approx 35\, \mathrm{GHz}$ near the free–free region to $\approx 21\, \mathrm{GHz}$ in the outer regions of the ring, which is the first detection of AME spectral variations across a single region. A strong correlation between AME peak frequency, emission measure and dust temperature is an indication for the dependence of the AME peak frequency on the local radiation field. The AME amplitude normalized by the optical depth is also strongly correlated with the radiation field, giving an overall picture consistent with spinning dust where the local radiation field plays a key role.
Context.
Wide-field spectrometers are needed to deal with current astrophysical challenges that require multiband observations at millimeter wavelengths. An example of these is the KIDs ...Interferometer Spectrum Survey (KISS), which uses two arrays of kinetic inductance detectors (KIDs) coupled to a Martin-Puplett interferometer (MPI). KISS has a wide instantaneous field of view (1 deg in diameter) and a spectral resolution of up to 1.45 GHz in the 120–180 GHz electromagnetic band. The instrument is installed on the 2.25 m Q-U-I JOint TEnerife telescope at the Teide Observatory (Tenerife, Canary Islands), at an altitude of 2395 m above sea level.
Aims.
This work presents an original readout modulation method developed to improve the sky signal reconstruction accuracy for types of instruments for which a fast sampling frequency is required, both to remove atmospheric fluctuations and to perform full spectroscopic measurements on each sampled sky position.
Methods.
We first demonstrate the feasibility of this technique using simulations. We then apply such a scheme to on-sky calibration.
Results.
We show that the sky signal can be reconstructed to better than 0.5% for astrophysical sources, and to better than 2% for large background variations such as in “skydip”, in an ideal noiseless scenario. The readout modulation method is validated by observations on-sky during the KISS commissioning campaign.
Conclusions.
We conclude that accurate photometry can be obtained for future KID-based interferometry using the MPI.
We present observations with the new 11-GHz radiometer of the COSMOSOMAS experiment at the Teide Observatory (Tenerife). The sky region between 0°≤ RA ≤ 360° and 26°≤ Dec. ≤ 49° (ca. 6500 deg2) was ...observed with an angular resolution of . Two orthogonal independent channels in the receiving system measured total power signals from linear polarizations with a 2-GHz bandwidth. Maps with an average sensitivity of 50 μK per beam have been obtained for each channel. At high Galactic latitude (|b| > 30°) the 11-GHz data are found to contain the expected cosmic microwave background (CMB) as well as extragalactic radiosources, galactic synchrotron and free–free emission, and a dust-correlated component which is likely of Galactic origin. At the angular scales allowed by the window function of the experiment, the 100–240 μm dust-correlated component presents an amplitude ΔT∼ 9–13 μK while the CMB signal is of the order of 27 μK. The spectral behaviour of the dust-correlated signal is examined in the light of previous COSMOSOMAS data at 13–17 GHz and Wilkinson Microwave Anisotropy Probe data at 22–94 GHz in the same sky region. We detect a flattening in the spectral index of this signal below 20 GHz which rules out synchrotron radiation as being responsible for the emission. This anomalous dust emission can be described by a combination of free–free emission and spinning dust models with a flux density peaking around 20 GHz.
ABSTRACT
The Andromeda Galaxy (M31) is the Local Group galaxy that is most similar to the Milky Way (MW). The similarities between the two galaxies make M31 useful for studying integrated properties ...common to spiral galaxies. We use the data from the recent QUIJOTE-MFI Wide Survey, together with new raster observations focused on M31, to study its integrated emission. The addition of raster data improves the sensitivity of QUIJOTE-MFI maps by almost a factor 3. Our main interest is to confirm if anomalous microwave emission (AME) is present in M31, as previous studies have suggested. To do so, we built the integrated spectral energy distribution of M31 between 0.408 and 3000 GHz. We then performed a component separation analysis taking into account synchrotron, free–free, AME, and thermal dust components. AME in M31 is modelled as a log-normal distribution with maximum amplitude, AAME, equal to 1.03 ± 0.32 Jy. It peaks at ${\nu _{\rm AME}}=17.2\pm 3.2{\rm \, GHz}{}$ with a width of WAME = 0.58 ± 0.16. Both the Akaike and Bayesian information criteria find the model without AME to be less than 1 per cent as probable as the one taking AME into consideration. We find that the AME emissivity per 100 $\mu$m intensity in M31 is ${\epsilon _{\rm AME}^{\rm 28.4\, GHz}}=9.6\pm 3.1\,\mu$K MJy−1 sr, similar to that of the MW. We also provide the first upper limits for the AME polarization fraction in an extragalactic object. M31 remains the only galaxy where an AME measurement has been made of its integrated spectrum.
This paper presents the first results from a comparison of Planck dust maps at 353, 545 and 857GHz, along with IRAS data at 3000 (100 μm) and 5000GHz (60 μm), with Green Bank Telescope 21-cm ...observations of Hi in 14 fields covering more than 800deg2 at high Galactic latitude. The main goal of this study is to estimate the far-infrared to sub-millimeter (submm) emissivity of dust in the diffuse local interstellar medium (ISM) and in the intermediate-velocity (IVC) and high-velocity clouds (HVC) of the Galactic halo. Galactic dust emission for fields with average Hi column density lower than 2 × 1020 cm-2 is well correlated with 21-cm emission because in such diffuse areas the hydrogen is predominantly in the neutral atomic phase. The residual emission in these fields, once the Hi-correlated emission is removed, is consistent with the expected statistical properties of the cosmic infrared background fluctuations. The brighter fields in our sample, with an average Hi column density greater than 2 × 1020 cm-2, show significant excess dust emission compared to the Hi column density. Regions of excess lie in organized structures that suggest the presence of hydrogen in molecular form, though they are not always correlated with CO emission. In the higher Hi column density fields the excess emission at 857 GHz is about 40% of that coming from the Hi, but over all the high latitude fields surveyed the molecular mass faction is about 10%. Dust emission from IVCs is detected with high significance by this correlation analysis. Its spectral properties are consistent with, compared to the local ISM values, significantly hotter dust (T ~ 20 K), lower submm dust opacity normalized per H-atom, and a relative abundance of very small grains to large grains about four times higher. These results are compatible with expectations for clouds that are part of the Galactic fountain in which there is dust shattering and fragmentation. Correlated dust emission in HVCs is not detected; the average of the 99.9% confidence upper limits to the emissivity is 0.15 times the local ISM value at 857 and 3000GHz, in accordance with gas phase evidence for lower metallicity and depletion in these clouds. Unexpected anti-correlated variations of the dust temperature and emission cross-section per H atom are identified in the local ISM and IVCs, a trend that continues into molecular environments. This suggests that dust growth through aggregation, seen in molecular clouds, is active much earlier in the cloud condensation and star formation processes.
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