2 results
The QUIJOTE experiment
- Marcos López-Caniego
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- Journal:
- Proceedings of the International Astronomical Union / Volume 11 / Issue A29B / August 2015
- Published online by Cambridge University Press:
- 27 October 2016, p. 54
- Print publication:
- August 2015
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The QUIJOTE (Q-U-I JOint Tenerife) Experiment† (Rubiño-Martín et al. 2010)) is observing the polarization of the Cosmic Microwave Background and other Galactic and extragalactic signals at medium and large angular scales in the frequency range of 10-40 GHz. This experiment is going to provide valuable information about the polarization properties of synchrotron and anomalous microwave emission at these frequencies. It consists of two telescopes and three instruments located at the the Teide Observatory (2400 m) in Tenerife, Canary Islands, Spain. This project has two phases: Phase I, the first telescope (QT1) and a multi-frequency instrument (MFI) are in operations since November 2012 observing between 10 and 20 GHz. A second instrument (TGI) with 31 polarimeters working at 30 GHz is expected to start operations in Autumn 2015 and will be devoted to primordial B-mode science. This instrument will include a fixed polariser and 90 and 180 phase switches to generate four polarization states to minimize the different systematics in the receiver; Phase II, a second QUIJOTE telescope (QT2), already in operation, and a third instrument (FGI) with 40 polarimeters working at 41 GHz, safely below the 60-GHz oxygen absorption band, will significantly increment the sensitivity of the QUIJOTE project to detect the r parameter (tensor-to-scalar ratio). The reason for this is not only the significant reduction of noise due to the number of polarimeters that will incorporate but also the lower synchrotron signal from our galaxy expected at these higher frequencies.
The maps obtained with the multi-frequency instrument (10-20 GHz), in combination with data from other experiments like Planck and the VLA, will be used to clean the diffuse and compact foreground emission at 30 and 40 GHz, the cosmological channels. After three years of effective observations we expect to reach the required sensitivity to detect a primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r = 0.05. At the moment we have completed the Wide Survey with the multi-frequency instrument, covering 20.000 square degrees of the Northern hemisphere. In addition, we have deep integrations of our main calibrators Taurus A, Cassiopea A, Jupiter and of the Perseus molecular complex.
In particular, the first results obtained from the measurement of the intensity and polarisation of the anomalous microwave emission inthis region, G159.6-18.5, have been recently published in Génova-Santos et al. 2015). This article presents the most precise spectrum of the anomalous microwave emission (AME) measured to date in an individual region, with 13 independent data points between 10 and 50 GHz being dominated by this emission. The four QUIJOTE data points provide the first independent confirmation of the downturn of the AME spectrum at low frequencies, initially unveiled by the COSMOlogical Structures On Medium Angular Scales (COSMOSOMAS) experiment in this region. We also have observed several regions of interest for our science program where we plan to study the compact and diffuse polarized emission.
The Planck Compact Source Catalogues: present and future
- Marcos López-Caniego, on behalf of the Planck Collaboration
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- Journal:
- Proceedings of the International Astronomical Union / Volume 11 / Issue A29B / August 2015
- Published online by Cambridge University Press:
- 27 October 2016, p. 61
- Print publication:
- August 2015
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- Article
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- You have access Access
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The Planck Collaboration has produced catalogues of radio and sub-millimeter compact sources at the nine Planck frequencies in total intensity and polarization. In particular, the 2015 Second Planck Catalogue of Compact Sources (PCCS2) contains over 45.000 sources detected in the Planck full mission maps. Since the Planck instruments have polarization capabilities in seven of its nine detectors, we were able to measure the polarized flux density of over 600 sources between 30 and 353 GHz. But we are searching not only for compact sources in single frequency maps, and we take advantage of the large frequency coverage of Planck to search for objects with specific emission laws. This is the case of the SZ catalogue of cluster of galaxies (PSZ2), that lists 1653 clusters, 1203 of which are confirmed clusters with clear associations in external data-sets, and the Galactic cold clump catalogue (PGCC) with 13188 objects. The Planck Collaboration has also published a list of high-redshift source candidates (see the report by Ludovic Montier here). These objects are rare bright sub-millimeter sources with an spectral energy distribution peaking between 353 and 857 GHz, and have been detected combining Planck and IRAS data. The colours of most of these objects are consistent with redshifts z>2, a fraction of which could be lensed objects with redshifts between 2 and 4.
But new catalogues are foreseen. A multi-frequency compact source catalogue is being produced selecting sources at radio frequencies and studying them across all Planck bands. Multi-frequency catalogues can be difficult to produce in experiments like Planck that have a large frequency coverage and very different resolutions across bands. In some cases, a source can be very bright across the whole Planck frequency range and it is easy to do the associations across channels. However, it frequent to find unrelated sub-millimeter sources within the half-degree beam of the 30 GHz low frequency detector, and the association work must be done with great care. For this purpose, we are combining a multi-frequency detection procedure with a principal component analysis to produce the catalogue. In addition, for those sources where a clear identification can be made, we will attempt to include flux density information from Herschel and other experiments, in particular for those blazars that are bright in radio, sub-mm and even in gamma-ray frequencies, as seen by Fermi. Moreover, Planck has made available to the community the single survey frequency maps that allow astronomers to study the long-term variability of their favourite sources. New functionalities will be also added to the Planck Legacy Archive†, for example a timeline-cutting tool that will allow one to produce full-sky maps from the Planck timelines for specific periods of time allowing for short-term variability studies of compact sources (e.g., flares). The unique frequency coverage of Planck make these catalogues very valuable for other experiments using the Planck compact source catalogues. For example, experiments like QUIJOTE use Planck selected sources to study the impact of polarized radio source emission on their cosmological fields and other CMB experiments will use Planck polarized compact source information for calibration.