Extracting cosmological signals from foregrounds in deep mm maps of the sky

The high Galactic latitude sky at millimeter and submm wavelengths contains significant cosmological information about the early Universe (in terms of the cosmic microwave background) but also the process of structure formation in the Universe from the far infrared background produced by early galaxies and the Sunyaev-Zeldovich effect in clusters of galaxies. As the Planck mission will produce full sky maps in this frequency range, deeper maps of selected low-foregrounds patches of the sky can produce complementary and important information. Here we analyze the performance of a balloon-borne survey covering a 10^\circ x 10^\circ patch of the sky with a few arcminute resolution and very high pixel sensitivity. We simulate the different components of the mm/submm sky (i.e., CMB anisotropies, SZ effect, radio and infrared sources, far infrared background, and interstellar dust) using current knowledge about each of them. We then combine them, adding detector noise, to produce detailed simulated observations in four observational bands ranging from 130 to 500 GHz. Finally, we analyze the simulated maps and estimate the performance of the instrument in extracting the relevant information about each of the components. We find that the CMB angular power spectrum is accurately recovered up to l ~ 3000. Using the Sunyaev-Zel'dovich effect, most of the galaxy clusters present in our input map are detected (60% efficiency overall). Our results also show that much stronger constrains can be placed on far infrared background models.Comment: 10 pages, 8 figures, accepted for publication in A&

Pegaso: an ultra-light long duration stratospheric payload for polar regions flights

Stratospheric balloons are powerful and affordable tools for a wide spectrum of scientific investigations that are carried out at the stratosphere level. They are less expensive compared to satellite projects and have the capability to lift payloads from a few kilograms to a couple of tons or more, well above the troposphere, for more than a month. Another interesting feature of these balloons, which is not viable in satellites, is the short turnaround time, which enables frequent flights. We introduce the PEGASO (Polar Explorer for Geomagnetism And other Scientific Observations) project, a stratospheric payload designed and developed by the INGV (Istituto Nazionale di Geofisica e Vulcanologia), Rome and La Sapienza University, Rome. The project was sponsored by the PNRA (Progetto Nazionale di Ricerche in Antartide), Italy (Peterzen et al., 2003). This light payload (10 kg) was used by the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) for five different scientific missions. PEGASO carries a 3-component flux-gate magnetometer, uses a solar cell array as the power source and has a GPS location system. The bi-directional telemetry system for data transfer and the remote control system were IRIDIUM basedINGV, PNRA, ASI, ARR, CNR, La SapienzaPublishedBeijing, China1.10. TTC - Telerilevamentoope

PEGASO: LONG DURATION BALLOONS FROM NORTH POLE

In a joint effort, the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) have initiated the development of a European balloon center in Svalbard, Norway that is an ideal location for performing Long Duration Balloon (LDB) flights. After the identification of the launch location several light balloon flights have been performed since 2003. The 2004 campaign utilized a 10000 m³ balloon produced for the program by Aerostar of Sulfur Springs, Texas USA. This flight lasted 40 days and was an excellent test of the small PEGASO payload, developed (for use in Antarctica) by the National Institute of Geophysics and Volcanology (INGV) with the PNRA (Progetto Nazionale di Ricerche in Antartide) sponsorship. This payload uses an IRIDIUM based bi-directional telemetry system. During summer 2005 two flights have been performed using balloons of the same size. They carried an updated telemetry and a scientific payload which analyzed the magnetic field of the Earth. The Institute of Information Science and Technology (ISTI-CNR) team computed predictions of the balloons trajectories, both before and during flights, as well as statistical evaluations of the seasonal flight windows at the beginning of the ASI LDB program. The 2004 and 2005 missions have been defined to investigate the stratospheric winds structure and they tested the possibility for future heavy LDB flights. The Italian scientific community foresees this kind of missions from 2007-2008 campaigns. Next sections, starting from a general overview of the Italian LDB program, give the description of the Pegaso flights and, in particular, the adopted technical solutions for the on-board and ground-based equipments

PEGASO: LONG DURATION BALLOONS FROM NORTH POLE

In a joint effort, the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) have initiated the development of a European balloon center in Svalbard, Norway that is an ideal location for performing Long Duration Balloon (LDB) flights. After the identification of the launch location several light balloon flights have been performed since 2003. The 2004 campaign utilized a 10000 m³ balloon produced for the program by Aerostar of Sulfur Springs, Texas USA. This flight lasted 40 days and was an excellent test of the small PEGASO payload, developed (for use in Antarctica) by the National Institute of Geophysics and Volcanology (INGV) with the PNRA (Progetto Nazionale di Ricerche in Antartide) sponsorship. This payload uses an IRIDIUM based bi-directional telemetry system. During summer 2005 two flights have been performed using balloons of the same size. They carried an updated telemetry and a scientific payload which analyzed the magnetic field of the Earth. The Institute of Information Science and Technology (ISTI-CNR) team computed predictions of the balloons trajectories, both before and during flights, as well as statistical evaluations of the seasonal flight windows at the beginning of the ASI LDB program. The 2004 and 2005 missions have been defined to investigate the stratospheric winds structure and they tested the possibility for future heavy LDB flights. The Italian scientific community foresees this kind of missions from 2007-2008 campaigns. Next sections, starting from a general overview of the Italian LDB program, give the description of the Pegaso flights and, in particular, the adopted technical solutions for the on-board and ground-based equipments.PublishedVOLTERRA, PISA1.10. TTC - Telerilevamentoope

QUBIC: The QU Bolometric Interferometer for Cosmology

One of the major challenges of modern cosmology is the detection of B-mode polarization anisotropies in the CMB. These originate from tensor fluctuations of the metric produced during the inflationary phase. Their detection would therefore constitute a major step towards understanding the primordial Universe. The expected level of these anisotropies is however so small that it requires a new generation of instruments with high sensitivity and extremely good control of systematic effects. We propose the QUBIC instrument based on the novel concept of bolometric interferometry, bringing together the sensitivity advantages of bolometric detectors with the systematics effects advantages of interferometry. Methods: The instrument will directly observe the sky through an array of entry horns whose signals will be combined together using an optical combiner. The whole set-up is located inside a cryostat. Polarization modulation will be achieved using a rotating half-wave plate and interference fringes will be imaged on two focal planes (separated by a polarizing grid) tiled with bolometers. We show that QUBIC can be considered as a synthetic imager, exactly similar to a usual imager but with a synthesized beam formed by the array of entry horns. Scanning the sky provides an additional modulation of the signal and improve the sky coverage shape. The usual techniques of map-making and power spectrum estimation can then be applied. We show that the sensitivity of such an instrument is comparable with that of an imager with the same number of horns. We anticipate a low level of beam-related systematics thanks to the fact that the synthesized beam is determined by the location of the primary horns. Other systematics should be under good control thanks to an autocalibration technique, specific to our concept, that will permit the accurate determination of most of the systematics parameters.Comment: 12 pages, 10 figures, submitted to Astronomy and Astrophysic

PEGASO: An ultra light long duration stratospheric payload for polar regions flights

Stratospheric balloons are powerful and affordable tools for a wide spectrum of scientific investigations that are carried out at the stratosphere level. They are less expensive compared to satellite projects and have the capability to lift payloads from a few kilograms to a couple of tons or more, well above the troposphere, for more than a month. Another interesting feature of these balloons, which is not viable in satellites, is the short turnaround time, which enables frequent flights. We introduce the PEGASO (Polar Explorer for Geomagnetism And other Scientific Observations) project, a stratospheric payload designed and developed by the INGV (Istituto Nazionale di Geofisica e Vulcanologia), Rome and La Sapienza University, Rome. The project was sponsored by the PNRA (Progetto Nazionale di Ricerche in Antartide), Italy (Peterzen et al., 2003). This light payload (10 kg) was used by the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) for five different scientific missions. PEGASO carries a 3-component flux-gate magnetometer, uses a solar cell array as the power source and has a GPS location system. The bi-directional telemetry system for data transfer and the remote control system were IRIDIUM base

QUBIC: The QU Bolometric Interferometer for Cosmology

Context. One of the major challenges of modern cosmology is the detection of B-mode polarization anisotropies in the Cosmic Microwave Background. These originate from tensor fluctuations of the metric produced during the inflationary phase. Their detection would therefore constitute a major step towards understanding the primordial Universe. The expected level of these anisotropies is however so small that it requires a new generation of instruments with high sensitivity and extremely good control of systematic eects. Aims. We propose the QUBIC instrument based on the novel concept of bolometric interferometry, bringing together the sensitivity advantages of bolometric detectors with the systematics eects advantages of interferometry. Methods. The instrument will directly observe the sky through an array of entry horns whose signals will be combined together using an optical combiner. The whole set-up is located inside a cryostat. Polarization modulation will be achieved using a rotating half-wave plate and the images of the interference fringes will be formed on two focal planes (separated by a polarizing grid) tiled with bolometers. Results.We show that QUBIC can be considered as a synthetic imager, exactly similar to a usual imager but with a synthesized beam formed by the array of entry horns. Scanning the sky provides an additional modulation of the signal and improve the sky coverage shape. The usual techniques of map-making and power spectrum estimation can then be applied. We show that the sensitivity of such an instrument is comparable with that of an imager with the same number of horns. We anticipate a low level of beam-related systematics thanks to the fact that the synthesized beam is determined by the location of the primary horns. Other systematics should be under good control thanks to an autocalibration technique, specific to our concept, that will permit the accurate determination of most of the systematics parameters

QUBIC: the Q&U Bolometric Interferometer for Cosmology

The primordial B-mode polarisation of the Cosmic Microwave Background is the imprints of the gravitational wave background generated by inflation. Observing the B-mode is up to now the most direct way to constrain the physics of the primordial Universe, especially inflation. To detect these B-modes, high sensitivity is required as well as an exquisite control of systematics effects. To comply with these requirements, we propose a new instrument called QUBIC (Q and U Bolometric Interferometer for Cosmology) based on bolometric interferometry. The control of systematics is obtained with a close-packed interferometer while bolometers cooled to very low temperature allow for high sensitivity. We present the architecture of this new instrument, the status of the project and the self-calibration technique which allows accurate measurement of the instrumental systematic effects

The BRAIN project: looking for B-mode from Dome-C

Texte integral disponible sur http://proc.sf2a.asso.fr/sf2a06.phpInternational audienceThe detection and characterisation of Cosmic Microwave Background B-mode polarization is one of the next challenges in observational cosmology. This primordial polarization mode is only due to tensor perturbations of the metric produced by primordial gravitational waves, which could have been generated during the inflation epoch. With a signal of less than 0.1? K, B-mode measurement requires very sensitive experiments and also an extremely good control of instrumental effects. In this paper we present the BRAIN experiment, a bolometric interferometer devoted to B-mode detection. This new detection architecture allows to directly measure the Fourier modes of the Stokes parameters. High sensitivity is obtained by using low temperature bolometers while systematic effects are reduced by using the interferometric technique