35 research outputs found
First Constraints on Source Counts at 350 Microns
We have imaged a 6 arcminute region in the Bo\"otes Deep Field
using the 350 m-optimised second generation Submillimeter High Angular
Resolution Camera (SHARC II), achieving a peak 1 sensitivity of 5
mJy. We detect three sources above 3, and determine a spurious source
detection rate of 1.09 in our maps. In the absence of detections, we
rely on deep 24 m and 20 cm imaging to deduce which sources are most
likely to be genuine, giving two real sources. From this we derive an integral
source count of 0.84 sources arcmin at mJy,
which is consistent with 350 m source count models that have an
IR-luminous galaxy population evolving with redshift. We use these constraints
to consider the future for ground-based short-submillimetre surveys.Comment: accepted for publication in The Astrophysical Journa
The first ISO ERO: a dusty quasar at z = 1.5
We report the discovery of an extremely red object (ERO) in a medium-deep
ISOCAM extragalactic survey. The object is also a radio source. Subsequent VLT
NIR spectroscopy revealed a prominent Halpha line giving a redshift of 1.5. We
present the spectrum and photometric data points and discuss evidence that ISO
J1324-2016 is a quasar harbouring a significant amount of very hot dust.Comment: 5 pages, including 5 figures, A&A accepte
Stellar Evolutionary Effects on the Abundances of PAH and SN-Condensed Dust in Galaxies
Spectral and photometric observations of nearby galaxies show a correlation
between the strength of their mid-IR aromatic features, attributed to PAH
molecules, and their metal abundance, leading to a deficiency of these features
in low-metallicity galaxies. In this paper, we suggest that the observed
correlation represents a trend of PAH abundance with galactic age, reflecting
the delayed injection of carbon dust into the ISM by AGB stars in the final
post-AGB phase of their evolution. AGB stars are the primary sources of PAHs
and carbon dust in galaxies, and recycle their ejecta back to the interstellar
medium only after a few hundred million years of evolution on the main
sequence. In contrast, more massive stars that explode as Type II supernovae
inject their metals and dust almost instantaneously after their formation. We
first determined the PAH abundance in galaxies by constructing detailed models
of UV-to-radio SED of galaxies that estimate the contribution of dust in
PAH-free HII regions, and PAHs and dust from photodissociation regions, to the
IR emission. All model components: the galaxies' stellar content, properties of
their HII regions, and their ionizing and non-ionizing radiation fields and
dust abundances, are constrained by their observed multiwavelength spectrum.
After determining the PAH and dust abundances in 35 nearby galaxies using our
SED model, we use a chemical evolution model to show that the delayed injection
of carbon dust by AGB stars provides a natural explanation to the dependence of
the PAH content in galaxies with metallicity. We also show that larger dust
particles giving rise to the far-IR emission follow a distinct evolutionary
trend closely related to the injection of dust by massive stars into the ISM.Comment: ApJ, 69 pages, 46 figures, Accepte
ISOCAM Mid-InfraRed Detection of HR 10: A Distant Clone of Arp 220 at z=1.44
We report the detection of the extremely red object (ERO), HR 10 (I-K= 6.5,
z=1.44), at 4.9 and 6.1 microns (rest-frame) with ISOCAM, the mid-infrared
(MIR) camera onboard the Infrared Space Observatory (ISO). HR 10 is the first
ERO spectroscopically identified to be associated with an ultra-luminous IR
galaxy (ULIG) detected in the radio, MIR and sub-millimeter. The rest-frame
spectral energy distribution (SED) of HR 10 is amazingly similar to the one of
Arp 220, scaled by a factor 3.8+/-1.3. The corresponding 8-1000 microns
luminosity (~ 7x10^12 h70^{-2} Lsol) translates into a star formation rate of
about 1200 h70^{-2} Msol/yr if HR 10 is mostly powered by star formation. We
address the key issue of the origin of the powerful luminosity of HR 10, i.e.
starburst versus active galactic nucleus (AGN), by using the similarity with
its closeby clone, Arp 220.Comment: accepted for publication in Astronomy and Astrophysics Letter (4
pages, 2 figures
Detection chain and electronic readout of the QUBIC instrument
The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10â»ÂčⶠW/âHz
Detection chain and electronic readout of the QUBIC instrument
The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10â»ÂčⶠW/âHz
Simulations and performance of the QUBIC optical beam combiner
QUBIC, the Q & U Bolometric Interferometer for Cosmology, is a novel ground-based instrument that aims to measure the extremely faint B-mode polarisation anisotropy of the cosmic microwave background at intermediate angular scales (multipoles o
Etude multi longueurs d'ondes des galaxies normales et à flambées d'étoiles de l'univers local
PARIS7-BibliothĂšque centrale (751132105) / SudocSudocFranceF
En Commun ! Ăloge des institutions partagĂ©es
EAN : 9782356879417.Avec les articles de : Michel Bauwens, François Bordes, Benoit Borrits, Philippe Chanial, Pierre CrĂ©tois, Pierre Dardot, Marion Fourcade, Jean-Marc Ghitti, Edouard Jourdain, Laurence Kaufmann, Daniel N. Kluttz, Serge Latouche, Christian Laval, Guillaume le Blanc, Paulo Henrique Martins, Thomas Perroud, Christophe Petit, Pierre SauvĂȘtre, FrĂ©dĂ©ric Vanderberghe.Chacun connaĂźt cette scĂšne originaire qui ouvre la seconde partie du cĂ©lĂšbre Discours sur lâorigine et les fondements de lâinĂ©galitĂ© parmi les hommes de Jean-Jacques Rousseau : « Le premier qui, ayant enclos un terrain, sâavisa de dire : Ceci est Ă moi, et trouva des gens assez simples pour le croire, fut le vrai fondateur de la sociĂ©tĂ© civile. Que de crimes, de guerres, de meurtres, que de misĂšres et dâhorreurs nâeĂ»t point Ă©pargnĂ©s au genre humain celui qui, arrachant les pieux ou comblant le fossĂ©, eĂ»t criĂ© Ă ses semblables : Gardez-vous dâĂ©couter cet imposteur ; vous ĂȘtes perdus, si vous oubliez que les fruits sont Ă tous, et que la terre nâest Ă personne. »DĂ©nonçant le « Ceci est Ă moi » du premier planteur de pieux, Rousseau dessinait, en creux, la sociĂ©tĂ© telle quâelle devrait ĂȘtre : « Ceci est Ă nous. » Il nous rappelait ainsi, Ă travers cette fable, combien lâhistoire humaine est contingente et ouverte Ă dâautres possibles. Parmi ces possibles sâaffirme aujourdâhui un nouveau paradigme au sein duquel cherchent Ă se penser une dĂ©mocratisation de la sociĂ©tĂ© et un dĂ©passement des dĂ©sordres et des hiĂ©rarchies imposĂ©s par le capitalisme : le paradigme des « communs ».Les communs dĂ©signent une forme immĂ©moriale de conception de la propriĂ©tĂ©, largement rĂ©pandue, notamment jusquâĂ la fin du Moyen Ăge, lorsque, dans les campagnes, lâorganisation coutumiĂšre des usages de la nature â pĂąturages, Ă©tangs, forĂȘts â primait sur la notion de propriĂ©tĂ©. Lâhistoire rejoignant la fable, ces modes dâaccĂšs aux ressources dĂ©clinĂšrent Ă mesure que sâimposĂšrent les fameuses « enclosures » dĂ©crites par Marx, ces « dĂ©crets dâexpropriation du peuple » au moyen desquels « les propriĂ©taires fonciers se font eux-mĂȘmes cadeau des biens communaux ».Face Ă lâhĂ©gĂ©monie du rĂ©gime propriĂ©tariste, radicalisĂ©e par les nouvelles enclosures promues par les politiques de privatisation et de marchandisation nĂ©o-libĂ©rales, lâoriginalitĂ© du paradigme du commun est de dĂ©passer les dichotomies classiques opposant propriĂ©tĂ© privĂ©e et propriĂ©tĂ© publique, rĂ©gulation marchande ou Ă©tatique, ainsi que les formes de domination qui rĂ©sultent de lâappropriation des ressources naturelles et des moyens de production. Comme le montrent de multiples expĂ©riences contemporaines, et notamment les travaux du prix Nobel dâĂ©conomie, Elinor Orstrom, partout dans le monde, des communautĂ©s sont capables dâorganiser durablement des « rĂšgles dâusage » afin de garantir Ă la fois la survie des habitants et la prĂ©servation dâun rĂ©servoir de ressources pour les gĂ©nĂ©rations suivantes. Câest ce paradigme alternatif et ces expĂ©riences foisonnantes que ce numĂ©ro propose dâinterroger, tant pour en souligner la richesse que les conflits quâils suscitent. En effet, trĂšs polysĂ©miques, le ou les « communs » constituent lâun de ces concepts essentiellement contestĂ©s dont le milieu militant sâest saisi comme dâune banniĂšre pour des initiatives diverses et, parfois, divergentes, et dont les chercheurs tentent de dĂ©limiter les contours dans les domaines Ă©conomique, juridique, politique, anthropologique et philosophique. Quâil sâagisse des communs numĂ©riques, environnementaux, urbains mais aussi des communs politiques ou de la redĂ©finition de la notion mĂȘme dâentreprise, lâespace de dĂ©bat et de controverses quâouvre ce numĂ©ro se veut rĂ©solument pluraliste, comme les formes, plurielles, de propriĂ©tĂ© quâappelle une dĂ©mocratie radicale