257 research outputs found

    Multiwavelength Observations of one Galaxy in Marano Field

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    We report the multiwavelength observations of one intermediate redshift (z=0.3884) galaxy in the Marano Field. These data include ISOCAM middle infrared, VLT/FORS2 spectroscopic and photometric data, associated with the ATCA 1.4 GHz radio and ROSAT PSPC X-ray observations from literature. The Spectral Energy Distribution obtained by VLT spectroscopy exhibits its early-type galaxy property, while, in the same time, it has obvious [OIII]5007 emission line. The diagnostic diagram from the optical emission line ratios shows its Seyfert galaxy property. Its infrared-radio relation follows the correlation of sources detected at 15 \mu and radio. It has a high X-ray luminosity of 1.26*10^{43} ergs/s, which is much higher than the general elliptical galaxies s with the similar B band luminosity, and is about 2 orders of magnitude higher than the derived value from the star forming tracer, the FIR luminosity. This means that the X-ray sources of this galaxy are not stellar components, but the AGN is the dominant component.Comment: 6 pages, 1 PS figure and 4 tables. Publication in ChJAA, Suppl., the Special Issue for The Fifth Microquasar Workshop 2004: http://chjaa.bao.ac.cn/, 2005, Vol.5, 335-34

    Rejection of randomly coinciding events in Li2_2100^{100}MoO4_4 scintillating bolometers using light detectors based on the Neganov-Luke effect

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    Random coincidences of nuclear events can be one of the main background sources in low-temperature calorimetric experiments looking for neutrinoless double-beta decay, especially in those searches based on scintillating bolometers embedding the promising double-beta candidate 100^{100}Mo, because of the relatively short half-life of the two-neutrino double-beta decay of this nucleus. We show in this work that randomly coinciding events of the two-neutrino double decay of 100^{100}Mo in enriched Li2_2100^{100}MoO4_4 detectors can be effectively discriminated by pulse-shape analysis in the light channel if the scintillating bolometer is provided with a Neganov-Luke light detector, which can improve the signal-to-noise ratio by a large factor, assumed here at the level of 750\sim 750 on the basis of preliminary experimental results obtained with these devices. The achieved pile-up rejection efficiency results in a very low contribution, of the order of 6×105\sim 6\times10^{-5} counts/(keV\cdotkg\cdoty), to the background counting rate in the region of interest for a large volume (90\sim 90 cm3^3) Li2_2100^{100}MoO4_4 detector. This background level is very encouraging in view of a possible use of the Li2_2100^{100}MoO4_4 solution for a bolometric tonne-scale next-generation experiment as that proposed in the CUPID project

    Observations of the Sunyaev-Zel'dovich effect at high angular resolution towards the galaxy clusters A665, A2163 and CL0016+16

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    We report on the first observation of the Sunyaev-Zel'dovich effect with the Diabolo experiment at the IRAM 30 metre telescope. A significant brightness decrement is detected in the direction of three clusters (Abell 665, Abell 2163 and CL0016+16). With a 30 arcsecond beam and 3 arcminute beamthrow, this is the highest angular resolution observation to date of the SZ effect.Comment: 23 pages, 8 figures, 6 tables, accepted to New Astronom

    The SciCryo Project and Cryogenic Scintillation of Al2O3Al_2O_3 for Dark Matter

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    International audienceWe discuss cryogenic scintillation of Al2O3. Room-temperature measurements with α particles are first carried out to study effect of Ti concentration on response. Measurements under X-rays between room temperature and 10 K confirm a doubling of light output. The integration of a scintillation-phonon detector into an ionization-phonon dark matter search is underway, and the quenching factor for neutrons has been verified

    The Role Of Cuticular Pheromones In Courtship Conditioning Of Drosophila Males

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    Courtship conditioning is an associative learning paradigm in Drosophila melanogaster, wherein male courtship behavior is modified by experience with unreceptive, previously mated females. While the training experience with mated females involves multiple sensory and behavioral interactions, we hypothesized that female cuticular hydrocarbons function as a specific chemosensory conditioned stimulus in this learning paradigm. The effects of training with mated females were determined in courtship tests with either wild-type virgin females as courtship targets, or with target flies of different genotypes that express distinct Cuticular hydrocarbon (CH) profiles. Results of tests with female targets that lacked the normal CH profile, and with male targets that expressed typically female CH profiles, indicated that components of this CH profile are both necessary and sufficient cues to elicit the effects of conditioning. Results with additional targets indicated that the female-specific 7,11-dienes, which induce naive males to court, are not essential components of the conditioned Stimulus. Rather, the learned response was significantly correlated with the levels of 9-pentacosene (9-P), a compound found in both males and females of many Drosophila strains and species. Adding 9-P to target flies showed that it stimulates courting males to attempt to copulate, and confirmed its role as a component of the conditioned stimulus by demonstrating dose-dependent increases in the expression of the learned response. Thus, 9-P can contribute significantly to the conditioned Suppression of male courtship toward targets that express this pheromone

    First test of an enriched 116^{116}CdWO4_4 scintillating bolometer for neutrinoless double-beta-decay searches

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    For the first time, a cadmium tungstate crystal scintillator enriched in 116^{116}Cd has been succesfully tested as a scintillating bolometer. The measurement was performed above ground at a temperature of 18 mK. The crystal mass was 34.5 g and the enrichment level ~82 %. Despite a substantial pile-up effect due to above-ground operation, the detector demonstrated a high energy resolution (2-7 keV FWHM in 0.2-2.6 MeV γ\gamma energy range), a powerful particle identification capability and a high level of internal radiopurity. These results prove that cadmium tungstate is an extremely promising detector material for a next-generation neutrinoless double-beta decay bolometric experiment, like that proposed in the CUPID project (CUORE Upgrade with Particle IDentification)

    Star Formation Activities of Galaxies in the Large-Scale Structures at z=1.2

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    Recent wide-field imaging observations of the X-ray luminous cluster RDCSJ1252.9-2927 at z=1.24 uncovered several galaxy groups that appear to be embedded in filamentary structure extending from the cluster core. We make a spectroscopic study of the galaxies in these groups using GMOS on Gemini-South and FORS2 on VLT with the aim of determining if these galaxies are physically associated to the cluster. We find that three groups contain galaxies at the cluster redshift and that they are probably bound to the cluster. This is the first confirmation of filamentary structure as traced by galaxy groups at z>1. We then use several spectral features in the FORS2 spectra to determine the star formation histories of group galaxies. We find a population of relatively red star-forming galaxies in the groups that are absent from the cluster core. While similarly red star forming galaxies can also be found in the field, the average strength of the hd line is systematically weaker in group galaxies. Interestingly, these groups at z=1.2 are in an environment in which the on-going build-up of red sequence is happening. The unusual line strengths can be explained by star formation that is heavily obscured by dust. We hypothesize that galaxy-galaxy interactions, which is more efficient in the group environment, is the mechanism that drives these dust obscured star formation. The hypothesis can be tested by obtaining spectral observations in the near-IR, high resolution imaging observations and observations in the mid-IR.Comment: 12 pages, 12 figures. Accepted for publication in A&

    Calibration and First light of the Diabolo photometer at the Millimetre and Infrared Testa Grigia Observatory

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    We have designed and built a large-throughput dual channel photometer, Diabolo. This photometer is dedicated to the observation of millimetre continuum diffuse sources, and in particular, of the Sunyaev-Zel'dovich effect and of anisotropies of the 3K background. We describe the optical layout and filtering system of the instrument, which uses two bolometric detectors for simultaneous observations in two frequency channels at 1.2 and 2.1 mm. The bolometers are cooled to a working temperature of 0.1 K provided by a compact dilution cryostat. The photometric and angular responses of the instrument are measured in the laboratory. First astronomical light was detected in March 1995 at the focus of the new Millimetre and Infrared Testa Grigia Observatory (MITO) Telescope. The established sensitivity of the system is of 7 mK_RJ s^1/2$. For a typical map of at least 10 beams, with one hour of integration per beam, one can achieve the rms values of y_SZ ~ 7 10^-5 and the 3K background anisotropy Delta T/T ~ 7 10^-5, in winter conditions. We also report on a novel bolometer AC readout circuit which allows for the first time total power measurements on the sky. This technique alleviates (but does not forbid) the use of chopping with a secondary mirror. This technique and the dilution fridge concept will be used in future scan--modulated space instrument like the ESA Planck mission project.Comment: 10 pages, LaTeX, 12 figures, accepted for publication in Astronomy and Astrophysics Supplement Serie
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