. (2019). Nanometre-scale infrared chemical imaging of organic matter in ultra-carbonaceous Antarctic micrometeorites (UCAMMs) (Vol. 622). Bachelor's thesis, , .
Keywords: astrochemistry comets: general interplanetary medium meteorites meteoroids meteors methods: laboratory: solid state techniques: imaging spectroscopy
Programme: 1120
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Bigot-Sazy M-A, Charlassier R, Hamilton J-Ch, Kaplan J, Zahariade G, . (2013). Self-calibration: an efficient method to control systematic effects in bolometric interferometry
. ASTRONOMY & ASTROPHYSICS, 550(A), 59.
Abstract: Context. The QUBIC collaboration is building a bolometric interferometer dedicated to the detection of B-mode polarization fluctuations in the cosmic microwave background.
Aims: We introduce a self-calibration procedure related to those used in radio-interferometry to control a wide range of instrumental systematic errors in polarization-sensitive instruments.
Methods: This procedure takes advantage of the need for measurements on redundant baselines to match each other exactly in the absence of systematic effects. For a given systematic error model, measuring each baseline independently therefore allows writing a system of nonlinear equations whose unknowns are the systematic error model parameters (gains and couplings of Jones matrices, for instance).
Results: We give the mathematical basis of the self-calibration. We implement this method numerically in the context of bolometric interferometry. We show that, for large enough arrays of horns, the nonlinear system can be solved numerically using a standard nonlinear least-squares fitting and that the accuracy achievable on systematic effects is only limited by the time spent on the calibration mode for each baseline apart from the validity of the systematic error model.
Programme: 915
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L. Abe, I. Goncalves, A. Agabi, A. Alapini, T. Guillot, D. Mekarnia, J.-P. Rivet, F.-X. Schmider, N. Crouzet, J. Fortney, F. Pont, M. Barbieri, J.-B. Daban, Y. Fantei-Caujolle, C. Gouvret, Y. Bresson, A. Roussel, S. Bonhomme, A. Robini, M. Dugue, E. Bondoux, S. Peron, P.-Y. Petit, J. Szulagyi, T. Fruth, A. Erikson, H. Rauer, F. Fressin, F. Valbousquet, P.-E. Blanc, A. Le van Suu, S. Aigrain. (2012). The secondary eclipses and phases of WASP-19b as seen by the
ASTEP 400 telescope from Antarctica. ASTRONOMY & ASTROPHYSICS, 553, 13.
Abstract: The ASTEP (Antarctica Search for Transiting ExoPlanets) program was originally aimed at probing the quality of the Dome C, Antarctica for the discovery and characterization of exoplanets by photometry. In the first year of operation of the 40 cm ASTEP 400 telescope (austral winter 2010), we targeted the known transiting planet WASP-19b in order to try to detect its secondary transits in the visible. This is made possible by the excellent sub-millimagnitude precision of the binned data. The WASP-19 system was observed during 24 nights in May 2010. The photometric variability level due to starspots is about 1.8% (peak-to-peak), in line with the SuperWASP data from 2007 (1.4%) and larger than in 2008 (0.07%). We find a rotation period of WASP-19 of 10.7 +/- 0.5 days, in agreement with the SuperWASP determination of 10.5 +/- 0.2 days. Theoretical models show that this can only be explained if tidal dissipation in the star is weak, i.e. the tidal dissipation factor Q'star > 3.10^7. Separately, we find evidence for a secondary eclipse of depth 390 +/- 190 ppm with a 2.0 sigma significance, a phase consistent with a circular orbit and a 3% false positive probability. Given the wavelength range of the observations (420 to 950 nm), the secondary transit depth translates into a day side brightness temperature of 2690(-220/+150) K, in line with measurements in the z' and K bands. The day side emission observed in the visible could be due either to thermal emission of an extremely hot day side with very little redistribution of heat to the night side, or to direct reflection of stellar light with a maximum geometrical albedo Ag=0.27 +/- 0.13. We also report a low-frequency oscillation well in phase at the planet orbital period, but with a lower-limit amplitude that could not be attributed to the planet phase alone, and possibly contaminated with residual lightcurve trends.
Programme: 1066
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Barthelemy M, Lystrup M B, Menager H, Miller S, Lilensten J,. (2011). First detection of polarization in jovian auroral H+3 emissions. A&A, 530.
Keywords: polarization / molecular data / planets and satellites: aurorae / planets and satellites: individual: Jupiter
Programme: 1026
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R. Charlassier, E.F. Bunn, J.-Ch. Hamilton, J. Kaplan, S. Malu. (2010). Bandwidth in bolometric interferometry.
. ASTRONOMY & ASTROPHYSICS, 514.
Abstract: Context. Bolometric interferometry is a promising new technology with potential applications to the detection of B-mode polarization fluctuations of the cosmic microwave background (CMB). A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers to be competitive with imaging experiments. A crucial concern is that interferometers are assumed to be significantly affected by a spoiling effect known as bandwidth smearing. Aims: We investigate how the bandwidth modifies the work principle of a bolometric interferometer and affects its sensitivity to the CMB angular power spectra. Methods: We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. If the phase shifters produce shifts that are constant with respect to frequency, the instrument works like its monochromatic version (the modulation matrix is not modified), while if they vary (linearly or otherwise) with respect to frequency, one has to perform a special reconstruction scheme, which allows the visibilities to be reconstructed in frequency subbands. Using an angular power spectrum estimator that accounts for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation is performed that confirms the analytical results. Results: We conclude that (i) broadband bolometric interferometers allow broadband visibilities to be reconstructed regardless of the type of phase shifters used and (ii) for dedicated B-mode bolometric interferometers, the sensitivity loss caused by bandwidth smearing is quite acceptable, even for wideband instruments (a factor of 2 loss for a typical 20% bandwidth experiment).
Programme: 915
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Geoffroy L., Callot J.P., Aubourg C. & Moreira M. (2002). Magnetic and plagioclase linear fabric discrepancy in dykes: a new way to define the flow vector using magnetic foliation. Terra nova, 14(3), 183–190.
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Barnes P.R.F., Mulvaney R., Wolff E.W. & Robinson K. (2002). A technique for the examination of polar ice using the scanning electron microscope. Journal of microscopy-oxford, 205(2), 118–124.
Abstract: The microstructure and location of impurities in polar ice are of great relevance to ice core studies. We describe a reliable method to examine ice in the scanning electron microscope (SEM). Specimens were cut in a cold room and could have their surfaces altered by sublimation either before (pre-etching) or after (etching) introduction to the cryo-chamber of the SEM. Pre-etching was used to smooth surfaces, whilst etching stripped away layers from the specimen surface, aiding the location of particles in situ, and allowing embedded structures to be revealed. X-ray analysis was used to determine the composition of localized impurities, which in some cases had been concentrated on the surface by etching. Examining uncoated surfaces was found to be advantageous and did not detract from qualitative X-ray analysis. Imaging uncoated was performed at low accelerating voltages and probe currents to avoid problems of surface charging.
Programme: 960
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. (2016). Atmospheric drying as the main driver of dramatic glacier wastage in the southern Indian Ocean (Vol. 6). Bachelor's thesis, , .
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MacIntosh Andrew J J, Pelletier Laure, Chiaradia Andre, Kato Akiko, Ropert-Coudert Yan, . (2013). Temporal fractals in seabird foraging behaviour: diving through the scales of time
. Scientific Reports, 3.
Keywords: Behavioural ecology, Scale invariance, Statistical physics, Theoretical ecology,
Programme: 1091
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. (2020). The genetic legacy of legendary and historical Siberian chieftains (Vol. 3). Bachelor's thesis, , .
Abstract: Seventeen years of archaeological and anthropological expeditions in North-Eastern Siberia (in the Sakha Republic, Yakutia) have permitted the genetic analysis of 150 ancient (15th-19th century) and 510 modern individuals. Almost all males were successfully analysed (Y-STR) and this allowed us to identify paternal lineages and their geographical expansion through time. This genetic data was confronted with mythological, historical and material evidence to establish the sequence of events that built the modern Yakut genetic diversity. We show that the ancient Yakuts recovered from this large collection of graves are not representative of an ancient population. Uncommonly, we were also able to demonstrate that the funerary preference observed here involved three specific male lineages, especially in the 18th century. Moreover, this dominance was likely caused by the Russian conquest of Siberia which allowed some male clans to rise to new levels of power. Finally, we give indications that some mythical and historical figures might have been the actors of those genetic changes. These results help us reconsider the genetic dynamics of colonization in some regions, question the distinction between fact and myth in national histories and provide a rare insight into a funerary ensemble by revealing the biased process of its composition.
Programme: 1038
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