The Local Bubble and Interstellar Material Near the Sun

The properties of interstellar matter (ISM) at the Sun are regulated by our location with respect to the Local Bubble (LB) void in the ISM. The LB is bounded by associations of massive stars and fossil supernovae that have disrupted natal ISM and driven intermediate velocity ISM into the LB interior void. The Sun is located in such a driven ISM parcel. The Local Fluff has a bulk velocity of 19 km/s in the LSR, and an upwind direction towards the center of the gas and dust ring formed by the Loop I supernova remnant interaction with the LB. When the ram pressure of the LIC is included in the total LIC pressure, and if magnetic thermal and cosmic ray pressures are similar, the LIC appears to be in pressure equilibrium with the local hot bubble plasma.Comment: Proceedings of Symposium on the Composition of Matter, honoring Johannes Geiss on the occasion of his 80th birthday. Space Science Reviews (in press

Inversion of the Lyman-α\alpha forest: 3D investigation of the intergalactic medium

We discuss the implementation of Bayesian inversion methods in order to recover the properties of the intergalactic medium from observations of the neutral hydrogen Lyman-$\alpha$ absorptions observed in the spectra of high redshift quasars (the so-called Lyman-$\alpha$ forest). We use two complementary schemes (i) a constrained Gaussian random field linear approach and (ii) a more general non-linear explicit Bayesian deconvolution method which offers in particular the possibility to constrain the parameters of the equation of state for the gas. While relying on prior assumption for the two-point correlation functions, we show how to recover, at least qualitatively, the 3D topology of the large scale structures in redshift space by inverting a suitable network of adjacent, low resolution lines of sight. We also discuss the inversion of single lines of sight observed at high spectral resolution. Our preliminary investigations suggest that the explicit Bayesian method can be used to derive quantitative information on the physical state of the gas. Redshift distortion is considered by simultaneous constrained reconstruction of the velocity and the density field in real space while assuming statistical correlation between the two fields. The method seems to work well in the strong prior regime where peculiar velocities are assumed to be the most likely realization in the density field. Finally, we investigate the effect of line of sight separation and number of lines of sight. Our analyses suggest that multiple low resolution lines of sight could be used to improve most likely velocity reconstruction on a high resolution line of sight.Comment: 24 pages, 9 figures, LateX (MN format), accepted for publication in MNRA

Confinement sans faille. Magazine "Plein Sud" de l'Université de Paris-Sud XI d'Orsay

Magazine "Plein Sud" de l'Université de Paris-Sud XI d'Orsayp. 16-2

Confinement sans faille. Magazine "Plein Sud" de l'Université de Paris-Sud XI d'Orsay

Magazine "Plein Sud" de l'Université de Paris-Sud XI d'Orsayp. 16-2

Multi-step retrieval of soil moisture from space borne radiometry

National audienc

Influence of P/T conditions on the style of normal fault initiation and growth in limestones from the SE-Basin, France

International audienc

Structural records of the late Cretaceous-Cenozoic extension in eastearn china and the kinematics of the southern Tan-Lu and Qinling Fault Zone (Anhui and Shaanxi provinces, PR China)

International audienceOur study of the Late Cretaceous-Cenozoic extension in Eastern China is a kinematic analysis of faults (≈ 1500 striated fault data, 175 stress solutions at 90 sites) that has permitted us to separate stress fields belonging to six tectonic events. A WNW-ESE extension (1) has affected Eastern China from the Campanian to the Late Palaeocene-Early Ypresian. Under this extension, the Qinling (QLFZ) and Southern Tan-Lu (STLFZ) Fault Zones have been dextral transtensional fault zones. A first transpressional event (2) (NNE-SSW shortening) has occurred during the Late Ypresian-Lower Lutetian; the QLFZ and the STLFZ have been dextral transpressional fault zones. A NE-SW extension (3) has affected the Weihe graben during the Palaeogene; after a second transpressional event (4), the NE-SW extension (5) has been rejuvenated during the Late Miocene and the QLFZ has been a normal fault zone again and the STLFZ a sinistral transtensional fault zone; synrift subsidence has occurred in the Weihe graben. The second transpressional event (4) (WNW-ESE shortening) has occurred during the Late Oligocene-Early Miocene, during a period of uplifting and exhumation. At that time, the STLFZ and the QLFZ have become sinistral transpressional fault zones. A period of extension (6) has taken place during the Late Pliocene-Quaternary; the extensional direction has trended ≈ NNW-SSE; during this event, the QLFZ has been a sinistral transtensional fault zone and the STLFZ a dextral transtensional fault zone. These results are compared with those previously published in order to evaluate the regional significance of these tectonic events

Sea surface salinity estimates from spaceborne L-band radiometers : an overview of the first decade of observation (2010&8211;2019)

Operated since the end of 2009, the European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite mission is the first orbiting radiometer that collects regular and global observations from space of two Essential Climate Variables of the Global Climate Observing System : Sea Surface Salinity (SSS) and Soil Moisture. The National Aeronautics and Space Administration (NASA) Aquarius mission, with the primary objective to provide global SSS measurements from space operated from mid-2011 to mid-2015. NASA's Soil Moisture Active-Passive (SMAP) mission, primarily dedicated to soil moisture measurements, but also monitoring SSS, has been operating since early 2015. The primary sensors on board these three missions are passive microwave radio-meters operating at 1.4 GHz (L-band). SSS is retrieved from radiometer measurements of the sea surface brightness temperature (TB). In this paper, we first provide a historical review of SSS remote sensing with passive L-band radiometry beginning with the discussions of measurement principles, technology, sensing characteristicsand complementarities of the three afore mentioned missions. The assessment of satellite SSS products is then presented in terms of individual mission characteristics, common algorithms, and measurement uncertainties, including the validation versus in situ data, and, the consideration of sampling differences between satellite SSS and in situ salinity measurements. We next review the major scientific achievements of the combined first 10 years of satellite SSS data, including the insights enabled by these measurements regarding the linkages of SSS with the global water cycle, climate variability, and ocean biochemistry. We also highlight the new ability provided by satellites to monitor mesoscale and synoptic-scale SSS features and to advance our understanding of SSS'role in air-sea interactions, constraining ocean models, and improving seasonal predictions. An overview of satellite SSS observation highlights during this first decade and upcoming challenges are then presented