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Schönau-Berzdorf, Germany

Muller S.,Chalmers University of Technology | Black J.H.,Chalmers University of Technology | Guelin M.,Institute Of Radioastronomie Millimetrique | Guelin M.,Ecole Normale Superieure de Paris | And 12 more authors.
Astronomy and Astrophysics | Year: 2014

We report the first extragalactic detection of chloronium (H 2Cl+) in the z = 0.89 absorber in front of the lensed blazar PKS 1830-211. The ion is detected through its 111-0 00 line along two independent lines of sight toward the North-East and South-West images of the blazar. The relative abundance of H 2Cl+ is significantly higher (by a factor ∼7) in the NE line of sight, which has a lower H2/H fraction, indicating that H2Cl+ preferably traces the diffuse gas component. From the ratio of the H2 35Cl+ and H2 37Cl+ absorptions toward the SW image, we measure a 35Cl/37Cl isotopic ratio of 3.1-0.2 +0.3 at z = 0.89, similar to that observed in the Galaxy and the solar system. © 2014 ESO. Source

Muller S.,Chalmers University of Technology | Combes F.,Paris Observatory | Guelin M.,Institute Of Radioastronomie Millimetrique | Guelin M.,Ecole Normale Superieure de Paris | And 18 more authors.
Astronomy and Astrophysics | Year: 2014

We present the first results of an ALMA spectral survey of strong absorption lines for common interstellar species in the z = 0.89 molecular absorber toward the lensed blazar PKS 1830-211. The dataset brings essential information on the structure and composition of the absorbing gas in the foreground galaxy. In particular, we find absorption over large velocity intervals (≳ 100 km s-1) toward both lensed images of the blazar. This suggests either that the galaxy inclination is intermediate and that we sample velocity gradients or streaming motions in the disk plane, that the molecular gas has a large vertical distribution or extraplanar components, or that the absorber is not a simple spiral galaxy but might be a merger system. The number of detected species is now reaching a total of 42 different species plus 14 different rare isotopologues toward the SW image, and 14 species toward the NE line-of-sight. The abundances of CH, H2O, HCO+, HCN, and NH3 relative to H2 are found to be comparable to those in the Galactic diffuse medium. Of all the lines detected so far toward PKS 1830-211, the ground-state line of ortho-water has the deepest absorption. We argue that ground-state lines of water have the best potential for detecting diffuse molecular gas in absorption at high redshift. © 2014 ESO. Source

Shannon R.M.,Cornell University | Shannon R.M.,CSIRO | Cordes J.M.,Cornell University | Metcalfe T.S.,Space Science Institute | And 15 more authors.
Astrophysical Journal | Year: 2013

Pulsar timing observations have revealed companions to neutron stars that include other neutron stars, white dwarfs, main-sequence stars, and planets. We demonstrate that the correlated and apparently stochastic residual times of arrival from the millisecond pulsar B1937+21 are consistent with the signature of an asteroid belt having a total mass ≲ 0.05 M ⊕. Unlike the solar system's asteroid belt, the best fit pulsar asteroid belt extends over a wide range of radii, consistent with the absence of any shepherding companions. We suggest that any pulsar that has undergone accretion-driven spin-up and subsequently evaporated its companion may harbor orbiting asteroid mass objects. The resulting timing variations may fundamentally limit the timing precision of some of the other millisecond pulsars. Observational tests of the asteroid belt model include identifying periodicities from individual asteroids, which are difficult; testing for statistical stationarity, which becomes possible when observations are conducted over a longer observing span; and searching for reflected radio emission. © 2013. The American Astronomical Society. All rights reserved.. Source

Muller S.,Chalmers University of Technology | Beelen A.,University Paris - Sud | Black J.H.,Chalmers University of Technology | Curran S.J.,University of Sydney | And 7 more authors.
Astronomy and Astrophysics | Year: 2013

Context. According to the Big Bang theory and as a consequence of adiabatic expansion of the Universe, the temperature of the cosmic microwave background (CMB) increases linearly with redshift. This relation is, however, poorly explored, and detection of any deviation would directly lead to (astro-)physics beyond the standard model. Aims. We aim to measure the temperature of the CMB with an accuracy of a few percent at z = 0.89 toward the molecular absorber in the galaxy lensing the quasar PKS 1830-211. Methods. We adopted a Monte-Carlo Markov chain approach, coupled with predictions from the non-LTE radiative transfer code RADEX, to solve the excitation conditions of a set of various molecular species directly from their spectra. Results. We determine T CMB = 5.08 ± 0.10 K at 68% confidence level. Our measurement is consistent with the value TCMB = 5.14 K predicted by the standard cosmological model with adiabatic expansion of the Universe. This is the most precise determination of TCMB at z > 0 to date. © ESO, 2013. Source

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