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The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2 mm Extragalactic Background, and Properties of the Faintest Dusty Star-forming Galaxies
Smail, I.; Magnelli, B.; Daddi, E. +31 more
We present an analysis of a deep (1σ = 13 µJy) cosmological 1.2 mm continuum map based on ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field. In the 1 arcmin2 covered by ASPECS we detect nine sources at \gt 3.5σ significance at 1.2 mm. Our ALMA-selected sample has a median redshift of z=1.6+/- 0.4, with only one …
Estimating Distances from Parallaxes. II. Performance of Bayesian Distance Estimators on a Gaia-like Catalogue
Bailer-Jones, Coryn A. L.; Astraatmadja, Tri L.
Estimating a distance by inverting a parallax is only valid in the absence of noise. As most stars in the Gaia catalog will have non-negligible fractional parallax errors, we must treat distance estimation as a constrained inference problem. Here we investigate the performance of various priors for estimating distances, using a simulated Gaia cata…
LOFAR/H-ATLAS: a deep low-frequency survey of the Herschel-ATLAS North Galactic Pole field
Prandoni, I.; Brunetti, G.; White, G. J. +25 more
We present Low-Frequency Array (LOFAR) High-Band Array observations of the Herschel-ATLAS North Galactic Pole survey area. The survey we have carried out, consisting of four pointings covering around 142 deg2 of sky in the frequency range 126-173 MHz, does not provide uniform noise coverage but otherwise is representative of the quality…
A New Distortion Solution for NIRC2 on the Keck II Telescope
Ghez, A. M.; Anderson, J.; Lu, J. R. +3 more
We present a new geometric distortion model for the narrow-field mode of the near-infrared camera (NIRC2) fed by the adaptive optics system on the W. M. Keck II telescope. The adaptive optics system and NIRC2 camera were realigned on 2015 April 13. Observations of the crowded globular cluster, M53, were obtained before and after the realignment to…
Planetary surface dating from crater size-frequency distribution measurements: Poisson timing analysis
Michael, G. G.; Kneissl, T.; Neesemann, A.
The predictions of crater chronology models have customarily been evaluated by dividing a crater population into discrete diameter intervals, plotting the crater density for each, and finding a best-fit model isochron, with the uncertainty in the procedure being assessed using 1/√n estimates, where n is the number of craters in an interval. This a…
The discovery, monitoring and environment of SGR J1935+2154
Campana, S.; Tiengo, A.; Götz, D. +13 more
We report on the discovery of a new member of the magnetar class, SGR J1935+2154, and on its timing and spectral properties measured by an extensive observational campaign carried out between 2014 July and 2015 March with Chandra and XMM-Newton (11 pointings). We discovered the spin period of SGR J1935+2154 through the detection of coherent pulsat…
An evaporating planet in the wind: stellar wind interactions with the radiatively braked exosphere of GJ 436 b
Vidotto, A. A.; Ehrenreich, D.; Lecavelier des Etangs, A. +2 more
Observations of the warm Neptune GJ 436 b were performed with HST/STIS at three different epochs (2012, 2013, 2014) in the stellar Lyman-α line. They showed deep, repeated transits that were attributed to a giant exosphere of neutral hydrogen. The low radiation pressure from the M-dwarf host star was shown to play a major role in the dynamics of t…
Enceladus's internal ocean and ice shell constrained from Cassini gravity, shape, and libration data
Bourgeois, Olivier; Massé, Marion; Čadek, Ondřej +8 more
The intense plume activity at the South Pole of Enceladus together with the recent detection of libration hints at an internal water ocean underneath the outer ice shell. However, the interpretation of gravity, shape, and libration data leads to contradicting results regarding the depth of ocean/ice interface and the total volume of the ocean. Her…
Estimating Distances from Parallaxes. III. Distances of Two Million Stars in the Gaia DR1 Catalogue
Bailer-Jones, Coryn A. L.; Astraatmadja, Tri L.
We infer distances and their asymmetric uncertainties for two million stars using the parallaxes published in the Gaia DR1 (GDR1) catalogue. We do this with two distance priors: A minimalist, isotropic prior assuming an exponentially decreasing space density with increasing distance, and an anisotropic prior derived from the observability of stars…
Gamma-ray spectroscopy of positron annihilation in the Milky Way
Diehl, Roland; Greiner, Jochen; Siegert, Thomas +5 more
Context. The annihilation of positrons in the Galaxy's interstellar medium produces characteristic gamma-rays with a line at 511 keV. This gamma-ray emission has been observed with the spectrometer SPI on ESA's INTEGRAL observatory, confirming a puzzling morphology with bright emission from an extended bulge-like region, while emission from the di…