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Evidence against a supervoid causing the CMB Cold Spot
Kovács, András; Shanks, Tom; Bremer, Malcolm N. +5 more
We report the results of the 2dF-VST ATLAS Cold Spot galaxy redshift survey (2CSz) based on imaging from VST ATLAS and spectroscopy from 2dF AAOmega over the core of the CMB Cold Spot. We sparsely surveyed the inner 5° radius of the Cold Spot to a limit of IAB ≤ 19.2, sampling ∼7000 galaxies at z < 0.4. We have found voids at z = 0.1…
Astrometric Evidence for a Population of Dislodged AGNs
Chambers, Kenneth C.; Magnier, Eugene A.; Rest, Armin +5 more
We investigate a sample of 2293 ICRF2 extragalactic radio-loud sources with accurate positions determined by VLBI, mostly active galactic nuclei (AGNs) and quasars, which are cross-matched with optical sources in the first Gaia release (Gaia DR1). The distribution of offsets between the VLBI sources and their optical counterparts is strongly non-G…
A Multi-planet System Transiting the V = 9 Rapidly Rotating F-Star HD 106315
Vanderburg, Andrew; Cargile, Phillip A.; Bieryla, Allyson +10 more
We report the discovery of a multi-planet system orbiting HD 106315, a rapidly rotating mid F-type star, using data from the K2 mission. HD 106315 hosts a 2.51 ± 0.12 R ⊕ sub-Neptune in a 9.5-day orbit and a {4.31}-0.27+0.24 {R}\oplus super-Neptune in a 21-day orbit. The projected rotational velocity of…
HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies
Menten, K. M.; van der Werf, P.; Stutzki, J. +10 more
We present a systematic survey of multiple velocity-resolved H2O spectra using Herschel/Heterodyne Instrument for the Far Infrared (HIFI) toward nine nearby actively star-forming galaxies. The ground-state and low-excitation lines (E up ≤ 130 K) show profiles with emission and absorption blended together, while absorption-fre…
The selection function of the RAVE survey
Grebel, Eva K.; Steinmetz, Matthias; Bland-Hawthorn, Joss +23 more
We characterize the selection function of RAdial Velocity Experiment (RAVE) using 2 Micron All Sky Survey (2MASS) as our underlying population, which we assume represents all stars that could have potentially been observed. We evaluate the completeness fraction as a function of position, magnitude and colour in two ways: first, on a field-by-field…
The age of 47 Tuc from self-consistent isochrone fits to colour-magnitude diagrams and the eclipsing member V69
Grundahl, F.; Milone, A. P.; Bedin, L. R. +3 more
Our aim is to derive a self-consistent age, distance and composition for the globular cluster 47 Tucanae (47 Tuc; NGC104). First, we re-evaluate the reddening towards the cluster resulting in a nominal E(B - V) = 0.03 ± 0.01 as the best estimate. The Teff of the components of the eclipsing binary member V69 is found to be 5900 ± 72 K fr…
Ultraviolet C II and Si III Transit Spectroscopy and Modeling of the Evaporating Atmosphere of GJ436b
Loyd, R. O. Parke; Redfield, Seth; France, Kevin +2 more
Hydrogen gas evaporating from the atmosphere of the hot-Neptune GJ436b absorbs over 50% of the stellar Lyα emission during transit. Given the planet’s atmospheric composition and energy-limited escape rate, this hydrogen outflow is expected to entrain heavier atoms such as C and O. We searched for C and Si in the escaping atmosphere of GJ436b usin…
The ISLAnds Project. III. Variable Stars in Six Andromeda Dwarf Spheroidal Galaxies
McQuinn, Kristen B. W.; Dolphin, Andrew E.; Skillman, Evan D. +15 more
We present a census of variable stars in six M31 dwarf spheroidal satellites observed with the Hubble Space Telescope. We detect 870 RR Lyrae (RRL) stars in the fields of And I (296), II (251), III (111), XV (117), XVI (8), and XXVIII (87). We also detect a total of 15 Anomalous Cepheids, three eclipsing binaries, and seven field RRL stars compati…
CMB signatures of metal-free star formation and Planck 2015 polarization data
Heinrich, Chen He; Miranda, Vinicius; Hu, Wayne +1 more
Standard analyses of the reionization history of the Universe from Planck cosmic microwave background (CMB) polarization measurements consider only the overall optical depth to electron scattering (τ), and further assume a step-like reionization history. However, the polarization data contain information beyond the overall optical depth, and the a…
Inflation model selection meets dark radiation
Tram, Thomas; Vennin, Vincent; Vallance, Robert
We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few represen…