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Hard X-Ray Morphological and Spectral Studies of the Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
Hailey, Charles J.; Mori, Kaya; Bauer, Franz E. +15 more
In 2013, NuSTAR observed the Sgr B2 region and for the first time resolved its hard X-ray emission on subarcminute scales. Two prominent features are detected above 10 keV: a newly emerging cloud, G0.66-0.13, and the central 90″ radius region containing two compact cores, Sgr B2(M) and Sgr B2(N), surrounded by diffuse emission. It is inconclusive …
Polyspectra searches for sharp oscillatory features in cosmic microwave sky data
Shellard, E. P. S.; Fergusson, J. R.; Gruetjen, H. F. +1 more
Despite numerous efforts, the search for oscillatory signatures in primordial spectra has not produced any convincing evidence for feature models to date. We undertake a thorough search for signatures of sharp features in the WMAP9 power spectrum and bispectrum as well as in the Planck power spectrum. For the first time, we carry out searches in b…
Evidence of Cross-correlation between the CMB Lensing and the γ-Ray Sky
Fornengo, Nicolao; Perotto, Laurence; Regis, Marco +1 more
We report the measurement of the angular power spectrum of cross-correlation between the unresolved component of the Fermi-LAT γ-ray sky maps and the cosmic microwave background lensing potential map reconstructed by the Planck satellite. The matter distribution in the universe determines the bending of light coming from the last scattering surfac…
Possible evidence for a methane source in Enceladus' ocean
Mousis, Olivier; Bouquet, Alexis; Waite, J. Hunter +1 more
The internal ocean of Enceladus can be expected to present conditions favorable to the trapping of volatiles in clathrates. This process could influence the eventual composition of the ocean and therefore of the plumes emitted by the south polar region. Here we used a statistical thermodynamic model to assess which species detected in the plumes b…
The X-ray outburst of the Galactic Centre magnetar SGR J1745-2900 during the first 1.5 year
Campana, S.; Tiengo, A.; Mereghetti, S. +17 more
In 2013 April a new magnetar, SGR 1745-2900, was discovered as it entered an outburst, at only 2.4 arcsec angular distance from the supermassive black hole at the centre of the Milky Way, Sagittarius A*. SGR 1745-2900 has a surface dipolar magnetic field of ∼2 × 1014 G, and it is the neutron star closest to a black hole ever observed. T…
On the origin of excess cool gas in quasar host haloes
Johnson, Sean D.; Chen, Hsiao-Wen; Mulchaey, John S.
Previous observations of quasar host haloes at z ≈ 2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we compiled an exhaustive sample of 195 quasars at z ≈ 1 with constraints on chemically enriched, cool gas trac…
The Black Hole in the Compact, High-dispersion Galaxy NGC 1271
Gebhardt, Karl; Richstone, Douglas O.; Husemann, Bernd +4 more
Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2 kpc and a large bulge stellar velocity dispersion of 276 km s-1 for its K-band luminosity of 8.9× {10}10 {L}⊙ . We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observa…
Electromagnetic ion cyclotron waves in the Earth's magnetosphere with a kappa-Maxwellian particle distribution
Omura, Yoshiharu; Summers, Danny; Shoji, Masafumi +3 more
A theoretical model to study electromagnetic ion cyclotron (EMIC) waves in kappa-Maxwellian plasma is developed. The plasma is assumed to have five components, i.e., electrons, cool and hot protons, and singly charged helium and oxygen ions. The kappa-Maxwellian anisotropic particle distribution function is assumed for the hot protons. We use the …
Transient internally driven aurora at Jupiter discovered by Hisaki and the Hubble Space Telescope
Hasegawa, H.; Fujimoto, M.; Masters, A. +12 more
Jupiter's auroral emissions reveal energy transport and dissipation through the planet's giant magnetosphere. While the main auroral emission is internally driven by planetary rotation in the steady state, transient brightenings are generally thought to be triggered by compression by the external solar wind. Here we present evidence provided by th…
No breakdown of the radiatively driven wind theory in low-metallicity environments
Bouret, J. -C.; Martins, F.; Hillier, D. J. +3 more
We present a spectroscopic analysis of Hubble Space Telescope/Cosmic Origins Spectrograph observations of three massive stars in the low metallicity dwarf galaxies IC 1613 and WLM. These stars, were previously observed with Very Large Telescope (VLT)/X-shooter by Tramper et al., who claimed that their mass-loss rates are higher than expected from …