Search Publications
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 …
Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. IV. Results of the 2014 Follow-up Campaign
Stern, D.; Smith, Howard A.; Masetti, N. +7 more
The extragalactic γ-ray sky is dominated by the emission arising from blazars, one of the most peculiar classes of radio-loud active galaxies. Since the launch of Fermi several methods were developed to search for blazars as potential counterparts of unidentified γ-ray sources (UGSs). To confirm the nature of the selected candidates, optical spect…
Asymmetric magnetic reconnection with a flow shear and applications to the magnetopause
Drake, J. F.; Eriksson, S.; Wilder, F. D. +3 more
We perform a systematic theoretical and numerical study of antiparallel two-dimensional magnetic reconnection with asymmetries in the plasma density and reconnecting magnetic field strength in addition to a bulk flow shear across the reconnection site in the plane of the reconnecting fields, which commonly occurs at planetary magnetospheres. We an…
A Connection between Obscuration and Star Formation in Luminous Quasars
Gorjian, Varoujan; Alberts, Stacey; Jones, Christine +16 more
We present a measurement of the star formation properties of a uniform sample of mid-IR-selected, optically unobscured, and obscured quasars (QSO1s and QSO2s) in the Boötes survey region. We use a spectral energy distribution analysis for photometric data spanning optical to far-IR wavelengths to separate the active galactic nucleus (AGN) and host…