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On High-energy Particles in Accretion Disk Coronae of Supermassive Black Holes: Implications for MeV Gamma-rays and High-energy Neutrinos from AGN Cores
Inoue, Susumu; Inoue, Yoshiyuki; Doi, Akihiro +1 more
Recent observations with ALMA have revealed evidence for nonthermal synchrotron emission from the core regions of two nearby Seyfert galaxies. This suggests that the coronae of accretion disks in active galactic nuclei (AGNs) can be conducive to the acceleration of nonthermal electrons, in addition to the hot, thermal electrons responsible for the…
Compositions of Planetary Debris around Dusty White Dwarfs
Zuckerman, B.; Dufour, Patrick; Xu, Siyi +5 more
The photospheres of some white dwarfs (WDs) are “polluted” by accretion of material from their surrounding planetary debris. WDs with dust disks are often heavily polluted and high-resolution spectroscopic observations of these systems can be used to infer the chemical compositions of extrasolar planetary material. Here, we report spectroscopic ob…
Globular cluster number density profiles using Gaia DR2
Balbinot, E.; Hénault-Brunet, V.; Gieles, M. +4 more
Using data from Gaia DR2, we study the radial number density profiles of the Galactic globular cluster sample. Proper motions are used for accurate membership selection, especially crucial in the cluster outskirts. Due to the severe crowding in the centres, the Gaia data are supplemented by literature data from HST and surface brightness measureme…
Kinematic Detections of Protoplanets: A Doppler Flip in the Disk of HD 100546
Pérez, Sebastián; Casassus, Simon
Protoplanets and circumplanetary disks are rather elusive in their thermal IR emission. Yet they are cornerstones to the most popular interpretations for the protoplanetary disk structures observed in the gas and dust density fields, even though alternative theories exist. The gaseous velocity field should also bear the imprint of planet-disk inte…
Dust of comet 67P/Churyumov-Gerasimenko collected by Rosetta/MIDAS: classification and extension to the nanometer scale
Ehrenfreund, P.; Bentley, M. S.; Mannel, T. +9 more
Context. The properties of the smallest subunits of cometary dust contain information on their origin and clues to the formation of planetesimals and planets. Compared to interplanetary dust particles or particles collected during the Stardust mission, dust collected in the coma of comet 67P/Churyumov-Gerasimenko (67P) during the Rosetta mission p…
Imaging [CI] around HD 131835: reinterpreting young debris discs with protoplanetary disc levels of CO gas as shielded secondary discs
Kral, Quentin; Wyatt, Mark C.; Marino, Sebastian +2 more
Despite being >10 Myr, there are ∼10 debris discs with as much CO gas as in protoplanetary discs. Such discs have been assumed to be 'hybrid', i.e. with secondary dust but primordial gas. Here, we show that both the dust and gas in such systems could instead be secondary, with the high CO content caused by accumulation of neutral carbon (C…
In the Galactic Disk, Stellar [Fe/H] and Age Predict Orbits and Precise [X/Fe]
Rix, H. -W.; Hawkins, K.; Bird, J. C. +4 more
We explore the structure of the element abundance-age-orbit distribution of the stars in the Milky Way’s low-α disk, by (re-)deriving precise [Fe/H], [X/Fe], and ages, along with orbits, for red clump stars from the APOGEE survey. There has been a long-standing theoretical expectation and observational evidence that metallicity ([Fe/H]) and age ar…
Cosmological constraints on post-Newtonian parameters in effectively massless scalar-tensor theories of gravity
Rossi, Massimo; Ballardini, Mario; Braglia, Matteo +4 more
We study the cosmological constraints on the variation of Newton's constant and on post-Newtonian parameters for simple models of the scalar-tensor theory of gravity beyond the extended Jordan-Brans-Dicke theory. We restrict ourselves to an effectively massless scalar field with a potential V ∝F2, where F (σ )=Npl2…
Near-infrared Spectroscopy of Galaxies During Reionization: Measuring C III] in a Galaxy at z = 7.5
Papovich, Casey; Finkelstein, Steven L.; Dickinson, Mark +9 more
We present Keck/MOSFIRE H-band spectroscopy targeting C III] λ1907, 1909 in a z = 7.5056 galaxy previously identified via Lyα emission. We detect strong line emission at 1.621+/- 0.002 µ {{m}} with a line flux of (2.63 ± 0.52) × 10-18 erg s-1 cm-2. We tentatively identify this line as [C III] λ1907, but we ar…
Molecular and Ionized Gas Phases of an AGN-driven Outflow in a Typical Massive Galaxy at z ≈ 2
Lutz, D.; Wuyts, S.; Genzel, R. +22 more
Nuclear outflows driven by accreting massive black holes are one of the main feedback mechanisms invoked at high-z to reproduce the distinct separation between star-forming disk galaxies and quiescent spheroidal systems. Yet our knowledge of feedback at high-z remains limited by the lack of observations of the multiple gas phases in galaxy outflow…