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Quasars as standard candles. I. The physical relation between disc and coronal emission
Lusso, E.; Risaliti, G.
Context. A tight non-linear relation exists between the X-ray and UV emission in quasars (I.e. LX ∝LUVγ), with a dispersion of 0.2 dex over approximately three orders of magnitude in luminosity. Such observational evidence has two relevant consequences: (1) an ubiquitous physical mechanism must regulate the energy transfer fr…
A New Stellar Atmosphere Grid and Comparisons with HST/STIS CALSPEC Flux Distributions
Koekemoer, Anton M.; Gordon, Karl D.; Bohlin, Ralph C. +3 more
The Space Telescope Imaging Spectrograph has measured the spectral energy distributions for several stars of types O, B, A, F, and G. These absolute fluxes from the CALSPEC database are fit with a new spectral grid computed from the ATLAS-APOGEE ATLAS9 model atmosphere database using a chi-square minimization technique in four parameters. The qual…
Electron holes in phase space: What they are and why they matter
Hutchinson, I. H.
This is a tutorial and selective review explaining the fundamental concepts and some currently open questions concerning the plasma phenomenon of the electron hole. The widespread occurrence of electron holes in numerical simulations, space-craft observations, and laboratory experiments is illustrated. The elementary underlying theory is developed…
Active Cryovolcanism on Europa?
Spencer, J. R.; Sparks, W. B.; Hand, K. P. +4 more
Evidence for plumes of water on Europa has previously been found using the Hubble Space Telescope using two different observing techniques. Roth et al. found line emission from the dissociation products of water. Sparks et al. found evidence for off-limb continuum absorption as Europa transited Jupiter. Here, we present a new transit observation o…
The Remarkable Similarity of Massive Galaxy Clusters from z ∼ 0 to z ∼ 1.9
Gladders, M. D.; Gaspari, M.; Hlavacek-Larrondo, J. +12 more
We present the results of a Chandra X-ray survey of the eight most massive galaxy clusters at z > 1.2 in the South Pole Telescope 2500 deg2 survey. We combine this sample with previously published Chandra observations of 49 massive X-ray-selected clusters at 0 < z < 0.1 and 90 Sunyaev-Zel’dovich-selected clusters at 0.25 < z…
The dust mass in Cassiopeia A from a spatially resolved Herschel analysis
De Looze, I.; Rho, J.; Gomez, H. L. +4 more
Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 M⊙), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g. SN 1987A, Crab nebula). In …
Acceleration and Propagation of Solar Energetic Particles
Klein, Karl-Ludwig; Dalla, Silvia
Solar Energetic Particles (SEPs) are an important component of Space Weather, including radiation hazard to humans and electronic equipment, and the ionisation of the Earth's atmosphere. We review the key observations of SEPs, our current understanding of their acceleration and transport, and discuss how this knowledge is incorporated within Space…
SMASH: Survey of the MAgellanic Stellar History
Bell, Eric F.; Monachesi, Antonela; Choi, Yumi +36 more
The Large and Small Magellanic Clouds are unique local laboratories for studying the formation and evolution of small galaxies in exquisite detail. The Survey of the MAgellanic Stellar History (SMASH) is an NOAO community Dark Energy Camera (DECam) survey of the Clouds mapping 480 deg2 (distributed over ∼2400 square degrees at ∼20% fill…
ISM Properties of a Massive Dusty Star-forming Galaxy Discovered at z ∼ 7
Menten, K. M.; Béthermin, M.; Murphy, E. J. +28 more
We report the discovery and constrain the physical conditions of the interstellar medium of the highest-redshift millimeter-selected dusty star-forming galaxy to date, SPT-S J031132-5823.4 (hereafter SPT0311-58), at z=6.900+/- 0.002. SPT0311-58 was discovered via its 1.4 mm thermal dust continuum emission in the South Pole Telescope (SPT)-SZ surve…
Solution of Heliospheric Propagation: Unveiling the Local Interstellar Spectra of Cosmic-ray Species
Orlando, E.; Jóhannesson, G.; Moskalenko, I. V. +14 more
Local interstellar spectra (LIS) for protons, helium, and antiprotons are built using the most recent experimental results combined with state-of-the-art models for propagation in the Galaxy and heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosm…